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The issue I'm having is that I parked my 2007 CL550 in the garage for 2 months during the pandemic and did not use it at all. Yesterday I tried to open to unlock the door and the car seems to be totally dead. It is unlocked but the windows won't lower and thus I couldn't open the doors because windows did not roll down a bit to release the door and I had to pull them heavily to open the door. But the car easily started and then windows started working and side mirrors opened on both sides.
drove the car for a few minutes and parked the car and after a few minutes, the same problem happened again. The car starts easily and everything works properly when the engine is on but it controller of windows and mirrors and trunk dies when I turn off the engine.
Does anybody know which battery has a problem?
Thank you in advance
Problem is with the battery in the trunk. If you drive for about 30 minutes it might get charged enough for things to start working. I still have the original trunk battery in my 2007 CL550 manufactured in Sept 2006, but have experienced similar problems when it is discharged. Among the symptoms was the trunk could not be opened without the engine running. All was well after I drove for a while. the battery is behind the passenger seat accessible from the trunk. If you are an original owner, call Mercedes roadside assistance, they will come out for free and change the battery and will NOT charge for labor, only the retail price of the battery.
Last edited by steveb9771; Aug 7, 2020 at 02:34 AM.
Do yourselves a favor and invest in a battery tender and not a cheap one. I have 10 cars that have been parked since February and I know I can get in and drive any of them without a any problems.
My CL600 has connection posts under the hood for the rear battery, so I use 2 tenders. One is for the start battery connected directly to the battery and one for the rear battery connected to the posts.
These cars HATE low voltage. They will save you a lot of grief.
Thanks for your reply.
That's exactly what happened to my car too and the trunk is not functioning properly unless I start the car and drive for a few miles. Wtunahat is the name of that battery in the trunk? Is it the "Auxillary Battery"? Unfortunately, I'm not the original owner and was thinking to watch a video on YouTube and replace the battery myself.
Do you have a link or brand to a battery tenders you use for your cars?
Do a Google search for the best price. My favorite is the NOCO Genius G3500. I believe that's correct. Should be in the $60 range plus or minus. Let me know how you make out. I have purchased through Amazon and ebay. Wherever I can get the best price.
The one in the trunk, I call PITA because of it's location, but it's the one that powers all the "toys". The one under the hood just starts the car. Which us why it doesn't drain as fast. The computers are always drawing from the other one. At least that's how it works on my '07 CL600.
Last edited by PhoenixOp; Aug 7, 2020 at 03:35 PM.
OK, folks, the problem was the battery in the trunk. I purchased the battery from PepBoys and replaced the battery myself. It just takes a few minutes. Check out this website to find out to buy the correct battery. https://www.youcanic.com/post/merced...ment-w221-c216
All the problems are gone now.
Hope this helps.
The new battery I replaced myself(In the trunk behind the passenger seat on the right)
I have have a W216 AMG 2012 w/ 42k miles. Out of nowhere I am getting the "Aux Battery" message and have lost my brake hold function and maybe an ECO problem as well.
Question One: Does the aux battery charge along with the main starter battery? I have had the main on the charger for a several days but it didn't help the problem. Maybe it needs to charge longer or maybe I need to take a road trip?
The car does not get used very much.
Question Two: Where in the world is the aux battery. I have found info saying upper left dash, trunk behind passenger seat, trunk inner floor and other places. I'd sure like a definitive answer so I don't have to take the car apart.
I'm new to this so any help would be wonderful and appreciated. Thanks in advance.
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Battery Problem
