2007 R Class Main and Auxiliary Battery Replacement

Changing the main battery in R Class (also in M, GL, GLE and GLS) is not simple. However, when you replace the auxiliary battery as well, things are getting a little more complicated.
I apologize for the quality of the camera work. It is hard to work with one hand and hold the phone with the other. Please let me know if you have questions.
There is an error code that you need to erase at the end for the SRS, right passenger seat, if you chose to disconnect it. A scanner, should do the trick.

[@ianduckworth8595]

A useful video Conrad however by positioning the seat fully up and fully forward (fully back for negative terminal)you can remove the main battery from the rear of the drivers seat (UK) without removing the seat. I’ve not done my small battery yet but would recommend moving seat fully up & back to access the front carpeted area 😁🤗

[@konradspages7937]

Hi Ian, thanks for the comment. To replace the main battery, you can move the seat fully forward but you will need to cut the carpet, which I didn't want to. As for the auxiliary battery, it might be possible to replace it with the seat fully backwards, but I think it would be a major head ache. I find that removing the seat creates plenty of room to work comfortable. Also keep in mind that all R Classes sold in North America are long wheel base. The standard ones I assume are more cramped. Anyways, good luck!

[@arminashirinyan1737]

Thanks for sharing, very informative! Such a pain for a simple battery replacement.

[@konradspages7937]

You are welcome :). I agree, it could have been done more ergonomically, but I guess they want to force people to go to the dealership and charge them royalty for the service.

[@ieism1]

A simple 5 hour job, brilliant engineering! I'll just take it to my local battery shop and get a quote in writing beforehand i think. I doubt they will correctly estimate the amount of work this is.

[@Theanatolievich]

Are you being sarcastic "brilliant engineering"?

[@CapnChapster]

Thanks for posting this. I’ve just replaced the perished rubberised steering wheel switches on my R320 . Epic job. Massive fiddle. The new ones look great though. Disconnected the battery to avoid any unwelcome air bag excitement . Didn’t need to to remove the seats, access was fine . I replaced the battery a while back, again no need to remove the seats .

[@konradspages7937]

Yes, you are right. To access the main battery you don't need to remove the passenger seat. However, for the auxiliary one, you have to do that. For me it's a learning process and I like "to have space" when I work. I tend to disassemble more than necessary, but this will help everyone with a better understanding of how the things are put together.

[@smithimitron]

very informative video. Thank you for the information, as most videos I keep seeing on this topic missparts

[@konradspages7937]

Thank you for your nice comment. I learn a lot from the internet and giving back to the community is the right way to go :)

[@missimani]

Hey there thanks so much this is so helpful step by step and I will be buying everything I need to do it myself so tired of dealerships trying to charge so much for stuff. I had a question also if the main battery is brand new and the auxiliary needs to be replaced will that cause the car to be dead all together ?

[@konradspages7937]

Hi @missimani, no, even if the auxiliary is discharged, and the main one is new, you will still be able to drive the car normally. However, at some point, you might get a message on the dashboard to replace the auxiliary. Mine was good to go after 16 years and two main battery changed.

[@CapnChapster]

It’s there because there’s no room in the engine bay . A design compromise. Aimed at maximising interior space.

[@konradspages7937]

Yes, it makes sense :) The hood is so short and the engine is practically buried half way under the windshield.

[@walalshammari2831]

thanks man

[@konradspages7937]

Anytime.

[@edwinhandybuddy1038]

I think I will re-wire it to somewhere easier to access.

[@konradspages7937]

Hi Edwin, actually this is a great idea. I don't think it will apply to me, as we are planning to drive the car to the ground and then get a new one :) But if the next car will have the same challenges, I will take this into consideration!

[@ilverhamidovic4090]

Thanks

[@konradspages7937]

Anytime!

[@markfitzy.86]

What a pain in the ass

[@konradspages7937]

You are absolutely right. I am not looking forward to the next battery replacement on the R Class :):):)

[@markfitzy.86]

@Konrad's Pages thanks for making the video by the way. Very helpful 👌 I have to do this job on my r class

[@konradspages7937]

@@markfitzy.86 You are welcome. That's why the internet exists, we can help each other. As for the job, take your time, pick a day with nice weather and have fun. If you disconnect the passenger's seat, make sure you have a scanner to reset the error code at the end. No big deal, but you need it.

[@markfitzy.86]

@@konradspages7937 ok o will. Cheers bro

[@AsianBlackR3501]

I replaced mine without taking the seat out or unplug the connectors.

