What would happens when if a car battery is drained of all its fluid and then hooked up to a 12v battery charger. It's a long story I did it to my car battery accidentally for about a minute. What could have happened if I had left it on to charge for longer?

  • Welcome to Motor Vehicle Maintenance & Repair! Aug 30, 2018 at 10:23

1 Answer 1


In a word: nothing.

If a battery is completely dry, or has a lack of electrolyte which doesn't contact the bottom of the charge plates, then nothing will happen. Even if one cell of a 6-cell battery (typical lead-acid 12vdc battery) is dry, nothing would happen. The reason is, the electrolyte (sulfuric acid) allows connectivity between plates. If there is no electrolyte, there is no connectivity. It's like a wire with an open circuit ... it doesn't work. You need to have the electrical circuit within the battery to have a clear path between posts. If it it isn't there, no electrons will flow, and therefore nothing happens.

  • If the “padding” or support beneath the plates is still moist then you can get an appreciable voltage but no significant power.
    – Solar Mike
    Aug 30, 2018 at 13:33
  • @SolarMike - Agree with you. I guess in this case it all depends on the OP's definition of "drained". I'm taking them at their word and the common meaning of the term. Aug 30, 2018 at 13:53

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