Liquid LA batteries should be charged at a max current equal
to 25% of the AH capacity (100AH bat, 25A max charge).
For gels it is 50%, for AGM it is 100% or even greater under certain
conditions. The deal with overcharging has to do with overvoltage.
If you charge/float at a voltage higher than recommended, the
lifetime of the battery can be severely reduced very quickly. They
are unforgiving in this sense.

Doug
s/v Callista

"Jeff Morris" wrote in message
...
I seem to recall that the "margin of safety" WRT overcharging is smaller
with
AGMs. Heavy duty flooded batteries can handle considerable abuse as long
as you
add water when needed. In fact, periodic controlled overcharging is
useful for
keeping them healthy.

I've gathered that this is not true for AGMs.



"Doug Dotson" wrote in message
...
The possability of overcharging is not unique to AGM. It will
quickly destroy most any battery.

Doug
s/v Callista

"Jeff Morris" wrote in message
...
I put in two to replace my starting batteries. They appear to have
survived the
winter. In my research I couldn't find a downside, other than the
cost,
and the
possibility of overcharging. I'm thinking of replacing my house bank
with them
when the need arises.



"Bob Whitaker" wrote in message
om...
Does anybody have any direct experience with the AGM (Absorbed Glass
Mat) batteries? One manufacturer claims that these batteries are
completely sealed against fumes and don't require venting. Does
anybody have these on their boat?

Bob Whitaker
"Free Spirit"