LiBaC Kit User’s Manual - Jameco Electronics...Page 1 of 50 LiBaC Kit User’s Manual Optional...

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LiBaC Kit User’s Manual Optional Assembly Component, Hookup and Usage, Performance Data and Specifications,

Technical Data including Schematics, et al.

Thomas W. Gustin

12/12/2015

This kit was developed by GUSTECH as Club JameCo’s Project #21405. The Schematic and Board Layout

were developed using EAGLE PRO 6.3.0 tools; these design files are available upon request. The 2-layer

printed circuit board measures just 3.90” x 3.03”, and the assembly uses mostly thru-hole components.

This User’s Manual for the LiBaC Kit is all of the documentation needed by the kit-builder, beyond that already used to assemble the kit, to understand all of the technical aspects of the design. There is an optional mounting method for one last component to be installed. There are several ways to wire the power to the LiBaC board, and many ways to use it, as explained in this document. This document includes some general information on LiPo Cells, as well as a short list of some examples. The performance data includes plotted data for various sizes and charging rates for a few LiPo cell examples, including an introduction to the LELTx5 (another kit) used to discharge LiPo Cells using a simple ‘Electronic Load’ circuit. The technical presentation includes the fully annotated schematic, black and white photoplots of the printed circuit board layers, and other great user information. ENJOY!

JameCo ‘imprint’

PART NO. 2258881

Manufacturer: JAMECO KITPRO

Manufacturer No.: CJKIT-21405

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Figure 1: The LiBaC [kit] Assembly in its Enclosure

SAFETY ADVISORY SSAAFFTTEEYY AADDVVIISSOORRYY:

NEVER short the LiPo Cell leads or puncture its soft packaging; doing so can cause sparks, arc-welding of cutting tool, expletives that may need to be deleted, and can also damage the cell/battery.

NEVER operate a LiPo Cell without also using SAFETY Electronic Protection Circuitry, usually at the cell’s connection tabs.

NEVER use a LiPo Cell if it has noticeably leaked or one can smell the electrolyte. LiPo Cells, if mishandled or misused, can overheat, can catch fire, and can even explode.

NEVER burn or incinerate a LiPo Cell.

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CONTENTS

Table of Contents SAFETY ADVISORY ........................................... 2

CONTENTS ....................................................... 3

TABLE OF FIGURES: .......................................... 4

OVERVIEW: ..................................................... 6

TITLE:........................................................... 6

BLOCK DIAGRAM: ........................................ 6

FEATURES & FUNCTIONS: ............................ 7

FINAL ASSEMBLY STEP: .................................... 8

NOT IN THE BOX: ......................................... 8

IN THE BOX: ................................................. 8

OVERVIEW OF LITHIUM-ION POLYMER CELL

TECHNOLOGY: ................................................10

Resources: ..................................................10

NOTES of INTEREST: ................................ 10

REGARDING "C" ...................................... 10

VOLTAGES .............................................. 11

PROTECTION ........................................... 11

CHARGING LiPo CELLS .................................11

LiPo CELL EXAMPLES ...................................12

ABOUT THE LiPo CELLS................................13

Figure 6 Item #1...................................... 13

Figure 6 Item #2...................................... 13

Figure 6 Item #3...................................... 13

Figure 6 Item #4...................................... 14

Figure 6 Item #5...................................... 14

Figure 6 Item #6...................................... 14

ABOUT THE PROTECTION CIRCUITS .............14

Figure 6 Item #7...................................... 14

LiPo VOLTAGES in APPLICATION ................. 15

NOTE about charging profile .................. 15

BATTERY VOLTAGE EVENTS .................... 16

LiBaC SWITCHES ............................................. 17

S1............................................................... 18

S1 Setting example 1 .............................. 18





S2............................................................... 19

S3............................................................... 20

S4............................................................... 21

INPUT POWER CONNECTION.......................... 21

POLARITY ................................................... 22

WHEN TO CONNECT INPUT POWER ........... 23

HOW TO CONNECT the LiPo CELL ................... 23

WRONG WAY ............................................. 23

Some Right Ways ....................................... 23

USING the LiBaC ............................................. 25

PERFORMANCE .............................................. 25

Test Setup Introduction .............................. 25

TEST 1 CHARGING 700mAh LiPo CELL ..... 28

Test 1 Setup ........................................... 28

700mAh LiPo-cell (re)Charging ................... 29

Time Marker (pre-) T0 ............................ 30

Time Marker T0 ...................................... 31

Time Marker T1 ...................................... 31

Time Marker T2 ...................................... 31

Time Marker T3 ...................................... 31

Time Marker T4 ...................................... 32

Time Marker T5 ...................................... 32

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TEST 2 700mAh LiPo-cell Discharging @

500mA ........................................................32

DISCHARGE TIMES .................................. 34

TEST 3 CHARGING 2,000mAh LiPo CELL ..34

Test 1 Setup ............................................ 34

TEST 3 CHARGING 2,000mAh LiPo CELL ..35

***** HOW NOT TO DO IT: ***** ........ 36

Time Marker (pre-) T0 ............................. 36

Then configured LiBaC ............................ 36

Time Marker T0: ..................................... 36

Time Marker T1: ..................................... 36

Time Marker T2: ..................................... 37

Time Marker T3: ..................................... 37

Time Marker T4: ..................................... 37

TEST 4 CHARGING 6,000mAh LiPo CELL

with INTERRUPTS: .......................................37

Test Overview: ........................................ 37

SUMMARY: ............................................. 39

CHARGED NOTES: ................................... 39

Time Marker T1: ..................................... 39

Time Marker T2: ..................................... 39

Time Marker T3: ..................................... 40

Time Marker T4: ..................................... 40

Time Marker T5: ..................................... 40

Time Marker T6: ..................................... 40

Time Marker T7: ..................................... 40

TEST 4’s STARTUP DETAILS: ..................... 41

TEST 4’s MANUAL INTERRUPTION DETAILS:

............................................................... 41

TEST 4’s TIMER-INTERRUPT DETAILS: ...... 42

BEFORE TIMER-SHUTDOWN: .................. 44

AFTER RESTART: ..................................... 44

HIGH CURRENT CHARGING POWER SOURCE

note: .......................................................... 44

TEST 5 disCHARGING 6,000mAh LiPo: .... 44

TEST OVERVIEW: .................................... 44

TECHNICAL DATA: .......................................... 46

SCHEMATIC: ............................................... 46

PRINTED CIRCUIT BOARD: .......................... 47

TOP COPPER: .......................................... 47

BOTTOM COPPER: .................................. 48

Both EAGLE COPPER LAYERS:.................. 49

BLOCK DIAGRAM: ....................................... 50

TThhiiss CCoommpplleetteess tthhee LLiiBBaaCC’’ss UUsseerr MMaannuuaall ........ 50

TABLE OF FIGURES: Figure 1: The LiBaC [kit] Assembly in its

Enclosure ......................................................... 2

Figure 2: LiBaC Block Diagram and Blank PC

Board ............................................................... 6

Figure 3: LiBaC's Features and Functions

Diagram ........................................................... 7

Figure 4: Dual Binding Posts Installation Options

........................................................................ 8

Figure 5: Detail of Dual Binding Posts (alone)

Assembly for Box Usage ................................... 9

Figure 6: LiBaC with protected and unprotected

LiPo Cells........................................................ 12

Figure 7: LiPo Cell Voltages Table with

Application Notes & Charging Profiles ............ 15

Figure 8: LiBaC's Four Control Switches .......... 17

Figure 9: Input Power Sources and Connections

...................................................................... 22

Figure 10: LiPo Cell Connections: How NOT to

do it; several right ways... .............................. 24

Figure 11: LiBaC Performance Testing

Equipment Setup ........................................... 26

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Figure 12: The LELTx5 (kit) Developed for

