bennelson972

I need to change the battery in my 2006 CLK 500 convertible (W209 I believe). I thought I read a post a few months ago about it not being as simple as disconnect old and reconnect new. Are there pitfalls I need to worry about? I plan on disconnecting the old battery and having it tested before buying a new one so the car may be without a battery for 45 min to an hour. TIA

Rudeney

I like the Advance Auto Platinum battery - It's an AGM with a 3 year full replacement warranty. There are no issues disconnecting the battery. You may need to re-normalization the power windows and the ESP steering angle sensor. Instructions are actually in your owner's manual. For the windows, you raise them and then hold the switch up for an extra 5 seconds. For the steering angle sensor, if you get the "ESP Unavailable" message, then start the engine and while sitting in park, turn the steering wheel fully lock to lock several times.

Oh, and do b careful not to "stutter" the negative terminal when you disconnect and reconnect it. You will get a small spark, but it's not dangerous. If you "stutter" it and create a spray of sparks, you can damage the electronics in the car.

bennelson972

Thank you Rodney!

dzmitry

If you're from California (could be relevant for some other states) you'll have to complete Drive Cycle before going to Smog Check.

bennelson972

I went with the Duralast Platinum from Autozone. It's also an AGM with a three year warranty. I had no spark when disconnecting the battery. Let's hope it goes just as smooth on install!

clydem

When I pulled my battery out, the base plate was filled with Norway spruce needles from a local tree. It took a bit to clean them out. Also, clean the drain pipe and make sure to feed the battery overflow into the proper holes (unless agm batts dont have them)

Rudeney

When I pulled out my battery, I found the drain hose routed under it, which umped any acid burped out onto the tray. After neutralizing and cleaning the mess, I properly routed the hose. here are some photos of how it should look:

Looking from the top, the green arrow shows the drain from the windshield water collector, the yellow is the battery drain, and the blue is the water drain for the tray:



And from underneath (remove the fender shroud to see):

sailorben

Ahhh I did wonder where it went Rodney. I couldn't see that little hole for that pipe so put a slit in the water drain pipe and just fed it through there instead, glad to know it provides the same result.

Audi Junkie

It's a tight fit and the unit is pretty heavy. I'm pretty experienced and not exactly a small guy, but it was tough, an 11/10 as far as batteries go.

sailorben

Agreed it's quite a pita. You can make it a little easier by lifting the bonnet into its vertical service position, if you weren't aware.