Adding battery, dinghy battery, starting while on shore power

[trevvahhh]

Hey all - first post, have learned a ton from the forum

Rewiring and adding a battery to a ‘74 Newport 27 w/ Atomic 4. 37amp alternator. Currently has one starting battery on a 1-2-Both switch. I’m adding a house battery/bank that we will use to start from and keep the old battery as an emergency reserve. Trying to also include capacity for charging a small 35AH battery for the dinghy motor both at shore and while out for a few days, will only be away from shore power for a week or so at the moment

Have read much about using a VSR to keep starting batt charged, both with alternator and shore power sending to house bank first. Considering hooking the dinghy battery to either a second VSR or to the Starting batt to allow it to charge in the same way

My concern is that the dinghy batt has 10awg wire to SAE connector, and even with a fuse, if someone starts the motor (~150 amps starting) with the switch set to BOTH. or with shore power connected and holding the VSR’’s open, i’m picturing it pulling starting current through the 10awg wire

Any thoughts on fool proofing this? VSR’s for both and a larger gauge wire with some sort of quick disconnect in case the shore power is left plugged in? or not trying to charge the dinghy batt from the alternator at all and use a multi bank charger at shore and just VSR the starting batt?

Thanks so much for any insight! and for reading this far

-Trevor

[rslifkin]

I'd probably use a DC to DC charger for the dinghy battery. No danger of drawing from it that way, plus it'll get charged with an optimal curve regardless of what the other batteries need.

Personally, I like to have multi bank or multiple chargers so batteries charge independently on shore power. And then use VSRs that have an enable/disable input wired to engine ignition so they're only used when the engine is running.