In article ,
"Roger Long" wrote:

Is there any reason to consider using dual purpose or a one starting, one
deep cycle set up with a 20 hp Yanmar diesel? I would think the starting
loads on the small engine are low enough that two deep cycle batteries would
do fine.


Just about everything I've seen in the thread is correct, but I have a
couple of odd thoughts for you to consider.

We currently have 2 group 31s, about 230 total AH. Our 2GM20F will start
off a half-discharged group 27, so starting isn't a serious issue. Major
consumption is lights -- many, many lights -- as we're addicted to
reading and night sailing.

Our main problem has been that we motor too little. Usually, we've been
lucky to have even 50% charge.

----

Our last charter, the starting battery connected directly to the
alternator. The house battery was tied in via a simple on-off switch: On
to charge, off otherwise. That's not the best way to charge and it's
possible to drain all the batteries, but you can't fry the regulator.
-----

Last spring, we got a 12 watt solar charger which changed our habits
significantly. When we weekend, we're charged to 100% as we start out.

On our annual 3 week cruise around the Chesapeake, that little charger
satisfied our needs completely as long as we motored into a harbor every
few days. One morning, the battery was dead. A few hours of sun later,
we had enough charge to start.

I'll probably combine the two ideas next time I have to replace a
battery. Remaining 31 goes next to the engine, short leads. House bank
gets beefier, panel goes directly to it. Battery switch is almost always
off.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/