I have two 36 volt, 20 amp golf-cart chargers that no one else in town
would be interested in repairing. One broke ten years ago, one two
weeks ago, and the business which owns them have already bought a new
one, and told me I could throw the old ones away.

Do you think it would have any other use for someone who didn't own a
golf-cart, like me?

I'm sort of curious what's inside that might be different from any
other charger -- it's fancier than my 1 amp and my 10 amp, with
circuits to turn it off at full charge, to time how long it charged
before that, etc. -- plus I just generally hate to throw things away.

One of them flashes numbers it shouldn't flash, and one was just dead
iirc when they plugged it in. I'm thinking this second one might be
easier to fix, but it seems to depend on being connected to a set of
three car batteries in series to turn on, even when it is working.
Maybe I can connect three 12 volt UPS /
home-burglar-alarm-backup-batteries and get the same effect, or maybe
it will overcharge them if it ever works???

They weigh about 20 pounds each, 8w x 7d x 10h inches and have a
handle. Plus it sells for about 600 dollars locally and 300 and up
online. A shame to throw it away.