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Large Format Carbon Enhanced VRLA Battery Test Results

EESAT 2009Funded by the Energy Storage Systems Program of the U.S. Department Of Energy (DOE/ESS) through Sandia

National Laboratories (SNL)

October 4 - 7, 2009Seattle, Washington

Presented by:Tom Hund

Sandia National LaboratoriesAlbuquerque, NM(505) 844-8627

tdhund@sandia.gov

*Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,for the United States Department of Energy’s National Nuclear Security Administration under Contract DE-AC04-94AL85000.

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Objective

Test Advanced Lead-Acid Battery Consortium (ALABC) technology for utility partial state of charge (PSOC) cycling applications. Utility applications may include:Wind farm energy smoothingPhotovoltaic energy smoothingUtility ancillary services

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Energy Storage System

East Penn Manufacturing Large format ALABC carbon enhanced absorbed glass

mat (AGM) valve regulated lead-acid (VRLA) for utility PSOC cycling applications

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Test Plan For Battery

Capacity. DC Ohmic resistance Float current Utility PSOC cycle test (10% DOD @

50% SOC) Final DC Ohmic resistance Final capacity

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Capacity Curve For Unigy II and Carbon Enhanced Battery

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

0 1 2 3 4 5 6 7 8 9 10 11

Discharge Time (h)

Am

p-H

ours Carbon Enhanced Battery, (AVR85-25)

Unigy II Specification, (AVR85-25)

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Alber Cell Impedance After Indicated Cycles

0

20

40

60

80

100

120

140

160

180

200

220

240

260

Cell 1 Cell 2 Cell 3 Cell 4 Cell 5 Cell 6 Cell 7 Cell 8 Cell 9 Cell 10 Cell 11 Cell 12

Cell #

Res

ista

nce

mic

ro-O

hm

0 Cycles5,547 Cycles7,734 Cycles8,529 Cycles

All Measurements at 100% SOCSum For All Cells = 2.2 to 2.7 milli-Ohms

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Ohmic Discharge Voltage Drop After Cycling

200 Amp Discharge After 8,529 Cycles100% SOC

25.60

25.70

25.80

25.90

26.00

26.10

26.20

26.30

26.40

26.50

-15 -10 -5 0 5 10 15

Time (ms)

Volts

-225

-200

-175

-150

-125

-100

-75

-50

-25

0

Am

ps

VoltsAmps

Battery Discharge Voltage Drop100% SOC

25.70

25.80

25.90

26.00

26.10

26.20

26.30

26.40

26.50

26.60

26.70

26.80

-250 -200 -150 -100 -50 0

Amps

Volts

8,529 Cycles7,734 Cycles0 Cycles

2.4 milli-Ohms

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Float Current

2.000

2.050

2.100

2.150

2.200

2.250

2.300

2.350

2.400

2.450

2.500

0 5 10 15 20 25 30 35 40

Time (h)

Volts

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

4.000

4.500

5.000

Am

ps

Cell 1 (V) Cell 2 (V) Cell 3 (V) Cell 4 (V) Cell 5 (V) Cell 6 (V) Cell 7 (V)Cell 8 (V) Cell 9 (V) Cell 10 (V) Cell 11 (V) Cell 12 (V) Current(A)

0.176 A @ 2.27 vpc

1.318 A

High V (Cell #2, 2.290V)

Low V (Cell #1, 2.247V)

Cell 11, 2.388V

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Utility PSOC cycle test at 200A(10% DOD @ 50% SOC)

20.00

21.00

22.00

23.00

24.00

25.00

26.00

27.00

28.00

29.00

30.00

0 100 200 300 400 500 600 700

Time (h)

Volts

20

25

30

35

40

45

50

55

60

65

70

Tem

pera

ture

(C)

Volts, Cycle #8,529Volts, Cycle #1,371Temp, Cycle #8,529Temp, Cycle #1,371

Volts1,000 Cy

777 Ah1,008 Ah833 Ah, Cycle 1,371

&990 Ah, Cycle 8,529

305 Cy

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Utility PSOC cycle test at 400 A(10% DOD @ 50% SOC)

15.0016.0017.0018.0019.0020.0021.0022.0023.0024.0025.0026.0027.0028.0029.0030.00

0 20 40 60 80 100 120 140 160 180

Time (h)

Volts

20

30

40

50

60

70

80

90

Tem

pera

ture

(C)

Volts, Cycle #5,547Volts, Cycle #1,909Temp, Cycle #5,547Temp, Cycle #1,909

186 Cy

Volts290 Cy

762 Ah802 Ah

780 Ah, Cy 1,909 &

795 Ah, Cy 5,547

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Capacity As A Function of PSOC Cycles

50

60

70

80

90

100

110

120

130

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 18,000 20,000

Cycle Number

% O

f Ini

tial C

apac

ity

East Penn Carbon Enhanced Battery (200A & 400A Rate)

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Initial and Final CapacityAt 200A

20.00

21.00

22.00

23.00

24.00

25.00

26.00

27.00

28.00

29.00

30.00

-200 0 200 400 600 800 1000

Amp-Hours

Volts

Cycle #8,529Cycle #0

Charge

Discharge

32°C 32°C

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Summary

The East Penn ALABC carbon enhanced large format VRLA has proven to cycle well at a partial state of charge. Final capacity at 200A after 8,529 PSOC cycles was measured at

851 Ah at 32 C. This is 102% of initial capacity measured at 32 C. During PSOC cycling the capacity exceeded 120% of initial

capacity after 8,529 PSOC cycles. Capacity increased after 3,400 cycles from a low of 87% of initial

capacity to over 120% at 8,529 PSOC cycles Capacity measured during PSOC cycling was much higher than

capacity after an extended rest Ageing Performance degradation:

Higher operating temperature (from 9 to 12 C above ambient) Fewer PSOC cycles (about 1/3 to 2/3 of initial number) Increased Cell voltage divergence at end of PSOC cycling

Future work will include an energy storage system for photovoltaic grid tied energy smoothing.