290enticer

us1, for clarification, I only have one switch, and the converter/charger will power my ac accessories in the cabin as well as charge two batteries. The boat has a nice stereo and looks like only the amp is connected to it, there are some leads that power a fuse box which goes to the amp. there are only 2 fuses in it, not sure what the other fuse is powering, I really want to run all my accessories off the house battery. I might have to take some of the leads off the starting batteries and move them to the house battery when i figure out what is what. when i overnight, i only want to be pulling from the house and not either of the starting batteries. Question: I think the cranking battery for one engine, or can i crank both engines with only one battery?? Not sure how the switch is wired.

STV_Keith

I'm still at a loss as to how you are running two engines off one battery switch. I know in the outboard world, tying the fields of two alternator charging systems together is a bad thing. I'd recommend that you install another battery switch and use the OUT of each switch to it's own motor.

Here's a diagram drawing that I did for another guy a while back. Ignore the multiple house batteries and inverter, but the rest is pertinent.

290enticer

um...i can't tell you? I am still familiarizing myself with this twin engine set up. I know i only have one bat switch, two group 24 cranking batteries and one group 27 house battery. Like i said, the house battery looks like it was added just for the stereo system and the only way it is charged is by the inverter/charger which i don't want it like that. I want all of them to be tied so when my engines are running, it is charging all batteries. I never run just one engine. The engines may be able to crank with just one battery, i don't know how the switch is built inside, when it gets warmer im gonna do some investigating to see how everything is wired. Some of the accessories may be coming off one or both of the cranking batteries but i want all of it to be coming of the house battery. The inverter/charger will only charge two batteries, one is on one cranking battery and the other on the house. i will wiring them to charge both the cranking batteries, that way i know both engines will start. who knows....maybe the engines can be started off of just one of the batteries.....don't know. I can tell you this...the twin engine set up is more complex that just a single

capt2130

This is what I am currently hooking up on mine now. If memory serves me right. I think I found it in a thread from US1. But don`t hold that to me. I am setting up 2 house and 2 cranking batteries.

http://atkinsonelectronics.com/manuf...fs/MBCM-12.pdf

Tim

290enticer

um, it looks like it pretty much does the same thing as the acr. but what about the 85amp max alt output?? I don't know what mine is but will it fry if its over that, maybe its 100-120 amp alt? Seems like the acr is much more simplier...as fas as wiring and hookup. acr is in and out plus a ground.

US1 Fountain

iTrader: (1)

I'm with STV. 1st thing I'd do is replace your battery switch with a single Dual Circut PLus switch. That will work the same as 2 switches, but with less cables. Keep those motors isolated from each other. Been told EFI motors don't like to be combined, the ecms get some cross talk thru the common cables. Carbed motors no problem.
By adding that switch, and then the ACR between 1 of your start batteries (the one that powers your cabin lights) and the house battery, you'll never be dead in water. All 3 batteries will be isolated from each other when no charging source is operating. You can then hook all you want to that house battery and not worry about either of your start batteries getting ran down from it. For your house battery circut to be ABYC and CG compliant, those accessories need to go thru a battery switch, (On-Off) and then fused within 7" of the battery post.
Worst case sceneiro is you kill your house and the 1 start battery from running all your lights and stereo. No problem, just turn the dual circut switch to COMBINE, and now both motors will start from the always fully charged battery as it will never be connected to anything more than the 1 motor for starting. Providing you do away with the 1/2/All/Off switch.
I'm curious if your invertor parallels your house battery to your start battery? You know what brand/model it is?

This is the ACR going in my cruiser. It can handle 500A. It will also parallel the battery banks if I run 1 down, by a remote switch at the dash. No need to manually switch the battery switch itself. The ACR's so far in this discusion do not have the go-nads to act as a parallel switch for starting draw current, charging only.

capt2130

My alternators are 65 amps. The configuration I`m doing is application 3.

290enticer

us1, my engines are not efi, they are carbs. The battery switch shouldn't be a problem then...right. I don't really want to change that cause there are like 4 big cables that are routed very nicely to it. I will look tonight after work on the brand of converter/charger i have. All that was in the boat when i purchased it, that stuff is new to me cause this is the first twin engine boat i have owned. Thanks!

Audiofn

I think your best bet is going to be a battery isolator like they are talking about above. You can do a few other things to make it work like pulling a power wire from one side of your battery switch to the "house" battery. This works but you have to remember to turn your battery's to the off position when you overnight or are listening to the tunes. A battery isolator is your best bet in this situation. Also make sure your grounds are all tied together really well!

US1 Fountain

iTrader: (1)

You wont change a thing by using the Dual Circuit switch. Your current switch has 3 studs on it, with both motors connected to 1 of them, and a battery to each of the remaining 2 studs.

The switch I'm suggesting has 4 studs, so you simply connect each motor to a stud of its own. The bolt pattern of this switch is the same as the Guest and Perkos, so even easierr. A simple 10 min swap and you will have a fool proof setup.

The Blue Seas 'Add a Battery' has both the ACR and battery switch for around $120.



Option 2, Easiest with only a new switch and battery required. For your application, this would be my recommendation. Simply and fool proof.

Replace 1 of your start batteries with another matching deep cycle battery.

1 motor to remaining start battery. (This motor/battery on it's own)

2nd motor to the 2 deep cycle batteries that are connected in parallel. You will do no harm using them to start your motor.

Use the Dual Circuit Plus switch to switch on/off both motors. Also requires no changing of wires as above, from what you have now. Just reconfiging them.

Use no ACR. Your inverter/charger is connected to your now house bank, giving you double the capacity for your house load, cabin lights and inverter power. When plugged into shorepower, the charger will charge your 2 house batteries, or all batteries if switch is in the COMBINE position.

If by chance you run the house bank down, simply turn the battery switch to COMBINE, and start your motors off the start battery.