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Revive Over discharged battery?

#1
Hey guys,

I recently found one of my 2200mah 3s lipos to have one over-discharged cell. The voltages were 4.13,4.14 and 1.72!

I was wondering if there was a way to recover that cell since its a relatively new lipo :( What i don't get is that I always balance charged my lipos and this one was perfect until today when i found out that my charger refused to charge it.

Any help would be appreciated.

Thanks.
 

lobstermash

Propaganda machine
Mentor
#2
Recharging an overcharged lipo cell is what causes most lipo fires. These batteries are cheap and not worth the risk.

However, check whether you're getting an accurate reading on the 3rd cell on a couple of devices if you can. I've had a couple of chargers tell me lies in the past...
 

lobstermash

Propaganda machine
Mentor
#4
Oops, glad you knew what I meant. Yeah, overcharging doesn't happen too much nowdays thanks to the decent quality of most of the ones around.

Just FYI, and for interest of other people thinking about over-discharged (I got it right this time!), when a Lipo cell falls below ~3.3V, there is an exponential amount of damage to the internal resistance in the cell (as in, makes it higher). As the internal resistance increases, the rate at which the battery can be safely charged and discharged (think of the corresponding C numbers e.g. 20C discharge, 2C charge) decreases. This is shown in the discharge of the battery by increased voltage sag under load, and shown in the charge phase by the creation of heat, because they battery can't handle the electrons being pumped into it.
 

pgerts

Old age member
Mentor
#5
Try to find a reason for the cell to fall out.
It has happened to me once caused by a puncture on one cell.
A tiny spot indicated that there was a damage.
It might have been from the storing place but i never found anything sharp.
It is not impossible that something can happen in the manufacturing process with the foils making a leak efter some cycles.
 

earthsciteach

Moderator
Moderator
#7
You can fool your charger by setting it to NiMh. Keep a constant eye on it!!!! Check it to see if it is getting warm. If so, unplug it. If you can get that one cell back up above the minimum threshold, you may be able to balance it. Or, you may burn down your house. Since it is only a single cell that is low, I don't think I'd risk it.
 
#8
Yeah its not worth the risk. I'm a college student living in a dorm at the moment. Last thing I need is to burn the place down and faces fines over the exorbitant tuition lol thanks anyway guys. Appreciate your advice :)