Did I destroy my battery

[Gardner Yeaw]

I usually disconnect the coach and generator battery when I leave my
coach at the storage facility (no electric hookup). I forgot the
generator battery and it fed through the isolator and ran down
completely. I ran the generator for several hours to charge it (I
manually activated the relay to couple the coach batteries to get it
started). The battery reads 10 volts when disconnected. I hooked the
coach up to power and I am waiting till tomorrow to see if there is an
improvement.
Am I beating a dead horse here? I don't know the age of the battery,
but it seems to be a few years old.

Gardner