tlc118 wrote:While I only have one engine my setup is the same.
When I'm home, plugged in to shorepower, I run the fridge (12v) with the charger (to maintain the batteries and the fridge) with the selector on "ALL", with each battery supplying half the power to the fridge.
When we go to the lake I'll switch to one battery, alternating 1 or 2 each trip.
The Charles charger is wired up to both batteries directly, so it doesn't matter where the switch is.
I believe the alternator only charges through the switch.
Be careful on the "ALL" position for long term, its not good to do. If one battery goes bad the other will follow as you are paralleling them. As an example if one cell shorts out it will pull the other battery down to it and keep it there as well. The other battery can actually supply full current into the shorted battery and bad things can happen if the "bad" one would overheat. It will also start to generate huge amounts of hydrogen off-gas during that situation as well and things can go boom. This is why its smarter to use large 6v batteries in series if you need a capacity increase instead of paralleling them up with two 12v. Obviously that will only work to a point and at some point for a large bank you will both have to parallel and series them.
If you are plugged into shore power then the charger will supply 100% of the power to the fridge, leave the selector in the 1 or 2 position only. The output voltage will increase on the charger, taking over for any loads that are "on" while its powered up to its rated capacity. The only reason to leave it on position 1 or 2 would be that way if AC power goes out, it will run the fridge it until it AC power is restored.
You are correct the charger should be wired on the battery side of the switches. And the alternating between 1 and 2 is correct as well as it keeps them both exercised. If on the charger full time make sure that you check the fluid levels as well if they are flooded cells. The chargers can tend to boil them off sometimes, and that can be due to the above if other things are running the voltage will increase on the charger which depending on how long thats for can slightly overcharge the batteries causing the boil down.