LFP Batteries - Frequently Asked Questions
Q: How much do Lithium Ion batteries cost?
A: Lithium Ion cells are a relatively new technology, especially so in the formats of 40Ah and greater. Thunder Sky make some of the most cost effective batteries available. However the price is still 2-3 times that of Lead Acid. Any new technology requires time to grow the manufacturing capabilities and begin the automation that ultimately reduces the price.
However Lithium (phosphate) Ion batteries have several times the discharge cycle life of Lead Acid. They will also deliver almost their entire amp hour capacity at high rates of discharge. In EV applications Lead Acid batteries will barely deliver half of the rated amp hour capacity because of the Peukerts effect. This makes the total cost of ownership for Lithium Ion cells lower than Lead Acid.
Q: How long will they last?
A: They should last at least 1000 cycles at 70% depth of discharge (DOD). However much depends on how they are treated. A battery management system (BMS) is important. In terms of time it is unknown because this technology hasn’t been around long enough. However 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: Thundersky also supply 12V batteries. Do they require a BMS?
A: The LP 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: Its best if they are mounted upright and all together in one pack. Engineer your vehicle around the batteries, not the reverse.
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!
20. LFP Battery Usage Guide
Features: 1C continuous current, 3C short duration current, high capacity at high current, robust, longer life cycle than lead acid, high Coulomb efficiency, excellent for traction drive applications.
please note - when sizing cells for an electric vehicle application the average (cruising speed) current draw should be maximum 0.8CA and the peak current draw should be less than 3CA (C is the cell capacity in Amp hours) This will ensure the longest life for the batteries.
- LFP40AHA - suitable for scooters and motorbike applications.
- LFP60AHA - Also most suited for scooters and motorbikes.
- LFP90AHA - best used in small cars up to 900kg at 144VDC, >60km range.
- LFP160AHA - for larger cars up to 1300kg at 144VDC, >120km range
- LFP200AHA - for very large cars to 1800kg.
- LFP260AHA - new range for very large cars and trucks.
- LFP400AHA - for very large applications such as boat and household power supplies.
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
Curtis 1231C Wiring Diagram
It is very important that A2 is left unconnected on road going vehicles. This is used for plug braking on NEVs only. Please note that this wiring diagram is a suggestion only and EV Power takes no responsibility for any errors or ommissions which might result in damage or injury or death.
See the official Curtis 1231C specifications here
We recommend Advanced DC motors for use with Curtis Controllers. Other types of series DC motor can cause controller damage in certain circumstances.
