On Wed, 19 May 2004 17:09:07 -0400, "Eisboch"
wrote:
This is an often debated subject, because it depends on the type of battery,
temperature, aging, etc. In general for lead acid batteries:

Open circuit voltage Charge in %
12.6V and higher 100%
12.4 - 12.6V 75 - 100%
12.2 - 12.4V 50 - 75%
12.0 - 12.2V 25 - 50%
11.7 - 12.0V 0 - 25%
11.7V and less 0%

==============================

Debated indeed, but that seems a wee bit harsh to me on the low end.
I routinely run my deep cycles down to 11.5 under moderate load and
they still have lots of juice left at that level, more than enough to
start the engines for example. I've always regarded 11.5 volts as the
50% mark where you really should recharge but don't necessarily need
to. A battery discharged to that level should be recharged ASAP of
course.

Regarging Chuck's 13.2 volts, that is about the right voltage for
"floating" a fully charged battery, but the battery will soon drop
back to 12.6 or 12.7 once the float charger/battery eliminator is
turned off.