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I am using a 3-cell LiPo battery for a quadcopter. My charger is the Prophet Sport Mini Multichemistry charger. It has built-in undervoltage protection, meaning it will not charge a LiPo or LiFe battery with cell voltages deemed "too low (I'm not sure of the specifics of that lower threshold)." When the main and balance leads of the drained pack are plugged in and the charger is set to LiPo, the charging does not start. All the solutions I have found online about "resurrecting" these batteries involve setting the charger to a separate, non-cell-balance-based chemistry like NiMH, letting the entire pack's voltage rise a little bit so as to be detected and accepted by balance charging, and then switching back to balanced LiPo charging. The entire voltage of my 3-cell pack is 0.32 volts. My charger does not allow that voltage to charge on LiPo or NiMH. I am wondering if anyone has some insight or ideas for a solution to this problem. Any help or ideas will be appreciated and responded to quickly.

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    $\begingroup$ buy new cells ... 0.32 V is dead $\endgroup$
    – jsotola
    Commented Jul 3, 2023 at 1:59

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First: Did you measure correctly? I know its not that difficult, but 0.32 V seems very low too me, even for a dead battery if its not a very old one.

If you measured correctly, I would recommend to buy a new battery. With such a low voltage the battery is definitely over-drained and you won't be able to use it again.

There are "tricks", such as very quickly applying a higher voltage on the battery to "revive" it or charging it with a very low current (there may be special modes on your charger), until it is at an appropriate voltage. However, I would not recommend those things for batteries which are way under the minimum voltage, like in your case. This may work for batteries which are only slightly over-drained.

Just as a reminder: Playing around with LiPo batteries can be quite dangerous. People who don't know what they are doing should contact experts and always be aware of the potential dangers such a battery can bring!

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This problem was solved… dangerously. I knew my charger needed to detect a high enough voltage to even begin charging. So I took ANOTHER (admittedly 4S) battery, and plugged that into a positive and negative jumper cables coming out of the charger. This battery provided the voltage the battery needed to begin charging. Then I plugged the 3S into the XT60 and balance plugs. I began charging in NiMH mode. I had to unplug the good 4S right after charging started (sparks included. I made sure to move my fire extinguisher right into my lap for this one). I charged the 3S for 1 ish minute, then switched to LiPo. It worked! I slapped it on my quad and ripped it just like I normally would (again fire extinguisher on hand) and nothing horrific happened! No swelling, no crazy voltage spikes or sag, and I made sure to charge it to storage voltage and keep it outside for at least a few more cycles. Thank you for all who made suggestions!

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