Charles,
Strangest electrical problem I came across was when a car battery would
go dead all the time. I hooked up a test light in series with the positive
cable and sure enough had a current drain, commenced to pull out the fuses
to isolate the circuit but with all the fuses out and the clock disconnected
I still had the drain. I eventually started to remove the battery and
noticed that as soon as I lifted the battery off of its metal holder the
test light went out. Turned out to be a cracked case on the bottom of the
battery. Also realize that a good quality digital volt meter puts virtually
no load on a battery, it can at times show the battery to have sufficient
voltage but in reality it's only measuring a surface charge that quickly
dissipates under a load. If you put a small load across the battery such as
a small light, you'll get a more realistic reading.
Paul

"Charles T. Low" wrote in message
...
I am taking the "bold" (for me) step of leaving my two batteries in the
boat
over the long, cold Canadian winter, a common practice, based on the
theory
that a good, well-charged battery won't freeze, and if it does, it wasn't
good and should have been replaced anyway. Furthermore, keeping it cold
should prevent it from self-discharging as quickly as it would in a warm
place.

So, I disconnected the negative leads (which sounds backwards, but that's
what many pros do), turned the switch OFF, and tested the voltages with a
digital multimeter. This was after an hour or so off the trickle charger,
which has been on for weeks. The water levels are fine.

One battery, my new-this-season deep cycle, read 13.45V. The older one,
the
starter battery, said 13.33V. These, of course are resting voltages, and I
realize not as valuable as voltage under load, and I didn't test the
sg's -
I may still do that. (Although my deep cycle batterry which failed
mid-season had had good sg's until it died, then they went way south in a
hurry.)

However, the thing which really puzzles me is that when (for some reason)
I
tested the voltage between the positive and negative posts of the opposite
batteries, i.e. neg on battery one and pos on battery two, and vice versa,
there was a momentary reading in the 5V range, which within a split second
dropped to 1.5V, and from there plummeted. I watched it down to about
0.6V,
but it was still dropping rapidly.

If I let them rest for a minute, the same sequence would repeat. So, I
disconnected the positive leads too, and wiped off any dust and grime from
the battery surfaces, but the same thing kept happening.

Any explanation? I doubt very much that it indicates any kind of a
problem.
But I'm not sure. Mainly, however, I'm curious and puzzled. Thanks in
advance.

Charles

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Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

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