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Optima in a JK

Group 34 Optima Yellow Top

Part #:

Jeep changed the position, size and orientation of the batteries in the new 2012 Jeep Wranglers. Almost seems like a cost savings on the wiring harness since there is virtually no slack and the wires are about 8 inches shorter for the positive cable's. This unfortunately doesn't allow for an easy swap of your old batteries into your new Jeep. I ended up trading in my 2007 with an Optima Yellow top under the hood. The Optima has about 150% the capacity and power of the stock JK battery, so having that would be really nice. I wondered if it was actually possible to put a group 34 Optima in the new tray. Of course having a spare sitting in my garage cabinet and a little spare time started a little experiment. What would it take, and could it be done. Here is the results.

Additional Parts:

Tools Needed:
10mm Combo Wrench
10mm socket
Long extension
Flat tip screwdriver
Needle Nose pliers


Removal and Installation:
1. Remove the old (in my case 63 mile old) battery from the Jeep.
2. Remove the positive and negative battery cables by looseing the clamp bolt with a 10mm combo wrench. Loosen the nut and the clamp should slide free. You may need to pry the cable clamp loose with a flat tip screwdriver, but mine came off easily. Be careful not to touch the two terminals with the wrench, though it does make a nice light show and noise.
2a. Make sure the cables are back away from the battery terminals.
3. Remove the clamp bar from the bottom of the battery tray. You will need a 10mm socket and long extension to get down to it. It's a fairly long bolt, so unscrew it long ways. I kept reaching down and finding that it was still screwed in.
Size comparison. The stock battery is longer and the terminals are on the opposite side. The stock battery also has a bigger lip on the bottom, but the hold downs in the new tray didn't look any different than the hold downs in my old tray and that optima stayed in place.
4. Lower the Optima in place. One thing I did notice was that it was heavier than the stock battery.
5. Reinstall the hold down clamp. Check to make sure the battery is tight in it's mount. I just grabbed it and tried to move it around. Nice and secure.
Okay, here is the problem, as you can see the battery cables do not reach the terminals on the Optima.
6. Getting the negative cable over was fairly easy. I just had to pull the the holder out of the side of the plastic tray. I just pulled up and grabbed it with a needle nose pliers to pry it out.
7. The positive cable was going to present a little more difficulty. I had hoped that I could get it by just pulling out the next cable mount, but it was also secured by one along the fire wall.
7a. The positive cable bundle runs back down along the firewall behind the engine. Here is what it looks like before and after. It doesn't appear to be touching anything other than the automatic transmission dipstick when I pull it over.
8. Reinstall the positive and negative battery cables and tighten the clamp bolts with a 10mm combo wrench. Be careful not to touch the two terminals with the wrench, though it does make a nice light show and noise.
Is it really worth for the optima or Diehard Platinum? I don't really know for a little more CCA, with less Amp Hours and the fact that I have pulled a battery cable bundle out of the manufacturers mount position, and even though I can't see it rub against anything doesn't mean I won't have problems with it later. Best solution would be to buy a Group 35 Diehard Platinum battery, that way your not changing the positon of the cables in an already cramped engine compartment. Diehard Platinum P5 (Group 35) Battery will work as reported by a couple of people. The terminals are in the right position. The Optima and Diehard do have a few advantages in the fact that they are a sealed AGM spiralcell battery and the Optima does have side terminals so you can mount a few accessories in that location. Other than that here is a quick comparison. I did see a post where someone posted that the stock battery only has 600 CA and 475 CCA which was incorrect. It's 600 CCA (SAE) and 475 CCA (EN), different country standard measurements, we use SAE here.
Battery Comparison:
Stock Battery Optima Diehard Platinum P5  
CCA: 600 CCA: 750 (125%) CCA: 740 (123%)  
AH: 70 AH: 55 (78%) AH: 59 (84%)  
RC: RC: 120 RC: 100  
CCA = Cold Cranking Amps - This is the rating used by the battery industry to define the battery's ability to start an engine under low- temperature conditions.
AH = Amp Hours - Represents the amount of energy a battery can hold. This measurement helps determine how long the battery will power the equipment it is used in. The more 'Amp Hours' the longer the run time.
RC = Reserve Capacity - Defines a battery's ability to maintain a low amperage load (how long, in minutes, the battery will maintain a 25amp load until voltage drops to 10.5volts)



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This page last updated: 26-Apr-2012

Content and Design © 2002-present WanderingTrail,  Ron Seegert
Common Sense and Safety should always be observed when working on your vehicle or doing modifications. Jackstands, wheel blocks, disconnecting the battery are a few of the basic safety precautions that should be used and may not be mentioned in the write ups on this site. You are responsible for your own installation, these write ups are a helpful guideline and should not be taken as an official installation instruction. My write up may be different from the kits currently out there, so alwasy double check the manufacturers installation instructions when installing anything. I try to keep the site up to date with changes that have occured as I discover them, but may not have the latest unless someone lets me know. If you feel that an install is above your capabilities after reading my write ups, I recommend getting together with a club and getting some help. Only a few times have I needed to employe some actual help from a shop to get something done. Usually welding or A/C work.
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