Discharge Testing ...........................................27

Figure 13: LiBaC Test Connections to a 700mAh

LiPo Cell..........................................................29

Figure 14: LiBaC Charging a 700mAh LiPo Cell at

two different rates .........................................30

Figure 15: 500mA Discharge Plot of Previously

Charge 700mAh LiPo Cell. ...............................33

Figure 16: LiBaC Test Connections to a

2,000mAh LiPo Cell .........................................34

Figure 17: LiBaC (re)Charging 2,000mAh LiPo

Cell .................................................................35

Figure 18: LiBaC (re)Charging 6,000mAh LiPo

Cell after Full Discharge ..................................38

Figure 19: LiBaC Charging 6,000mA LiPo Cell

from Complete Discharge Startup Details .......41

Figure 20: LiBaC Charging 6,000mHa LiPo Cell

mid-way Manual Interruption Details .............42

Figure 21: LiBaC Timer-Controlled Charging

Automatic Termination Detail.........................43

Figure 22: Full-to-Empty 500mA (rate) Discharge

of 6,000mAh LiPo Cell .....................................45

Figure 23: LiBaC Schematic .............................46

Figure 24: LiBaC Printed Circuit Board: Top

Copper ...........................................................47

Figure 25: LiBaC Printed Circuit Board: Bottom

Copper ...........................................................48

Figure 26: LiBaC Printed Circuit Board: Both

Copper Layers with the Silkscreen ..................49

Figure 27: LiBaC's Functional Block Diagram ...50

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OVERVIEW:

TITLE:

Generic Li-Ion Battery-Cell Charger [LiBaC] Kit

BLOCK DIAGRAM:

Figure 2: LiBaC Block Diagram and Blank PC Board

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FEATURES & FUNCTIONS:

Figure 3: LiBaC's Features and Functions Diagram

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FINAL ASSEMBLY STEP: The assembly instructions stopped (at step 20) with the installation of the two different input (power)

connectors. This final step deals with the output connection scheme, and its mounting notes. There are

two methods that are dependent (mostly) upon how the final assembly is to be mounted and/or used.

Page 2 showed the LiBaC installed in a JameCo #141832, grey 4.9" x 4"w ABS case with a clear top. It is,

of course, possible to use the LiBaC in the open-air, not installed in a box. The following describes both

approaches. Since the dual-binding posts are NOT soldered, their installation can be changed at any

time from one mounting technique to the other, as desired.

NOT IN THE BOX: The first picture for this step has two

different 'side' views of the 5-way dual

binding post jacks assembly. The bottom

view is the 'normal' assembly view where

the printed circuit board is between the two

large black insulators and the pair of nuts

per post bolt are below the bottom

insulator (on the left side of the board in the

picture's view). This bottom 'normal' view

also shows the solder turrets still intact.

If the kit-builder intends to mount the LiBaC

board "open-air" on stand-offs, then choose

stand-offs that are tall enough (at least 3/4"

long) to accommodate the long reach of

hardware below the printed circuit board

using the 'normal' hardware stackup.

Figure 4: Dual Binding Posts Installation Options

IN THE BOX: If the kit-builder wants to be able to mount the LiBaC in the box for which the printed circuit board was

designed, JameCo's #141832, a grey 4.9" x 4"w ABS case with a clear top (so you can see the JUMBO

LEDs), then a slight modification to the assembly stackup is recommended. The top portion of Figure 4

shows these slight modifications and the stack up.

First, file or grind off the two solder turrets at the bottom (saving 1/2" of length; they are not needed).

Then locate (not in your kit, common-hardware) four #8 flat washers that will be used as (extra) spacers.

Next, remove all four nuts and washers from both posts. Next place the bottom insulator up against

the bottom of the top insulator (see top portion of Figure 4 for details).

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Then install one nut on each post and tighten to hold both insulator pieces tightly. Now install two #8

flat washers on each post below the nuts just installed. Now pass this assembly through the holes in the

LiBaC Printed Circuit Board, MAKING SURE THE RED POST is in the RED/+ Hole and the BLACK POST is in

the BLK/- hole. Now install a split locking washer and nut on each bolt (below the board) and tighten.

The side view of the board will look like the top portion of the Figure 4.

NOTE: No soldering is done in this step. Also, if you want to remove the LiBaC from the box at some

later time to use it open-air on stand-offs, you can change the binding posts back to their 'normal'

stackup, if desired.

Figure 5: Detail of Dual Binding Posts (alone) Assembly for Box Usage

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OVERVIEW OF LITHIUM-ION POLYMER CELL TECHNOLOGY: WARNING - WARNING - WARNING - WARNING - WARNING- WARNING - WARNING - WARNING

NEVER short the positive and negative leads of a LiPo Cell together (even when

cutting them). A fully protected cell (see Protection topic on the next page) will 'electronically open' the

cell, while an unprotected one may overheat, burn, explode, cause arc-welding of diagonal-cutters

(experience speaking here), etc.

LiPo cells, when compared to other chemistries, offer a good balance for the price, size, weight,

rechargeability, life, self-discharge characteristics, and maximum current ratings. If you have a cell

phone, iPad, Laptop computer, rechargeable toys, etc., you are using LiPo cell technologies already.

Resources: The two 'locations' that I use the most for understanding the really technical aspects about LiPo cells

and how best to use it are the "Battery University" and "ICCNexergy."

The two 'locations' where I buy my hardware and obtain really good 'practical' applications information

are "BatterySpace" and "SPARKFUN." Pictures of some of this hardware are presented in the next

figure.

NOTES of INTEREST:

ICCNexergy, in their White Paper "Roadmap for Lithium-Ion Battery Technology" (on page 7) share that

"Sony, the first company to commercialize Lithium-Polymer back in 1999,..." and that the 2014 Volume

of Laminate (polymer cells) was 2200 Million Cells. It is a stable, well-accepted technology with a

growing market base.

There are two types of Laminate cells, often confused: Prismatic, and Polymer. Their electrolytes are

slightly different, as are their containers. "Prismatic cells are in an aluminum can, while polymers are in

a form of bag or a sandwich of polypropylene and aluminum that is heat sealed around the outer edge."

All of the cells I use are actually polymer types (some of which are depicted in the next figure).

There seems to be three general classes of LiPo cells: "High Power" which can be discharged at very high

rates for short periods of time; "Mid-Rate" which can be discharged at moderately high rates and have

higher capacities than the High Power versions; and, "High Capacity" which have the highest overall

capacity but are generally limited to '1C' discharge rates. These classifications seem to be manufacturer

specific, as they are more Marketing differentiations than those based upon established standards.

REGARDING "C":

LiPo cells are discharge rated in terms of 'capacity', abbreviated as "C", a function of the specific

classification and chemistry. A (high capacity) 750mAh LiPo cell rated as "1C" can safely discharge at a

rate of 750mA (for 1 hour). A 750mAh LiPo cell rated as "2C' can safely discharge at a rate of 1.5Amps

(for 1/2 hour). A (high power) 750mAh LiPo cell rated as "10C" can safely discharge at a rate of 7.5amps

(for 6 minutes).

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Note that the "C" ratings are for just the cells; they do NOT include the (perhaps further) limiting factors

imposed by the attached or integrated Protection Circuit Board, or even the wiring.

VOLTAGES:

An older LiPo technology found in many earlier technology cell phones are rated at 3.6volts (nominal)

with a typical maximum peak "float" voltage of 4.1volts. The LiBaC can work with these older 3.6volt

LiPo Cells if you happen to have them around.

The newer (much more common) LiPo cells are rated at 3.7volts (nominal) with a maximum peak "float"

voltage of 4.2volts. The LiBaC is designed to recharge these cells also. The performance data presented

later only works with the newer 3.7volts LiPo Cells (and only with those that have Protection Circuits

attached or integrated).

PROTECTION:

All Lithium-Ion cells are capable of delivering very high discharge current levels; can be over-charged;

and can be over-discharged. All of these abnormal conditions can damage the cells; can cause

overheating; can burst the packages; and, cause very hot-burning fires.

Standard, or custom, Protection Circuit Boards MUST be used with LiPo cells to prevent over current

(charge or discharge) conditions beyond their specific "C" ratings; and to prevent over(voltage)Charge

conditions; and to prevent over(voltage)Discharge conditions. A common (tiny) module (as depicted in

the next figure) will limit the current to 1Amp, the upper voltage to 4.275volts, and the lower voltage to

2.30volts before electronically disconnecting the Cell from the application circuitry. Other protection

modules may raise the lower voltage limit to prolong the cell's life-cycle because over-discharging a LiPo

cell significantly shortens the total usefulness. A different module may raise the maximum current limit

to match the "C" rating for a higher power delivery (for a shorter time). Some of these design tradeoff

issues will be explored in the next two topics.

