LFP Batteries - Frequently Asked Questions
Q: How much do Lithium LFP batteries cost?
A: The price is about double that of quality Lead Acid batteries. However Lithium batteries have many times the discharge cycle life of Lead Acid. They will also deliver almost their entire amp hour capacity at high rates of discharge. This makes the total cost of ownership for Lithium cells lower than Lead Acid.
Q: How does the capacity of a Lithium Battery relate to Lead Acid.
A: A Lithium LFP battery can be about 60% of the capacity of a Lead Acid battery and still deliver a similar amount of energy. This is because Lithium batteries can be routinely discharged to a deeper level than Lead Acid without damage. They are also more efficient at returning the stored energy.
Q: How long will they last?
A: They should last at least 2000 cycles at 70% depth of discharge (DOD). However much depends on how they are treated. A battery management system (BMS) is important. Rapid improvements are being made constantly.
Q: Do they require maintenance?
A: No they are completely maintenance free for their entire life.
Q: Lithium Ion Batteries can explode and catch fire can’t they?
A: Under normal circumstances with a good BMS no. However if ruptured of incorrectly discharged and charged the cells can die an early death and may catch fire because of the organic electrolyte. The LFP series are much safer then Lithium-Cobalt and Lithium-Manganese batteries.
Q: You also supply 12V batteries. Do they require a BMS?
A: The 12V series are actually 4 LFP cells in one package. They do not have any management. For systems of more than 12V nominal individual cell management is recommended.
Q: Can the cells be mounted in any position?
A: Yes, there is no evidence of cell degradation if mounted on their side.
Q: My batteriies have run flat and I cannot recharge them?
A: This is a very bad situation! The only chance to resurrect them is to use a very small trickle current to get each cell back up to 3.2V. Then they can be recharged normally. Most likely they will be permanently damaged and require replacment. DO NOT ALLOW LITHIUM BATTERIES TO RUN FLAT. YOU HAVE BEEN WARNED!
Sky Energy vs Thundersky Comparison
A series of tests were performed on equivalent capacity Sky Energy (CALB) and Thundersky LiFePO4 cells. The results are in this report
LEAD ACID vs LITHIUM ION in an ELECTRIC VEHICLE
Some stats on the Electric Mighty Boy. The conversion was completed August 2004. Originally it had Lead Acid batteries which were upgraded to Lithium Ion (phosphate) in Feb 2007.
A kWhr meter was permanently connected in the cab on the AC side of the on-board charger so the measurements shown here are from wall-to-wheels which is the most honest measurement of electricity consumption for an EV. Measurements are up to December 2008.
LEAD ACID (flooded, 12 x TROJAN SCS225, 312kg, batteries exhausted at end)
time used - 29 months
average speed (estimate) - 65-75kmh
distance travelled - 10741 km
energy consumption - 2811 kW hr
fuel economy 261.71 Whr/km (421.18 Whr/mile)
LITHIUM ION (phosphate, 45 x LFP90AHA, 135kg, batteries still good Jan 09)
time used - 23 months
average speed (estimate) - 70-80kmh
distance travelled - 15151 km
energy consumption - 2843 kW hr
fuel economy - 187.64 Whr/km (301.98 Whr/mile)
LEAD ACID - 421.18 Whr/mile
LITHIUM ION - 301.98 Whr/mile
