Summary: If you mount a remote OFF-1-2-ALL (let's call it a OFF-HOUSE-START-ALL) switch to the end of the Starter battery cable, that cable then becomes dual-use for multiple banks. Say, for example, to keep the existing Start battery on the START side of the remote switch and then to add one or more Deep-Cycle batteries to the HOUSE side of the remote switch (each, alternately sharing the START battery cable).
The full story: This one came to me totally by coincidence. I happened to inherit a trolling motor with the new (used) Walker Bay dinghy I bought last summer. In figuring out how to charge my trolling motor battery along with my two deep cycle "House" batteries, I came upon an idea I thought might be helpful to others.
The built-in battery box on my 32-3, located in the quarter-berth platform below the DC panel, is only big enough for two Group 24s, which make up my House system. My Starter (automotive) battery sits starboard of the prop shaft, in the forward part of the "lazaretto" or cockpit seat locker. This spot is also a convenient place to keep the trolling motor battery because I can lift it easily through the locker door. I didn't want to run new charging leads all the way to this spot, so I just used the existing ~10 ft START battery cable (1/0 ga) to bring charging power from the DC panel to the trolling motor battery. What makes it work is a second, remote BEP-type (small) battery switch, mounted to the side of the Start battery's plastic battery box.
Again, mounting the remote OFF-HOUSE-START-ALL switch to the end of the Starter battery cable, makes that cable dual-use to both sets of batteries.
But because the trolling motor battery needs to be quickly removable, my installation is slightly different. I just used the remote ON-OFF battery switch (shown above) I had already, previously attached to the START battery & box (for use as a kill switch). This switch can only either connect or disconnect the START battery from the START cable. Then I wired a trolling motor plug to the CABLE side of the remote battery switch (not the BATTERY side), with an in-line 40A fuse for protection.
When the plug is inserted into the trolling motor battery, charging (or discharging) is available by selecting the MAIN battery switch to START or ALL (the REMOTE battery switch has no effect on the trolling motor plug). The Starter battery remains disconnected as long as the remote BATT switch is OFF.
The full story: This one came to me totally by coincidence. I happened to inherit a trolling motor with the new (used) Walker Bay dinghy I bought last summer. In figuring out how to charge my trolling motor battery along with my two deep cycle "House" batteries, I came upon an idea I thought might be helpful to others.
The built-in battery box on my 32-3, located in the quarter-berth platform below the DC panel, is only big enough for two Group 24s, which make up my House system. My Starter (automotive) battery sits starboard of the prop shaft, in the forward part of the "lazaretto" or cockpit seat locker. This spot is also a convenient place to keep the trolling motor battery because I can lift it easily through the locker door. I didn't want to run new charging leads all the way to this spot, so I just used the existing ~10 ft START battery cable (1/0 ga) to bring charging power from the DC panel to the trolling motor battery. What makes it work is a second, remote BEP-type (small) battery switch, mounted to the side of the Start battery's plastic battery box.
Again, mounting the remote OFF-HOUSE-START-ALL switch to the end of the Starter battery cable, makes that cable dual-use to both sets of batteries.
-To use all your HOUSE batteries:
Main BATT SW-->ALL ,
Remote BATT SW-->HOUSE
-To use only your original HOUSE batteries:
Main BATT SW-->House
(Remote BATT SW N/A)
-To use only your new HOUSE batteries:
Main BATT SW-->START,
Remote BATT SW-->HOUSE
-To crank the engine from the starter battery:
Both switches-->START
-To parallel ALL batteries:
Both switches-->ALL
I connected the BEP switch to the first battery using a bent link-bar and by screwing it to the plastic battery case. It would take a short length of 1/0 battery cable, and an additional fuse, to connect the switch to a second battery.But because the trolling motor battery needs to be quickly removable, my installation is slightly different. I just used the remote ON-OFF battery switch (shown above) I had already, previously attached to the START battery & box (for use as a kill switch). This switch can only either connect or disconnect the START battery from the START cable. Then I wired a trolling motor plug to the CABLE side of the remote battery switch (not the BATTERY side), with an in-line 40A fuse for protection.
When the plug is inserted into the trolling motor battery, charging (or discharging) is available by selecting the MAIN battery switch to START or ALL (the REMOTE battery switch has no effect on the trolling motor plug). The Starter battery remains disconnected as long as the remote BATT switch is OFF.
To use the starter battery for starting:
Pull the plug from the trolling battery,
Main BATT SW-->START,
Remote BATT SW-->ON.
This has been working well for charging my add-on battery. Maybe someone else can use the idea to enlarge their HOUSE bank without the usual need for extensive re-cabling.
