The Battle of the Under-Seat Battery
Sometimes fresh juice doesn't mean breakfast.
All seemed well as I got behind the wheel of my Grand Cherokee diesel. I put my foot on the brake and hit the go button. The dash and radio went black, then restarted a couple of seconds later. Tried again, same thing. I've seen that type of behavior before with a large engine that needs a lot of power to crank over, and I knew the battery was getting to be about that age. I had a... (dun-dun-dun) dead battery!
This is a 2014, so it's the refreshed WK series. I knew the battery was under the passenger seat, but I hadn't gone looking for it. The magic of Youtube gave me some demos, and after a quick check of web sites I had a battery on its way to my door. After moving the seat all the way forward+up (thankfully I still had enough power to run accessories) and a surprisingly difficult struggle with the battery compartment cover, I was looking down at my dead battery. My weirdly inaccessible dead battery.
As I said, this is the 3.0L diesel (branded EcoDiesel here in the US). The diesel uses a larger battery than the gas engines - it's group H8, while the gas engines for that year use H7 batteries. The H7 is about 10lbs lighter and 1.5in shorter. That last part matters. The H8 almost completely fills the battery compartment. We'll come back to that.
I was fully prepared to do the swap by the time the battery arrived. But I had also realized that it was a harder job than I had expected for something as routine as a battery change, and it was getting close to dark. I definitely didn't want to tackle it without enough light and the next day was supposed to be warmer anyway. In the morning I powered myself up with plenty of coffee and My Little Pony, then informed the new battery that one of us was going to end up in a hole before the day was over.
A quick scan/squint through the battery's instruction sheet, which was oddly tiny for being taped to such a large battery, helpfully pointed out that the positive terminal cover had a plug (visible in the blurry foreground of the above photo) to stick in whichever vent hole you're not using. I jammed it in and went to work on the old battery.
Remember I said the gassers use smaller batteries than the diesels? The battery is held in place by a metal plate all the way down at the bottom of the compartment. If you search for photos or video of a battery change you'll see people reaching in to grab the plate and the two nuts holding it down. Those are H7s (maybe even H6s, I think some newer year/engine combos use those). The H8 is a little bit tighter.
H8 battery bracket
Luckily (well, somewhat luckily), my arms and hands aren't that big. After disconnecting the vent tube and moving it to one side I could just barely get an ungloved hand down by the side of the battery and across the end to get the two nuts after I had them loose. And I could also cut my finger because there were jagged metal burrs down in there and I had to take off my glove to get at the plate. What I couldn't do was get the bracket out because I could only hold it from the left end and I couldn't get it off both bolts at the same time. My magnetic pick-up tool, which I think has paid for itself many times over (especially since it came from a clearance bin), was able to grab the end I couldn't reach so I could lift the whole plate straight up until it cleared the bolts and then pull it out from the side.
Magnet to the rescue
With everything disconnected and the hold-down plate pulled, it was time to yank the old battery out. There isn't space to do a straight lift, you have to lift the back end and slide it up and out at an angle. On the one hand, that meant I didn't have to lift the full ~60lbs at once. On the other, it meant I was trying to shift a 60lb weight around in a tight space without dropping the end on the bolts for the hold-down plate. With what I consider to be a perfectly reasonable amount of profanity, I was able to hold the near end up with one hand and use the battery handle to pull it back enough to rest on the edge of the hole, then grab the far end to pull it up on to the floor of the back seat.
Not surprisingly, sliding the new battery in was much easier. It was still rough because it's 60lbs and I couldn't let it drop on to the bolts, but at least I only had to control the battery while gravity did its thing. And then I went to hook up the positive terminal (at the front) and couldn't. Why not? Because, again, the battery is big enough to completely fill the compartment, so I couldn't move the cable and connector where I needed them, and I couldn't move the battery enough to make space. After a little more profanity, I was able to gently rest the back end of the battery on the two bolts long enough to shove the connector on the post and then move it forward again in to its place. The negative terminal was easy enough and it lit up the interior lamps so I knew I was in good shape. I used the magnet again to help me lower the hold-down plate on to the two bolts, contorted my arm enough to get the two nuts started (this time with no blood), tightened everything, and stuck the vent tube in. I left the cover open, started the engine, and did a 30 minute drive to make sure everything looked good and wasn't coming loose. It seems like I didn't lose any settings, not even the radio stations.
Victory is mine!
I think this might have been a lot harder if I were either bigger or smaller. I'm on the small side, but not unusually so - about 5ft6in tall and 140lbs. If my arms were much larger, I would have been completely reliant on magnetic tools or other grabbers for that hold-down plate. If my arms were much smaller, I might have had a lot more trouble handling such a large battery safely.
So, to recap: 60lb battery, down in a hole barely larger than the battery itself, with bolts sticking up from the bottom of the hole, positioned where you can't do a straight lift in and out, held in place by a metal plate you can't reach, which needs a deep socket and >6in extension. It took me over an hour, much swearing, and a few drops of blood. I could probably do better now that I've been through it once but... instead maybe I'll set a calendar reminder and pay somebody else to do it for me in a few years.