Hi,

I have a dead main battery on my Benz C400. I got the typical Yellow battery indicator on the dashboard, so I decided to get a new battery from the Benz Dealership. After swapping the battery myself. The battery still dies out on me over night. Even after charging it over night its doesn't hold enough power to start car. I check the voltage and current and all the fuse to see if there is any parasitic drain. Nothing found. I took it to local Mechanic and he did a load test on it and He confirmed the battery doesn't hold charge.
Now I went back to the dealership asking them to swap the battery. They say in order for us to swap it and claim it as warranty it need to be check by the Benz Service professional, and Service appointment is required which is weeks from now and $200 in cost. Why can't I just bring in the battery and swap it without going thru a service? Have anyone else ran into similar situation and how did you handle it?

Please help. From my understanding if I were to buy a battery from AutoZone or Oreily or other auto shop, it would be a simple exchange by bringing in the battery so why does the Benz dealership have to do it thru service?

I had the same issue on my C300 where the replacement battery started dying overnight after about two months. Fortunately I had purchased the battery at Costco and replaced it myself. No questions asked when I returned it to Costco, except the did not have the replacement in stock. Got my money back and went elsewhere to get a battery. All has been well since the new battery.

Unfortunately working with the dealership is often a trying experience. I'd go back and be firm with them that there is a problem and the need to fix the issue immediately. Perhaps it would be better to get another battery on your own, swap it , and take the bad one back for refund. They can test it on their own time.

The dealers are in business to milk your wallet not to help with your troubles for free. They are trained to deal with all sorts of customers.

When you come in there demanding attention without paying for any of the show, you get politely guided to get lost with proper excuses.


Your car having low battery has little to do with the battery itself and more than likely ECU + SAM'S.

My Txsgiving gift to you is to concider this:

1. float your main battery
2. reboot your car computers
3. scan your OBD2 network

Start focusing on the root cause to stop changing batteries needlessly. Are you familiar with the "engineering Menu" to display live battery vitals?

Hope this can help many wise owners 🦃

Thanks for the info. Appreciate the consideration. Just to be clear that I paid full price for the battery and installed it myself so there is nothing free in the first place. My issue is that i bought a battery just like one would from a Thrid party auto shop. If the battery is at fault it should have been a simple return or exchange. Benz dealership have made it unnecessarily complicated and time consumption and headache.

Problem Solved: The dealership replaced the battery and there was no parasitic drain or any other issue found.
I did an emergency drop off of the vehicle at the dealer service. They said they will get it to it when they can. I had to authorize to do the diagnostic which they said would cost $250 + installation of new battery cost. Since the battery that I bought recently from the dealership is at fault it was fully covered under the warranty. Honestly this was the most troublesome and unnecessary thing to do. The issue could have been resolved by doing a quick battery load test at service drop. the whole multiple day seating at the shop is not needed.

Thank you for the help and suggestion everyone.