I have some questions in regards to installing a dual battery and relocation. I see tons of forums with all mixed information saying 15 different things, and honestly there seems like a lot of good points its just that my brain is starting to hurt here....

Here is some background:

I have killed two batteries in the last year and also had a circuit stay open a drain my battery in about 5-6 hours for a month until I found what it was. So needless to say I need a better battery management system. I want to relocate two new batteries in my passenger compartment between two future bucket rear seats in my XJ. Now I here is why I am posting this. I want to have my main battery be a 850cca battery and my second be a larger deep cycle. I know that a lot of people say you can't run two different battery types without a battery management system. I want to have a marine selector switch selector switch that will let me self rescue with the deep cycle if needed and a charging system that will always keep both charged but isolated so if one battery fails or drains I can still have juice to start. I also plan on running my winch to the deep cycle and have that battery still powered by the alternator while winching. The last time I got stuck I fried my regular battery on a relatively short pull.

I also plan on using a larger durango alternator, 2/0 ga cable, have the deep cycle hooked up to an Anderson connection with a jumper connection, and welding connection. Marine switch will be ran to the center console that I plan on fabricating with a hand throttle switch for long pulls.

-Can I use the two different types of batteries like this?
-Can I use the 4 position(OFF,battery 1, battery 2, Battery 1&2) marine switch in this fashion on the ground side? Turn it to 1&2 to allow the isolator to freely charge both batteries while driving. Then switch it to the starting battery to start and the deep cycle to run the winch, other accessories, and rescue jump.
-Will 2/0 ran to that location be big enough?
-Can I just ground the connection to the frame at that point after the marine switch. I know my other two vehicles just ground the battery to the frame and nothing else is grounded to the battery directly.

I hope this makes sense. Let me know what you think.

 

please keep us all up to date on your dual battery setup !!

 

OK, so first of all, most everyone in here is probably gonna tell you to just fix your current system, and run a single (good) battery. It's the most practical and should be fine, plenty of people are winching with the stock setup.

Anyways, i'll give some input on what I can help with. If you relocate the batteries inside the cab make sure they have a protective cover, are securely mounted, and airtight/vented to the outside. For the new cable 2/0 would be overkill IMO, 1 or 0 gauge should do fine, even with a higher output alt. Grounding to the frame back there would be the way to go. Just make sure you get a good clean metal-metal contact. Also, running battery cables in the cab make sure you've got a properly sized fuse near your battery.

 

2/0 would be great. If your going to do it, you might as well over do it. If you do that upgrade the rest if the big 3 as well with 2/0.

 

Thanks for the replys. I have upgraded all in engine compartment cables and fixed the open circuit. I have a sealed battery box for the batteries and have a vent to the outside of the vehicle cuz no one likes explosions in your own vehicle... the reason I want the master shut off is reliability. Last time my curcuit drained I was stranded for a while back in the woods. Now that I fixed the problem I dont want to do that again. With this setup I'll just switch it to the deep cycle so if something else comes up I'll be set. Also if I do that, it shouldn't reset the computer, and the starting battery should be fine. This isnt a DD by any means but more of a rec/work vehicle and snow day vehicle. There is sometime thar I go a week or two without driving it and the temps have been -10 lately at night. More reliability the better.

Thanks,

 

- You should run an isolator - especially if the batteries are dissimilar!
- Better off using an isolator.
- 00AWG will be OVERKILL. Save your money - unless you're getting stupid, 1AWG is just fine.
- Yes, you may ground all batteries to the chassis, it's the ground plane for everything anyhow.

 

I run a yellow top primary and red top secondary. A switch on my dash powered by ignition on switches a relay that combines the two when needed. Charging two different batteries won't hurt them- leaving them connected when not charging is what drains them because a difference in amperage causes "competition," for lack of a better word.


What if I completely drain the yellow top? Even the slightest juice in the yellow top will be enough to throw a relay to engage both batteries. In fact, I've drained that yellow top so much that I lost the time on my stereo once or twice, yet flip the switch and I'm back up to full power. Love it for the -30°F cold starts too.


I've run this setup for four years without a hiccup. And despite mixed reviews, the optima batteries I've run have always lasted exactly three years. I'd recommend upgrading the positive from your alternator and the grounds from your batteries to the chassis and block as well.

 

Would that combination of manual marine selector switch and isolator work for what i'm describing? My first battery I killed was a yellow top.. not a big fan of that option. I also have the batteries picked out. I think I'll take peoples advise and downsize to 1 ga. I ran the numbers and that size should be just fine.

With this set up is it fine to mix batteries as long as I use that switch to select the deep cycle when I shut the vehicle off? The way I see it is that if I use that selector then the only circuit that would be grounded would be the deep cycle.

If i'm correct, as long as I switch the battery over to the deep cycle when power off there should be no chance the starter battery would power down for any reason because it wouldn't be grounded. In theory there would be no need for the isolator other than a second safety switch and prioritized charging?

 

So I crunched some numbers and for the length im running I want to run 1/0. This is one size bigger than I need with expected peak amp load. I have a buddy who runs an audio shop and can get me a really good deal on audio "ground" cable. He said it would work, as copper is copper and that it would be better for corrosion resistance. The only thing he said I would have to do is beef up the insulation around any contact points as its a softer insulation.

Does this sound correct? Local welding shop charges $4.25 a foot and I could get the audio for 1.30 a foot in 1/0.

 

1.30$ for a "true" 1/0 is crazy cheap. But that's just it, if it really is 1/0 or not

 

Im guessing it's his cost.

 

Do you know what company the wire is?

 

Yeah I'd make sure it's real copper. Not Copper Clad Aluminum.

Although I know at the welding shop I work I can get 1/0 for about 1.50/foot (at cost). It is pure copper too.

 

Copper is copper - but, unless you're going to go over 300A, going with 0AWG is overkill (if you're getting it cheap, no ache.)

Just make sure to use some way to distinguish the positive cable from the negative on cursory inspection - using RED and BLACK heat shrink to seal the ends, respectively, will do. You may use nominal 3/4" heat shrink for 0AWG wire, and it may be installed over the lugs after termination, if you have your wiring terminated for you.

 

is 2awg over 15-20ft good for 200a continuous
Stranded copper oxygen free