Didn’t see anything super thorough on here about a C63 battery replacement so figured I would share in case it helps anyone.

My 2016 gets put on a battery tender each winter, but the life of the OEM battery reached its end the other day. The car started perfect fine just days before. The only odd sign of anything was that the dash prompted me to remove the start button and insert the key. I started it up with no issue doing that, so thought nothing of it. Came out the next day to a 100% dead car. Nothing at all when the door was opened.

I made a mistake at that point and figured I would try my jump pack to start it in case I somehow left the ACC on and killed the battery myself (although I am pretty sure it’s tough to do that without the car shutting down before there’s an issue). I have a beefy jump pack, and it was extra annoying to have to rip off the plastic and foam over the + access point under the hood to fit the clip. After I did that, all it gave was two turns and wouldn’t fire. What I didn’t know was that it is BAD to jump pack a completely dead AGM battery. I’m guessing it was dead anyway, but doing that may have been the final straw.

I made a last ditch effort to recover it by putting it on an automatic charger that has a repair mode for AGMs. By that way this entails getting to the actual battery in the trunk, so I had to have the charge pack still clipped onto the access point under the hood to get power to open the trunk.
Anyway, the repair process failed twice and said Battery Not Repairable.

Before I replaced the battery, I figured I would call various shops to get pricing and see if there was any magic ECU work that has to be done as in BMWs to pair a new battery to the vehicle. The stealership told me $410 and yes it has to be done on Xentry or it won’t work. One independent told me $300 and nothing extra to do at all. Another independent told me $310 and yes, there WAS a setting that had to be put in with Xentry, to tell the car that it does have a new battery, but that it will drive just fine in the meantime and no codes on the dash (unlike BMW).

So I figured I’d just try it and see, rather than having to get the car towed to a shop since it wouldn’t start.

FYI, MB uses Interstate for their OEM batteries, but they aren’t marked as such. I’m lucky enough to have an Interstate distribution center 5 minutes from me. Called them up and asked them about the battery and they had it in stock for $205 plus the old battery. FYI, this is the model for our cars.

https://www.interstatebatteries.com/products/mtx-49/h8

Next was getting the old battery out. I have never seen such an over engineered thing for a battery in my life. Basically, lift the trunk liner, pull out the large tray of stuff with the manual, emergency vest etc., undo 4-5 plastic trim clips that hold in the black tray with the tire inflation items and pull that out. Then you can see most of the battery housing.

Undo the 8 bolts holding the large aluminum casing around the battery. Unclip the wire harness in the two spots it has plastic holders. I also Unclipped the wire connector going to the ground terminal so I could get stuff out of the way better. Naturally, one of the 8 bolts doesn’t allow a socket wrench to fit, so your choice is a box wrench or ratcheting closed wrench.

After that you can lift the aluminum cage out. Then there is ANOTHER bolt clamping in the battery.

At that point you can disconnect the terminals (ground first). Be careful to isolate the positive terminal so it doesn’t get caught against stuff. It’s clunky.

Disconnect the vent hose from the left side of the battery and that’s that. Now you get to lean way down into the trunk and lift out a 50lb battery.

Installation was basically a reverse of the above. Connect the positive first.

I let the car sit for 3-5 minutes and it made ALL KINDS of crazy noises as each ECU came to life and did it’s thing.

Car fired right up and no dash warnings or codes.

So, I still am not 100% sure if the setting in Xentry is true. I do tend to believe to one independent shop who is typically pretty
good, who said that there is a setting to let the car know it’s a new one. There is programming, according to them, that makes the car behave differently as the battery ages, as far as shut down time, charging voltages, etc. So, since I need new rear tires anyway, I plan to bring it there since I doubt it can be much $ for them to go in and do that in Xentry.

Hope this helps others not get taken by the stealership for $400+.

 

Thanks for the write up! I would personally change to this battery https://www.optimabatteries.com/prod...8%204.0L%20Gas

 

Thanks. Those Optimas are nice. But the Interstate is not slouch. OEM quality.

 

Thanks for sharing all the details. It was amazingly difficult to find information on what seems like such a common task.

 

Thanks for the writeup. I recently swapped the battery in my wife's GLE350, and that was located under the front passenger seat, in a tray. Fortunately I was able to remove and replace it without removing the seat, but it was a bear pulling out the old battery, which had to weigh closer to 65lbs.

 

Not to revive an old thread but when replacing the battery the shop is correct in stating it needs to be told it has a new battery. Resetting the starter battery charge throughput counter in the SAM module (N/10) is the operation needed to be carried out with Xentry or an AUTEL scanner. Check out this thread

https://mbworld.org/forums/c63-c63s-...ml#post8934306