CHARGING LiPo CELLS:

The old-fashioned Lead-Acid battery 'trickle' charger is NOT going to work for this new technology. All

LiPo chargers include at least a two-stage controller that charges at a (maximum) constant current until

the cell reaches its maximum (float) voltage (4.1 or 4.2volts normally); after which, the controller enters

its constant voltage mode where the cell's voltage is maintained at the terminal maximum (4.2volts for

instance) while the current decreases. Once the current reaches a certain very low level, the cell is

considered fully charged. Most LiPo chargers also include a 'preconditioning' trickle-charger for safely

increasing the voltage level of a severely-discharged cell prior to entering the constant current mode.

Many LiPo chargers also include integrated timing circuits for terminating charging sequences if they

take too long because the cell has been damaged (over current, over-charge or over-discharge) and it

simply won't take a charge. The LiBaC has this timer; but it is optional in that it can be disabled for good

reasons. Some chargers also include integrated thermal-sensing circuits to reduce the charging power

profile should the LiPo cell become too warm from the charging operation. The LiBaC's integrated

circuit has this capability; but, the feature is NOT implemented on the LiBaC. Nearly all of the existing

LiPo Cell chargers only run at a fixed, single maximum constant current rate, which significantly limits

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the usefulness. The LiBaC has five different switch selectable maximum constant current rates; making

it extremely generic and useful for a wide assortment of applications.

LiPo CELL EXAMPLES:

Figure 6: LiBaC with protected and unprotected LiPo Cells

Figure 6 presents the assembled LiBaC surrounded by various LiPo cells, with and without PCB's, as well

as an inset of a typical PCB. This brief topic discusses some of these, as well as others, and how they can

be charged safely using the LiBaC.

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ABOUT THE LiPo CELLS:

Figure 6 Item #1:

is a 6,000mAh '2C' LiPo Cell-Pack from SPARKFUN. It is a triple-pack (in parallel) of three of their

2,000mAh LiPo Cells (see Item #2 below) with matched impedance for balanced charging and

discharging with an integrated PCB. Note that the wires attached to this LiPo-pack can only handle

1Amp maximum, despite the '2C' rate level = 12Amperes for maximum discharging. Based upon the

#585460 specifications, the maximum charge current is at '1C', and the minimum discharge cut-off

voltage is 2.75volts.

A 'complete' discharge test conducted on this cell (on 2Jul15) captured the actual electronic-disconnect

by the integrated PCB to be at a LiPo Cell voltage of 2.3405volts (well below the manufacturer's

recommended minimum voltage 2.75volts).

A second sample of another 6Ah LiPo cell-pack (not shown) was tested for a complete discharge

sequence (on 4Jul15) with its automatic-electronic-disconnection by the integrated PCB occurring at a

LiPo Cell voltage of 2.3542volts. Again, this voltage is far below the manufacturer's recommended

minimum of 2.75volts.

Since this LiPo cell has wires (with a 2-pin JST connector attached) that can only handle 1Amp maximum,

the LiBaC can safely charge it using any of the four lower maximum constant current levels [codes 0, 1,

2, and 4]; while code 8 for 1.5Amps should not be used.

I have used these in several super-low-power wireless sensing applications with the need for recharging

occurring as infrequently as 14 months.

Figure 6 Item #2:

is a 2,000mAh '2C' LiPo Cell-Pack from SPARKFUN. As noted in Item #1, it is based upon the #585460

specification with the same '2C' discharge current capacity resulting in 4Amperes maximum. Like item

#1 (above) its wires and connector can only handle 1Amp maximum, so code 8 for 1.5amps should not

be used when charging it with the LiBaC.

Figure 6 Item #3:

is a 700mAh 2.59Wh LiPo cell (with tabs only, no integrated PCB, wires, or connector) based upon the

PL-503048-2C specification from Battery Space (#1253). Across the tabs a PCB (see item #7 below) was

attached, with a pair of pig-tail wires (no connector), enabling charging and discharging tests to be

conducted.

Two different charging tests, and two different discharging tests were conducted on this 700mAh (with

PCB) assembly. The first discharge test (3Jul15) at a rate of -300.0mA resulted in an automatic

electronic-disconnect by the PCB at 2.2782volts, while the second test (also on 3Jul15 on the same LiPo

cell and PCB) at a higher discharge rate of -500.0mA resulted in the over-discharge disconnect event at

2.2764volts (almost identical). The PCB's undervoltage cutoff is specified at 2.30volts (very close to

measured).

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This '2C' discharge rated LiPo cell could be safely run into a load at 1.4amperes for 30 minutes.

However, the PCB installed only permits charging and discharging rates to 1Ampere. Therefore, the

LiBaC can be used to charge this cell at 100mA, 333mA, 600mA, and 1Ampere rates safely. The

performance tests results (later) present data acquisition waveforms while charging at the maximum

1Ampere rate.

Figure 6 Item #4:


PL-703562-2C specification from Battery Space (#4312). Since this LiPo cell is just slightly smaller than

item #2 above, it was not modified for testing by installing a PCB and wires.

Figure 6 Item #5:


PL-603048-10C specification from Battery Space (#4542). Since this LiPo cell is just slightly larger than

item #3 above, it was not modified for testing by installing a PCB and wires. Also note that the

maximum discharge rate for this particular LiPo (at "10C") is 7.5Amperes (for only 6 minutes maximum).

To use its full capacity, a special PCB would need to be developed for its operations at these high current

levels (see note with Item #7 below).

Figure 6 Item #6:


PL-383562-2C specification from Battery Space (#1120). Since this LiPo cell is just slightly larger than

item #3 above, it was not modified for testing by installing a PCB and wires.

ABOUT THE PROTECTION CIRCUITS:

Figure 6 Item #7:

These tiny PCB's are #PCB310A1 devices rated at 4.275OV & 2.30UV with 0.1volt current sense for a

maximum current flow of 1Ampere (in either direction); from Battery Space (#2156). One of these

installed on the 700mAh LiPo Cell's tabs (see Item #3) showed that the undervoltage trip point was

measured very close to its specification.

As shown so far, different LiPo cells have different capacities and ratings and could benefit in many

applications by having different over-current limit capabilities, and even different undervoltage (over-

discharge-voltage) specifications. Generally, the charging circuitry, like those within the LiBaC,

automatically prevents over-voltage events from being handled by the PCB circuitry.

Not (really) a part of this particular technical presentation is the fact that other protection circuits'

components can be purchased for developing custom PCB's. These include the following parts (have

bought them and successfully used them on various LiPo-powered projects):

1) Seiko Instruments' S8241ABKMC; Digikey's #728-1032-1-ND.

2) Seiko Instruments' S8241ABPMC; Digikey's #728-1033-1-ND.

3) Seiko Instruments' S8241AAJMD; Digikey's #728-1034-1-ND.

4) On Semiconductor's ECH8601M-C-TL-H (dual 8amp 24v n-Channel MOSFET's); Digikey's 863-

ECH8601M-C-TL-H.

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... and an assortment of surface mount resistors and capacitors for setting parameters.

LiPo VOLTAGES in APPLICATION:

Figure 7: LiPo Cell Voltages Table with Application Notes & Charging Profiles

Figure 7 presents a table of voltage and 'events' based upon a LiPo Cell's voltage levels; and, an ideal

depiction of a three-phase charger (in the bottom right corner).

NOTE about charging profile:

The 'ideal' waveforms are rarely real, and this topic is breached here as a best place for it. If a

'precondition' phase is needed (due to over-discharging of a LiPo Cell) then a very low (40mA in this

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example) constant current is applied until the LiPo cell voltage reaches +2.85volts (in this example).

Then the charger enters the constant current phase (400mA in this example) and stays there until the

cell voltage reaches 4.2volts (in this example) provided it is not terminated by a safety timer due to too

long of a period spent in this phase. Once the cell voltage reaches the terminal-float value of +4.2volts

(in this example) then the charger switches to its constant voltage mode of charging, allowing the input

current to decrease while maintaining the +4.2volts on the LiPo Cell. Once the decreasing current

reaches a low value of 32mA (in this example) charging is complete. You will note later (from actual

performance plots of charging operations) that the 'real' profiles don't exactly fit the 'ideal' curves

depicted in Figure 7.

