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How Do I rescue over-drained LiPo batteries?


We’ve all done it, you plug in your battery tester or goggles and forget to unplug when you’re done. Then when you find out, the battery tester won’t even display a voltage.

..Great, according to many manufacturers you should replace the battery as it is no longer going to function properly.
Well they might be right, but you might also be able to rescue that battery and use it for a bit longer.

Disclaimer: If you attempt to rescue a battery using these instructions you do so at your own risk. If you are not comfortable with the possibility that your battery may catch fire, you may just want to discard the battery.

When a LiPo battery is fully drained it oxidizes the cells and this is part of what makes them perform poorly.
However, if you can catch it quick enough you can usually save the battery without too much reduction in performance.

So to rescue your battery you will need:

  • A dead LiPo battery.
  • A LiPo balance charger.
  • A NiMH charger.

With these tools, It’s actually pretty easy to recover these batteries.

  1. Connect the main plug of your LiPo battery to your NiMH charger and start charging at the lowest current possible. Typically this is 0.1A. If your charger allows you to select the voltage you should select a voltage that matches your LiPo battery’s nominal voltage.
  2. After a minute or two your battery should recover to about 3.3 volts per cell. To check this simply read the total voltage of your battery and divide that by the number of cells.
  3. When the total voltage is equal to about 3.3 volts per cell you can move the battery over to your LiPo balance charger and balance charge at 0.5C rating. This will take longer than charging at 1C but is safer.
  4. Once the balance charge has completed balancing you should have a fully recovered LiPo battery.

And that’s all there is to it!


Do not leave a recovering battery unattended!

If your battery starts to puff or deform in any way during charging you should stop.

You should always charge batteries in a fireproof location with good ventilation.

If the battery is unable to balance you may want to consider retiring that battery as it could be very unpredictable during use and possibly catch fire.


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