Do this test to determine if your charger is designed to be left
on indefinately:

1. Connect and leave the charger on for 24hours.
2. Using a digital voltmeter (known to be better than
0.5% accuracy) measure the battery voltage under charge.
Touch the meter probes directly to the lead posts.

If the battery voltage under charge exceeds 13.80V, then the
charger should not be left connected more than 24 hours per month...

If the voltage is more than 13.00V but less than 13.60V, then it
is ok to leave the charger on indefinately.

If the voltage is between 13.6 and 13.8, then it depends on
some other parameters, like temperature. However, the charger
should not be left on indefinately...

As I have previously written, the best solution is often
a time clock and a 2A constant-current charger. This allows
you to "charge" the battery for about 8-10 hours at times
you control. I would do it about once month if the battery
is below 80 deg F, and once every two weeks if the
battery is at more than 80 deg F

see: http://makeashorterlink.com/?I66613A07

MikeM
Skylane '1MM
Pacer '00Z

Roger Long wrote:

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