Thursday, August 20, 2009

Battery Cost Analysis

I've been encouraged to post my recent evaluation of the cost of various models of traction batteries for EVs. I basically ran the numbers three ways, to answer three different questions:

1) What is the cost per mile to use a particular type of battery? This is answered by the "Total, cents/mile" row under the "System Detail" section. I didn't include the cost of support systems such as charger or battery balancers because, although they may cost more for one type of battery than for another, they are a fixed cost and don't need to be replaced when the battery pack is replaced.

2) What is the overall cost to use a particular type of battery for 120,000 miles? This is answered by the "Cost, $ (incl. electric)" row under the "120K miles" section.

3) How far can you drive on a particular type of battery before you exceed the cost of buying Lithium batteries at today's prices? This is answered by the "Total Miles" row under the "Equal Lithiums" section.

The Range figures were obtained from EV Calculator, using a '92 Metro, ADC FB-4001A, Kelly controller, battery specs available online, Range calculated to 80% Depth-of-Discharge, and a driving mix of 85% @ 30-40mph in 2nd gear and 15% @ 60mph in 3rd gear.

Here are my calculations. I'll let you interpret the numbers as you like. Sorry it's showing up triple-spaced; I can't find a way to correct that.

Cost

Battery Mftr / Model

Analysis

Prices as

Optima

Trojan

Discover

Sky Energy

of 6/15/09

D34M

T-1275

EV31A-A

SE100AHA

Battery

Detail

Chemistry

SLA-AGM

FLA

SLA-AGM

LiFePO4

Cost, $

188

200

490

121

Source

amazon

batteriesin

batteries

evcompo

.com

aflash.com

direct.com

nents.com

Voltage, V

12

12

12

3.2

Weight, lbs

43.5

84

74.1

7.04

Capacity, Ah

55

150

115

100

System

Detail

#(batts)

12

10

12

45

Voltage, V

144

120

144

144

Pack cost, $

2256

2000

5880

5445

Capacity, Wh

7920

18000

16560

14400

Weight, lbs

522

840

889

317

Range, mi

25

40

35

60

#(cycles)

600

600

600

2000

Miles/pack

15000

24000

21000

120000

Electricity, $

428

972

894

2592

(@9¢/kWh)

Total, ¢/mi

17.9

12.4

32.3

6.7

120K miles

#(packs)

8

5

6

1

Total miles

120000

120000

126000

120000

Cost, $

21469

14860

40645

8037

(incl. elec.)

Equal

Lithiums

#(packs)

3

3

1

1

Total miles

45000

72000

21000

120000

Cost, $

8051

8916

6774

8037

(incl. elec.)