If your vessel is wired like many Bene's & Jenneau's, you may not have "HOUSE" and "START". What many have is two battery banks that are
in parallel when both switches are set to ON. Leave both switches set to ON, discharge too far, and you're dead in the water. We've a number of Bene & Jenneau customers who've learned this lesson the hard way.
Unfortunately many, but not all Beneteau's, have a bussed switch system where by HOUSE and START switches are permanently bused (hard wired) together on the load side of the switches. Any time both red switches are turned ON both battery banks are
in parallel. Many owners are unaware of this wiring scenario and incorrectly assume they have "isolated" HOUSE & START banks.. If your boat has this wiring it is best to correct this issue. I have even heard of some owners and delivering dealers removing this jumper but not addressing it any further with regard to charging both banks..
If you decide to pull the jumper, you'll need to make sure house loads stay on the house switch and the engine remains with the start switch. You can then re-purpose the negative switch for an emergency parallel.
Below is what this wiring typically looks like. The issues are listed on the drawing, if your boat has this wiring scenario. Link to full size image if needed:
http://www.pbase.com/mainecruising/i...1/original.jpg
The diagram below (drawn for a customer) corrects for the Beneteau bused switch system and adds alternator to house bank wiring plus an emergency parallel (the old negative switch), dedicated & isolated start and house banks, full isolation of each bank and full cross over and an ACR for automatically charging both banks.