Basic elec. system with 2 batteries

[Baggywrinkle]

I like them because they are reliable and work well, but not a fan of the Start Assist function. It's OK if the engine battery is slightly depleted, but not likely to start the engine if it's totally flat or faulty. I prefer the emergency switch in my schematics above as this can be used if the engine battery is totally flat or if a battery is faulty/shorted etc that battery (domestic or engine) can be isolated and the remaining battery used for both domestic and engine circuits to get you home.

Interesting .... I used the (Cyrix 230) combine function in anger on my last boat when the starter battery was only able to make the relay click. The button was at the helm, pushed it once and hit start again and off it went. Replaced the starter battery a few days later as it wasn't holding charge. It was very convenient. The wiring was of an appropriate guage for an engine start.

I'm cautious about the switch arrangement because on my particular boats, the wiring was exactly like your first VSR diagram. My VSR was a Cyrix with the emergency start button wired up to a button on the helm. The battery isolators were out of the way and when on board, switched on and never touched.

If my incompetent crew were to have access to a combine switch, I can guarantee that at some point I'd get an accidental load dump as they tried to turn the combine off using the wrong switch sequence.

Your Argofet diagram prevents that by bypassing the switches so a load dump is avoided regardless of the switch positions.

Guess the OP has to pick his poison.

 

[zoidberg]

I refer to Paul Rainbow's #5 diagram.

You could use an Argofet if you wanted. It is more money than a VSR though.

I have a new Victron Argofet 100/3 which was mounted but then removed - never used - in favour of a rather different LFP/AGM setup which didn't need an Argofet 'vsr'.

You've reminded me to put it on the 'For Sale' forum....

 

[Leslie frank]

The DC-DC charger does not connect directly to the batteries, it should be connected between the load terminals of the domestic and engine battery isolators, however, a DC-DC charger is an expensive solution to such a simple system, a VSR would make more sense.

You need to fit an isolator for the engine battery.

The Smartshunt only monitors the domestic battery, but will show the voltage of the engine battery.

Ignoring the fact there are 3 domestic batteries in the schematic below, this is a how i would connect everything.

View attachment 207880

Paul
Is the purpose of the shunt (top right) for an ammeter? Just interested to check my set up against your diagram.
Cheers

 

[PaulRainbow]

Paul
Is the purpose of the shunt (top right) for an ammeter? Just interested to check my set up against your diagram.
Cheers

Intended to be for a battery monitor, but an ammeter would be the same, if intended for the domestic batteries.