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!

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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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