A123 M1 Lithium cells for robot power
The Lithium Iron Phosphate (LiFePO
4), also know as Lithium nano-phosphate,
M1 cells produced by
A123Systems promise to provide a high performance rechargeable
cell, substantially lighter than NiCads, suitable for use in
fighting
robots, without the disadvantages of current LiPo technology (fire risk,
short life, fragility, limited current handling, high cost).
Advatages of M1 Lithium batteries
- Lightweight - finished 34V 2.2Ah battery pack = 0.9 kg.
- Similar cost to good NiCads - around £90 for 10 cells (34V) on eBay.
- High current ability - up to 70 Amps continuous. Less when built into a pack.
- Fast charging - 10 Amps is fine.
- Safe - Do not suffer from thermal runaway. Enclosed in a metal case.
- Long life - over 1000 cycles if not abused.
- Only require a very simple voltage cutoff charger if not balancing.
Disadvatages
- Life will be reduced if cells are over charged, so cells in a pack need to be carefully balanced,
or a cell monitoring charger used.
- The cells will be damaged if deep discharged - must avoid any cell being discharged below 2 Volts.
- Do not like getting hot - if the cells get to over 60ºC, their life will be reduced significantly,
although this may be acceptable in this sort of application.
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John Reid 2007