VSR overcharging my Starter Battery?

[argold57]

I am getting my 1999 Bavaria 38 Ocean ready for some long-term cruising next year. I am waiting for delivery of some solar panels now.

My first step was to install a Blue-sea 1830 SOC monitor yesterday and did a little load testing, dropping my house battery SOC a bit with the charger off, then disconnecting all loads and turning on the AC charger. The first thing I noticed is that when the AC charger is operating and providing 18.5 amps with the DC panel off (no load), the starter and house batteries (both are AGM) are at about the same 14.4 volts.

I'm sure my starter battery is fully charged. I have an older BEP Marine Voltage Sensitive Relay Module - Dual sense (not the one marked "digital) I see the VSR is labeled Cut-In 13.7V and Cut-Out 12.8V.

Am I over-charging the starter battery because the VSR is closed while the house battery is charging? I have had the boat for 10 years and always leave the boat charging when I am away. Has the starter battery been over-charging all this time?

When I install the solar (to charge the house battery) what should I do about the VSR? I'd like the alternator to always charge the starter first then connect to the house. I think that will be enough so solar and AC should prefer the house without overcharging the starter.

Links to other threads are appreciated also.

[argold57]

Nevermind Ifound this excellent article that answered this.

https://marinehowto.com/automatic-charging-relays/