Flat / Dead NOS battery; worth attempting to revive?

[mikemex]

Hi,

I've been renovating my fleet of Thinkpads (if you can call a bunch of X1C4s in 2022 "renovation") and I've got lot's of spares left from my refurbishing process. Among them is a NOS battery that turned out to be dead.

By dead I mean it won't take a charge and battery voltage is low (about 4v when 15.8v is the nominal value). I believe this battery sat in storage and self-discharged to the point it won't work anymore (triggered the low voltage protection). Otherwise it's detected properly and all.

I'm wondering: given than it was manufactured in 2017, do you really think the cells got damaged? I was thinking about buying one of those balancing charges and try to raise the cell voltage to the point it can start charging again, but I'm wondering if this is worth the hassle. Or maybe transplant the cells to another battery (I've got a couple I discarded due low capacity, but otherwise work fine). Maybe I can put them one by one?

I'm mostly willing to revive it for ecological reasons as buying another is not a problem. But I'm mostly concerned that it might catch fire later, or something.

[axur-delmeria]

I wouldn't bother reviving it as a laptop battery pack. I would, however, tear it apart and charge and use the lithium cells individually.

[TTY]

Hello,
the only experience i have with seemingly dead batteries is from a Li-Ion battery. As the X1C4 have Li-polymer batteries, my experience might not apply. I once got a Compaq Evo notebook with a seemingly dead battery - it wouldn't charge. However, i left the battery in the notebook while i updated and configured software. A week later, i noticed that the battery had started charging and was fully functional again. So i would suggest you leave the notebook connected to mains for a week and check whether it will start charging again. However, I don't want to induce too high hopes, as Li-polymer is a different chemical system.

[kfzhu1229]

Hello,
the only experience i have with seemingly dead batteries is from a Li-Ion battery. As the X1C4 have Li-polymer batteries, my experience might not apply. I once got a Compaq Evo notebook with a seemingly dead battery - it wouldn't charge. However, i left the battery in the notebook while i updated and configured software. A week later, i noticed that the battery had started charging and was fully functional again. So i would suggest you leave the notebook connected to mains for a week and check whether it will start charging again. However, I don't want to induce too high hopes, as Li-polymer is a different chemical system.

How that works is that when the battery was overdischarged, the charging current will be very low and it would take a long time before it would charge to something like 10V, and then the charging speeds up and charges like normal.
However, for modern battery packs, this is pretty much no longer possible, as the battery BMS will kill the battery pack under those circumstances, because it is a bit risky to charge such overdischarged batteries, and also they can make a quick buck when you have to go for a new battery. Not to mention for Li-Po batteries, in those circumstances the battery cells would become pillows already

[mikemex]

Well, I opened it up (it's really just peeling the label) and the terminals of the cells are readily accessible. I'm going to buy one of those balancing chargers and see what happens. I have a lot of 2" kapton tape, so if I manage to revive it, I'll just wrap it again.

I'm just doing it outside in case the thing catches fire.

I'm just afraid that the battery circuitry has a built-in fuse, so it refuses to charge again even if the voltage becomes normal. Swapping cells around is definitely too much to ask, since they are soldered.

[kfzhu1229]

Well, I opened it up (it's really just peeling the label) and the terminals of the cells are readily accessible. I'm going to buy one of those balancing chargers and see what happens. I have a lot of 2" kapton tape, so if I manage to revive it, I'll just wrap it again.

I'm just doing it outside in case the thing catches fire.

I'm just afraid that the battery circuitry has a built-in fuse, so it refuses to charge again even if the voltage becomes normal. Swapping cells around is definitely too much to ask, since they are soldered.

I won't even bother with a balancing charger. I have some pre-charged 18650 cells and a multimeter and I just measure the voltages across each group of cells of the battery pack, then boost it with the 18650 cell if the voltage is too low.
But it is entirely possible you will have one of those firmware based fuse and by the end of all this, you get a flashing amber battery LED and the battery is dead. Modern BMS controllers are generally more "evil" than the older ones.

[mikemex]

I tried to recharge the cells. Didn't work.

Now they are bulged. Not trying again. I'll ditch the cells and keep the circuitry. Maybe I can recycle the connector to save another battery I have.

[axur-delmeria]

I tried to recharge the cells. Didn't work.

Now they are bulged. Not trying again. I'll ditch the cells and keep the circuitry. Maybe I can recycle the connector to save another battery I have.

Yikes. That's very bad.