It is time for me to replace both batteries. In the past, I always bought OEM from the dealer. Now that I live in the middle of nowhere, the closest dealer is 90 miles away. So far, none of the online stores like Pelican will ship a battery because of the hazardous nature of it. I am considering going to a parts store like NAPA or Autozone and see what they have.

Just thought I would see what others are doing.

 

I got my AGM battery from Autozone. The starter battery you should be able to get from either store or even Walmart.

 

This may help

https://mbworld.org/forums/sl55-amg-...ml#post6618041

 

Thanks for the help guys! I am going go local for both batteries.

 

Got the trunk battery from autozone and the location where it needs to breath needs an adapter for the original hose, don'tforget to buy that as well. Hell just ask them to install it for you.

 

I ordered both batteries at Advance Auto today. The batteries will be in tomorrow. When I was ordering them, one of the parts guys told me I risk frying the electronics if I don't do the battery removal and install properly. He went on to say they refuse to replace batteries for MBs. I wasn't planning on having a parts guy replace my battery anyway.

I pulled the WIS for the replacement and the only thing I see of interest called out by Mercedes is to disconnect the on-board electrical system battery neg cable before removing the engine start battery. Also, keep fobs away outside of range so no electrical consumers can come on by accident. It also said to make sure all switched consumers are in the off position.

To me it doesn't look like a big deal at all. I plan to pull the electrical system battery first starting with the neg cable. Then pull the starter battery. Take both batteries to the parts store to drop off for core when I pick up the new batteries. Install the starter battery first starting with pos cable. Finally, install the trunk battery starting with pos cable.

If anyone see issues with the procedure, please let me know.

By the way, it looks like I can remove the vent tube fitting from the existing battery and plug it into the vent on the new battery.

OH YEAH! Then make sure all windows are at upper stop. hold switch up for 1 second. Reset clock. Finally, activate steering angle sensor by starting car turning wheel lock to lock.

 

Sounds right, except I thought you had to hold window switches for 2 seconds in both directions to set the parameters. I was nervous about the SBC in my car so I put little jumper wires to a spare battery and never lost voltage while it was out.

 

The WIS says "approx. 1s." I did two Mississippis and it worked.

Anyway, got the batteries in no problem. One thing for others to consider is depending on the trunk battery you purchase, the breather holes may not be in the identical place as the MB battery. The one I bought ended up having the breather hole I wanted to use covered up by the bracket at the back of the trunk. I pulled the plastic bracket and cut a small groove in it so the breather fitting would stick through. Another option would be to buy a piece of clear tubing about 18 inches or so. You could then use the breather hole on the other end (toward bumper) of the battery and fish the hose back to the little hole in the trunk floor.

After I replaced the batteries. I had no codes at all on the MFD. I then drove the car awhile without issue. The next day, I drove on a 100 mile or so trip. Again, car was great. On the way home, I stopped for gas. When I tried to restart, I heard the car crank, but no fire. It cranked until it timed out. This sounded just like a failing crankshaft positioning sensor (CPS) to me. I let the car cool down for ten minutes or so and sure enough, the car fired almost instantly. When I got home, I shutdown the car and attempted a restart. It cranked but no start. Today the car has started and restarted no problem. No CEL or codes on the MFD at this point.

The thing is, I replaced the CPS about four years ago. I was under the impression the new CPS design eliminated the no start when hot issue. I am beginning to wonder if it is the camshaft positioning sensor. Any input on this would be appreciated. I might get a chance to plug in my DAS/Xenty diagnostic system. I will report back if I find something. All these years on the boards and I don't recall ever reading about a camshaft sensor failure. I did replace one on my ML though.

 

Call AAA. They will come over and replace the batteries right in your garage.