Hi BLF!
A friend of mine gave me as a gift a brand new still in box old dumb GP nimh battery charger which includes 2x 2700 mAh AA cells.
The problem is that one of the batteries has some kind of sustance coming out of the vents of the positive pole…
It is some kind of thick white dust…
Is it safe to use?
I still have not open the package….
Thanks in advance
Just try them.
The one with the unidentified white dust is probably ruined, though…
What a pity… They are not eneloop, but 2700 mAh real capacity is good too.
I will try and see
Ok… They dont leaked… One of them had white powder coming out the positive pole.
Ok… I finally opened the package.
I managed to clean the powder…
The problem is that BOTH batteries are at 0 volts.
Dont know how many years the blister was resting without being sold and used. Maybe more than 10 years.
Obviously, none of my chargers want to charge them.
The smart chargers… Some dont see them when I put them to charge… Some refuse them instantly
The dumb chargers seems to show “charging” but after more that 1 hour the batteries are at 0 volts.
What a waste…
Anyone knows a way to revive them?? (If there is a way to…)
Thanks!
Sounds like they may be done for.
I don’t think i’ve ever seen a NiMH battery at 0.0 (zero) Volts.
The white powder could be due to a leak, maybe what leaked dried up so maybe it’s some crystallized metal oxide.
Maybe they had a couple of too hot summers…
.
I’ve never seen 2700mAh NiMH AA’s before.
I doubt they exist now, let alone 10 years ago, so may be a little too ambitious claim.
My personal experience with the GP brand is not that good either.
They are over priced and don’t last long (it seems they slowly die in a number of recharges…)
Yep… 2700 mAh do exists.
Sanyo has them… I already have 2700mAh genuine sanyo cells… (They are not as good as eneloop… In fact they are not LSD, they are regular nimh)
And gp also have 2600 and 2700.
They are the highest true capacities as far as I know.
And yes. These gp 2700 are totally dead. No way to recover. Internal short circuit…m
However… If someone knows a miracle…
I got some Ikea NiMh batteries a few years ago that were at 0.0 volts. Had to charge them for a bit on a dumb charger in order to have a smart charger recognize it. After a few refresh cycles they performed as well as any of the other ones I got from Ikea.
I’ve also had some Rayovac batteries go down to zero in a motion sensor and they recovered fine after refreshing them.
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.
I will try bursts at 12v
I’ve “sparked” cells by hitting ’em quick with blasts from a 12V-18V laptop adapter, but in theory, you want to control/limit the maximum zappage by using a cap.
Then again, I recall someone using a Lionel train transformer the size of an anvil to electroshock some cells back to life (mightta been NiCd). Yeah, AC. Worked, but I wouldn’t try it.
How many amps do I need to use? Should I limit the current??
For Ni-MH to develop internal “short circuit” it must be reverse polarized (like what can happen to some cells when you over-discharge a series battery pack) and let it rest without recharging some time. A friend of mine did this to a drill pack he had, he discharged it and let it rest without recharging a few days. Sometime later I had the pleasure to service his pack, for obvious reasons. The moral of this is always recharge a discharged series Ni-MH/Ni-CD pack as soon as possible at least a few minutes, for quick cell de-reversal. Of course damaged cells by reverse polarization don't become dead shorts, they still pose good burdening resistance (the damaged pack could work but quite badly).
So, did you set the GP cells in a charger? I guess not. Do it! If the charger refuses to charge them, set them in parallel with some good battery, be it alkaline, Ni-MH, LiFePO4 or even li-ion, and connect both cells in a pulse width modulation way, i.e. give it a good bunch of zaps until the GP cells measure at least ≈0.7 V with a multimeter. If using alkaline just connect 'em dead flat for maybe half a minute tops, alkaline cells have quite high internal resistance so no current inrush problems. 
Sorry didn't pay attention to this, I find it quite funny. :-D
To limit the current set your own built in constant current converter to some safe value like 100 - 300 mA, for example. ROFLMAO!!! 
Translation: see my post above.
I had a couple of 26650 Goalisi high drains do the same.
Thaaaaat’s why you want to use a big capacitor instead.
Yeah, hitting a cell with 12 Volts or something can surely work.
I had an Aspire 18350 drained to the bone (zero volts), and then i hit it with short 12 Volts bursts from a lead acid battery, making sparks and the battery got pretty warm too, and i stopped when it had reached 2.7 Volts or something, and then i gave it 2 charging cycles, and it seems to have worked well enough.
Wait, i’ll put it in the charger for a NOR test.
(I’ll report back on it)
Update.
Thanks to all of you who tried to help me.
Finally (I am crazy!!!) I connected them to a 12v car battery with thick wires… Only touch and release… For less than a second…. Positive to positive and negative to negative.
The one which did not had white powder, instantly got the voltage up to 1.3volts (in less than a second).
Now the chargers “see it” and it is being charged at 0.5Amps.
I stopped the charge, put it in a flashight and it seems to work….
Lets see what happens after a few cycles lf full charge and discharge…
The one which had the powder… Did the same… Touched + with + and - with - with the car battery for less than a second.
The voltage raised to 0.9… Then slowly dropping… I touched again the car battery and voltage raised to 1.2 and drops fast.
This cell still is not detected by any smart or dumb charger…
Lets experimemt