Difference is starter battery vs house battery. A starter battery
is generally discharged a small amount and then recharged quickly.
The alternator is then expected to power everything as long as the
engine is running. A cruising boat is a different animal. All the
boat systems run off the batteries for the most part. The engine
is run once or twice a day to recharge the batteries (not to
power the boat). Since a marine engine running without propelling
the boat has alot of excess horses, a large alternator is used to
charge the batteries as quickly as possible. Quite a different scenario
than a Toyota or a Greyhound.

Doug
s/v CAllista

"Tim" wrote in message
ups.com...

Doug Dotson wrote:
You need to learn more about the requirements of a marine
charging system. Alternator requirements have only little to do with
loads directly supported by the alternator. High charge rates are
used to
recharge a large battery bank in a short period of time.



Doug, I'm glad you reminded me of that. I've run a starter/alternator
shop for the last 23 yrs. and maybe I missed something along the way.

Whether on a "marine" application, a 73 toyota corona, or a greyhound
bus, you have batteries, an alt/gen, a regulation system, and a
.....load.

inverters, split voltages, hi/lo amp settings, DUVAC, etc, are all in
between.

The products you utilize in this situation is the key...

I suppose what I'm saying is, that you can buid a 350 chevrolet engine
and say "This things got 450 horsepower, You don't need that Cummins to
pull that 52 foot van trailer"! .. and in theory, that's true. But in
practicality..its waning badly.