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.

Hey Easyrider1340, did you parallel in a 2nd house battery with a switch or "add-a-battery" with an ACR to your start battery like HyFive578?
Either way thanks for the reply!

I don't think you want to install an ACR with what you are wanting to do. You are just adding a 2nd battery to your port battery/motor for a 2 battery house bank/start, (think of it as now 1 big battery) while keeping your SB battery/motor separate. An ACR is for 2 separate batteries (not paralleled) with 1 single charging source, for example; 1 motor and 2 batteries, (1 battery is house, 1 is start)
Just keep your battery switches set to that each motor and it's battery are separate from the other.

I agree on the ACR...great product but not for this application. I believe my boat is wired as per DIAGRAM #2 in the attached pic. With this, the PORT battery in the diagram will be the "big battery" I create with 2 parallel batteries. I would think my battery switching would stay the same...select STB battery to start each engine, then leave one switch on STB battery to charge it, and switch the other to PORT to charge the "big battery". I don't know how it works but currently I run with both switches on "ALL" , presumably using both alternators to charge both batteries (I always thought that was trouble, but it hasn't been. This would actually be helpful with my new 3 battery setup if it will work...thoughts????
...and thanks again, you are always helpful on this site!

[IMG]http://i210.photobucket.com/albums/b...psludlpeoa.png[/IMG]

Personnaly, I'm not a believer of switching battery switches all the time, or running in the ALL position. My preference is to always have them set so 1 motor starts from and charges 1 battery, and the same for the other. That way you'll never end up stranded because you forgot to switch the switch once you reached your destination and ran them all down. The switches are for use for a dead battery start, always 1 good battery. IMO. But you ain't the only to run as you do and I'm sure you are aware of the possible result,

Deep cycles require a lot longer time to recharge. Not something short motor run time will achieve, at least for long term charging. If you are determined to charge by alt, have you considered upgrading to a high output alt? Need to change the alt wire too. Or if possible on board charger and plug it in in the evening. Best option if possible.

Disclaimer, I don't know how well 2 alts work together to charge 1 bank when the other is low when all are tied together. Just not my method, thus no experience. I guess it sounds good in theory :) Ideally, you would send charging from both alts to the house bank, and then use an Echo Charge or an ACR to keep the isolated start battery topped off.

But then what you propose to try, it' simple, easy and requires no added accessories, just memory. see if it works for ya and tweak if need be.


Thanks

I have an ACR on my house battery also. Works great without fear of killing my port starting battery when voltage drops.

The "house" pulls against both batteries until voltage drops to 12.75 then disconnects the starting battery. It reconnects when starting is at 13volts hence a charge is present.

Sounds like your wanting to let your stereo kill both batteries and rely on your S battery to crank both engines. I wouldnt want to do that do to our type of boating long distances from shore. But, it depends on your level of saftey.

If it were me, I would install 2 house batteries with both house batteries set up with ACR on both engines to allow charging. Best of both worlds with piece of mind for both motors. I have been out there when an starting battery died and had to use other battery to start engine. If you killed the other with stereo, well, hope you have plenty of beer for the tow home :-)

Take care!

+1

Good stuff! The sad thing is I have a nice onboard Pro Sport20 2 bank charger installed. It is, by far, the best way to bring them back. But since moving to Las Vegas, my boat is kept in storage and there is no power source. I keep a generator in the storage garage with it, and run it when I'm there, but as you know, many hours are needed to charge and maintain these deep cycles. I've considered a solar charger but expect it would "disappear"...and yes a high amp alternator might help. I'll just trial and error myself through this like most projects. :drink:
Thanks!

Hey nailit! I hear ya, and that was my original thinking when I was reading about the ACR's. But I just couldn't figure how to accomplish the actual wiring. I hate being such a "diagram guy" but sometimes I just need to see it to get it. Do you know of any diagram of what you are describing. I'm interested in this thought!
Thanks!

So 4 batteries. 2 start and 2 as house totally isolated from start except for the 2 ACRs between each side and possibly a battery switch for that super rare condition?
Is there any conflict of 2 ACRs working together?

I think this is what Nailit is describing. You have two house batteries and two starting batteries. The ACR's on both sides will combine each side's batteries from the respective engine alternator and then you can combine the two house batteries via the switch to power your stereo and never have to worry about depleting the starting batteries.

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I used an ACR. I didn't buy the add-a-battery kit, as I found someone here that sold me a used ACR on the cheap, so I just bought an on/off switch that is inline between house battery and house breaker panel.

The ACR is in-between port start battery and house battery, but this is not a parallel circuit with starting battery. It is isolated from starting battery (by the ACR).

Several have chimed in above, but wanted to clarify my original post.

If you see my diagram above, the two ACR's are independent of one another when the battery switch is set to OFF. The ACR's work purely on the detection of voltage levels, ie: they close the relay when voltage above 12.75 is detected and open it when it drops below so in theory with one engine running and the battery switch to all, it might be possible for one bank to detect the voltage going up on the other. not sure if thats a problem or not.

For example, using my diagram.. say the port engine is running. The port ACR will detect voltage going up on the start battery from the alternator, close the relay and start charging House battery #1, if the switch is set to ALL, that current could travel across the switch to House battery #2 and the starboard ACR detecting voltage going up on House 2, will close the relay to combine the starboard bank as well. That scenario might be too much for a single alternator to handle. This is not an issue with the battery switch set to 1, 2 or off.. only when on ALL..

Good diagram HyFive, it actually makes sense. I can see the usefulness of the ACR's in that scenario. To your point, I want to accomplish this in a way where I can't make a mistake by switching something that creates a nuclear back feed! :)
Thanks again for the clarification!

I don't think there is any foolproof option here. If you want to add a house battery, you need a way to charge it. if you hook it up in parallel with another battery, that creates the possibility that one battery can drain the other. So you have two choices, use the engine to charge or a battery charger.

If you want your engine(s) to be the charging source, then you really should use an ACR to safely parallel the batteries when theyre charging and isolate them when discharging or you run the risk of one battery draining the other whether you're using the stereo or not. I would highly advise against configuring something that runs the risk of depleting the starting battery(s) because you are guaranteed for that to happen at the worst possible time (like a sudden raging thunderstorm)...If you don't want to go the ACR route, install two house batteries and use a charger but you'll have to remember to always charge them and deep cycle batteries can take a long time to recharge when run all the way down. In either case, you will have to remember to do something.

I think my diagram gives you a really good solution. You would have two house batteries available for your stereo that will be charged by your engines. You would have automatic isolation when they are discharging and not risk your starting batteries. And I'm not certain that having the switch in the "ALL" position is really a problem, thats the one unknown for me, but you could easily make shutting that switch part of your startup ritual.

Agreed! This also has some installation advantages with my current setup, and eliminates the awkward need to have passengers move off the bench so I can constantly switch switches. Memory is NOT my strong suit anymore, so having the ACR do the combining/isolating automatically is a big plus!

Going off the above posted diagram, put a battery solenoid between the 2 house battery's of the NC state and use your ignition signal as the power lead to switch the state to disconnect condition. This way when you are sitting with the motors off, the house batteries are paralleled. As soon as you start your motors, the relay will open and the house batteries will unparallel and be charged thru the ACRs. All automatic, no owner/operator input required. no switches need to be remembered to be switched.


http://www.allbatterysalesandservice...fm/4,2914.html