How to install dual batteries in your Jeep Wrangler TJ

Great write up and I really appreciate the parts list!

How have the Optimas held up in the AZ heat? I used to run them in my F250 but Costco got tired of me returning them and stopped carrying Optimas.

When you winch have you tried using snatch blocks to reduce the load on the winch?

I'm in Gilbert, hope you'll check out my Jeep group at EVrockers.com
I have always been a believer in the Optimas, but since have moved to Odyssey except for in my Jeep. Ever since interstate sold them they have not been good. I bought a blue top for my camper, and it didn't even last 6 months. It was a joke, then I bought a red top and a yellow top for my Chevy. I got a year out of the red top, but all of my yellow tops are going strong.

I am kind of stuck on the Jeep. There really is only two kits or brackets you can buy unless you custom fab something. If you don't have A/C then you have more room, but I have to have A/C. I am older and not as tough as I used to be, so I went with the yellow tops. If you go odyssey then you give up cca's by a lot. Which means a lot smaller battery for winching. So I still stand by my yellow tops. It has been a couple years now and they are still going strong and they are both mounted sideways.

In my Chevy I have a pc1500 Odyssey for my main battery and a yellow top for my aux and my aux battery is coming up on 4 years. So if I were to endorse the optima, I would stay with the yellow tops, but honestly when I do lose my aux in my Chevy, I will probably buy an Odyssey for the secondary battery.

For now I will just stay with the yellow tops in my Jeep. I have had pretty good luck with them.

Thanks for the flowers on the write up. I appreciate that!
 
I have always been a believer in the Optimas, but since have moved to Odyssey except for in my Jeep. Ever since interstate sold them they have not been good. I bought a blue top for my camper, and it didn't even last 6 months. It was a joke, then I bought a red top and a yellow top for my Chevy. I got a year out of the red top, but all of my yellow tops are going strong.

I am kind of stuck on the Jeep. There really is only two kits or brackets you can buy unless you custom fab something. If you don't have A/C then you have more room, but I have to have A/C. I am older and not as tough as I used to be, so I went with the yellow tops. If you go odyssey then you give up cca's by a lot. Which means a lot smaller battery for winching. So I still stand by my yellow tops. It has been a couple years now and they are still going strong and they are both mounted sideways.

In my Chevy I have a pc1500 Odyssey for my main battery and a yellow top for my aux and my aux battery is coming up on 4 years. So if I were to endorse the optima, I would stay with the yellow tops, but honestly when I do lose my aux in my Chevy, I will probably buy an Odyssey for the secondary battery.

For now I will just stay with the yellow tops in my Jeep. I have had pretty good luck with them.

Thanks for the flowers on the write up. I appreciate that!
There's another option besides Optima and Odyssey, for deep cycle purpose which is what the Yellow Top batteries are truly made for even though they do have great starting qualities. Prices are (or used to be) fairly similar but Lifeline has WAY more sizes for different applications. (group sizes)
https://lifelinebatteries.com/products/
 
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There's another option besides Optima and Odyssey, for deep cycle purpose which is what the Yellow Top batteries are truly made for even though they do have great starting qualities. Prices are (or used to be) fairly similar but Lifeline has WAY more sizes for different applications. (group sizes)
https://lifelinebatteries.com/products/

Thanks for that! This is exactly why I love this forum. We always get to learn new things and products. I for one have not ever heard of these yet. So I am going to check them out. Probably if they are good put one in my camper since one is due now and test one.

Thanks for the link!
 
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Thanks for that! This is exactly why I love this forum. We always get to learn new things and products. I for one have not ever heard of these yet. So I am going to check them out. Probably if they are good put one in my camper since one is due now and test one.

Thanks for the link!
I learned about them along with many other types and styles of batteries when I worked for a battery store in Everett, WA called Pacific Power Batteries.
 
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I have never felt a major need for dual batteries, but it is something I've contemplated on doing, simply for the reason you mentioned, for the backup and to not be stranded.

I had been thinking on using the driver's side, as that seemed to be the option. I've learned something today with this one. Awesome write-up and well done! Thanks, man!
 
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Great write up and your efforts to promote dual batteries continues to be of assistance. Your nearly on working on year six. My F250 also killed so many optima batteries that I stopped using them. I do have one in the LJ, however, I don't trust it.
 
I gave up on optima a few years back and had to remind Costco they used to prorate them for six years, I’ve used lifeline batteries in our rv for a couple of years now
 
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I gave up on optima a few years back and had to remind Costco they used to prorate them for six years, I’ve used lifeline batteries in our rv for a couple of years now
Lifeline is an excellent battery! I sold them when I worked for a battery store in Everett, WA.
I did quite a few 4D and even a few 8D conversions for customers on their motorhomes.
 
