What temperature should NiMh batteries get up to when being recharged?
Have four Sony brand AA being recharged in the Sony brand recharger they came with. They feel very hot to me.
Might be time to claim a warranty swap.
Depends on how much current it's pushing into them. At medium/low currents, it's generally considered charged when cell temperature rises 5C above starting ambient. However, at fast charge rates, it's "normal" for them to heat up past that anyway. My charger heats some AAs to fairly warm. Wouldn't quite say hot though. I've read some reports (with my charger) that with some batteries, they can get quite hot at completion of charge, so expect that to be 'normal'.
I'd also hazzard a guess and say if you do warranty swap, you'll see the exact same thing happen again.
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Thanks. Helpful. It was normally 24hours to charge up the AA. Trouble is I have no idea of the actual capacity (~700 digitial images in the camera is the only clue), so I have no idea if that is fast or slow.
Well, at least I'll have lights then. After I posted, the led went out (orange for charging, green for charged), so I'd say the unit is cactus.
Most chargers with maximum temperature cutoff are set to around 45C.
However, how hot the batteries get during charging is a function of how much current you're putting into them - for example, with a typical overnight trickle charge (0.1C), I wouldn't expect the batteries to get noticeably warm at all, while with a 15 minute fast charger, I'd expect them to almost get too hot to touch.
Peter
Have a look at:
For some details of charging NiMH Batteries.
Alan
It's normal if they are "fast" charge. The Varta 15 minute, AA NiMH charger elevates the 2 AAs temperatures to bordering on hot. Its one of the best rechargeable battery setups I've used.
Jason
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