BATTERY VOLTAGE EVENTS:

The events in black ink in the table on the left hand side of Figure 7 include (at the low end) the

manufacturer's recommended minimum cell (cut-off) voltage of 2.75volts, followed by (moving up) the

disconnect voltage (2.973volts) level for over-discharge parameter of the PCB and its (slightly higher)

discovery level of 3.178volts.

As the application drains the battery voltage, we want to be notified of when recharging must be done

before circuits start to fail, and certainly before the PCB disconnects the LiPo cell electronically.

If super-low-power CPLD or FPGA digital hardware-only circuits are used, then the I/O circuits can all be

run at 3.1volts (the low end of the LVCMOS33 standard), allowing at least 100mV of headroom on low-

dropout regulators to work properly down to 3.2volts. In this particular application, a notification was

'sent' to the user at 3.3volts that recharging was needed, and different (non-PCB) voltage detection

circuits actually turned off most of the hardware when the voltage reached 3.2volts (in the case where

the recharging did not start in a timely manner). These two-important 'events' in red ink in the table are

"low battery voltage on" at 3.3volts and "circuitry disabled" at 3.2volts.

If the circuitry is disabled before recharging started (at 3.2volts), and battery recharging subsequently is

started, then when the cell voltage reaches at least 3.5volts, the application circuitry is restarted, as

noted in red ink in the table. This hysteresis (3.2volts-to-3.5volts) prevents ping-pong oscillations of on-

off-on-off...

As the battery (cell) continues to be recharged, the notification that the battery needs to be recharged is

turned OFF as the cell voltage approaches the high end (still in the constant current phase, though), at

4.15volts in red ink in this table. After the battery charger reaches 4.2volts, it enters the constant

voltage (decreasing current) charging phase; and later turns itself off when the current drops very low.

If the terminal voltage control circuits within the battery charger fail to terminate the rise in cell voltage

at 4.2volts, then the PCB circuits will detect this problem at 4.230volts (second line in black ink in the

table) and the PCB will electronically-disconnect the Cell from the application (open-circuit via

MOSFET's) at 4.255volts (top line in black ink in the table).

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These two layers of protection, the LiPo cell's PCB and application-based voltage-level detections

provide fail-resistant (no such thing as fail-safe) operations that are very important many wireless

sensing applications.

LiBaC SWITCHES:

Figure 8: LiBaC's Four Control Switches

Figure 8 highlights the locations of the four control switches by their schematic reference.

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S1:

digitally sets the approximate maximum charging current during the constant current phase of the

charging cycle.

100mA => Code 0

330mA => Code 1

600mA => Code 2 and 3

1.0Amp => Code 4, 5, 6, and 7

1.5Amp => Code 8 and 9

The range selected depends upon:

1) The LiPo Cell's capacity value, in milliamp-hours (mAh).

2) The LiPo Cell's maximum charging rate from its data sheet expressed in "#C" values

(proportional capacity).

3) The maximum current rating permitted by the attached or integrated Protection Circuit Board

(1Amp maximum, charge & discharge, is VERY common).

4) The maximum current carrying capacity of the wires (1Amp maximum is very common).

5) The current capacity of the power supply being used to run the LiBaC.

S1 Setting example 1:

The power supply running the LiBaC can only supply 400mA maximum, while charging a 1,000mAh LiPo

cell with a 1Amp current limit in its integrated protection circuits with 1Amp capacity flying leads.

a) Use code 0 (with S3 disabled - see below), or

b) Use code 1 for 330mA maximum current because the power supply can only deliver 400mA

maximum. S3 should be disabled because the comparatively low charging rate will take too long

and the timer will probably terminate the timing cycle before the full charging operation is

complete.


The same LiPo Cell as in example 1 is now being charged from a 1.5Amp power supply running the

LiBaC.

a) Use code 0 (with S3 disabled), or

b) Use code 1 (with S3 disabled), or

c) Use code 2 (with S3 enabled or disabled), or

d) Use code 4 (with S3 enabled or disabled).

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A 250mAh "4C" LiPo cell with a 1Amp current limit in its protection circuit and 1Amp capacity flying

leads is to be charged using a 3.3Amp Wall-wart power supply. A check of the data sheet for the LiPo

Cell states that it is safe to charge the cell at a "2C" maximum rate, and that the "4C" rating is for the

maximum discharge rate. This means that the maximum charging current is 500mA.

a) Use code 0 (with S3 disabled), or

b) Use code 1 (with S3 enabled or disabled).


a 700mAh "2C" LiPo cell with a 1amp current limiting and leads with a JST connector is to be charged

using a 2.2Amp power supply. The data sheet indicates that the Maximum Charging rate is "0.5C",

which means the maximum charging current should NOT exceed 350mA.


b) Use code 1 (with S3 disabled).


A 6,000mAh "2C" LiPo cell with a 1amp current limiting and leads with a JST connector is to be charged

using a 3.3Amp power supply. The data sheet indicates that the Maximum Charging rate is "1C", which

means the maximum charging current should NOT exceed 6Amps. However, since the current is limited

to 1Amp by the protection circuits and its leads, the maximum charging current is 1Amp.


b) Use code 1 (with S3 disabled), or

c) Use code 2 (with S3 disabled), or

d) Use code 4 (with S3 disabled).

S2:

is the Main Control switch that either shuts down the charger, or enables it, as shown by the arrows

and labels on the board's silkscreen.

ALWAYS keep this switch in the SHUTDOWN position when connecting or disconnecting the input power

supply and the LiPo Cell.

ONLY move this switch to the CHARGE position after all of the following are true:

1) The LiPo Cell is connected to the dual-binding-posts.

2) The Connection-FAULT Red LED is OFF

3) The Power Supply is Connected via either the 2.1mm x 2.5mm Power Jack or the 2-position (blue)

terminal block.

4) The "PWR in OK" Green LED is lit.

5) S4 (see below) has been selected for the proper terminal-float voltage.

6) S3 (see below) has been placed in its desired position (Timer enabled or disabled).

If all of these (6) 'checks' are true, then it is safe to start the charging cycle by moving S2 to the

"CHARGE" position.

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S3:

is the TIMER Enable or disable control switch.

This extra charging safety feature, when enabled, runs a timer that lasts about 3 hours long (as set by

capacitor C2). If the charging phase is not completed within 3 hours (when enabled) the charger

automatically terminates the charging operation. An example of this is presented later in the

performance test results section of this manual.

Determining whether the TIMER should be used or not is somewhat difficult to ascertain. If there is a

possibility that the LiPo Cell has been damaged by overcharging or undercharging (used without an

integrated or attached protection circuit board) or it has self-discharged from lack of use (in storage for

a very long time) or some other form of abuse, then it is fairly wise to use the TIMER at least the first

time the cell is recharged to ensure that it will take a charge properly within a reasonable time span.

A 'healthy' (not near the end of its life-cycle) LiPo Cell will generally recharge in about 1-1/2 times its

capacity if it is performed at the full rate. A few examples might help clarify this over-simplified

generalization, taken from some of the examples cited in the discussion on S2 settings.

Examples 1 & 2 were for a 1Ah LiPo Cell with 1Amp current limitations. This means that a 'good,

healthy' cell should be able to recharge fully in about 1-1/2 hours if charged at a 1Amp rate. It would

take 3 hours at a 500mA rate, which is the maximum time permitted if enabling the TIMER. Using Codes

0 or 1 (100mA or 333mA charging rates) would take too long to use the TIMER without an automatic

termination taking place before charging was completed. However, using Codes 2 or 4 (600mA or

1Amp) would permit enough current to flow to enable charging to be completed in less than 3 hours.

Therefore, in these two (latter) codes and current levels, using the TIMER is possible, if desired.

Example 3, where the 250mAh LiPo Cell could be charged at a '2C' rate of 500mA maximum, could not

complete a full charge in less than 3 hours when using Code 0 (100mA charging current); while it could

finish in less than 3 hours when using the Code 1 (333mA) charging current.

Example 4, where the 700mAh LiPo cell had a maximum charging current rating of "0.5C" (from its data

sheet) permits a maximum safe charging rate of 350mA (Codes 0 and 1, only). Using Code 1 for 333mA,

it would take approximately 3 hours and 9 minutes to complete a full charge on a 'healthy' cell, longer if

it has been in use for a while. Therefore, the TIMER should NOT be enabled when charging this cell,

unless it is suspected of being a 'bad' cell where it might not properly charge due to internal weaknesses

(due to usage or abuse).

