[Moru]

Just to clarify your point there: Charging batteries as pairs is what kills the rechargeable batteries. There is no way for the charger to keep track of both batteries at the same time so it just charges until both should be done.

If one of them is bad, the charger will kill the other one too. If they are differently charged, it will kill one of the batteries and next time it will kill the other battery. (Kill as in make worse and worse until it finaly doesn't charge at all.)

I have mostly stopped using rechargeable AA and AAA batteries because of the bad quality of the last ones I bought. They took 3-5 charges before dying with a good charger that does all batteries separately.

[MaKey]

Modern chargers are microprocessor controlled and are able to keep track of each battery individually.

[Moru]

Yes, but only the ones that does not require charging in pairs. Most people only use the bundled chargers and they all work with pairs.

[alliao]

I have an eneloop bundled that charged individually... BQ-CC55

[mnw21cam]

I have never seen a charger that charges in pairs. Every charger I have ever used or seen has charged each cell individually. Charging in pairs is a terrible idea - the chargers should be returned as unsuitable for purpose.

[jandrese]

This is what killed me when I started swapping Alkalines for NiMH in the 00s. Every single charger sold in stores only charged in pairs, and because even then USB was creating a 5V world most things that needed batteries used 3 of them.

Even the charger that Panasonic sold with the Eneloops requires matched pairs.

The other issue being that NiMH seems to top out at AA size. Finding C or D sized rechargeables is basically impossible.

[2muchcoffeeman]

There is a more expensive eneloop charger that does individual cells. I have been mixing cells for charging for years with no problems.

[exhilaration]

I got the Panasonic advanced charger (BQ-CC17) in 2016, it charges individual batteries. Amazon link:

https://www.amazon.com/Panasonic-K-KJ17M3A4BA-Individual-ene...

[zackees]

Also, NiMH batteries can reverse charge and ruin themselves. This happens a lot when batteries are in series and the load will continue to run the batteries until 0 voltage. The weakest battery will deplete first but then the other batteries will continue to pump current through until that weak battery reverses polarity and wrecks itself.

[hilbert42]

Correct, ages ago, I was testing a batch of them and came across several reversed charged ones. At first I thought I must have got my multimeter leads reversed but I found that was not the case.

For a long while I kept them to prove the point to anyone who thought I'd must have lost my ability to distinguish plus from minus.