title_body: Restore over-discharged LiPo batteries ~2.0V/cell I have a LiPo battery which is ~2.0V/cell, how can I restore it safely? By "safely" I mean how can this be controlled as I know LiPo batteries can be dangerous.
upvoted_answer: Firstly, I'll add the usual statement that mistreated LiPos can be dangerous and you are almost always better getting new ones.
  
  In some cases, a 'smart' battery charger will refuse to charge cells which have dropped between a certain (manufacturer-determined) voltage. In this case, you can connect the battery to a current limited voltage source and charge the batteries manually with a very low trickle current - 0.1 to 0.2C is more than enough. It will take a while, but speed is not the aim here. You might be able to do this with the charger, by telling it the battery is a different type, or by using a separate supply. In either case, you must ensure the max voltage is within the normal range for the LiPo (4.2V/cell.)
  
  You should only attempt recovery of a suspect battery in a safe, supervised environment - charging is the most likely time for such a battery to fail, and particularly so if it has been over-discharged.