3 Hours and 9 minutes was arrived at by this quasi-formula:

[ ( mAh x 1.5 ) / MAX-CHARGE-CURRENT ]

= [ 700mAh X 1.5 / 333mA ]

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Remember that the 1.5 multiplier is merely an approximation based upon observed charging operations

over a few years on many different size LiPo cells; and is NOT typically found in 'official' or 'standards-

based' documentation; it is simply something I have noticed.

Also be aware that the TIMER's period is set by a capacitor, and is therefore subject to (significant?)

variations based upon the tolerance of the capacitor used. Again, an example of this is presented later

in the performance test results section of this manual.

Example 5: The 6,000mAh LiPo cell is simply too large with the given 1Amp maximum current level to

charge any faster than 9 hours; so the TIMER normally is not enabled. An actual 'recharge' test

conducted (but NOT presented in this manual), demonstrated that it actually took 9 hours and 23

minutes to recharge this 6Ah cell from a completely discharged state (PCB auto-disconnected the cell),

where it may have been closer to 9 hours had the cell only been discharged to the level of 3.2volts.

S4:

selects the maximum, terminal, 'float' voltage of 4.1volts or 4.2volts, LiPo Cell dependent. Generally,

older LiPo cells, often rated as 3.6Volt cells (nominal) had a top voltage of 4.1volts, while newer (3.7volt

nominal) cells top out at 4.2volts. It has been suggested (but not personally tested) that charging a

3.7volt cell to only 4.1volts maximum increases it life-cycle. This concept is true with some other

chemistry batteries (like Lead-Acid); but it is not known for certain if it is also true for various Lithium-

Ion Cells.

INPUT POWER CONNECTION:

Figure 9 (on the next page) highlights the locations of the power input, with a couple of additional

technical notes of interest.

Three different JameCo 'wall-wart' power supplies were tested with this LiBaC unit. Two of them

worked just fine, as noted in the picture for this step. One did NOT work for the LiBaC because it applied

a voltage way above the maximum allowable input voltage to IC1 (which could damage the device).

If the kit-builder prefers to use a bench power supply connected to the 2-position terminal block, then it

is recommended that the starting voltage, which can be adjusted later, be at around 6.5volts.

There is a significant voltage drop, starting at about 0.6volts minimum (with only the Green LED lit while

the charger is in SHUTDOWN mode via S2) between the input power connections and the voltage

applied (referred to as "V+") to the charging IC1. This voltage drop increases to over 1.1volts as the

charging (input) current increases.

It is important to maintain the "V+" voltage level between +4.50volts (minimum) and +6.50volts

(maximum) under all charging conditions for maximum efficiency and quickest charging times.

If using an external variable bench power supply to power the LiBaC, the input voltage can be adjusted

after CHARGING has started by monitoring the "V+" voltage level across C1, as shown in the picture for

this step. This is important mainly for the two higher charging current ranges (Codes 4 and 8) as the

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voltage drop across the DB1 and F1 components will be higher, perhaps dropping the "V+" voltage level

below that recommended for optimum charging operations.

Figure 9: Input Power Sources and Connections

Examples of this voltage-droop issue will be pointed out in the performance test data later in this

document, since only JameCo supplied wall-warts were used for these (presented) tests.

POLARITY:

DB1 provides "goof-proof" input wiring capability (steering diodes) so that wall-warts with either

positive-center or negative-center power plugs can be used. This is also why the 2-position terminal

block lacks polarity markings, since it is in parallel with the power-jack before DB1. DB1 is also the

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'warmest' component on the board during higher current charging operations, as will be shown with

some 'spot measurements' of temperatures during some of the performance tests (later).

WHEN TO CONNECT INPUT POWER:

It is recommended that the LiPo Cell that is to be charged be connected (with S2 in the SHUTDOWN

position) to the dual-binding-posts prior to plugging in the power plug or turning on the bench power

supply. Repeating again:

1) With S2 in SHUTDOWN, the LiPo Cell is connected to the dual-binding-posts***.

2) Ensure that the Connection-FAULT Red LED is OFF; IF IT IS LIT reverse the connections of the

LiPo Cell.

3) The Power Supply is connected via either the 2.1mm x 2.5mm Power Jack or the 2-position

(blue) terminal block, and power is applied.

4) Ensure that the "PWR in OK" Green LED is lit.

5) S4 has been selected for the proper terminal-float voltage.

6) S3 has been placed in its desired position (Timer enabled or disabled).

7) S2 can then be moved from SHUTDOWN to CHARGE.

8) The Orange "CHARGING" LED is lit (assuming that the LiPo Cell is not already fully charged).

*** How to connect the LiPo Cell is discussed next…

HOW TO CONNECT the LiPo CELL:

Figure 10, on the next page, points out "HOW NOT TO DO IT" as well as a quasi-generic method for

connecting to many different kinds of LiPo Cell connection schemes.

WRONG WAY:

The top portion of Figure 10 (on the next page) depicts TWO problems:

1) Polarity is incorrect and the (bright) Red LED for "Connection FAULT" is lit. This is a major

issue. Do NOT move S2 to CHARGE if the Red LED is lit. Disconnect the LiPo cell and reverse

the connections.

2) Unless you are very experienced using LiPo cells do NOT attempt to use them without their

Protection Circuit Boards [PCBs]. The PCB is designed to prevent cell damage (and other

nasty, perhaps harmful effects) by moving too much current into or out of the cell, by

applying too high a voltage to the cell during charging operations (possible if not using a

integrated circuit designed to execute the proper constant-current then constant-voltage

charging phases), or by discharging the LiPo cell to a too-low voltage that could permanently

damage the cell. Figure 10 shows a 'bare-tabs' LiPo cell without a PCB being attached to the

LiBaC briefly (only to light the red "Connect-FAULT" LED).

Some Right Ways:

See the bottom of Figure 10 for some of the ideas that work for me; and, create your own…

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Figure 10: LiPo Cell Connections: How NOT to do it; several right ways...

The bottom of Figure 10 depicts a multi-connect harness that I use for connecting several different types

of LiPo cells in my project work. It uses a dual-banana-plug that fits into the dual-banana-jack on the

LiBaC for the connection. It includes a 0.10ohms series resistor between the positive plug and the

positive leads in order to measure the current flowing into or out of the LiPo Cell. There are three leads

in this harness, two with 2-pin JST connectors of opposite polarities, and a pair of alligator clips.

Not shown is the much simpler method of connecting LiPo Cell flying leads directly to the dual-binding-

posts on the LiBaC board itself. Connect your LiPo Cell(s) as needed.

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USING the LiBaC:

There is no separate figure for this text. It is a reiteration and summary of the preferred steps for

charging a LiPo Cell:

1) With S2 in SHUTDOWN, the LiPo Cell is connected to the dual-binding-posts.

2) Ensure that the Connection-FAULT Red LED is OFF; IF IT IS LIT reverse the connections of the

LiPo Cell.

3) The Power Supply is connected via either the 2.1mm x 2.5mm Power Jack or the 2-position

(blue) terminal block, and power is applied.

4) Ensure that the "PWR in OK" Green LED is lit.

5) S4 has been selected for the proper terminal-float voltage.

6) S3 has been placed in its desired position (Timer enabled or disabled).

7) S2 can then be moved from SHUTDOWN to CHARGE.

8) The Orange "CHARGING" LED is lit (assuming that the LiPo Cell is not already fully charged).

The Orange LED will turn OFF near the end (but, prior to the final charged state) of the charging cycle. It

is recommended that the S2 be left in the "CHARGE" state for a while after the Orange LED is no longer

lit to 'top-off' the LiPo Cell. Examples of this will be presented later in the Performance Test Results

section of the Manual.

PERFORMANCE:

Test Setup Introduction:

This section introduces the Kit-Builder to the general test setup, consisting of the LiBaC and other

equipment, used to study a few LiPo cells' charging and discharging characteristics.

The Kit-Builder has been shown 'ideal' performance values, (see Figure 7) so far. Now it is time to see

the 'real' operations of the LiBaC charging LiPo Cells. To accomplish this in an easy-to-understand

graphical method, a Multi-channel Commercial-grade Data Acquisition System (DAS) is used to record

and plot data for various long-period tests.

