feetwet wrote:
My boat has an Interstate Lead-Acid RV/Marine Battery the dealer installed
this spring. When I picked up the boat with this battery I noticed the
voltage was low (probably around 11.5 v?). I've charged it since, but it
seems to lose charge quickly.

I disconnected all leads from the battery for 3 days and it held 95% without
drop. Once I re-connect the wires, it lost 7% charge in one day (95% @12.75v
to 88% @12.63v), this seems like a lot of drop for not having any
accessories turned on. I'm certainily interested in a battery shut-off
switch... but perhas I should warranty the battery first?

Can anyone validate if this is unusually high capacity drop for a 35-40 ma
load (as measured by my digital voltmeter)?



A continuous 0.040 ampere load over a 24-hour period is equivalent to
one amp-hour. I would not expect a fully charged lead-acid battery to
see that much voltage drop.

If the voltage was constant for three days prior to the test, the
battery was probably well-charged. The battery voltage will drop more
under load when the battery is not fully charged, however, and the only
way to really be certain is to use a hydrometer (inexpensive). Make sure
you get one that has temperature compensation.

An increase in battery temperature could also produce the result you
have observed.

As could a poor connection to the battery terminals.

Does the battery voltage increase again when you remove the load?

Chuck