On Thu, 27 Mar 2008 12:08:40 -0700 (PDT), "
wrote:

On Mar 26, 5:46 pm, Larry wrote:
... A 100A alternator will NOT put out 100A! It will put out 100A for a FEW
MINUTES, then must be cut back to prevent its heat destruction....and I
didn't know that, myself. ...

I'm sure you're right. On the advise of a rather eccentric, but I
think very competent EE (Gary Pacey of Outback Marine) we installed
oversized alternators and then down-rated them. At least in theory
they are supposed to be able to run continuously around 100 amps. At
any rate, I've used them to charge my ~500ah bank of AGM's for years
and they've handled it well. Underway that means they run full out
for ~15 minutes a couple of times a day. At anchor the solar panels
do most of the work and I the alternators much less of a workout.

I seem to recall that for best battery life you should charge it at
the 20 hour rate. You have a 2000 AH starting battery? [Ten times the
size of the one on Cat's biggest bulldozer]. Charging a 25 AH battery
at the fifteen minute rate has to be a poor idea.

Casady