The Kit-Builder will also see a picture of another kit that is useful (and was used for these tests) for

performing controlled discharging operations (more on this soon).

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Figure 11: LiBaC Performance Testing Equipment Setup

For every charge there needs to be a discharge...

Figure 11, in the top right corner, introduces the concept of a controlled-load discharger for the various

LiPo cells being studied. Using a simple resistor as a load for a LiPo-cell discharge test would work; but,

the load changes as the LiPo-cell's voltage changes; it is not constant. Most electronic circuits, on the

other hand, present a fairly constant load as a function of the varying input voltage. Therefore, a

Constant Current (and therefore, a Constant Power) load is preferred for studying the discharge

characteristics of a LiPo cell 'in action'. More details on this electronic load are presented soon.

The LELTx5 is a five-channel Electronic Load for performing discharge testing in this section.

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To keep the PERFORMANCE section of this manual from turning into a multi-volume book of its own,

only a few of the many tests conducted (focusing on checking the functionality of the LiBaC) will be

presented.

The tests that will be included (in general) are:

1) LiBaC Charge Test of 700mAh LiPo Cell

2) LELTx5 Discharge Test of the 700mAh LiPo Cell

3) LiBaC Charge Test of 2,000mAh LiPo Cell

4) LiBaC Charge Test of 6,000mAh LiPo Cell

5) LELTx5 Discharge Test of the 6,000mAh LiPo Cell

The DAS Waveforms for the LiBaC "charging" tests include the input current as sensed as a voltage drop

across a 0.10ohms resistor. Two other current sensing channels exist using the same method, including

the charge/discharge current as sensed at the LiPo Cell, and a separate current sensor on the input of

the (five-channel breadboard version only) electronic load for some of the discharging tests.

During 'charging' tests, some temperature samples were (manually) recorded to ensure that the burn-

off heat due to voltage drops across various components was being safely dissipated by the heat-sink

design of the printed circuit board, especially around IC1. These temperature 'spot-checks' are noted in

the text for the appropriate tests.

DISCHARGING LiPo Cells with the LELTx5:

Figure 12 shows the five-channel LiPo-cell Electronic

Load Tester [LELTx5], available from JameCo as part

number 2259489, developed as Club JameCo project

21418.

A single-channel breadboard version was first developed

for the first tests on the 700mAh LiPo-cell, and will

appear as such in the picture for those tests (later). It

was determined then that a single 100.0mA load, while

useful and functional, would not present enough data to

the kit-builder for potentially much larger loads that

may exist in 'real' project circuits (like Robots, remote

actuators, etc.).

Figure 12: The LELTx5 (kit) Developed for Discharge Testing

A five-channel breadboard LELTx5 was built using on-hand bench-stock components. The breadboard

used a pair of series wired (precision) 15ohm resistors as the main load (per LELT channel) while the

LELTx5 (JameCo) kit uses three-series-wired 10ohm resistors. The breadboard LELTx5 used 10uF

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(Tantalum) load filter capacitors, while the LELTx5 (JameCo) kit uses smaller value, non-polarized filter

capacitors.

The primary design goal of the LELT is to maintain constant (current/power) loading characteristics for

all useful (down to +3.2volts) LiPo-cell-based circuits. Below +3.2volts (at 100mA’s) from the LiPo-cell

being tested, the LP2951 LDO regulator is out of regulation and its output droops with the continued

falling input voltage from the LiPo-cell; presented a decreasing load to the LiPo-cell as it continues to

discharge. The LP2951 (and its load) maintains a full 100mA load to the LiPo-cell down to +3.2volts

input.

Due to the potentiometer calibration design, it is possible to create other constant load values. When

decreasing the load currents presented by the LELT, lower LiPo-cell voltages will maintain

(proportionally) constant-loading characteristics. Note, the LP2951 is only rated to work properly to

100mA. However, tests demonstrated that it will work at higher current (with higher input voltages).

This is NOT advised, though, due to the higher heat levels that will exist due to the power losses across

the LP2951.

After the first 700mAh discharge test, four more channels were added to the breadboard LELT prototype

board for the remaining tests. Each channel, using an inline digital ammeter, were calibrated for exactly

100.0mA loading using the +3.70volts nominal LiPo cell input voltage from a bench power supply as the

calibration point.

TEST 1 CHARGING 700mAh LiPo CELL:

Test 1 Setup:

This first test introduces the Kit-Builder to the first, simplest version of the test setup used to charge and

discharge various LiPo cell, and capture some of the data for (analysis) review.

Figure 13 on the next page, depicts the LiBaC with a protected 700mAh LiPo cell attached and charging,

an attached, single channel (breadboard version) of the LELT for discharging tests (but not now

discharging), a meter for monitoring the cell voltage during operations to spot-check verify functionality,

and DAS connections.

For this first test (of many) only four channels on the DAS were originally configured. Reference the

schematic (later in this document) for some of the following connections:

1) Channel 1 = Total Input Current; recording the voltage drop across the 0.10ohms resistor in

series between the 6Vdc 500mA 'wall-wart' center lead and J1 pin 2.

2) Channel 2 = The voltage drop between J1 pin 2 and V+, measured across DB1 and F1, with

the V+ connection being at the positive lead of C1.

3) Channel 3 = V+, the input to IC1, referenced to '0V' (ground). This important potential is

basically the wall-wart's voltage minus the tiny loss across the input shunt resistor (of

channel 1) plus the much larger, current-dependent losses across DB1 & F1 (of channel 2).

4) Channel 4 = The LiPo Cell's voltage, measured at the top of the output filter's R4 referenced

to 0V.

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Figure 13: LiBaC Test Connections to a 700mAh LiPo Cell

700mAh LiPo-cell (re)Charging:

Figure 14 (see next page) and this text presents some technical data and a plot of the recharging

operations at two different constant current rates on the 700mAh LiPo-cell after it had been completely

discharged (prior to the test).

The picture for the step depicts the DAS' (full view) screenprint plot, with notes, during a recharging

operation on the 700mAh LiPo-cell after it had first been completely discharged.

See Figure 5 for more details

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Figure 14: LiBaC Charging a 700mAh LiPo Cell at two different rates

There are six time markers in the picture, T0 to T5, that mark a few significant points warranting data

and further discussion (below). Most notably, time marker "T2" is where the LiBaC was briefly

"SHUTDOWN" (via S2, and subsequently changed back to the "CHARGE" position) in order to change the

constant current charging level from the lowest 100mA level (Code 0) to a Code 1, 333mA level to both

see the differences in various test points and to move the test along a little faster.

Time Marker (pre-) T0:

Enabled the LELT and waited (hours) for its Green LED to extinguish. When this occurred, the voltmeter

was used to verify that the LiPo cell was open (floating ~0volts).

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Then the LiBaC was configured:

Power Supply disconnected

LiPo Cell disconnected

Code 0 (100mA) charge current selected

Timer DISABLED

SHUTDOWN Mode.

then...

Time Marker T0:

Started DAS, then connected LiPo Cell, plugged in wall-wart power supply, and the moved S2 to

"CHARGE". There was a very brief (only 15 seconds long) 'trickle-charge' phase before moving into the

constant current charging phase.

Time Marker T1:

At time = 3,628seconds (little over 1 hour):

Input current = 116mA

DB1 + F1 Voltage drops = 0.806volts

V+ (to IC1) = 4.49volts, and

LiPo-cell voltage = 3.73volts

A quick check of temperatures:

o 82.7F ambient board surface (at Code 8 silkscreen label away from circuits)

o 83.8F on top of IC1

o 84.7F on top of DB1 (typically the hottest component under all charging conditions)

o 78.8F Input Shunt Resistor (open air away from DAS)

o 79.1F on top of LiPo Cell (which is on top of the DAS, which is warmer than the ambient air).

Time Marker T2:

SHUTDOWN -> CODE 0 to CODE 1 change -> CHARGE

The 'glitch' at T2 is actually 18 seconds wide. Notice how there is a big drop in the V+ level after T2 due

to the higher voltage drops across (mostly) DB1 & F1 because the input current was increased by the

Code change. Also notice how the voltage increase on the LiPo Cell is steeper due to the higher charging

current.

