I wouldn't do that. Here's why. I used an old car battery to
turn over a smallblock I had just finished. Battery was old, and
should have been thrown out. Anyway, it cranked a few rounds, (I was
just setting #1 Cyl, and no sparkplugs) and gave up. So of course
I grabbed the battery charger, and hooked it up. Gave it 10 mins.
Hit the starter again, and was lucky enough, or smart enough, (doubtful)
to be wearing goggles. The charger clamps arced a bit, and the battery
had a dead cell. Hence lots of hydrogen, and oxygen. The battery lids
are yet to be found, and all four sides split. I was close to water,
and goggles protected my eyes. Clothes did not survive washing. A
couple of small puncture wounds. I never was pretty anyway.
After all this, BE CAREFUL with batteries. Don't overcharge, and
don't use what you know is garbage.
bj