I have a 115AH deep-cycle battery that I bought as a stand-by battery
for my amateur radio station. It has been in a "battery box" on
trickle-charge (using a charger with a "deep-cycle" setting) for most of
the time since I bought it over a year ago, and it has been called on to
supply power only a few times.

Recently I noticed that the "fully charged" LED on the charger was not
on and started investigating further.

Having not encountered any batteries in the last few decades that have
not been sealed and "maintenance free," I was surprised to find tiny
print about checking the electrolyte level every 30 days -- but even
then it took me a few minutes to figure out how to get access to the
cells to check this.

Anyway, when I removed the cunningly disguised covers, I found that the
cells looked totally dry, and each took close to a pint of distilled
water to bring the electrolyte level above the plates.

The battery has now been on charge for about 20 hours at the charger's
12A setting, but most of the time the ammeter on the charger has shown
only about 5A. The cells are all still gassing.

Is this battery likely to come back to life again, or is it toast? Any
remedial actions to take?

Perce
(This is my usenet alias. I *am* an FCC-licensed "ham," but my real name
and callsign have no relevance to this question.)