Blue Sea add a battery kit, arkpak or national luna

[texascrane]

From the instructions:

: Stud terminals A and B are interchangeable. Either battery bank can be connected to A or B.
If the ACR is to be used for cross connect, fuses between ACR terminals A and B and each battery
positive are not required according to ABYC guidelines. If the ACR is not used for cross connect,
install fuses to prevent a hazard if there is damage to the wires connecting the batteries to the ACR.

And from the wiring diagram:

NOTE: Use circuit protection
only if ACR is not used for
emergency cross-connect.

My understanding is that they're telling you if you plan to self jump, don't install fuses between the battery and the relay.

 

[AndrewP]

Should 120 amp do it for a dual battery set up. Would that trip if I had to use the batteries to jump the truck? Due to it being over 300 amps? I guess how many amps does it take to start a truck?

It will be fine.

If your Alternator is less than 120 amps the 7610 will be sufficient. If it's larger, you probably want the MI-ACR.

The average starter is 100 amps or so, so even in a self jump situation, it's highly unlikely you will blow any fuses, assuming you have 2 ga wiring/150 amp fuses or better. Plus if you're worried, just jump the positive terminals with a standard jumper cable. THe Grounds are already connected, so connect the positive terminals and off you go. This bypasses any fusing situation.

Remember too, that fuses don't blow instantly. They are rated for time and amperage. So for instance, a 150 amp fuse would probably tolerate 200 amps for several minutes if not longer, and 300 amps for a short period. The higher the amperage above 150, the faster it will heat up and burn through, opening the circuit. The thing you need the fuses to do, it to blow before the insulation on the wire melts.

edit: Chart of time/amperage for 150 amp ANL fuses (just a for instance, but what I use with 2 ga)

https://www.bluesea.com/products/5127/ANL_Fuse_-_150_Amp


Edit: Not installing circuit protection on long runs of heavy cable is asking to have your truck burn down. The Coast Guard says any cable run over 7 inches must have circuit protection. I suppose that if your batteries are both within 7 inches of the ACR, you would be in compliance with the regulations for boats at least.

Combined battery winching(and maybe self jumping), are so rare that I would basically ignore that as a real job your system will do regularly. Concentrate instead on a safe install for the 99.99% of the time you are not doing those things. If you did happen to blow a fuse with combined winching for instance, how bad is that? Just install a new fuse when the winching is over-it's still going to pull just fine from the one battery it is actually connected to.

 

[DiploStrat]

...
Edit: Not installing circuit protection on long runs of heavy cable is asking to have your truck burn down. The Coast Guard says any cable run over 7 inches must have circuit protection. I suppose that if your batteries are both within 7 inches of the ACR, you would be in compliance with the regulations for boats at least.

Combined battery winching(and maybe self jumping), are so rare that I would basically ignore that as a real job your system will do regularly. Concentrate instead on a safe install for the 99.99% of the time you are not doing those things. If you did happen to blow a fuse with combined winching for instance, how bad is that? Just install a new fuse when the winching is over-it's still going to pull just fine from the one battery it is actually connected to.

I agree with Andrew on this; fuse it or lose it. If you are at all worried, go with a 200A+ fuse. The issue is not current draw, but protection in the case of a short, as will happen if the insulation rubs through.

And, in any case, design your system correctly and you will never have to jump start yourself. I regularly force combine all of my batteries when jump starting another vehicle.

 

[Mo4130]

%100 percent agree on the safe install vs the potentially for draining my starting battery being stuck and having to winch myself out of a predicament.
I would have a 150-175 amp breaker at the positive of each battery. Due to the run I would most likely use 1/0 at a minimum. From what I have read if possible you want to run your ground back to your main starting battery ground. Thus your run is going to be longer cause it's the entire length of the circuit.

Seems pretty simple all in all.

Also any wire that will run under my truck is obviously going to have chafe gear at all contact points.


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[Mo4130]

I have my blue seas acr and am going to install it this weekend. I was thinking 2/0 size wire due to the fact I am running it back to my truck bed. Also was thinking of running the negative just to my frame with maybe like a 1 or 2 gauge wire but that's hack status so I'm gonna run it back to my battery ground. I don't need to go same size for the ground do I? Also obviously have 200 amp fuses inline.


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[AndrewP]

The ground has to be the same size. Of course...it carries the same current.

While you will likely get away with grounding to the frame, it would be much better practice to use a dedicated ground wire.

2/0 is nice big wire and should serve well. 1/0 would likely be sufficient too. I don't have a fuse chart in front of me, but with 2/0, I think you can go larger than 200 amps. Blue Sea's circuit wizard (generally conservative) suggests 2/0 is rated up to 330 amps (280 engine room). So a 250-300 amp fuse would work perfectly.

Make sure you get good terminals and a good crimper, and finish off your cables with Marine heat shrink.

And beware of sticker shock on the 2/0 cable. The best price I have found is Greg's Marine Wire, which is also a good source for lugs, heat shrink, etc.