CLK 350 Battery Issues


Asked by gftclk350 Jan 22, 2012 at 02:32 PM about the 2008 Mercedes-Benz CLK-Class CLK350

Question type: Maintenance & Repair

I have a 2008 CLK 350 Coupe with 7k miles.  Earlier last year I reaplced the battery with a new MB battery because the car would not hold charge and when I attempted to jump or recharge -it would not, nor would it start.
Now, 5 months later, it is draining the battery.  I do not drive the car for a days, but try to start it in the garage.  Today I attempted to start it and "click", no go.  The dome lights came on, but it will not start.
I have attached it to my battery charger and hopefully later today it will start.
What is causing this to happen -- draining in only a few weeks ?
I have factory navigation and factory Sat radio.
Thanky ou.

13 Answers

Ted Halsall

Try pulling out the fuses for the front seat control units. They are on the fuse panel behind the headlight switch. If you notice your battery not dying anymore put one back in and try it again. Chances are one of the modules is faulty causing other control units in the vehicle to stay turned on thus killing your battery.


i bought a new battery it was faulty,,also your car alarm drains power 2 weeks is along time


This has driven me nuts for months now. And it is clearly a fault with this car!! It cannot be coincidence that so many of us have battery drain problems!! I have a trickle charger, I have had the RAC out (couldnt get into the boot myself of course because manual keys dont work!!), bought a new battery and within 2 days completely dead!!! I am getting rid of the car and suggest everyone does same!!

2 out of 2 people think this is helpful.
Ted Halsall

Mechanics love when customers give up on a car like that. I'm driving an S class a customer gave up on. All it needed was two fuses. Remove any aftermarket electrical consumers in your CLK. One of the biggest problems I see are tracking devices which are old or incorrectly wired into the vehicle. After that I'll guarantee one of the seat control modules is the problem. See my earlier post.

4 out of 4 people think this is helpful.

I purchased a NEW ($155,000) CLK 350 (2010 model) it has had two NEW batteries in two going to get its 3rd new battery in under two and a half years... The Technician told me it is problem with this model because of all the electronics its drains the battery and Mercedes have had lots of problems with them.. A solution would be good....

4 out of 4 people think this is helpful.

Well after a complete nightmare with this problem I now have my solution. My garage people fitted a battery turn off switch!! Sure theres a proper word for it, but it is located in the boot and I simply turn it and it disconnects everything. Nothing to drain far it has worked well. When they first fit it, they closed the lid aarhhh!!! instantly locking it of course. Needless to say they couldnt get back in with the manual key (they never work!) and they had to fit a new lock! Outrageous price from mercedes but they sourced a second hand one with its own key. But since there is now nothing to drain I leave the boot just slightly open so that I can always have access - not trusing any keys any more. I dare say it would go dead after some time but I have a trickle charger will I will also attach now and again to keep it topped up. Sorry for such a rambling reply!

1 out of 1 people think this is helpful.
John Leone

the manual locks are tricky, but they should have done a Parasitic Draw test, removing one fuse at a time, determining which one is using the current, glad you have a quick fix, but I agree, especially in the C-class, there have been NUMEROUS electrical issues, that have never been worked out, sadly, a HUGE Mercedes fan, will say that series is garbage, :( anymore questions feel free to let me know..

2 out of 2 people think this is helpful.

both my c class and s class have this problem , battery drain, i have a trickle charger that i have been using, i will try the seat fuses on both cars , thank you

1 out of 1 people think this is helpful.
John Leone

I hope it works, s-class has a computer which stays active, (pending the year)...let me know and i can help with further diagnosis

1 out of 1 people think this is helpful.

I am surprised to hear about the problems you have with CLK. I have a 2008 CLK cabriolet sitting in my garage since Nov/2013. I started the car only 3X during this below 0 temperature in Toledo. I never had any such problem, in fact, this is the most reliable mercedes I ever had.The battery is original, This has only 19K miles, only changed rear tires recently.

2 out of 2 people think this is helpful.

By the way, there is no 2010 CLK. This has been replaced by Eclass cabriolet costing over 70K. in 2010.


Your battery draining issue sounds like an alternator fault. I had the same problem on a Vauxhall (GM) Calibra and on a Volvo years ago. I now have a CLK350 (2006) for the past 4 years. The battery just failed this morning on my way to work!! ouch. Will spend about £80 on a new Bosch one. Kind regards, VJTheDJ.

2 out of 2 people think this is helpful.

Hi everyone......after being driven nuts by this problem my garage fitted me with a total immobiler (for the battery) so that it cant drain anything!! I do hve to leave the boot resting on something admittedly, to stop it from shutting....But it has worked a treat!! Its actually in the boot, and I literally turn it when the car is going to be standing. I have just got the car out again after four months....turned my key and hey presto%&!!!! Started first time!!!

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