Battery switch in salon

[RyDrew]

Hi,
Brand new owner of a 2004 360 Mariner, and relative newbie to boating (4 years). Lots of stuff to learn on this boat which is significantly more complicated than my previous four winns 268 vista.
Can someone explain what the "accessory" battery switch in the salon cabinet, to the right of the sliding door? It only has on or off. My previous boat had a similar switch which had 4 positions..... On (to use and charge the starting battery by the alternator) Accessory (to use/charge the house battery) Parallel (to use both batteries to start) and Off.

1. What does this switch control? When should it be on/off.
2. Is there a similar switch like my old boat? (can the House Battery be used to start in an emergency or some other way to start when one batt is dead?
Thanks, and please be patient with me as I learn the boat.

[bud37]

Hopefully someone with the same year can chime in. We had one a couple years earlier before the interior change and the switch in ours was as you had previously with the other boat.

My advice here, it would be wise to go thru all the dc stuff, batteries, switches etc and figure out what controls/powers what on your boat. The reason I say this is previous owners/mechanics can change things around from the oem set up and it can be quite different from what others have, even the exact same boat. Just don't assume.

Our old 350 mariner oem set up was, three batteries, one for each engine, one for the generator , the gen one had an on off switch in the bilge and a 1/2/all/off in that cabinet. It did not stay that way.....

Good luck with your new boat.

[RyDrew]

Thanks Bud37. Didn't you have a house battery for the ship systems?

[bud37]

Source of the post Thanks Bud37. Didn't you have a house battery for the ship systems?

In reality you chose which of the two batteries to use or both. Originally, the mercruiser install instructions mention having one battery for each engine requirement due to the ECU , which they sort of ignored.
I altered it all to basically have a 2 battery start bank and a 4x6volt battery house bank. A few others have done the same basic set up, there are always some slight variations to the theme though with extras.

[Carverlvr2]

I also have a 2004 but the aft cabin version and mine has a battery for each engine, one for the genny, and the house bank which I have expanded to 3 agm’s. Your accessory battery should be all your dc house loads like fridges, lights, and probably helm electronics. One switch to make sure they’re all off when you leave.

[RyDrew]

Thanks Carverlvr2. That makes sense. If I recall on my four winns, it controlled which batteries were getting charged off the alternator as well as which battery(s) were providing power to start the engine. Does this switch affect either starting or charge from the alternator?
Note: It has the same warning about not switching while engines are running.

[Carverlvr2]

I’m fairly sure that is all automatic. The systems charge the starting batts first and when they’re up, it diverts power to the house. I haven’t tested that but I know I was told that.

[RyDrew]

Sounds right. I'm just wondering exactly what that Guest rotary switch does.

[Carverlvr2]

Should shut off all the house dc bank except the bilge pumps.

[RyDrew]

So if i understand you, it prevents power from going to the distribution panel? Where the main switch in the panel only stops power to the individual circuits? For example the refer wont run on DC when disconnected from shore power unless rotary the rotary switch and the main in the panel are on?
And also, I assume it stops the alternator from charging the house battery(s)?