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Studies on the Failure Mechanism of VRLA Batteries Under High Rate Partial State-of-Charge (HRPSoC) Operation. Asian Battery Conference September 4, 2009 Macao, China Enders Dickinson V, Ph. D. Director of Research and Development edickinson@axionpower.com Axion Power International
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Studies on the Failure Mechanism of VRLA Batteries Under High Rate PartialState-of-Charge (HRPSoC) Operation Asian Battery ConferenceSeptember 4, 2009Macao, China Enders Dickinson V, Ph. D. Director of Research and Development edickinson@axionpower.comAxion Power International New Castle, Pa Tel: +1-724-654-9300 www.axionpower.com Advanced Lead-Acid Batteries for Tomorrows Demanding Energy Needs
Overview • Overview • Brief introduction to Axion Power • Description of the Axion PbC®Battery • Micro Hybrid Market • Micro Hybrid Testing • VRLA Battery Test Results • PbC®Battery Tests Results • Conclusion 1
Axion Power: New Castle, PA • 75,000 sq. ft. Mfg. Facility • 50,000 sq. ft. New Facility
PbC®Lead Carbon Battery Standard VRLA Cell(“Lead-Lead”) PbC®Cell (“Lead-Carbon”)
PbC®Battery Benefits • PbC®Battery Benefits • Manufacturing approach leverages existing lead-acid battery production base • Eliminates performance issues with lead-based negative electrodes • Low cost: target x1.5 the cost of lead-acid • Fully recyclable • Weight reduction 5
European Hybrid Vehicle Market 1.1 M vehicles /year 18 M vehicles/year 80% 54% 34% 6
Micro Hybrid Testing • Test Requirements • Battery SOC accurate to vehicle manufacturer needs[2C Charge/Discharge at 50% SOC not relevant] • Vehicle recharges battery via alternator- Conventional CC/CV charging- Currents up to 150A- Voltage limited to 14.0–14.8 (temperature dependant)- Operates at 80-100% SOC • Most effective CO2 reduction with high charge acceptance Battery must recover charge as quickly as possible, maximizing start/stop frequency and thus CO2 reduction 7
HEV Charge Acceptance Profile Recovery ChargeLimited Sustained Charge14.8 Voltage Limit150 A Current Limit Variable Time to Recovery (Depends on Battery) 150 A 100 A 50 A 20 A 22s 33s 66s 165s START300 A; 1 sDischarge STOP50 A; 60 sDischarge 8
HEV Charge Acceptance Test Algorithm PCRV PDRV EODV Initial Counter SettingN=100 Dynamically Adjusted OverchargeCharge step time =25 sec + 0.05 x N(initial t = 30 sec)Imax = 100 A Counter IncrementEvery cycle:If PDRV > SP N = N-1If PDRV < SP N = N+1 TOCV 9
Test Results: Standard Lead-Acid 367 cycles: 44 seconds (Imin=51 Amps) 4029 cycles: 85 seconds (Imin=18 Amps) 10
Test Results: High Surface Area Carbon 367 cycles: 35 seconds (Imin=65 Amps) 4029 cycles: 68 seconds (Imin=25 Amps) 11
Test Results: Conductive Carbon 367 cycles: 36 seconds (Imin=61 Amps) 4029 cycles: 62 seconds (Imin=28 Amps) 12
Test Results: Axion PbC®Battery 367 cycles: 30 seconds (Imin=100 Amps) 4029 cycles: 30 seconds (Imin=100 Amps) 13
Conclusions • Conclusions • Micro hybrid performance and life expectancy of VRLA batteries (conventional and “advanced”) is nominal at best, especially when considering potential efficiency improvements under harsh start/stop conditions • Axion PbC®Hybrid Battery/Supercapacitoris potential solution for micro hybrid vehicle applications- Rapid and consistent charge recovery- Accepts high charge currents- Can be operated as add-on to avoid one-battery limits- Operates at variable states of charge (14-7 V)- Requires no “equalization” or “conditioning” charges • Future work at Axion will focus on laboratory and field vehicle testing 14