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?
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.