Want to install a multiple battery switcher - Need some advice / help

[kevinstan]

I am looking to install a battery switcher on my mercruiser. We often stop and hang out on the lake listening to music, and If I were to run the battery dead I would like to be able to switch the battery over to the other one then start the motor. I went to academy sports yesterday to purchase one but ran into a problem - There were two of them around the same price, and not enough specifics listed on them for me to know which one to get.

One of them was about 2 inches square and just had a 1 a 2 and off - Which I assume is battery one battery 2 and off

The other one was about 8 inches in circumference (Much noticeably larger) and had the same on it.

What is the difference in these, and which one will I need to get ? Can anyone steer me in the right direction ?

Thank you everyone in advance!

 

[Scott Danforth]

Iboats sells battery stitches. Get the one that gables the amperage required for your boat

 

[Georgesalmon]

You want one that has "OFF, !, 2, BOTH. You can use #1 for starting and #2 for sitting around. Then switch to BOTH while running to put a tiny bit of charge back in. OFF is for when you are away from the boat.

 

[Stingrayaxe]

Kevinstan, What style batteries are you planning to use? One starting and the other a deep cycle? Both combo Starting/deep cycle? I'm just curious since I'm going to do the same project as soon as the boat comes out of storage in a few weeks. I'm thinking the Blue sea add a battery with ACR kit. Just can't decide what kind of batteries to use.

 

[airshot]

On my boat I have two batteries, one is a starting battery and that is all it does, nothing else other than a secondary emergency bilge pump. The house battery is a group 27 deep cycle battery and everything elase is hooked up to that one. Main bilge pump, s/s radio, gps, fishfinder, stereo, aerated minnow bucket, running lights etc. I have a switch to change back and forth but try not to use it. The deep cycle battery charges better at a low charge rate so I put it on the charger at home when it needs charged. I normally get 4-5 trips out before it needs to go on the charger. This way I always have a good battery to start the engine with. If you try to charge both batteries at the same time be carefull as you could over load your alternator. My electrical rebuilder recommended only charging one battery at a time and also said NEVER switch from one battery to both while the engine is running as this will cause major electrical issues. My switch even states do not switch from one batt to both with the engine running. A good deep cycle battery should easily last you all day on the water with any issue then use your start battery to get back in.

 

[bruceb58]

airshot A deep cycle battery can be charged at the same rate as a starting battery. Not sure who is telling you all this mis information. Deep cycle batteries need to be charged as soon as possible. Leaving them in a discharged state for days allows sulfation to occur. And just like the other thread, perfectly reasonable to switch to the BOTH setting which is basically the same as having an ACR in the system.

 

[frankk]

Ok, here is a sidebar question. I get using the battery #2 for "everything else" and battery #1 for starting, switching to 'both' when starting and leaving it there for charging... but how much stress are you placing on the system if you do this? Before starting battery #1 is discharging into battery #2. Then when running, you are charging both but again battery #1 is charging battery #2

 

[bruceb58]

You don't switch to BOTH until you get your boat started or you will have the scenario that you just mentioned. Once you get the engine started and the alternator is outputting, battery #1 is not charging battery #2 since the alternator voltage is higher than either batteries rest voltage.

BTW, using a 1/2/BOTH switch is not the type switch to use when you use a house battery unless it's in addition to a separate house switch or a switch that basically has 2 switches built into it like this one.
https://www.bluesea.com/products/551...Battery_Switch

The best system if you are using a house is that switch along with an ACR if you have everything on a separate house. They sell the switch and ACR together:
https://www.bluesea.com/products/765...ery_Kit_-_120A

I have 2 boats, one has just a 1/2/Both switch and I just leave it on battery one all the time while the ACR keeps both charged. Battery#2 is only there for when I over discharge #1. Both batteries are AGM deep discharge batteries.

On my pontoon, I use the battery switch I linked above with a start battery and a house battery with all loads on the house except for the motor. It also has the ACR to charge both with the engine running.

Using an ACR means you don't have to do the switch game. I never switch to BOTH. The ACR does that for you once the engine starts and disconnects the two once it stops.

Both boats have onboard chargers so they can be immediately charged when I get home too.

 

[frankk]

Have not seen this ACR before, thanks for sharing. I will consider that this Summer!

 

[Silverbullet555]

Use an ACR and a switch. Blue sea add-a-batter is what I installed. Charges both. I run 2 group 31 starting batteries and alternate their duties each year. They have a a lot of capacity and are deka 1131xmf or Duracell sli31sa.

One battery runs the boat and head unit for stereo. Other runs all the amps and other stuff. The last pair lasted 6 years which is good enough for me for $100 each.

 

[GA_Boater]

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