Dual battery

Jbetschart · 11-02-2009, 04:06 PM

I have a single deep cell on my Mariah 212 Z 94.

Next year I was going to buy two new batteries one deep cell and one starter battery. Is this the best bet or should I go with two deep cell?

Then my plan was to add a Blue Sea Battery switch?
Should it be just the switch or is the add a battery with the ACR much better.
So right now I have the battery in the back and I have a few positive leads coming to it and a few on the negative side.
When I add a switch needs to be located up front by the captains chair? Is this correct. If so so I need to rewire all the cables to my current battery.

or this one

MAJIC · 11-03-2009, 12:32 PM

On my '97 Z252 I have 2 deep cycle batteries with the standard OFF/1/2/1&2 switch, pictured in the bottom. I don't run many electronics - mostly my GPS/Fishfinder. I also keep my boat in a protected boat barn (I have an in/out service in NH) so it's not exposed to elements. I guess you need to look at how much electronics you'll use. I'm not sure about the autoswitching device. I'm not a big fan of them but again - it depends on the conditions you run in.

***ShabahZ250*** · 11-03-2009, 06:12 PM

I replaced both of my batteries this year. Last year when I had my boat in for service, they gave me a memo that stated Mercruiser had made a recommendation of 1000 CCA for MPI boats. When my battery died earlier this year, I replaced them both with the larger, group 35 deep cycle batteries. They had them at Wal-Mart for $79 with a 2 year warranty, and I figured at that price, I couldn't go wrong. So far, they've been great.

The Blue Sea switch and ACR setup is nice, but it requires a little bit of rewiring of the stock system to work properly, and if you're not familiar with how to do it properly, it could potentially cause all sorts of problems if not wired correctly. However it's pretty much a foolproof system for charging both batteries and regulating where the "juice" comes from. However the OEM setup was a dual battery selector switch. This allows you to independently switch which battery you want to use. If you've got two of the same batteries (ie deep cycle), you'll just have to remember to alternate which one you use each time so they maintain equal charge, since the engine will only charge the one that is selected with the switch. I would recommend dual deep cycles, possibly stepping up to a larger group battery so cranking amps isn't a huge concern.

If you've got more questions, I know this has been discussed a few times on here, and some of us have different battery setups. Feel free to search around and ask any further questions you might have!

Jbetschart · 11-03-2009, 08:34 PM

SHABAHZ

So the two batteries that you got at walmart are they both 1000CCA?

blockp · 11-04-2009, 04:06 PM

Sorry to leave you hanging on your other thread.

I was at my storage building last night and I meant to take some pictures of my setup but forgot to take the camera with. I'll try to remember it the next time I'm up there.

Chris is right though, the ACR is a little more involved than just adding the 2nd battery and wiring it to a selector switch. To me it was worth it though. I like not having to remember to switch back and forth between the two making sure they're both charged. Also the convenience that if we cove out until the radio cuts out, I can just go up and turn the key and the motor will start right up. The only downside to the ACR that I can think of is that it will be tougher to diagnose when the house battery quits holding a charge correctly.

Here's a diagram someone drew up that is more detailed than the blue sea diagram and is close to how I setup my system.

I left my switch under the engine hatch like it originally was. All of my heavy gauge wires are relatively short and I didn't have to move too much in the way of wiring. I did have to run a dedicated wire up to my ignition circuit in the breaker panel by the helm. Even though all the breakers are in the same panel, this wire is what separated my ignition from my accessories.

I didn't put fuses between the switch and ACR, mine are between the batteries and the switch. I went with waterproof circuit breakers rather than fuses. This way I don't have to worry about having the right replacement fuse on hand.

Also don't forget to add the ground wire to the ACR. Just a minor detail that I forgot when I first hooked mine up

The good thing was that I had two batteries in the boat and that nice little "combine" feature on the switch came in quite handy

Oh yeah, I have a deep cycle for my house battery and a regular 950 cca battery for starting.