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

samgalax · 2019-12-24T23:16:47.000Z

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…

SIGShooter · 2019-12-24T23:44:24.000Z

Jerommel:

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…)

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.

Lightbringer · 2019-12-25T01:30:04.000Z

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.

Lightbringer · 2019-12-25T01:32:39.000Z

Jerommel:

The one with the unidentified white dust is probably ruined, though…

samgalax · 2019-12-25T06:19:01.000Z

I will try bursts at 12v

Lightbringer · 2019-12-25T06:36:36.000Z

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.

samgalax · 2019-12-25T07:04:59.000Z

How many amps do I need to use? Should I limit the current??

Barkuti · 2019-12-25T08:07:25.000Z

samgalax:

…

And yes. These gp 2700 are totally dead. No way to recover. Internal short circuit…m

However.. If someone knows a miracle...

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.

Barkuti · 2019-12-25T08:14:38.000Z

samgalax:

How many amps do I need to use? Should I limit the current??

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.

fluke · 2019-12-25T13:39:18.000Z

I had a couple of 26650 Goalisi high drains do the same.

Lightbringer · 2019-12-25T13:44:21.000Z

samgalax:

How many amps do I need to use? Should I limit the current??

Thaaaaat’s why you want to use a big capacitor instead.

Jerommel · 2019-12-25T20:38:20.000Z

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)

samgalax · 2019-12-25T16:33:54.000Z

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

hank · 2019-12-25T17:25:07.000Z

Wear your safety eye protection when you do this kind of thing.
And remember the 12V Auto battery should not be used near electrical sparks.

samgalax · 2019-12-25T17:28:35.000Z

Muahahahah no… No safety glasses at all. ( I am crazy!)

Lightbringer · 2019-12-25T19:19:14.000Z

hank:

Wear your safety eye protection when you do this kind of thing.

As we learn from our Ukrainian friends, pool goggles, shorts, and flip-flops should be sufficient safety gear.

Wait… they’re not lithium cells, so you can be butt nekkid and do whatever you want. You’re good.

Jerommel · 2019-12-25T20:38:51.000Z

Jerommel:

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)

Wow, it’s still 1135mAh according to the Lii-500. :+1:

(which discharges down to 2.8 Volts by the way)

Pete7874 · 2019-12-25T20:41:19.000Z

Jerommel:

Jerommel:

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)

Wow, it’s still 1135mAh according to the Lii-500. :+1:

(which discharges down to 2.8 Volts by the way)

Wow, your Aspire has more capacity now, after being drained to 0, than mine ever did when new.

Jerommel · 2019-12-25T22:56:34.000Z

Pete7874:

Jerommel:

Jerommel:

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)

Wow, it’s still 1135mAh according to the Lii-500. :+1:

(which discharges down to 2.8 Volts by the way)

Wow, your Aspire has more capacity now, after being drained to 0, than mine ever did when new.

Yeah, when i got them new i NOR tested them and wrote the capacity on them, and this one was 1072 mAh.
But i haven’t used them that much, but they say that after the first few cycles the maximum capacity is reached.
This seems to be true then.
But apparently the worst possible over-discharging (it was really 0.0 Volts) didn’t harm this little fellow at all !
Maybe it was the shock therapy that made it behave so well?

Barkuti · 2019-12-25T23:00:11.000Z

Honestly speaking, using a few Ohms resistor as one of the jumper lead wires can limit the current enough for the experience to be a lot gentler.

Lightbringer:

…

As we learn from our Ukrainian friends, pool goggles, shorts, and flip-flops should be sufficient safety gear.

Wait... they're not lithium cells, so you can be butt nekkid and do whatever you want. You're good.