Time Marker T3:

After about 3 hours and 20 minutes, more samples were acquired (about midway through the constant

current phase at the higher 333mA rate):





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NOTE that the voltage into IC1 is below specifications, and a look at the data sheet reveals that there

will be a drop in the charging current as a result, as this data confirms.


o 80.6F ambient board surface (at Code 8 silkscreen label away from circuits; will always be

measured here and this additional note will no longer be repeated)


o 86.0F on top of DB1

o 77.5F on top of LiPo Cell. The LiPo cell never measured much above the ambient

temperature, regardless of charging current levels, and its reporting will no long be made.

Time Marker T4:

At time = 3 hours, 44 minutes, and 42 seconds, marked by T4, the charging phase changed from

constant current to constant voltage. This is most evident by the start of the (rising slope) increase in

the voltage applied to IC1 (as V+) due to the decrease in voltage drop across DB1 because the current is

decreasing while the LiPo Cell voltage is being held at a (nearly) constant value. The phases and their

changes were discussed as 'ideals' back in Figure 7.





Time Marker T5:

At the end of the charging operations:

Input current = 83mA (trickle charge level + LED)


V+ (to IC1) = 4.63volts (back in spec), and


NOTE: This is the only charging operation that involves two different current-rates. The test results in

the remaining steps in the PERFORMANCE section of this Manual will not include all of the 'extra' notes

that appeared in this step.

TEST 2 700mAh LiPo-cell Discharging @ 500mA:

This section presents a plot of the discharging of a (previously) fully charged 700mAh LiPo cell at a fixed

current rate of 500.0mA.

Test 1’s charging operation was conducted on 29Jun15, while this discharge operation in this step was

conducted on 3Jul15. There have been many other LiBaC and LELT tests in between, where the test

configuration has evolved. The big changes to the test connections are presented on the note at the

bottom of Figure 15 on the next page.

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Figure 15: 500mA Discharge Plot of Previously Charge 700mAh LiPo Cell.

The actual charging operation performed just prior to this discharge event was one conducted at a

"1.4C" rate of 1Ampere (but not reported in this document).

The top waveform (LiPo Cell Voltage) in Figure 15 shows why LiPo cell chemistry is so much better than

earlier battery-technologies; it is nearly flat for the duration of its energy delivery capabilities. It is also

ideal for running 3.3volt 'logic', most of which runs just fine at 3.1volts, where LDO regulators (like the

LP2951 used on the LELT) can maintain regulation to near the end of the LiPo cell's useful energy

delivery curve.

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DISCHARGE TIMES:

The theoretical 'ideal' discharge time for a 700mAh LiPo cell discharging at a 700mA rate is 1 hour (for a

healthy, not-at-end-of-life, cell). The theoretical discharge time for a (good) 700mAh LiPo cell

discharging at a 500mA rate is 1.4hours.

The ACTUAL discharge time measured in this test for a 700mAh LiPo cell discharging at a 500mA rate is

1.328hours (down to 3.2volts). The DAS data for this plot shows that the LiPo cell 'turned OFF' (by the

Protection Circuit Board's circuitry) at 4,944 seconds = 1.37hours; very nearly the theoretical ideal.

A different discharge test (on this same LiPo cell) at a rate of 300mA (plot not shown in this document)

presented a discharge time of 2hours, 10minutes and 20seconds (down to 3.20volts). This same test

measured the full discharge time (clear to Cell-disconnect by the PCB) of 2.23hours. This "0.43C"

discharge rate, again, is very close to the theoretical value of 2.33hours (for a full discharge to OFF).

TEST 3 CHARGING 2,000mAh LiPo CELL:

Test 1 Setup:

This step shows the Kit-Builder the

more evolved version of the test

setup used to charge and discharge

various LiPo cells, and capture some

of the data for (analysis) review.

Figure 16 depicts the LiBaC with a

protected 2000mAh LiPo cell attached

and charging, an attached, five

channel (breadboard version) of the

LELTx5 for discharging tests (also now

discharging), a meter for monitoring

the cell voltage during operations to

spot-check verify functionality, and

DAS connections.

Note: The “Step 41” reference in

Figure 16 refers to Figure 15 and its

associated text.

Figure 16: LiBaC Test Connections to a 2,000mAh LiPo Cell

The total number of DAS channels now defined and 'hooked' into the system number eight, although

some tests only use 6 or 3 of the channels, depending on the events of interest. All of the channels,

whether they are used for analysis for not, still sample at a rate of one sample per second per channel.

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TEST 3 CHARGING 2,000mAh LiPo CELL:

This section presents some technical data and a plot of the recharging operations of the 2,000mAh LiPo-

cell after it had been partially discharged (prior to the test). It also points out a MAJOR Power Supply

Issue to be aware of.

Figure 17 depicts the DAS' (full view) screenprint plot, with notes, during a recharging operation on the

2,000mAh LiPo-cell after it had first been partially discharged.

Figure 17: LiBaC (re)Charging 2,000mAh LiPo Cell

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***** HOW NOT TO DO IT: *****

Do NOT use JameCo's #220943, 6Vdc 1.2Amp wall-wart (Class 2 Linear, UNREGULATED) power supply

with the LiBaC kit. It's real output voltage, under 600mA loading is at a TOO HIGH level of 8.32volts,

which subjects IC1 to a TOO HIGH voltage input of +6.75volts. The maximum operating voltage into IC1

is rated at +6.50volts; and the ABSOLUTE MAXIMUM level is +7.00volts where IC damage or destruction

can occur. This test is the cause for the disqualification of the power supply with the big RED-X in

figure 9 – “DO NOT USE.”

There are five time markers Figure 17, T0 to T4, that mark a few significant points warranting data and

further discussion (below).

Time Marker (pre-) T0:

Enabled the LELTx5 (breadboard version depicted) to discharge at 500mA, and waited for a while for the

LiPo cell to lose some of its energy. Randomly stopping by disabling all five channels of the LELT, the

voltmeter was used to measure that the LiPo cell had about 3.5volts (open circuit) on it.

Then configured LiBaC:

Power Supply disconnected

LiPo Cell connected

Code 2 (600mA) charge current selected

Timer DISABLED

SHUTDOWN Mode.

then...

Time Marker T0:

Started DAS, and noted that the DAS reports an open circuit, partially discharged LiPo cell voltage of

3.5114volts. Then the wall-wart power supply was plugged in about 17 seconds later, and then moved

S2 to "CHARGE". The CHARGE operation, starting at time = 69seconds, resulted in an input current

653mA which includes the constant charging current of 600mA and the current for two of the Jumbo

LEDS (Green for "PWR in OK" and Orange for "Charging").

For about 52 seconds, then, there was close to 8volts applied to the input of IC1 (without significant

loading) where IC destruction or damage could have occurred.

Time Marker T1:

At time = 1428seconds (little over 23 minutes):

Input current = 644mA, and



o 88.1F ambient board surface



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Time Marker T2:

This marker shows where the LiBaC changes modes from constant-current to constant-voltage, at time =

7871seconds (little over 2 hours and 11 minutes).



Time Marker T3:

At time = 9548seconds (little over 2 hours and 39 minutes):







Notice how the temperatures are coming down with the decrease in input current, and that DB1 is (still)

always the hottest point measured.

Time Marker T4:

At the end of the charging sequence, when the Orange LED turned off (does not include final trickle-

charge):

Input current = 60.1mA, and


The Power Supply was unplugged right after T4 to prevent any potential damage to IC1 as the input

voltage was rising as the input current was falling.

TEST 4 CHARGING 6,000mAh LiPo CELL with INTERRUPTS: Test Overview:

This section presents some technical data and a plot of the whole recharging operation of the second (of

several) 6,000mAh LiPo-cell after it had been totally discharged (prior to the test). This operation also

presents seven temperature samplings.

Figure 18 (on the next page) depicts the DAS' (full view) screenprint plot, with notes, during a recharging

operation on the (first of several) 6,000mAh LiPo-cell after it had first been totally discharged. As noted

in Figure 18, the next three main topic presentations will provide additional details of three major areas

of interest for this charging sequence. There are seven time markers in the picture, T1 to T7, that mark

a few significant points warranting data and further discussion (below).

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Figure 18: LiBaC (re)Charging 6,000mAh LiPo Cell after Full Discharge

The startup sequence will be discussed in detail later. Generally, though,

The LiBaC is SHUTDOWN,

and Code 8 for 1.5Amp charging is selected,

and the TIMER is disabled (initially).

