Reviving lipo batteries

[Borneoboy]

Is it possible to revive a LIPO cell with no voltage ?
It was drained by a BMS down to 1.6 volts before I noticed anything amiss.
Cheap 100 amp/hr battery from Varicore/Littokala.

 

[Supervstech]

Possible? Sure.
Will the cell ever be trustworthy again? Unlikely.
Many have successfully trickle charged a cell back to full from zero. It can take weeks, as the charge has to be very very slow to avoid a blowout failure.

 

[Borneoboy]

Thanks for the very quick reply !
I did try my 5 amp charger and it tried, but after a minute or two it said "FULL" and I didn't know how to proceed.
The charger puts in about 3.6 volts and not sure what amps.

 

[DThames]

Is this a LiFePo4 battery? LiPo is Lithium Polymer and is charged at 4.1-4.2v per cell normally.

 

[Borneoboy]

LiFePo4

 

[DThames]

Thanks for the very quick reply !
I did try my 5 amp charger and it tried, but after a minute or two it said "FULL" and I didn't know how to proceed.
The charger puts in about 3.6 volts and not sure what amps.

Can you cycle test it? Put it under a light load, 5-10 amps, and see if will carry the load for several hours or not.

Can you explain how the BMS drained a cell? Is this a battery that you built?

 

[Borneoboy]

Yes, homebuilt battery, then wanted to change the cells. So disconnected all wiring except the BMS sensor wires and left it for a few days waiting for the new batteries to arrive.
When I got back with the new batteries I was horrified to find all the cells right down and this particular one at 1.6 volts....it subsequently continued falling to .2 volts I.e. "dead"

Is it likely to take any load ?

 

[DThames]

Yes, homebuilt battery, then wanted to change the cells. So disconnected all wiring except the BMS sensor wires and left it for a few days waiting for the new batteries to arrive.
When I got back with the new batteries I was horrified to find all the cells right down and this particular one at 1.6 volts....it subsequently continued falling to .2 volts I.e. "dead"

Is it likely to take any load ?

I really don't know. Everyone/Everything says over discharge will damage the cells. I have some small cylinder cells that seem to be okay after self discharge but as someone already asked, "Can you trust them?". What size cells are they?

I didn't know a BMS would do that but I can see where maybe part of the balance circuit would be connected in a way that it didn't have to be "on" to be a current path. It might be worth testing because a very slow discharge might be a totally different damage situation than a discharge under a measurable load.

 

[Borneoboy]

Thank you for your thoughts and suggestions.
I've written off that cell and replaced it now, but still have a small hope of reviving it.
But don't want to damage my newish chargers without advice from others... or worse still set fire to the house !

 

[JoeHam]

Yup, it’s a goner for sure.

The reason is dendrite formation which is not reversible.

If you have trouble getting to sleep read this paper in it’s entirety ?

https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.904.440&rep=rep1&type=pdf

 

[Borneoboy]

And the cell is only about a year old....

 

[RCinFLA]

Li-ion batteries, all chemistries, will grow dendrite shorts when cell is below about 1.5v. In time they grow and punch through the separator shorting out the cell.

You can attempt a low current charge to see if cell voltage comes up. The reason for low current is if there are dendrite shorts growing it is unlikely the cell voltage will rise and keeping the charge rate low prevents cell from overheating and bursting.

If cell gets above 2.8v at low charge current you can then raise the charge rate.

 

[Borneoboy]

Very interesting ...
Seems the cell is shorting out and refusing to take a charge.
Charger (e-bike type) is set for 3.2v, but just flashes red instead of steady red.
Voltage .1 or 0.

 

[Borneoboy]

My other cell which is a bit suspect - and I replaced in the main pack because it was charging too fast above 3.3 volts - now doesn't want to charge at all above 3.2v. So I upped the charge voltage and that worked, but very quickly it went above 3.7 (nearly 4.0v) so I had to turn off the charger. Next morning it was back at 3.2 (???).
Frankly most of my batteries (100 A/hr) seem to have idiosyncrasies and it's become a bit of a nightmare trying to control them all !!
Maybe I'll buy a ready made 24v battery next year....or would that be too defeatist ?

 

[JoeHam]

It’s a little defeatist since you now understand what happened to create the problem(s). And how to avoid it in the future.

Just a bit more tuition paid to the school of Hard Knocks. I’ve paid my share for sure. ?

Your money, your choice though.

 

[RCinFLA]

Very interesting ...
Seems the cell is shorting out and refusing to take a charge.
Charger (e-bike type) is set for 3.2v, but just flashes red instead of steady red.
Voltage .1 or 0.

Li-Ion supervisor IC's and chargers usually will refuse to charge a pack if there is a single cell in pack below 1.5vdc.

 

[Borneoboy]

Maybe I should put it back in a "pack" and hope its fellow cells help it to recover?

 

[JoeHam]

Maybe I should put it back in a "pack" and hope its fellow cells help it to recover?

Yuk, yuk, yuk

You did read about dendrite formation right? It’s a real thing.

And, high current delivered by “fellow cells” could case dendrite penetration.

That could be very bad. Spectacularly bad.

Sometimes when you find yourself in a deep hole the best thing to do is stop digging ?.

 

[Supervstech]

Maybe I should put it back in a "pack" and hope its fellow cells help it to recover?

Please do NOT attempt this…

I said VERY low current…

In a charged pack, it could receive hundreds of amps in an instant, and go VERY very bad…

 

[Borneoboy]

No, I understand that's not a good idea.
I already had it on the charger at 3.2 volts and around half an amp, but the charger gave up as described above.
So now i think i shall give up on this one cell...
Everyday now there seem to be new revelations about these batteries and even conflicting advice often, which doesn't help!
Wading through the info about dendrites...now that's all new ! (at least to me).