Battery storage?

We put a fresh battery in our plane for the winter starting season even
though the old one was in good shape. On advice from several sources, I put
the old one on a Sears trickle charger as a spare. The charger claims to
sense the battery condition and be suitable for long term connections.

I checked the battery after a couple months and there was electrolyte all
over the top and running down the sides and onto the shelf.

Is the battery toast? Are these maintenance trickle chargers inappropriate
for long term connection?


--
Roger Long