Over-discharged LiPo batteries sometimes cannot be recognized by LiPo chargers when their cell voltages drop below 3V. In this incidence, I accidentally over-discharged my LiPo battery in my radio transmitter by forgetting to turn it off. In this article I will show you how I fixed it.
If you attempt to rescue an empty-charged battery using instructions in this article, you do so at your own risk. Remember the longer you leave the battery over-discharged, the worse performance it becomes as internal resistance would start going up.
So when this accident happened, the voltage of the over-discharged LiPo battery was measured at a total 1.9V (that’s 0.63V per cell). My charger couldn’t recognize the battery and I thought it might be damaged permanently. But then a friend told me that there could be a fix to my problem.
My understanding is, as soon as we increase the voltage in each cell to a higher level (above 3V per cell) by charging it up using a Ni-MH charger, your Lipo charger might recognize it again. So that was what I did, if you decided to give it a try, do it extremely carefully and do it at your own risk, I won’t be held responsible if you burn your house down. :D
- So first of all, you will need a NiMH capable charger. A lot of LiPo chargers can charge NiMH too, like the Turnigy Accucel 6 I had at the time.
- I connected the main plug of my battery to the charger, and charge the Lipo with the lowest possible current, e.g. 0.1A. If you have to also set the charging voltage (I didn’t have to in my case), set it to the closest voltage to the nominal voltage of your LiPo pack. (i.e. 7.2v for 2S 7.4v pack, or 12v for 3S 11.1v pack).
- It should only take a few mins to bring the cell voltage back to 3.0V. I recommend to stop the charging as soon as the voltage reach around 3V-3.3V.
After these steps, I then tested it with my LiPo charger, and it finally recognized the recovered battery. I used the Lipo balance charging feature to charge up the Lipo battery to full capacity, and it seemed to work.
Although we can save over-charged batteries this way, over-discharging is not good for the battery life! So remember not to over-discharge your battery whenever possible, and remember to switch off / disconnect your equipment when not in use.
Read about the basics of LiPo battery in this guide.
- Dec 2013 – Article created
- May 2017 – Article revised