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mike_a_mechanic, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 5471
Experience:  17 years experience as a auto mechanic, foreign and domestic.5 years running my own repair business.
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Hi, I have a 2007 CL600 V12. I believe there are 2 batteries

Customer Question

Hi, I have a 2007 CL600 V12.
I believe there are 2 batteries on the car? - 1 under the bonnet (brand new) but quite small for a 5.5L V12) but we cant find the 2nd battery - the dealers said its in the boot but there is no sign of it -
The problem is occasionally the engine wont turn over - but keeping the starter pressed and it will then turn over quite fast and she starts straight away..
can you help?
Many thanks...
Submitted: 3 years ago.
Category: Mercedes
Expert:  Matt replied 3 years ago.


It is located in the boot on the passenger side. To access it you have to lift the spare tire cover and pull the battery cover panel (usually has a velcro strap). Be certain to pull cover bottom first, as there is a tab along the top of the panel.

Customer: replied 3 years ago.

Hi Matt,

thanks for coming back to me - unfortunately we already searched there - no battery to be found anywhere in this area - we've had the boot lining out on both sides to look - can you tell me what the size of the battery is and the A/H rating please?

The Vin/ chassis number is:- WDD2163762A004016 - if that helps?

Expert:  Matt replied 3 years ago.
Hello Martion

OK try looking behind the passenger seat in the cockpit

the main battery spec is
BCI Cold Cranking Amps (CCA): 900
BCI Cold Cranking Amps Value: Tested to BCI Standard
BCI Designation: Not Applicable
Battery Height: 190 mm - 7 1/2 in
Battery Length: 353 mm - 13 15/16 in
Battery Width: 175 mm - 6 15/16 in
Customer: replied 3 years ago.

Hi Matt,

Thank you - unfortunately no battery there either - under the rear seat squabs we have 2 inspection hatches, which lead to the fuel tanks (1 with sender in). there is nothing under the front seats or behind the rear seats... to be clear, the battery under the bonnet does the starter, but we believe that's it - and all ancillary electrics from the 2nd battery - so is it as large as you suggest?



Expert:  Matt replied 3 years ago.
Hello Martin

the small battery is meant for the starter as you say and the rest of the car electrics are off the large battery however if the starter battery needs extra power it'll draw from the main battery

Customer: replied 3 years ago.

Hi Matt,

Thank you, yes, I understand that, but the large battery is clearly in need of replacing, which goes back to my original question of where is it located!? -

Many thanks in anticipation,


Expert:  Matt replied 3 years ago.
Martin I'm going to have to opt out here as my information shows its in the trunk

don't reply to this post otherwsie it'll lock back to me

I'll get another expert involved
Expert:  Shantal-Mod replied 3 years ago.
Hi, I’m a moderator for this topic. It seems the professional has left this conversation. This happens occasionally, and it's usually because the professional thinks that someone else might be a better match for your question. I've been working hard to find a new professional to assist you right away, but sometimes finding the right professional can take a little longer than expected.

I wonder whether you're OK with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Thank you,

Customer: replied 3 years ago.

Hi Shantal,

If you can find the answer for me please I would appreciate it - from the vehicle VIN number this should be possible. Clearly there is a 2nd battery on the vehicle somewhere, but it is obviously well concealed! Any help here would be appreciated... if you cannot help then please let me know...



Expert:  Shantal-Mod replied 3 years ago.
Hello Martin,

Thank you for getting back to me. I have sent a couple of messages to a few experts, who may hopefully be able to assist you.

Thank you for your patience,

Expert:  mike_a_mechanic replied 3 years ago.
Hello, welcome. My name is Mike, I will do my very best to assist you with your question. I apologize if you have been waiting long for a response.

The main vehicle battery on your vehicle should be located under the rear seat, the seat will need to be lifted and then the battery cover to access the battery.
Customer: replied 3 years ago.

Hi Mike, Thank you, we have looked here, and there is an access hatch under both seats, which we have removed, but both appear to house the fuel tank - am I right? we can clearly see the tank sender connections under the left side seat. the other looks like the top of the fuel tank - def no sign of a battery. Can you tell me if the fuel tank is just under 1 seat or both? - I would not think the space under 1 seat is large enough for an 80 litre tank?

Thank you..