[vrathore]

The other day I left my headlights on my 2007 S550 with keyless go, cause I had turned on my fog lights and forgot to turn them off (no lights on warning). 3 hours later, when I got back, my battery was dead and nothing worked. No locks, no displays, nothing.

I knew there were two batteries, with the starter battery up front so I called for a jump while I tried to figure out how to get into my car and open the hood. Here's what happened.

1st, I used the L-shaped key inside the 'transponder' key to manually turn the lock, (which looks like it does nothing), and then pull the handle to unlatch the door.

2nd, I opened the hood and found the starter battery ready for the jump

3rd, I got in the car and just for kicks, I hit the start button and the alarm went of for about 1/2 a second, and the car fired up like nothing ever happened.

So here are my questions:

1) Was there a headlight on warning I missed (don't see one in the manual either)

2) Which battery died? Starter or Consumer

3) Should I try to recharge either of the batteries?

4) Are there any recommended chargers (other than OEM)

Thanks again for the replies.
Vinay

 

[Diesel Benz]

I should go and test with the car but I think you really should have had a "lights on" warning.

Your consumer battery died, should have been no need to jump start the car, just use the key at the ignition slot (and the mechanical key as you did to get into the car).

If the battery was not dead for a long time, you should not need to change any battery because of this incident.

 

[vrathore]

Thanks DieselBenz. I checked again today and there is a Lights On warning display, in between the 'don't forget your key' display, and the same warning bell. I guess I've learned to tune out the warning displays cause I hear it every time I get into or out of the car.

My wife laughs at me because her 2006 E320 CDI warns with an audible bell for the headlights or even if she leaves a window/roof slightly ajar. I won't even try to figure our why the car that costs half as much does that better.