Waiting for my wife in front of wallmart last night. Car is off but only the radio is on. After a short while, I see the comand shut off by itself. I didn't think anything of it as I thought this was a feature to save battery power. Then wife comes back, can't start the car...wtf

Lights are coming on but not enough juice to start the car. Had to call the towing service to get a boost jump, and it started right away.

Is this normal or is it time to get a new battery?

It might be that ur w204 doesn't like to listen to country music???

Even with a new battery, I would never listen to music for 10-15 minutes without the car running. Considering you have a 2009 I'm going to guess you have the original battery, so yes pretty normal that it died.

I have a 2009 have original battery and have played music many times more than twenty minutes and never has the battery died

i usually play music on 30min with the car off, but the screen not turned on

interesting, maybe the battery needs to be changed

Wouldn't temperature play a roll in how your battery maintains a charge? I noticed that you're located in Montreal. Maybe try using a battery maintainer and if it dies again because it won't hold a charge, change the battery.

Sounds like the battery needs to be changed, I got my changed before winter. I usually take my take my girlfriend to the hills with music and a/c on for about hour without turning the car on.

i noticed that when i play rock from the 80's or earlier my C300 runs faster and harder and drives effortlessly @ 110 mph down the highway of hell!

sitting at Walmart and playing country, i believe both myself and my car would be prone to dying rather than listening to THAT music

unusual for a 3 year old battery to crater should last around 8 years
best bet would be to take it to a battery shop and get a capacity test done
If it is faulty make sure it is replaced with the correct one

My 2009's battery recently died as well. I sometimes play music for a little bit after turning the car off as well. Just had to replace it and I haven't had any problems since. I was able to have it boosted and it ran for a while, but I didn't want to risk it dying in a bad location so I changed it just to be sure.

well, had the car checked at the stealership. They determined I had a weak battery and installed a new one...$340+labor+tax...geez, that's an expensive battery...let's hope this is the last of my eletrical gremlins for a long time...

Well, I stand corrected. they didn't screw around and installed an Interstate mega-tron plus mtp battery instead of the varta oem. glad to see this, plenty of power now

January 2016, just replaced a 40/08 stamped Varta Mercedes battery, original, that's the 40th week of 2008. I only replaced it because we just had some 30 degree weather and while it started it was very slow cranking.

Researching these batteries, I found that Pepboys had the best Consumer Reports battery in the Bosch. I opted for the best AGM 48 month replacement warranty Bosch with a 15% discount and a $20 mail in rebate it came to $182. Took me about 20 minutes to get it out and 15 minutes to get it back in. Only thing I had to do was reset the windows, my CLK is a Cabriolet so the windows would open when opening the door, but would not close again when you closed the door and reset the clock. Radio remembered the presets. All else was good.

That time is not bad in a hot climate.

I use a light smear of Vaseline on the post clips to prevent corrosion. Also on the hold down threads to make it easy next time.

Vaseline not a bad idea especially for a flooded battery, AGM's are not flooded and do not GAS as a flooded battery does, so no leaking and no corrosion, a huge plus. We've been using them on our aerial lifts for about 4 years now. While more expensive initially maintenance is far less.

Good info here:https://www.batterystuff.com/kb/arti...el-vs-agm.html