Li-Ion vs. Lead Acid

Li-Ion vs. Lead Acid 2 Ultralife Corporation Summary of Li-Ion advantages compared to Lead Acid • Li-Ion Advantages – Higher voltage in Lithium Ion over Lead Acid 3.7v vs 2.0v (almost 2x) – Greater Energy Density per unit Weight (3x), Volume (6x) – Lighter / smaller providing more portability, less storage space, could eveneliminate storage boxes – Tolerates Higher Temp (140F vs 80F), No Air Conditioning required (vs spending 10% of capacity) – Faster recharge time, and Moretime between recharges (26 wks vs continuous or max 2 wks) – Higher turnaround chargeefficiency (97% vs 75%) – More Discharge Cycles (2x) – Deeper Discharge Tolerance (95% vs 50%) – Can offset costdue to shallow Lead Acid discharge – State of Health and State of Charge can be readilyand remotely monitored – Longer time between service (24-36+ mos vs 6 mos) – Replacement timeframe Li-Ion 5-7 years Lead Acid 1.5 - 2 years • Li-Ion Disadvantages – Li-Ion Protection Circuitry is custom & expensive – Lead Acid Overall Circuitry is Commercial off the Shelf (COTS) & inexpensive – Li-Ion volatility must be closely managed and addresses with safety considerations in design – Individual Cell cost ROM Li-Ion $300-$400 / kWhr vs Lead Acid $80-$100 / kWhr – Sys Cost (with circuitry) ROM $500 / kWhr $125 / kWhr 3 Ultralife Corporation Details of Comparison: Lead Acid - Li-Ion Lead Acid Li-Ion (Cobalt) • Energy Density • Nominal Cell voltage 2.0v 3.7v • Voltage operating range 1.8-2.1v 3.2-4.1v • Wh/kg 35-40 140-150 • Wh/liter 70 400 • Size of a 1 kWh battery 14 Liters 2.5 Liters 873 cubic inches 153 cubic inches • Weight of a 1 kWh battery 25kg, 55lbs 6.7kg, 14.8 lbs • Size of a 1 MWh battery 14,285 Liters, 2,500 Liters, 504 cubic feet 88 cubic feet (1/2 of a 20’ shipping container) • Weight of a 1 MWh battery 25,000kg, 6,700kg, 55,115 lbs 14,770 lbs • Reference sizes and weights – 20 Ft Shipping container 1160 cu ft, 4928 lbs – 40 Ft Shipping container 2360 cu ft, 7392 lbs 4 Ultralife Corporation Details of Comparison: Lead Acid - Li-Ion Lead Acid Li-Ion (Cobalt) • Temperature Requires Air temp Control >75F Loses 50% every 10F >77F – High temp Survival / Life Reduction OK to 25C (77F) OK to 60C (140F) Life % remaining atDisch Temp 100% at 77F 100% 50% at 87F 100% 25% at 97F 100% 12% at 107F 100% 6% at 117F 100% 3% at 127F 100% 0% at 137F (60C) 100% – Low Temp (Partial Functionality) To -40C To -25C • Charging – Over-chargeability Tolerant (forms H2 gas) Intolerant - Vents – Protection Circuitry COTS, inexpensive Custom, expensive (Overvoltage and Discharge) – Constant Charging rate in terms of C 0.07C rate C rate (10x faster) – Recharging time duration 10 x the capacity 1x the capacity – Recharge interval needs recharge weekly needs recharge every 6 mos – Turnaround Charge Efficiency 75% 97% – Temp range of Charge -40C (-40F) – +27C (80F) -20C (-4F) – + 55C(131F) – Cost to recharge (as % of capacity) Self Discharge %/month or year 8%/month, 63%/year 1.5%/month, 17%/year 5 Ultralife Corporation Details of Comparison: Lead Acid - Li-Ion Lead Acid Li-Ion (Cobalt) • Operation • Voltage profile (duringdischarge) Sloping Flat • Failure mode will not acceptcharge predictive based on cycles • (assumes traditional control circuits) and efficiency • Cycles – At 10% discharge 1750 4000+ – At 50% discharge 500 1000 – At 95% discharge 250 500 • State of charge measured by Voltage level Coulombs transferred Rough Exact • Costs • Cell cost $80-$100 / kWhr $300-$400 / kWhr • Assembled Sys Cost (with circuitry) $125 / kWhr $500 / kWhr • Maintenance costs and frequency SLA = 2% None •VRLA=10% • Operating costs – Air conditioning 8% ofcapacity None required – Service Interval 6 mos 12 mos • Replacement timeframe 2 years 5-7 years – Assumes life is not limited by number of discharge cycles, instead by time