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?
Go back to the dumb charger?
“Smart” charger indicate why it won’t charge?
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.
@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.
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.
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:
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
Ah, the kiss of life!
Please correct me if I’m wrong: Plus to Plus, and Minus to Minus.
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?
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?
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.
and
Ni-Mh cell with white dust/powder in positive pole - #13 by Lightbringer .
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?
Nah, stick them in the microwave for 45sec!
Brilliant, I’ll save that for New Year’s Eve.
Sounds like Recycle Time to me
Don’t be silly
Save it for November 5th
Excellent! Celebrate Val Kilmer’s birthday!