After buying all the parts last March I'm finally doing this project. Yes I am a world class procrastinator but I also decided to break other stuff that was more pressing. SO the issue I'm running into is that on my 2004 there is a special two bolt tab that is bolted into the fuse box under the hood has a green and red wire running to it. The red wire goes to the main battery while the green is spliced to red then goes to the alternator (Factory connections as far as I can tell). My winch is also wired to the alternator not that I think that matters. So what I am thinking is that the main battery side of the solenoid is supposed to look exactly like what the battery looks like without a dual setup so I've used some of the old wires to splice into that red/green wire so that I can run it to the battery side of the solenoid and the other end to the alternator as it was.

I went with Odyssey batteries and hacked up my Rugged Ridge dual battery tray to get them to fit. I have Genright fenders and inner fenders now so there's plenty of room but as you can imagine the trays aren't going to be all that pretty. As a welder I'm a great grinder. I'll post some pics after it's powdercoated so I can save a little embarrassment lol.
 
Well I got them both in but looks like I'll need to take it all back out and move the tray closer to the engine. I had just enough room when I was mocking it all up as I went but when it came time to actually tighten things down it's all a little higher than I thought and the hold down is hitting the hood. I have almost an inch I can go closer to the engine so it shouldn't be a big deal though the damn AC lines are going to be tight. The Genright fenders and inner fenders helped a lot.

Hacking up the tray for the Odyssey's wasn't all that hard though as I forewarned it's not going to be pretty. I had to trip the extra plastic on the Odyessy's too as the fins they put on the side are right where the threaded rods go.

What I don't get is the Painless instructions say to wire all your accessories to your primary battery including the winch and basically just leave the secondary sitting there as a backup. I would think you would want to run all the accessories off that one and have the primary just used for starting. I think a power block would be the best option as I have a power inverter and my air compressor wired directly to the primary battery and if I move the winch there too it's not going to be enough room. Anyone have a recommendation for a water tight power block?
 
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Pics of the install.

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That is awesome. I love good hacks! I am glad I was able to help with this project. It looks great!!

I wanted to just give an update on my install!

I originally posted this thread on Oct 7, 2017 , and todays date is July 10, 2021, and I am still running both the same batteries. Everything is still running great. Both batteries are still doing great. And the main battery was already in the Jeep when I started this project which means it is even older than the aux battery. I am not saying that Opima is awesome, nor am I pushing their products. I am only saying that the ones I have, have lasted almost 4 years so far in Arizona.

I have also since bought a Alpicool C50 fridge that I run on the aux battery, and have used my winch quite a bit. I would definitely do this again.
 
I've considered adding a second battery, but for my use case, the biggest battery I could fit plus a bigger alternator seemed to make more sense. As of right now I don't have a lot of ignition-off draw, but the winch and other accessories suck a lot of power. So I went with a 180 amp alternator for now. If I find myself frequently overrunning that, I may step up to a 270 or 370 amp alternator.

I've also been tempted to wire in a 2kW or 3kW 120VAC inverter. That would certainly require the engine to be running to use, at least at higher consumption levels.

Another thing I did is I bumped up the PCM charge voltage from the factory 13.55 to 14.35 volts. AGM manufacturers specify that alternator charging voltage should be between 14.1 and 14.8 volts, and anything outside that range significantly shortens the life of the battery. The higher voltage promotes faster battery charge recovery, extends battery life, and also increases the power of any resistive electrical components in the jeep.

If I were to install dual batteries, I would be most tempted to try and fit a battery box or two in the space under the floor where people usually mount a second 12 gallon gas tank or a compressed air tank. I'll bet you could fit several large batteries there. It would keep a lower center of gravity and a cleaner engine bay. However, it would preclude the use of a second gas tank and maybe an air tank.

I do like the option in this thread as it is simple and easy to replicate.
 
Nice tips. Dual batteries isn't for everyone for sure. The sticker shock alone will stop most. I just have always had dual batteries, and was perplexed when I got my TJ. I do like to go camping a lot and by myself, so I wanted the extra insurance. I usually carry some sort of briefcase solar panel also just incase, and to keep the battery powered up when I am running the fridge.

I don't really notice a change in center of gravity since the upgrade, but I may have put on some weight to compensate on the other side of the Jeep lol

I picked this option because as you said it was pretty easy, and 4 years ago when I did it, there was absolutely no info on dual batteries in a Jeep.
 
What are the advantages and disadvantages, exactly, of connecting your winch to the alternator or by getting a higher output alternator?
 
Surge current can only be provided by the battery. The alternator, even a high output alternator cannot supply 300 amps. Connecting to the alternator instead of the battery means the current has to go through the fuseable link from the battery and then to the alternator and then to the winch. That will likely blow the fuseable link under heavy loads and leave you without an alternator.
 
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