NCC-1701

I have a 2005 SL55. Yesterday I purchased a new battery from Mercedes for the trunk (accessory battery) and I replaced it. The red light on the dash indicating battery and see shop soon went away. Drove the car last night with no problems. Today in the morning after I put the top down the red light on the battery came on again like it did the day before. The starter battery starts the car fine with no problems and cranks the motor like it should. Coming home the dash light indicated battery and alternator to turn motor off. Well since I was a mile from home I continued to drive it and a strong odor of something electrical burning was coming from beneath the hood as well as lots of white smoke. I get home shut the car off and the electrical odor is very strong. I get my battery tester and place it on the front battery and it is in the good area and when I put a load on it it remained in the good area. Did the same on the new rear battery and worked fine as well. I turned the car on again and started fine no white smoke and checked the alternator output and it was charging. Something had to fry but what could it be, I'm at a loss. By the way it was towed to Mercedes. One more thing and I don't know if it is a coincidence but I found grease on the passenger door near the bottom where like the tire kicked it up from the roadway but after I checked the tire I could not find any grease on it. Any suggestions to what this could be...

five337

After disconnecting and reconnecting my starter battery (hood) one time, I had a lot of white smoke and red alerts. Scared the heck out of me, I thought I blew something up. Turns out there was some corrosion on the terminal. I cleaned it and put it back on tighter and everything was fine. Is the terminal loose ?

NCC-1701

No the terminals are tight this is definitely some type of electrical problem. I just hope it is not the harness.

IngenereAMG

Possible alternator. Take it in and have it checked.