Neither do I know exactly what would happen if I lit a cigarette while filling my gas tank. And I don't intend to find out.
I put a couple of AAs in a charger by accident. They leaked all over the charger and made quite a mess. I do not recommend it unless you watch it the entire time.
“I don’t know the reason for sure.”
Ummm... maybe to sell more batteries?
Just ribbin ya!
Anyways, no matter what, one thing I should emphasize I DO NOT recommend that anyone use an auto-type charger for this types of operation. The reason being that an auto charge has a much higher amperage output than any type of trickle charger.
REPEAT: DO NOT USE AN AUTO BATTERY CHARGER!
The reason is that the chemical reaction is not 100% reversible; when charging some of the electrolyte is broken down into gases that can cause the casing to burst. At low charging current the casing will swell and leak but at higher levels it can explode.