Rechargeable Battery Efficiency
Rechargeable Battery Efficiency
(OP)
Does anyone have any data on the efficiency of rechargeable batteries. Something like (useable energy out)/(energy in) times 100, for one cycle. I could not find anything on this on Google. I am thinking of batteries of the type that can be found in a modern hybrid car.
HAZOP at www.curryhydrocarbons.ca





RE: Rechargeable Battery Efficiency
JMW
www.ViscoAnalyser.com
RE: Rechargeable Battery Efficiency
Used over less than their full range lead acids are pretty much 100% for coulombic, and around 90% for resistive. If you try to deep discharge them, and fully recharge them, the overall efficiency rapidly drops to 75% or worse. Also, the coulombic efficiency drops rapidly as you increase the current, this is called Peukert's effect. Energy density is say 30 Wh/kg
Early Priuss used NiMH, 60 Wh/kg, see http:/
for efficiencies. That article also has NiCd batteries, which would need very careful management in a hybrid.
Actually that's a good document, as it makes clear there is no such thing as one efficiency number for a given battery. say 1.0/1.2 coulombic, and 1.27/1.4 resistive, ie 75% overall
The next step in hybrid batteries is some sort of Lithium Ion based system. 86% resistive, very non linear coulombic efficiency. If you can figure out how to use them these are the best bet.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Rechargeable Battery Efficiency
HAZOP at www.curryhydrocarbons.ca
RE: Rechargeable Battery Efficiency