Need help with wiring a 3rd house battery
 

Hey guys, current setup: 2 motors,2 batteries, 2 Perkos in a Baja 302. Just installed power audio system and want to beef up power supply. Plan to add 2nd battery in parallel to port battery. Concerns are battery equalization and stress to alternator while charging 2 depleted deep cell batteries. Blue Sea ACR looks like the answer but how would I wire it up?
Thanks!
Dan

I just did something similar. Installed a house battery for my new stereo and connected it to my center engine using a Blue Sea ACR.

I used this one: https://www.bluesea.com/products/761...12_24V_DC_120A

It's pretty simple. You run 4-gauge wires from the positive terminals of both batteries to the ACR. Both of these wires need to have adequate fuse protection between the battery and the ACR.

I used these: https://www.bluesea.com/products/500...00A_with_Cover with 125A Mega fuses.

The ground from the ACR should be connected to the ground on the engine block. The ACR I used also has start isolation which will automatically open the relay and isolate the batteries when it detects a start charge. For this, you run a wire from the ACR to the terminal on the starter solenoid that is only hot when the key is turned to start.

All of this I'm describing is in the instructions that come with the unit by the way. It works great.

HyFive,

if that fuse block is in the engine compartment you should have used this one, its ignition protected.

https://www.bluesea.com/products/772...ety_Fuse_Block

Thanks Wildman. I made a mistake in my earlier post. I just checked and I used #7721 fuse blocks, not the one I indicated earlier.

https://www.bluesea.com/products/772...ety_Fuse_Block

No Problem, they make a ton. Nice stuff.

I knew I used the mega fuse blocks and I just did a quick search when I posted earlier, but then when I saw your post, you got me thinking... I wanted to confirm that I did use ignition protected devices... went back to my original order and saw that I had...

Look at the MRBF fuses too. Attach directly to battery terminal. 1 less battery cable needed, satisfy the 7" rule. I use them for a cleaner look too

Thanks for the reply!
That makes sense for what you were doing, but it's a little different than what I'm doing. I'm trying to create more battery capacity for heavy stereo use in a way that won't let a weak battery pull down the other, AND allows charging without damage to alternators. Using the ACR BETWEEN the 2 batteries would keep them separated during stereo use, therefore defeating the purpose. In your case, you WANT them separated except for when charging, so the ACR is perfect. Maybe I just need to hook up the 2 house batteries in parallel with another Perko switch between them so, if they are very run down, I can manually choose to use and/or recharge them 1 at a time while running??

I'm not familiar with those...will look them up.
Thanks!

I did same to mine last year - same as indicated above. Best thing I ever did, particularly for piece of mind when the stereo is on all day at a raft up. I moved everything from breaker panel to this house battery - I can run the fridge all weekend, as well as the stereo.