Winter cold killed my E-bike batteries. Can they be restored?

coinmaster

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Jun 13, 2017
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I left my E-bike with 1.4kw worth of hoverboard batteries in the garage over winter and I have been concerned about leaving them in the cold but I didn't think too much of it. I just took my bike out for a spin after charging the batteries and they died in under a minute. I tested this twice, there's no mistake, the batteries have nearly no capacity now. I didn't know the cold was that bad for them.
Is there a way to restore them?
 
I dont know if this will help

https://endless-sphere.com/forums/viewtopic.php?f=14&t=93414
 
Chances are it was not cold that killed them, but some tiny trickle short discharged them. Some bms will do that, so the best approach may be to charge monthly during the winter, rather than ignore.

Cool storage good, even froze ok if not charged while froze. But ingore them, often a disaster.

Restoring tricky, step one would be a thourough check of each cell groups voltage. Any at zero or less are at best risky as hell to recharge. Those closer to 2v might be savable, usable to rebuild a new pack from what is still good.

It might be the bms killed the first one or two groups in each pack, leaving you the rest still ok. ( the bms often runs on just cell one or one and two. )
 
Yeah I think you may be onto something. I noticed when charging the packs only certain cells are getting warm to the touch and the severity of damage is not uniform across battery packs.
 
Cold is actually good for storing the batteries. When I did my lithium testing at different temperatures the freezer was the best place to put them, the next best was the fridge.

Freezers are at 0 degrees Fahrenheit.

What the cold does is reduce the usable capacity so that a short or parasitic load will much more quickly discharge the batteries.
 
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