What to do when batteries won't charge?

phouton · 2019-12-25T04:32:05.000Z

I have a bunch of Sanyo NiMH AA (2500mAh, made in Japan) rechargeable batteries and some no name AAAs which my Panasonic CC-BQ17 smart charger refuses to charge.

The AAs measure at ~0.9V and the AAAs ~0.8V. They haven’t been used in some time, and were previously charged with a “dumb” charger.

Is there a way to recover them?

Lightbringer · 2019-12-25T06:30:07.000Z

Go back to the dumb charger?

“Smart” charger indicate why it won’t charge?

phouton · 2019-12-25T06:35:20.000Z

That smart charger only has LEDs that indicate charging/error/done.

Good point, I should try the dumb charger which got put aside. I think that was maybe not charging them either, but I don’t remember the details or what its LED indicators mean.

Jeffzhou2019 · 2019-12-25T08:21:30.000Z

@Phouton,The cut off voltage for 1.2V Ni-MH AA AAA battery is 0.9V, if the cell voltage keep at 0.9V or less than the 0.9V after charge. Means the battery is bad battery.

Henk4U2 · 2019-12-25T09:11:46.000Z

Put them in a “dumb” charge until they are “charged”. Then give them some refresh cycles in a smar charger.

I guarantee no results. One in a while I come across a LiION that is refused by my Opus because: out of sight is out of mind. But most of the time a few seconds in a charger with a revive or 0-Volt mode are enough to get them accepted again by my Opus. And they lived long and happily.

Barkuti · 2019-12-25T11:16:42.000Z

As to why smart stupid chargers refuse to charge Ni-MH cells below a certain thresold is a mistery to me. In my experience deeply over-discharged Ni-MH cells worked fully fine after 2 or 3 refresh recharge cycles.

Dumb chargers for the win!!! :CROWN:

chops728 · 2019-12-25T12:49:20.000Z

Hook your low batteries to a battery with more power for a few seconds ( jumper wire—foil —etc) —this will bring the voltage up high enough to trigger the charger—- I had to jump off some Eneloops out of a soap dispenser—–2 of the 4 batteries were below spec— worked great

Henk4U2 · 2019-12-25T13:13:15.000Z

Ah, the kiss of life!

Please correct me if I’m wrong: Plus to Plus, and Minus to Minus.

chops728 · 2019-12-25T13:13:58.000Z

phouton · 2019-12-25T19:46:01.000Z

Thanks for the suggestions. Tried the dumb charger and it too seems to indicate an error by flashing the charging LED. Measured voltage at 1.24V after “charging” only a couple of minutes. Putting into a flashlight, the brightness dropped to zero in a matter of seconds. Measuring voltage again, it seemed to have dropped to ~0.9V but it was increasing to 1.2V as I was measuring.

The smart charger gets it to 1.3V in a few seconds before stopping with the error indication, and the battery’s behavior is the same.

So it looks like the voltage isn’t stable, with huge sag when loaded, which superficially recovers when load is removed. Any idea how that happens? I’m guessing that means it’s dead?

Lightbringer · 2019-12-25T19:52:40.000Z

You could try blasting it some more, but if that doesn’t blow out what’s clogging it, dump it.

Got a Lionel train transformer?

phouton · 2019-12-25T20:54:25.000Z

Blasting how? Both the smart and dumb chargers stop after a few seconds. The “kiss of life” boost from another battery?

No, what is a Lionel train transformer?

Lightbringer · 2019-12-25T21:07:11.000Z

phouton:

Blasting how? Both the smart and dumb chargers stop after a few seconds. The “kiss of life” boost from another battery?

No, what is a Lionel train transformer?

Assumed you were following all the other similar threads.

Ni-Mh cell with white dust/powder in positive pole Rechargeable Batteries

Dunno NiMH cells but used to regularly blast NiCd cells to blow out the internal “whiskers” that’d develop. A few thousand µF charged to 12V or so, just keep hitting it ‘til the voltage would start to rise. Worst offenders might need a whole bunch of hits in Ol’ Sparky to come to life. Need to blow the fuses (whiskers) that keep the cell shorted out before it could keep any charge.

and

Ni-Mh cell with white dust/powder in positive pole - #13 by Lightbringer .

phouton · 2019-12-25T21:19:38.000Z

Oh that thread. I hadn’t seen the latest posts. That issue is about cells showing 0V, but mine are 0.9-1.3V with major sag when loaded. Should they be treated similarly?

Cereal_killer · 2019-12-25T21:27:51.000Z

Nah, stick them in the microwave for 45sec!

phouton · 2019-12-25T22:05:42.000Z

Cereal_killer:

Nah, stick them in the microwave for 45sec!

Brilliant, I’ll save that for New Year’s Eve.

chops728 · 2019-12-25T22:30:23.000Z

Sounds like Recycle Time to me

Kevin_Z · 2019-12-26T00:31:03.000Z

phouton:

Cereal_killer:

Nah, stick them in the microwave for 45sec!

Brilliant, I’ll save that for New Year’s Eve.

Don’t be silly

Kevin_Z · 2019-12-26T00:31:25.000Z

Save it for November 5th

Lightbringer · 2019-12-26T00:33:44.000Z

phouton:

Cereal_killer:

Nah, stick them in the microwave for 45sec!

Brilliant, I’ll save that for New Year’s Eve.

Excellent! Celebrate Val Kilmer’s birthday!