Replacing the accessory battery is a PITA

[inorganik]

Yesterday I replaced the accessory battery (some call it ESS or auxiliary battery) and wow that really had me cursing the Jeep engineers. My Jeep has 26K miles on it and is 4 years old, and it's frustrating they buried a part that needs to be replaced that often so far down.

To get at it you have to

1. remove the main battery
2. remove all connections to the fuse box (between 6-8 depending on your options)
3. remove the fuse box itself and remove 4 large plugs from the bottom
4. remove the fuse box tray
5. unscrew several ground wires from the side of the engine bay

All together it took me about 2.5 hours.

EDIT: don't do it this way, you are supposed to go through the fender well which I didn't know.

The whole impetus for putting an accessory battery there in the first place, in the already packed wrangler engine bay, to support a hacky workaround way of improving gas mileage that unnecessarily wears down parts that when disposed will cause more environmental harm than simply burning a tiny bit more fuel, made this task extra frustrating.

To add a little more background on my decision to replace the battery, I had already replaced my main battery about a year prior, and occasionally my Jeep would randomly not start after it had been sitting for a while. The main better tested good on the multimeter. When I pulled out the accessory battery I confirmed it was bad.

Here is a picture looking at the accessory battery with everything in the way taken out:

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[jellis4148]

You did it the hard way, at least in my opinion. Way easier to remove the passenger fender and drop the little batter out the bottom. That's the way I did it, and it didn't take long at all to do.

 

[Maverick909]

yes, jeep protocol is through the passenger fender. takes less than 30 mins to change it. or you can get the genesis dual battery kit with two 750s that are changeable from the top pricey but atleast you can get two full size batteries.

 

["D"]

Complete removed the battery and did the fuse etc. through the fender in less than 30 minutes. When I first saw the power box method I thought somebody had made a mistake. Liable to screw up more than you fixed using that method.

 

[munkeymike]

Aux delete! Aux delete! Aux delete!

Screw that dumb little battery. It's run in parallel with the primary battery which theoretically is fine, but what ends up happening is the small battery dies and ends up killing your main. The quality of the aux batteries available suck.

 

[inorganik]

You did it the hard way, at least in my opinion. Way easier to remove the passenger fender and drop the little batter out the bottom. That's the way I did it, and it didn't take long at all to do.

Welp, lesson learned I guess I should've looked past the first search result when I googled how to replace it

 

[1Evil55]

Best option IMO is to eliminate that worthless, useless mini battery.

 

[rcadden]

I've removed mine from the circuit but I still need to remove it from the Jeep. Not excited about it, lol.

 

[Deleted User 38384]

@inorganik More reason to delete it!!

That is one of the best things about the EcoDiesels. The auxiliary battery is underneath the main battery. So when you're changing the main battery, there's a little compartment right beneath it and makes it real easy to replace both at the same time. Thankfully when the little one goes it tends to kill the big one, so you're usually replacing them both at the same time anyways.

I've since deleted my auxiliary battery, just purchased a bigger more powerful battery for the main one to cover the loss in power of the auxiliary.

 

[2018JLUsed]

Same same. Removed the fuse, segregated the auxiliary battery at the negative cable. Replaced the H6 Mopar battery with a bigger, stronger H7.

edit: blurry photos show 650cca and 850cca

 

[inorganik]

Same same. Removed the fuse, segregated the auxiliary battery at the negative cable. Replaced the H6 Mopar battery with a bigger, stronger H7.

Mine came with the H7 because it has the towing package. So that's nice.

 

[mwilk012]

I have been saying for years that anyone suggesting removing the PDC for aux battery replacement should have their posts deleted. It is absolutely the wrong way to do the job.

 

[Lionel Hutz]

I just did the same work over the weekend. I went through the fender liner because the plugs under fuse panel didn’t come out during the first attempt. I didn’t force it and took it as a sign not to go that route although working on the battery from the top would have been much easier.

It was probably for the better as there is less that can wrong using the fender entry. It was a pain to install the aux tray from the bottom, but overall not terrible. The work that is, still a terrible design from FCA.

 

[Ratbert]

I have been saying for years that anyone suggesting removing the PDC for aux battery replacement should have their posts deleted. It is absolutely the wrong way to do the job.

So others can't learn from their mistakes?

 

[mwilk012]

So others can't learn from their mistakes?

The people who suggest it as the correct method are wrong and stubbornly refuse to admit it. They will, wrongly, suggest others do the same.

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