[@konradspages7937]

I agree, it is possible for the main battery. If you want to change the auxiliary as well, then it's getting complicated.

[@AsianBlackR3501]

@@konradspages7937 I changed both batteries (Main & Auxiliary batteries) without remove the seat. I have 2008 and 2012 Mercedes R350.

[@AsianBlackR3501]

@@konradspages7937 I replaced main & auxiliary batteries without remove the seat. I have 2008 & 2015 Mercedes r350.

[@AsianBlackR3501]

@@konradspages7937 I changed both batteries. I have 2008 & 2012 Mercedes R350.

[@ronpinto9588]

Unfortunately I only found this out after I bought my R 350. I will be selling it very soon.

[@ronpinto9588]

I called a mechanic to change the battery, and we didn't remove the seat, just put it as far forward as possible. Done. Then I started the car thinking I wouldn't see the battery warning anymore: Wrong. Instead of the red battery picture, I got a white battery picture, and found out that my auxiliary (I didn't know I had one) was gone as well. No big deal. A new one costs about $ 60. Then I went to find out where the little battery was located, and found out I had to dismantle the car to replace it. It is under the front passenger feet, and to change it I WILL have to remove the front passenger seat, the door sill, the carpet, and the wall lining (so that I can remove the carpet).

[@konradspages7937]

@@ronpinto9588 Hi Ron, yes, you are right. The main battery can be changed by pushing the front seat maximum forward. But for me, it was time to swap the auxiliary battery as well, hence the headache :). Honestly, it is not a difficult replacement, but it is long and cumbersome. I am sure, with a little bit of thought, this could have been done way better. Just pick a nice day, good music and a beer (or a cocktail) and it's actually fun. Fun fact, the dealer quote me $180 CAD and I bought a similar battery from Amazon for $24 CAD.

[@waynegodwin6860]

Best vehicle I’ve ever owned

[@benmallahsstockbroker3752]

@@ronpinto9588 don't be so lazy. Its 4 bolts. Are your kids as lazy as their dad ?

[@waynegodwin6860]

@@ronpinto9588Do you also step out of the shower to piss? Lazy twit 😮😮

[@user-xq3rc4me1s]

За какво служи малкия акумулатор?

[@konradspages7937]

It keeps all electronics in the car functioning during the start of the engine, or when the level of the main battery drops too much. I don't know if you are Ukrainian or Russian. This is Google Translate: Он поддерживает работоспособность всей электроники автомобиля во время запуска двигателя или при слишком сильном падении уровня заряда основной батареи.

[@user-xq3rc4me1s]

@@konradspages7937 Благодаря! Българин съм ако това има значение

[@konradspages7937]

@@user-xq3rc4me1s I just wanted to translate in your language. For me it is impossible to distinguish in writing Ukrainian from russian, (or Bulgarian) :) Просто исках да преведа на вашия език. За мен е невъзможно да различа писмено украински от руски или български :)

[@AsianBlackR3501]

I changed both batteries without removing seat or connectors. Don't delete the comment please

[@konradspages7937]

Hi @AsianBlackR3501, sorry, I have no idea why your comment had disappeared. I am not deleting anything. I have just replied to you a few minutes ago. I hope I didn't do anything by mistake. Actually I am glad when someone uses my videos and manages to get the job done easier and simpler. Honestly, while changing the main battery is possible without removing the passenger seat, I have never heard of anyone to change the auxiliary in the same way. OK, now I am very careful and make sure I just Reply to your message :)

[@AsianBlackR3501]

@@konradspages7937 No hard feeling buddy. I did it myself and I know it is possible to do it without remove seat or unplug the connectors. I own 2008 & 2012 Mercede r350 and do most DIY myself. Good job on your video.

[@Theanatolievich]

what? Does anybody holds responsibility for such anti human design? these engineers really commit crimes by making everything over-engineered and stupid!

[@donnfl]

What a stupid place to put a battery. I thought the Germans were supposed to be smart.

[@konradspages7937]

Yes, they are. But they are not perfect :)

[@5e34nut]

In the UK the battery is directly under the drivers seat So you have to take the drivers seat off and out the way ... Its yhe most ridiculous design ever

[@konradspages7937]

If you change only the main battery, there is a way to push the seat forward to the max and then roll the carpet behind it, to access it under the floor. If you need to change the auxiliary, you are doomed, the seat has to come out.