Laptop 18650 at 1.2v, safe to use?

[garilla]

I got a laptop pack discarded from work which contains 8 18650 unprotected cells, I measured the voltage on them at about 1.2-1.5 volts. Would these be safe to attempt to use by charging them up? It seems that to have the voltage so low someone might have depleted the battery at last use and then it sat unused for +2 years. So what do you think, safe or not ?

 

[Kremer]

That is too low, I would recycle it.

 

[garilla]

I am wondering if there is a hazard to charging these or not. When a cell is discharged very low I understand the cell is being harmed which effects cycles of charges and other things and I relieze that if usable they would be sub par... any hazard ?

 

[Benson]

I am wondering if there is a hazard to charging these or not. When a cell is discharged very low I understand the cell is being harmed which effects cycles of charges and other things and I relieze that if usable they would be sub par... any hazard ?

Yes there definitely is, and you should probably wait on an answer from a more knowledgable person than I, but I believe there's only really any hazard on the first charge, and they are often rechargeable successfully.

So if you have a charger you're willing to take the risk of ruining, you might take it outside on some concrete, and try charging them. Monitoring the temperature with an IR thermometer should also catch any problems and let you kill power before things actually explode, burn, or vent. Obviously, if you have to stop it because a cell is overheating, that cell has been permanently damaged, so mark it and either get rid of it or save it till the end to make a youtube video with.:laughing:

But they probably don't have enough capacity to be worth the time recharging them, anyway, especially giving them even better attention than normal....

 

[65535]

At that voltage the cells are pretty well damaged. They may be able to be cycled at a slow rate up to voltage but capacity will have suffered from the stress at extra low voltages.

Cells that are brought up from lower voltages like that are more likely to fail. I would stick to known good cells for flashlights.

 

[kramer5150]

My understanding is the cathode / anode are at greater risk of shorting the more frequently the cell is over charged / discharged. You are increasing the likelihood of an internal short + explosion + fire by using a cell thats been stressed in such a way.

I would recycle it, its just not worth the health risk.

When I pull laptop cells, anything thats below ~2.70V gets tossed.

 

[mdocod]

If they are quality name brand cells, then I'd say there is a good chance that they would not explode, but no guarantees there. More than likely they would take a charge, but you would find out very quickly that they won't hold a charge above 4V, and probably have less than half their original capacity. Which means they need to be discarded.