Dual Battery Setups! Let's see them! Multiple Batteries Thread!

Another question; In the diagram I posted above, I had a 300 Amp breaker after the ML-ACR. As mentioned, the relay can handle 500A so that breaker wouldn't handle it's capacity so it was advised not set it up that way. Now, I am mounting the second battery inside the cab so that run of 1/0 cable linking them is a little over 9 feet long. Wouldn't I at least want a fuse in between them? They do have the ANL 500A fuses that would match the rating.

I just think that's a long run of wire without any protection. Although the cable will be ran inside the cab, so not much of a chance of getting damaged from outside elements, or hung up on something, wouldn't you want something there to prevent that wire from becoming an arc welder in some freak situation, accident or whatever? If so, where would that fuse go or would you want one on each end?

Sorry if this is overthinking it, but I have a bad track record with fires and don't want to overlook something due to cost that may have prevented some freak accident.

Nate

 

Vibration can eventually rub a hole in the insulation it the wire crosses a piece of metal, so that is why conduit or grommets are used in holes in the firewall, frame, etc. to prevent a short to ground. Unprotected or undersized wire are some of the things insurance adjusters look for as a cause for a fire so they can deny a claim.

 

Yeah, that will all be addressed. I have some braided wrap that'll go on the entire run of the wire as well as some wire loom, grommets and edge trim where the cable will come in contact with metal or edges. That is definitely a concern! Thanks!

 

I'd put a fuse on any wire that comes off the positive terminal of your battery. You want to protect that 9'run of 1/0 cable and a fuse is cheap insurance. I have a similar setup with my aux battery in the cab and about the same length run of 1/0 and I put a 200 amp fuse about 12" from the battery.

 

And you fuse for the wire, not your solenoid/relay. So figure out the max amperage your 1/0 wire can take and put in a fuse that's lower amperage. I know a 9' run of 1/0 can't handle 500 amps, it's more like 150-200 depending on brand.

 

Thanks Alex! I don't know why I didn't think of that? To fuse to the wire and not the relay. I guess I got mixed up with a few things I've read.

Nate

 

x2 adding that I fuse size based on the load and surge for inductive loads, but not exceeding the wire's capacity. It can get tricky when you have multiple loads to protect as well as the wire.

 

Hey guys, I have a rough diagram of the set up I'm going for. Was wondering if I can get some feedback to see if I'm missing anything and if I messed anything up.

I currently have a yellow top Optima in the stock location (rotated) and I'm going to replace it with a red top, then move the yellow top to the pasenger side. Audio amp, winch, and Blue Sea aux fuse panel all going to the yellow top. Upgraded 250A alternator from Bama hooked up to the red top. And the Blue Sea 7622 unit between the two batteries.

My current set up


Proposed wiring diagram


I know there are more wires coming from the Blue Sea unit, but I didn't put them in the diagram. Do I need to add any circuit breakers or fuses anywhere in the diagram? Thanks

 

Fuses/breakers recommended on the connecting wire between the batteries. After both + terminals. If that wire rubs through and shorts you will have both sides zapping shit.

My next go around im going to use some breakers vs fuses. Easy to turn off for maintenance

 

Thanks for the info. I see some people use 300A circuit breakers. Is it necessary to go that big? (I'll have the 250A alternator from BamaToy)

 

I've always thought 80% of rated capacity. BTW, I would NOT put one on the starting battery.

I would go with a breaker for the each leg of the battery isolator. The Winch, Amp, and Blue Sea Panel should probably have them as well. And I would ground the batteries to the same point.

Like this:

 

I'm confused. The diagram you posted has a circuit breaker (or fuse) at both batteries, but then you said not to put one on the starting battery.

And is 80% the load pretty accurate? I'm assuming you have a 200A fuse in the diagram because that is 80% of the 250A alternator? Thanks!

 

I mean don't put a breaker between the alternator and the starting battery.

You don't want to load the breaker more than 80%.

 

Ahh gotcha! Also, what does grounding to the same ground do (for the winch, amp, and aux fuse box)? They're currently grounded separately and have been fine in the last few years that I've had this set up.

 

When you have multiple ground points, you may experience noise in audio systems due to ground loops. I don't worry about the winch so much as the batteries.

 

Good info! Thanks Ian. btw - if you go to mod day, I may ask for your help with the install

 

I'm a maybe for that but sure.

 

i think that having 2 fuses between the 2 batteries is redundant.
The biggest concern with fusing ones lines is MOSTLY incase of accident or an uncontrolled dead short.
Most people mount their isolators/ solenoid so close to that first battery that there is no risk of that segment shorting out. If the secondary battery is located a good distance away , i.e on the other side of the truck or the truck bed in the rear then id agree.

One thing id also consider looking at is the increased resistance all the additional fuses, solenoids, isolators and circuit breakers introduce. Generally this wouldn't be a big deal but if you winch allot and ur pulling 300-500 amps the resistance becomes a factor and you will see a greater voltage drop

 

Fuses protect the batteries and the stuff connected to them and it would be foolish not to protect your vehicle from a dead short or battery failure. Regardless of how near or far the batteries are from their solenoid.

A good design takes into account what you're trying to do and sizes cable, etc. accordingly so that resistance is not a problem.

 

when I installed my winch, I wired it to the starting battery per the instructions. I think it helps to minimize the traveling load from the alternator -> bat -> winch

All of my aux electrical are sourced to the aux battery(lights,compressor,etc) via bluesea fuse block and 200a breaker.

I only run my winch with the batteries linked though, and only pull load with the truck running.