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Old 01-07-2016, 07:22 AM   #11
Gdavid
Guru
 
City: Owings, Md
Vessel Name: Graceland
Vessel Model: Mainship 34 MK1
Join Date: Jan 2016
Posts: 1,381
The boat does have a Clipper BM-2 State of Charge Meter that can measure both starting and house batteries. It will be helpful in getting actual data for the house loading.

The refrigerator is dual voltage and runs off of ac when it is available, which would be the case with the generator running. That said it would only take that ac circuit tripping or the generator shutting down to start pulling dc amperage, that certainly could happen.

The bulk of my boating experience on this size boat comes from 3 different styles of boat with dramatically different power management schemes.

1) Mid 30'-40' sailboats with stock charging from the auxiliaries. These are racer/cruisers rarely motored and house batteries were used sparingly. Cooking is propane fueled and refrigeration (if any) was cold plates supported by a belt driven compressor on the auxiliary. Most sailing trips are 3-5 days and between motoring into a marina or anchorage or running the aux a little above idle for an hour, the batteries kept up with the navigation electronics and lighting loads.
2) Chesapeake dead rise styled charter boats with sparse accommodations, the most significant house battery loads these boats saw were fishing at night with spreader lights, sounder and gps left on (sometimes the radar at anchor) and a lectra-san running every time a customer drained his used beer. This would be for a max period of 6 hours, and the boat did not have any provision for shore powered charging. Stock charging from the internally regulated stock alt on the cta cummins.
3) Custom convertible with twin mains and generator. This boat was run charter fishing in the bay and offshore for 12hour day trips and occasional overnights. The generator ran anytime the boat was away from the dock and we used ac power like gluttons. The reverse cycle a/c units and residential refrigerator ran at all times as well as the dc charger. Power conservation was never considered.
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