Join Date: May 2015
Location: Western Massachusetts
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2015 TH Battery Replacement
I couldn't find any write-ups on DIY battery replacement, so I thought I'd share my experience.
I'm no auto mechanic but I try to do what I can. I've done my brakes and oil changes - that sort of thing. I've replaced batteries in plenty of other vehicles, so I thought I'd take it on here.
I own a 2015 Trailhawk (bought new) and I've heard of some people having problems when their battery dies, so I wanted to replace mine before that point. In my experience 5 years is a pretty good bet on how long a car battery will last if it is not abused (often deeply discharged - which mine was not).
I know FCA has made some changes to the battery terminals - so my experience is what I came across on my 2015 North American model.
I hooked up a battery tender to the cable terminals in the hope of maintaining power to the computers and radio. I don't usually bother with this, but I tried it here (more on this later).
The negative battery lead is removed first. I have a cam-lock style clamp on the negative lead. Those of you familiar with bicycle wheel skewers will recognize the mechanism. Just a quick flip of the lever and the negative lead can be wiggled off the battery post. I tucked it out of the way by the coolant reservoir.
Next, I removed the hold-down strap clamp (more on why I did this now in a minute). The nut that secures it is located near the bottom of the battery on the inboard side. It is 13mm and you'll need about a 12" extension to get to it easily. Once the nut was off and out of the vehicle (easily dropped), I wiggled the strap out past the positive battery leads and tucked it out of the way by the washer fluid reservoir.
On to the positive lead... so the reason I removed the hold-down strap before this, was that once the positive post is off the battery, the multitude of cables attached to the assembly (from several directions) limit how far I'd be able to move it out of the way. I thought it would be easier to get the strap out of the way first. Maybe not a big deal.
The positive terminal has a more traditional post clamp that uses a 10mm wrench. Before trying to wiggle the positive lead assembly off (I call it 'an assembly' because there's really quite a chunk of stuff that comes with it) there is an odd, red plastic "thing" that is held on to the battery (through the post assembly) with two Philips head screws - that must first be removed. Does anybody know what that is? Once the red thing is out of the way and the post clamp is loose, the positive assembly can be wiggled off the battery post. As I said it won't be able to move too far out of the way due to all the wires attached to the assembly. You could (I didn't) remove some of these wires as they are all bolted on. I kept them all together and attached to the battery tender.
At this point, the battery can come out. My OE battery had two built-in handles that made lifting it easier. I needed to hold the positive lead assembly out of the way as I finagled the battery out - front first. My battery has an insulated wrap around it. It stayed behind as the battery came out. I pulled the wrap out separately.
I brought the battery to my local parts store (I avoid dealers as if they have the plague). I use O'Reilly and they had a match in stock. I checked the physical dimensions before I departed for home (2 minutes away). For those of you interested, I bought O'Reilly item 48PLT. It has handles just like the OE battery and it even had the receptacles for the posts of that little red plastic clip thingy - whatever it is.
Back home, I wrapped the... wrap around the new battery (secured with hook-and-loop fasteners) and dropped the battery into place while holding the positive lead assembly back. Be aware that the battery insulated wrap is not symmetrical. It has an aluminized side to reflect radiant heat from the engine.
I maneuvered the positive lead assembly onto the positive battery post and secured the clamp with the 10mm wrench. It fit quite securely. I reattached the red thing with the two screws. At this point I still had the battery tender hooked up, so I couldn't snap the terminal cover back on yet.
On to the negative terminal. I slid it on the post and threw the cam-lock lever over to tighten it... and it was dead loose. I looked at the situation for a minute. The spit in the clamp was together tight, so the cam-lock was doing all it could. There was no way to make the split clamp clamp tighter. It was at the limit of the split.
My conclusion was that the battery post was just a little too small. What to do?
I recalled seeing something called 'battery post shims' with all the battery hardware at the store, so I zipped back over there and picked up a pack (comes in packs of two for <$3). These shims are basically lead (or something like lead) caps that fit over the battery posts and make them bigger. They are split on each side to allow room for them to compress down for a tight fit.
The only problem with the sims was that no matter how much I tried to open the negative lead clamp, I could not make it big enough to fit over the shim. So... I decided to use half a shim. Being soft lead (or whatever) I could rip it in two at the splits with my bare hands (I'm such a monster). I positioned the half shim on the post and slipped the negative lead clamp over it. The cam-lock clamp was now able to hold tightly on the negative post. The clamp split was no longer touching, so I knew all the clamping force was being applied to the post.
During the wrestling match with the negative lead, I dislodged my battery tender lead clip. I figured oh-well and took off the positive one too.
I re-routed the hold-down strap back around the battery and reinstalled the nut with a 13mm socket and extension.
So, home stretch: I snapped on the positive lead cover and climbed in my Jeep expecting to be greeted with some computer error message. Much to my surprise, there were no messages and all the radio presets remained! I started the Jeep and everything was fine. I guess I didn't need to apply the battery tender after all.
I placed the battery tender back on the battery to give it a full charge. The battery charger indicator showed it to be less than 25% charged. I belive it is not usually a great idea to leave charging a low battery to the alternator. It just makes it work extra hard for extra long.
So that's it. Anybody else have a problem with an undersized negative battery post? What is that red thing on the positive lead assembly? It must be removed to remove the assembly, but its design looks as if its sole purpose is not to keep the assembly in place. Odd.