Low discharge rechargeable batteries - failures?

[Dave2002]

I found a couple of low discharge rechargeable batteries in a computer mouse the other day. These were a pair of Uniross AAs - normally good. My charger is suggesting that they both have faults, and it doesn't seem to be possible to charge them.

I can accept that they've failed, but what goes wrong with them? Normally this type of battery does recover if they haven't completely lost charge. Although they will have been cycled quite a few times, I very much doubt that they have been cycled as many times as the specification claims to be possible.

There doesn't seem an obvious failure, such as leaking or swelling.

Perhaps not a big deal as I picked up some similar type of batteries from LIDL today at a reasonable price - 4 AAs and 4AAAs.

[Frances_iom]

depends on type but assuming NiCd - often they grow small internal whiskers that lead to complete discharge - if you think they are dead and have nothing to lose then get a 12V battery and a reasonable size capacitor (few microFarad) - charge the capacitor via the 12V battery then discharge it via the cell and then see if a now whiskerless cell will recharge - do NOT try to use the battery direct to the cell - nor try this with a Lithium Ion cell unless you want a firebomb!

[Bryn]

depends on type but assuming NiCd - often they grow small internal whiskers that lead to complete discharge - if you think they are dead and have nothing to lose then get a 12V battery and a reasonable size capacitor (few microFarad) - charge the capacitor via the 12V battery then discharge it via the cell and then see if a now whiskerless cell will recharge - do NOT try to use the battery direct to the cell - nor try this with a Lithium Ion cell unless you want a firebomb!

If they are low discharge, they are almost certainly modern NiMHs. I don't think NiCds are available for sale any more, due mainly to their environmentally hazardous Cadmium content. They have been illegal to sell for domestic use in the EU for some years. They may be used for certain medical and some other industrial applications, IIRC.

[Dave2002]

If they are low discharge, they are almost certainly modern NiMHs. I don't think NiCds are available for sale any more, due mainly to their environmentally hazardous Cadmium content. They have been illegal to sell for domestic use in the EU for some years. They may be used for certain medical and some other industrial applications, IIRC.

I didn’t know that NiCds are now illegal - I may still have a few. Why would anyone want those anyway, as the NiMHs are much better?

[Bryn]

I didn’t know that NiCds are now illegal - I may still have a few. Why would anyone want those anyway, as the NiMHs are much better?

Not illegal to own or use. they are, though, banned from sale, and must be recycled responsibly, as in through shop battery recycling schemes.

[Dave2002]

Not illegal to own or use. they are, though, banned from sale, and must be recycled responsibly, as in through shop battery recycling schemes.

I’m not sure whether I still have any NiCds. I used to have a whole bunch, but as I started to replace these with newer NiMHs I first used to use these as well - “in parallel”, but eventually decided/realised there’s no point as the NiMHs are better, and are now down to low prices. Occasionally I find an old NiCd which gets added to my dispose pile for recycling.

I do find that some rechargeables do now get into the recycle pile though, as some do seem to fail and can’t be rescued - including some NiMHs. It used to bother me as those used to be relatively expensive.

[Pulcinella]

My Energizer recharger seems only to accept Energizer batteries (I have checked that the others I have tried using are indeed NiMH not NiCd, in case that was the problem).
How can this be?

I have another charger that works satisfactorily with them.

I too have had some failures. I guess, as with batteries for iPads etc, the received wisdom is to let them drain completely every once in a while and give them a 'real' recharge, rather than keep them 'topped up' (though use in a cordless phone almost invariably means that the batteries are constantly getting topped up in the phone cradle).

[Bryn]

My Energizer recharger seems only to accept Energizer batteries (I have checked that the others I have tried using are indeed NiMH not NiCd, in case that was the problem).
How can this be?

I have another charger that works satisfactorily with them.

I too have had some failures. I guess, as with batteries for iPads etc, the received wisdom is to let them drain completely every once in a while and give them a 'real' recharge, rather than keep them 'topped up' (though use in a cordless phone almost invariably means that the batteries are constantly getting topped up in the phone cradle).

Curious. I have a couple of Energiser fast cargers for AA and AAA types. They handle any make of NiMHs.

[Pulcinella]

Curious. I have a couple of Energiser fast cargers for AA and AAA types. They handle any make of NiMHs.

Curious indeed!
I've just tried putting four Uniross batteries in to charge up, and I get a couple of 'faulty battery' symbols show up each time.
Even more curiously, switching the positions of the batteries reveals no correlation between the battery and the symbol.
I've just put them in another charger and will test their charge after a while!

[Dave2002]

I've just put them in another charger and will test their charge after a while!

I'll be interested to know if that succeeds. I have occasionally had success with that, but my latest charger (LIDL) bought a few years ago does battery reconditioning, and checks, and usually if it says the batteries are dud they can't be revived.

[Bryn]

I'll be interested to know if that succeeds. I have occasionally had success with that, but my latest charger (LIDL) bought a few years ago does battery reconditioning, and checks, and usually if it says the batteries are dud they can't be revived.

Way back in the mists of ancient time I recall a chemistry lesson in which the operation of zinc/carbon cells was discussed. The problem of a thin insulating film of hydrogen forming inside. This might be temporarily dispersed by mechanical action, i.e. banging the cell on a hard surface. One could get a little more service out of such a cell by this action. I have found similar success with some supposedly 'dead' NiMHs. Though in this case, it is perhaps a case of the shock braking up the crystal filaments mentioned earlier in the thread.

[Pulcinella]

Premature and unscientific previous reports!
Looks like I have (at least) one duff battery in each of a set of four non-Equalizer batteries I have lying around (Uniross and Fusiomax); though the Equalizer charger has a 'faulty battery' light under each of the batteries inserted, the faulty lights seem to operate in pairs, probably making me think I had some incompatability issue.

Time for a cull anyway, I think.
I'll keep my newer Equalizer batteries.
I don't use that many (Mac keyboard and mouse, primarily), so it's a bit silly to have a stock of which some might not be in that good condition.
Looks like the charger behaves OK with non-Equalizer batteries, Bryn, as you supposed.

[Dave2002]

I think, also, if there's a LIDL in your area, that this coming week they have AA and AAA rechargeables on offer - 4 for £2.99.
I may have paid slightly more than that the other day.

I have used quite a large number of batteries over the years, both non rechargeable, and rechargeable. Some do seem better than others, but the prices are overall coming down, and as replacements for ones needed in a hurry the LIDL ones seemed to me to be good enough.

Some applications seem to require non rechargeables.

Interesting the tip about banging the batteries - I might try that. Hammer at the ready!

[Pulcinella]

I think, also, if there's a LIDL in your area, that this coming week they have AA and AAA rechargeables on offer - 4 for £2.99.
I may have paid slightly more than that the other day.

I have used quite a large number of batteries over the years, both non rechargeable, and rechargeable. Some do seem better than others, but the prices are overall coming down, and as replacements for ones needed in a hurry the LIDL ones seemed to me to be good enough.

Some applications seem to require non rechargeables.

Interesting the tip about banging the batteries - I might try that. Hammer at the ready!

I have some non-rechargeables (Kodak, from Poundland!) for that eventuality.

[Dave2002]

I have some non-rechargeables (Kodak, from Poundland!) for that eventuality.

Depends on the application. I had some cheap Kodak batteries from Poundland - described as Heavy Duty, but were anything but. Absolutely useless in my camera - even from new. On the other hand they would probably keep a battery clock going for the best part of a year.

I tend to keep a few Duracell or similar - bought cheaply - for applications where rechargeables won't work, or for batteries needed in a hurry.