Anyone got any ideas about rejuvenating some AA NiMH batteries?
All these are being rejected by my charger as faulty, measuring them with multimeter, some are reading 0.00 volts, some reading between 1.2 and 1.3 volts, but these will power a torch for only a very short time before the bulb fades away to nothing.
I've never found one. Some say a massive pulse of current will sort them out, but IME once they are dead they are dead so to speak.
I'm afraid I cannot really help with NiMH batteries, but Nicads used to have a variety of approaches to recondition them.
Try uk.radio.amateur, the number of batteries turning up at radio rallies and junk sales used to make electrochemical experts of us all.
HN
The do not seem to respond to the nicad fixing ideas of big current pulses or freezing for long periods. One supposes that the internal shorts have done more damage or are unshiftable.
Brian
I had nothing but trouble with various brands of these - duracell, energizer and a german make eismann or similar, the crappy charger didn't seem to put anything in them, and I tried a few different chargers. I then started charging them 8 at a time in a 12 volt handset that has a recharging socket. Blasting 12v through them sorted the bastards out, although they get hot (not warm - hot!) after about an hour, but then they work all week in things like radios, torches cameras etc
How did you attach the 8 batteries to the 12v charger?
You can buy 8 in a pack AA cell holders, which has them in series, then just connect across the 12v.
I mean polarity wise. Do you match +/+ or +/-?
To charge them, +ve of charger to +ve of batteries.
The ones reading 0 are likely stone dead. Anything above a volt is probably recoverable but how much charge it will hold is anybodies guess. You want to try them in a dumb charger that will charge individual cells at a modest rate and for a fixed time.
They probably are faulty so watch out for signs of electrolyte leakage overheating and in extremis fire! ie don't put them on charge for 10-14 hours and forget about them or you may be in for a nasty surprise!
If they're reading zero volts they could be fine but being falsely rejected by a typical zombie "intelligent" charger. Trickle charge them on an old-fashioned bog standard charger until the volts go to
1.3-ish then a fast charger will accept them (or possibly not).rusty
Sling them in the recycle bin along with most / all of your other rechargeables. Then buy some Sanyo Eneloops and realise that all the hours and money spent on lesser rechargeables and rejuvenating etc simply isn't worth the effort.
(no connection etc except as a very satisfied customer)
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