The DAS was started with the LiPo cell physically connected (but, electronically disconnected due to the

prior-total-discharge operation); followed by the 6Vdc 3.3Amp power supply being connected.

then... S2 was moved to "CHARGE"

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SUMMARY:

After 4 Hours, 39 Minutes, and 25 Seconds, the charging sequence was 'manually' interrupted by briefly

moving S2 to "SHUTDOWN." While the LiBaC was shutdown, the TIMER switch was moved to ENABLE,

followed by S2 being moved back to its "CHARGE" position.

Then, after (a total of) 7 Hours, 43 Minutes, and 36 Seconds the TIMER automatically terminated the

Charging Sequence because it was not finished within 3 hours. There are two ways to restart the

charging sequence after a TIME-OUT event:

1) Disconnecting and reconnecting the input power source; or,

2) Moving S2 to "SHUTDOWN" and then back to "CHARGE." Option 1 was used in this particular

test sequence.

CHARGED NOTES:

As mentioned in the note for Figure 18, a separate picture and text is being replaced with a few notes in

this step:

At (total) time = 10 Hours, 47 Minutes, and 54 Seconds the Orange "CHARGING" LED finally turned off

and stayed off. At that time the LiPo Cell voltage = 4.156volts and its charging current = 125mA (from a

previous maximum of 979mA). This is technically still a trickle charge, and the system could have been

left to do so for a while longer to "top-off" the cell after the orange "CHARGING" LED turned off.

NOTE: Although a maximum charging current of 1.5Amps was selected as Code 8 on S1, the losses

across DB1 (& F1) reduced the V+ voltage to the input of IC1 to the point where the maximum charging

current desired could not be delivered. At the peak of 979mA, the input to IC1 was at a (too) low value

of 4.0935volts, some 407mV below specifications. To achieve maximum charging current capabilities, as

mentioned earlier in this document, a variable bench power supply is needed to increase the input

voltage enough to maintain proper charging capabilities.

Time Marker T1:

At time = 236seconds:







Time Marker T2:




Temperatures:



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Time Marker T3:




Temperatures:




Time Marker T4:

At time = 5932seconds (little over 98 minutes):



Temperatures:




Time Marker T5:

At time = 15052seconds (little over 4 hours & 10 minutes):



Temperatures:




Time Marker T6:

At time = 17872seconds (little over 4 Hours and 57 minutes):



Temperatures:




Time Marker T7:

At time = 32154seconds (little over 8 hours and 55 minutes):



Temperatures:

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Notice how the temperatures are (generally) coming down with the decrease in input current, and that

DB1 is (still) always the hottest point measured.

TEST 4’s STARTUP DETAILS:

Figure 19 presents some technical data as embedded notes in a plot of the startup portion of the

recharging operation of a

6,000mAh LiPo-cell after it

had been totally discharged

(prior to the test).

Figure 19 depicts the DAS'

screenprint plot, with notes,

during the initial startup

portion of the recharging

operation on the 6,000mAh

LiPo-cell after it had first been

totally discharged.

To place this 'zoom-in' view in

perspective, the displayed

plot is a total 90 seconds

wide; = 0.231% of the full

test. No additional notes are

needed beyond those in the

picture.

Figure 19: LiBaC Charging 6,000mA LiPo Cell from Complete Discharge Startup Details

TEST 4’s MANUAL INTERRUPTION DETAILS:

Figure 20 (on the next page) depicts the DAS' screenprint plot, with notes, during the portion of the

recharging operation on the 6,000mAh LiPo-cell where the charging cycle was deliberately interrupted

with a manual shutdown, during which 'pause' the Timer was enabled for future "TIMED" charging

operations.

This 'event' takes place after 4 hours, 39 minutes and 25 seconds from the start of DAS recordings. To

place this 'zoom-in' view in perspective, the displayed plot is a total 90 seconds wide; = 0.231% of the

full test. No additional notes are needed beyond those in the picture.

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Figure 20: LiBaC Charging 6,000mHa LiPo Cell mid-way Manual Interruption Details

TEST 4’s TIMER-INTERRUPT DETAILS:

Figure 21 (on the next page) presents some technical data as embedded notes in a plot of the portion of

the recharging operation of a 6,000mAh LiPo-cell where it was automatically terminated by the TIMER

and then (eventually) restarted.

Figure 21 depicts the DAS' screenprint plot, with notes, during the portion of the recharging operation

on the 6,000mAh LiPo-cell where the charging cycle was automatically interrupted with a TIMER

shutdown. After 45 minutes (after it was discovered that the LiBaC was NOT charging) it was restarted.

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Figure 21: LiBaC Timer-Controlled Charging Automatic Termination Detail

To place this 'zoom-in' view in perspective, the displayed plot is a total 45 minutes wide; = 6.938% of the

full test.

The following data are averages of 60 samples per parameter (1 full minute at 1 sample per second per

channel), the first set being those occurring the last minute just before the timer terminated charging

operations, and the second set being those occurring during the first minute just after the LiBaC was

restarted by the disconnection and reconnection of the input power supply.

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BEFORE TIMER-SHUTDOWN:

6.136V = Charge Voltage Input

468mA = Charge Current Input

887mV = Voltage drop across DB1 & F1

4.407V = V+ voltage input to IC1

394mA = Charging current into the LiPo Cell

4.094V = LiPo Cell Voltage.

after about 45 minutes of 'rest'...

AFTER RESTART:

6.132V = Charge Voltage Input

482mA = Charge Current Input

899mV = Voltage drop across DB1 & F1

4.377V = V+ voltage input to IC1

409mA = Charging current into the LiPo Cell

4.090V = LiPo Cell Voltage.

HIGH CURRENT CHARGING POWER SOURCE note: As mentioned many times, the minimum specified input voltage to IC1 is +4.50volts; and, both of these

sets of readings for that particular parameter indicate that the LiBaC is not charging the LiPo cell at its

optimum capability by using a 6Vdc-rated wall-wart. This is why it is recommended that the kit-builder

uses a variable voltage bench power supply when using the LiBaC to charge LiPo cells at the two highest

charging current ranges of 1.0amp and 1.5amp.

TEST 5 disCHARGING 6,000mAh LiPo:

TEST OVERVIEW:

Figure 22 (on the next page) presents an overview plot of the total discharging operation of a 6,000mAh

LiPo-cell starting after it had sat on a shelf for 11 months after its last full charge.

Figure 22 depicts the DAS' screenprint plot, with notes, during the discharging operation on the

6,000mAh LiPo-cell. Note that it did NOT start from a full charge state, having not been used for 11

months after its last full charging. This cell 'lost' less than 100mV over that time-span due to self-

discharging, an important parameter for some products.

This 'discharge' operation was actually performed just before the recharging operations were started for

Test #4 (above). Hence the order of Tests 4 and 5 are chronologically reversed.

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Figure 22: Full-to-Empty 500mA (rate) Discharge of 6,000mAh LiPo Cell

This finishes the PERFORMANCE section of this manual. It is hoped that the information provided have

helped the kit-builder understand how to use their new LiBaC for their own projects.

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TECHNICAL DATA:

SCHEMATIC:

Figure 23: LiBaC Schematic

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PRINTED CIRCUIT BOARD:

TOP COPPER:

Figure 24: LiBaC Printed Circuit Board: Top Copper

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BOTTOM COPPER:

Figure 25: LiBaC Printed Circuit Board: Bottom Copper

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Both EAGLE COPPER LAYERS:

Figure 26: LiBaC Printed Circuit Board: Both Copper Layers with the Silkscreen

Figure 26 depicts a screenshot of the Board Layout Tools, part of EAGLE PRO tools, with top (red) and

bottom (blue) copper layers with the Silkscreen Layer ‘turned on’.

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BLOCK DIAGRAM:

Figure 27: LiBaC's Functional Block Diagram

TThhiiss CCoommpplleetteess tthhee LLiiBBaaCC’’ss UUsseerr MMaannuuaall If the reader finds any errors, or has recommendations for improvements, please feel free to notify

JameCo Electronics, and they will pass along the request for consideration. Thank You. ENJOY!

LiBaC Kit User’s Manual - Jameco Electronics...Page 1 of 50 LiBaC Kit User’s Manual Optional...

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