Thermal Enforcement

Matt Reznicek

Tim Croyle

Scott Nedrow

Project Requirements

•Maintain Battery Pack at 100°F +-20°

•Provide responsive and accurate measurements of battery temperatures

•Be within budget of project ($3000)

•Have low impact on battery performance

Initial State of ProjectData Acquisition Temperature Measurement

Heating Concepts

1. Resistive Pad Heating

2. Convection Heating (i.e. Diesel Heater)

3. AC Internal Resistance Heating

Resistive Pad Heating

Test 1: 60 Watt Pad on side of battery

Pros:

• Fast

• Easy

Cons:

• Expensive

• Not uniform

• Installation

Pad Heater 60W on Side of Battery

0

20

40

60

80

100

120

0 10 20 30 40 50 60 70 80

Time (min)

Tem

p (

F)

Inside Middle Cell

Inside Outer Cell

Resistive Pad HeatingTest 2: 60 Watt Pad underneath battery

Pad Heater 60W Unerneath Battery

70

75

80

85

90

95

0 5 10 15 20 25 30 35 40 45 50

Time (min)

Tem

p (F

)

Outside on Long Side

Inside Top Temp

Inside Bottom Temp

Pros:

• Fast

• Easy

Cons:

• Expensive

• Not uniform

Resistive Pad HeatingTest 3: 80 Watt Wrap-around Pad

Pros:

• Inexpensive

• Uniform Heating

Cons:

• Bulky

• Slow

• Acts as insulator

• Inefficient

Wrap Around 80W Heater

0

10

20

30

40

50

60

0 10 20 30 40 50 60

Time (min)

Tem

pera

ture

(F)

Inside Outer Cell

Inside Inner Cell

Convection Heating

Cons:• Expensive ($2000+)• Slow• High air Temperatures• Quick cycle time

Pros:•Not Primarily Electric•Uniform Heating

Convection Heating testAmbient air at 195 F

6065707580859095

100105110

0 10 20 30 40 50

Time (min)

Te

mp

(F

)

Outside Temp

Inside Temp

AC Current Heating

Pros:

• Uniform Heating• Low Power• Inexpensive• Very Fast

Cons:

• Circuit Design

AC Heating Test (60A 200mV)

70

72

74

76

78

80

82

84

0 1 2 3 4 5 6

Time (min)

Tem

p

Inside Temp

Outside on Short Side

Outside on Long Side

Comparison

Heating Test Speed Power Draw Uniformity Feasibility Cost Average

Pad Heater on Side 2 3 4 1 4 2.8

Pad Heater Underneath 3 3 4 1 4 3

Pad Heater Wrap 4 4 2 4 2 3.2

Convection Heating 5 1 3 3 3 3

AC Resistance Heating 1 2 1 2 1 1.4

Cooling Fan Test

Observations:• Somewhat Linear cooling• Faster than anticipated• Power draw of ~240 W• Air leaking past box lid

Future Work

• More thorough cooling tests

• Get HEHMMWV mobile

• More AC internal resistance heating tests

• Circuit design for AC heating and cost analysis

• Troubleshoot LabView programming

Questions?