"evans" wrote in message
...
I am a boater who uses deep discharge marine batteries. I purchased
from West Marine a gauge that measurea percent discharged, based on a
narrow voltage band. Voltage itself is not a good indicator. A battery
can show 12V and be almost dead.

Check out West Marine or Defender Industries.

kip


On Sun, 27 Jun 2004 14:56:07 -0700, Jack Twilley
wrote:

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...Ideally, the meter I want to use would resemble an automobile fuel
gauge in that it would have some idea of what "full" was (whether by
testing via full discharge or by entering in data somehow) and it
would be able to handle charging and discharging without being
rewired. The latter is the truly crucial bit, as the former can be
implemented with a PIC. The PIC could do much more, of course, but as
a bare minimum, I'd like to know how much capacity remains and how
quickly I'm using it.

Is there anything out there like this?

The lead-acid battery does show capacity by measuring voltage, but it
MUST have "rested" for some time. That is, no discharge or charging.

I don't know how long, for sure, but I think it is on the order of
hour(s); perhaps one or two. A fully charged battery will show just over 13
volts...13.2 or 13.3 I don't remember the exact number, I always go on the
web for the exact numbers, or I just use the approximation. A dead one will
be on the order of just under 12 volts. Around 11.9 or 11.8. There's lots
of info on the web. No other common type of battery has this type of a
voltage characteriscic.
73,
--
Steve N, K,9;d, c. i My email has no u's.