[Tupelo]

I doubt if it will work but ....................
I think your 6-12 volt automotive charger is overkill for this. Most of these put out something like 10 amps which is too much. If I were going to try it, I would purchase a Battery Tender Jr in 6 volts. These are what is known as a float charger and only put out about 3/4 amps and will not over charge the battery. Plus the little green light will tell you when the battery is fully charged. Plus it will maintain the charge without over charging the battery. Charging time will probably be about 10-12 hours but if anything will work this will.
Battery Tenders are available at most auto supply stores and motorcycle shops. I use them on my motorcycles and know they work for that and I think they may/might/maybe work for your use.
Hope this helps.

[djf]

This one does 6 Amps at 6V. That’s why I have always watched it closely and never left it on for long.

But the way the auto chargers work is as the battery charges, the amps drop. So if you hooked the leads up to a completely dead battery with infinite resistance, it would read as fully charged on the charger and no current would flow.