Hello there my 2003 Mercedes S500 battery died because I left my hazards on after dropping off groceries at my house and then parking down the street (I didn't notice they were still on because my instrument cluster has recently just gone out and it doesn't make the clicking noise for turn signals). Anyways the battery died and I jumped the car later that day when I noticed the lights were on and it started fine and I drove it around the block a couple times. Now It's been a few days and I went out to drive the car today and it barley started but the engine was idling very rough and then it died out after a few minutes when I went around the corner of my street and it would not crank over again the key wouldn't even turn. So naturally I tried jumping it again. It didn't want to start for a long time of trying to jump it from my other car and then once i finally did get it to crank over it immediately died. So I decided to pull my battery from my s430 that was working and put it in there and it would crank over and start the engine but die immediately. If I start it up and give it gas it makes the most awful idling noise like its misfiring terribly just wants to die and then as soon as I let off the gas it turns off (it was running great before the battery died I don't think it's actually misfiring I think it's something to do with the battery or electrical). The original battery that was in the car and alternator are new and we're just replaced 6 months ago. So I took both the batteries and charged them on my industrial car battery charger (the kind a shop would have) and installed the charged battery and it's still doing the same thing it will turn over but immediately die after it turns on. Does anyone know what I should do? Sorry for the long post I'm just trying to explain everything... Please help any advice would be greatly appreciated. Thanks, Jake

 

yes, get a new battery.

These cars like a new and fully charged battery.

Also where did you jump the car?

 

I jumped the car on the battery in the trunk with jumper cables. Also the battery and alternator are like new and were replaced only 6 months ago. So I'm currently slow charging the battery tonight and will try it again tomorrow because I think the battery was a little low. I'm just concerned it messed up something else electrical like fuses or relay or something worse I don't even know where to start if the fully charged battery doesn't work.

 

I would start by checking the fuses, including the ones in the "hidden" fuse panel in the right end of the dash. A search will give you several ways to quickly and easily check the fuses.

 

I think you probably destroyed the antitheft system when you just jumpstarted it. You’ll have to replace for parts, key, shifter, ignition switch, and ECU. They must all come from the same donor car. You can find a match set of these four parts on eBay for about $350.