2.4 Shashikant Joshi

8/11/2019 2.4 Shashikant Joshi

1/24

Fast charging of Lead acid

batteries with pulse charger

Dr. S. N. Joshi,

Lalit Consulting Services,

Bangalore. INDIA

[email protected]


2/24

Lead acid battery application logic

Lead acid battery is a power source.

Need to put back energy once it is used.

Battery recharge becomes veryimportant.

Discharge followed by recharge is cycle.

Depending upon depth of dischargerecharge current & or voltage is decided

by the charger.


3/24

Fast charging of Lead acid battery

Lead acid batteries are very essential in

our daily life.

Many applications like SLI, UPS,

telecom etc. are well known.

Fast charging of batteries in case of

battery operated vehicles has

significance to the user.


4/24


Chargers used for battery operated

vehicles have basic features:

1.To convert AC to DC through rectifier

bridge.

2.Logic control & monitoring the charge

input.

3.Safety protection & display or record

events of the system.


5/24

Charging system for Lead acid battery

Selection of charger is very critical. Itdepends on:

1.Design of the system & nature of its load

requirement.2.Desired recharge time after every load

cycle.

3.Effect on battery life & maintenanceaspects.


6/24

Charging of Lead acid battery

Examples of recharging systems are:

1.SLI - Alternator charger

2.UPS - Float charging3.Power plants / telecom applications -

Float-cum-boost charger.

4.Fork lift / EVs / Golf cart - Taper / twostep / fast charging.


7/24

Chemical equation in battery reaction

Consider electrochemical reactions in

Lead acid battery producing electron

transfer & voltage across electrodes,

-DC

PbO2 + 2 H2SO4 + Pb 2PbSO4 + 2 H2O

+DC


8/24

Lead acid battery side reactions

There are however side reactions:

1. Generation of gases like oxygen &

hydrogen.

2. Loss of water.

3. Effect on life of battery.

4. Maintenance issue plays part.5. Charger, its design & method of

charging becomes crucial.


9/24


Fast charging in case of battery operated

vehicles is desired by users:

1. Fork lifts.2. Pallet trucks.

3. Cars, buses.

4. Scoter, bikes.


10/24


Battery operated vehicle should get

recharged quickly after specific task.

1. Desired work is done the vehicle.

2. Waiting time is minimum.

3. Utilization of vehicle is improved.


11/24


Fast charging means:

1. Reduction from normal recharge time.

2. At least 80% energy should be putback.

3. Battery plates should not be damaged.

4. Minimize side reactionsloss of water.

5. Reduce maintenance aspects.

6. Covert lead sulphate back into activemass !!!


12/24


Charger design:

Uses higher voltage for shorter timeintervals of seconds or mille-seconds.

DC current in PULSE form is appliedfor short durations of seconds or mille-seconds. Switched off for m-seconds.

Both voltage & pulse current are micro-processor controller with programmedembedded software.


13/24


Pulse charging:

1.The technique restores energy in quickest wayback into lead acid battery.

2.Pulse height & width are selected in such away that entire energy is accepted with leastloss.

3.Current in pulsating form is generated by

complex & intelligent electronic circuit coupledwith embedded software.

4.Temperature sensor employed to restrictenergy losses & undesired side reactions.


14/24

Laboratory testing


15/24



16/24

Bench test with DC motor

Table 1. Bench test results of recharge.

Bench test - DC Motor (250 W) testing system.

Duration 2 Hrs : 55 minutes, average current 5.5 A, End voltage 44.3 V

B1 V B2 V B3 V B4 V Total V

OCV 11.95 11.86 11.85 11.92 47.5

6 hours 13.57 13.52 13.57 13.51 54.10

8 hours 14.69 14.67 14.65 14.66 58.67


17/24

Road test on e-bike

Charge coverage test on road:

Covered 62 kms of distance.

B1 V B2 V B3 V B4 V Total V

OCV 11.63 11.45 11.68 11.47 46.23

6 hrs. 13.58 13.52 13.51 13.57 54.18

8 hrs. 14.32 14.35 14.33 14.37 57.37

Second road test covered distance of 60 kms.


18/24

EBike charging


19/24

Pulse charging of Lead acid battery

Application to battery operated vehicles

is very appropriate to bring in high

utilization of vehicles in shot time.

Electric vehicle (passenger) like cycle,

bike or car demands such type of fast

recharge of battery for the user.

Fork lifts / pallet trucks in industrial

application also need such charger.


20/24

Pulse charging of Lead acid battery

Pulse charger however calls for high end

complicated electronic circuit in combination with

1.battery chemistry,

2.impedance values of lead acid cell at various

SOC.

3.effect of temperature on charge acceptance.

4.correlation with battery voltages & pulseamplitude and time.


21/24

PULSE CHARGER: MAIN FEATURES

Desulfates & charges at the same time.

Automatically shuts off when battery isfully charged.

Helps ensure battery performance byeliminating the main cause of lead-acidbattery failuresulfation buildup &

related problems. Maximum Output: 110 volts DC, up to 35

amps DC.


22/24

PULSE CHARGER: MAIN FEATURES

Helps protect the environment.

Works with all conventional flooded lead-

acid batteries and sealed "maintenance-

free" batteries (VRLA).

Reverse polarity protection.

Over voltage protected. Short circuit protection.

Overload protection.


23/24

Pulse charger 48 V 3 A


24/24

Acknowledgement

Pulse charger is commercially build & supplied:

By M/s CHIRRA POWER TECHNOLOGIES,

Bangalore with technical assistance fromLalit Consulting Services, Bangalore. INDIA

E-mail: [email protected]

[email protected]

Thank you all
mailto:[email protected]:[email protected]:[email protected]:[email protected]

2.4 Shashikant Joshi

Documents

Transcript of 2.4 Shashikant Joshi