Battery switches on 99' Sundancer 380 DA

[Yellovette]

So can anyone explain the logic / function of the battery switches on my breaker panel?  One is for the Port battery and functions as an Off /On switch.  Beside it is the switch for the Stbd battery, and it functions only as a "Momentary On" switch, meaning that it has to be pressed and held to activate.  I am new to this boat and this makes no sense to me.  When I look at what I think are the starting batteries in the engine room, they appear to be connected in parallel.  I don't get the reasoning or function of this system.  Does anyone have an explanation for me?

Appreciate any  help on this.

[wingless]

Welcome to the forum.

The battery switches on the 380DA are a terrific system.

There are three switches, in two locations, one set in the salon, the other set in the engine room, both with identical function. There are switches for the PORT, STBD and GEN battery banks.

These switches are all momentary contact on and momentary contact off, (ON) / OFF / (ON).

These switches control latching contactors. A contactor is like a relay, but for much higher current.

Tapping any of these switches will toggle the selected contactor to latch on or off. These will latch the power on or off to the selected battery bank. These three contactors are located in the port side plastic box on the forward wall of the engine room.

If there is a functional issue w/ the system, then each contactor has a pair of standard low current blade fuses, maybe 5A.

The factory built the system w/ two parallel port batteries electrically isolated w/ two parallel starboard batteries, also electrically isolated from the single generator battery. (Negatives are all common.) Mine has been upgraded to add a sixth battery, in parallel to the starboard (house) bank, plus a manual rotary switch to permit connecting the port (helm) bank to permit extended run time for the 'fridge when on hook.

[Yellovette]

Thanks Wingless.  You obviously have much more understanding than I do.  Please explain a bit further.  From my wiring diagram and your explanation it seems that there are two starting batteries for each motor, correct?  Then there is a starting battery for the Genny?  What is being used for the house bank?  Starting batteries are normally designed for cranking and not deep cycle as typically suited to deeper discharging and recharging.  I understand you added a sixth battery for a house bank.  Are you saying the Stbd. batteries on your boat are the house bank?  This is all contrary to my pre conceived ideas for a 12 volt system, (1 starting battery per engine, 2, 4 or 6 house batteries, and 1 generator battery).  I think I must be missing something here.  Please help. 

[wingless]