Dual batteries selection

[DaveM]

This question has been asked before but do most of you set your Dual battery switch to: 1, 2, or 1+2 (both) selection on dial? I use one battery at a time in order to fully charge it. I try to rotate battery selection each day we go out keeping both charged. I think I read selecting both will not fully charge either battery. Is that correct?

[Isaguel]

There's a thread on this and as I understood it, you are correct, you should not use both. The engineers explain that the only instance you use both is if both batteries are low and you need both at same time to crank the engine. Otherwise the one being used is the one getting charged, so I agree wit alternating batteries.
I garage my boat and I plug it into the onboard battery charger when I get home.

[haknslash]

I rotate mine each outing as well and was told this is preferred method by my dealer. He said only use 1+2 in the event I can't crank the engine on one battery or the other.

[parrothd]

I rotate mine each outing as well and was told this is preferred method by my dealer. He said only use 1+2 in the event I can't crank the engine on one battery or the other.

I always leave it on 1&2 so both batteries are always being charged, if we hit the party cove with the stereo I switch to 1 or 2. That way you always have both batteries charged. Using 1 & 2 with two dead batteries will not start the boat..

[sandm]

same with parrot. 3rd boat doing this and no issues.
sure mla will chime in as he's educated a few on these. I know there's different models/designs and operate differently so might depend on which one you have.

[Bch53211]

I rotate mine each outing as well and was told this is preferred method by my dealer. He said only use 1+2 in the event I can't crank the engine on one battery or the other.

This is what I do as well.

[haknslash]

I always leave it on 1&2 so both batteries are always being charged, if we hit the party cove with the stereo I switch to 1 or 2. That way you always have both batteries charged. Using 1 & 2 with two dead batteries will not start the boat..

When I'm not using the boat the onboard charger gets plugged in which keeps both batteries in good condition and topped off. When I go to the lake I'll pick 1 or 2 and use it for the day and that battery gets charged while the other acts a reserve or backup. Or you can treat one as the start battery and 2 as the house battery. There's multiple ways to skin a cat I suppose in this instance. All I know is if you use an onboard charger then it's not likely you'll need to use both batteries to be charged in the 1+2 configuration on the water so long as both batteries are wired correctly to the switch. You can do it both ways and they achieve the same idea, I just prefer to use the onboard charger as my method for charging both batteries and like the idea of a reserve or backup rather than use 1+2.

[parrothd]

I'm in a wet slip all summer so there's no plugging in the charger, that only happens in winter.

[Turbinesurgeon]

Odd days use batt 1 and even days use batt 2


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[MLA]

There is no universal method IMO. How you use the switch has a lot to do with what type of batteries are there and how you use the boat.

The 2 main functions of the 1/2/BOTH switch, is to allow for emergency starting, and isolating one bank form the other, for anchoring. If you have 2 identical batteries and your usage is mostly engine running, then alternating between banks on outings is fine, so is running on both, as it keeps both banks topped off.

If you have a cranking battery and a deep-cycle and you spend time at anchor, then you need to use the switch differently. Obviously, you would want to switch over to the house bank (deep-cycle) when you anchor, keeping the cranking in reserve. Then restart on the cranking when you are ready to move again. So now what to do with the run down house bank? Heres where I may differ from what the dealers are telling people. You can run on both, and both banks get some charge. This helps to recover the house bank while the boat is in use. Or, move past the BOTH position and go to the house bank. Now, all the alternator output is hitting the house bank.

The Blue Sea switch Moomba uses, is a make before break, so its perfectly safe to move between the 1, BOTH and 2, which engine running. Just dont go to or through OFF with engine running.

The Blue Sea Dual-Circuit-Plus switch is a whole different animal, so note my thoughts are for a 1/2/BOTH/OFF switch.