Car locked- key fob did not unlock car
Car locked- key fob did not unlock car
MBWorld Fanatic!
Joined: Dec 2012
Posts: 2,473
Likes: 439
From: Ball Ground, GA (N of Atlanta)
2003 S500 2007 GL450
The W220 battery is under the trunk/boot floor, in the right rear fender.
If the problem is a low or dead battery, the easiest immediate response is to charge it in place. Getting it out can be difficult, given the weight, size, tight fit and lifting from an awkward position. Jump-starting with a slightly-low battery is okay, but is not a good practice if the battery is really low.
It is possible that the battery in the key fob has failed. The key fob battery operates the remote locking/unlocking, but has no effect on cranking the engine. Replacing the battery is tricky, but not difficult. There are numerous videos on YouTube showing the process - just make sure that you are looking at a similar key fob. Basically, you remove the mechanical key and use the little hook on the end to reach down inside the slot and pull out the battery tray.
If the problem is a low or dead battery, the easiest immediate response is to charge it in place. Getting it out can be difficult, given the weight, size, tight fit and lifting from an awkward position. Jump-starting with a slightly-low battery is okay, but is not a good practice if the battery is really low.
It is possible that the battery in the key fob has failed. The key fob battery operates the remote locking/unlocking, but has no effect on cranking the engine. Replacing the battery is tricky, but not difficult. There are numerous videos on YouTube showing the process - just make sure that you are looking at a similar key fob. Basically, you remove the mechanical key and use the little hook on the end to reach down inside the slot and pull out the battery tray.
MBWorld Fanatic!
Joined: Dec 2012
Posts: 2,473
Likes: 439
From: Ball Ground, GA (N of Atlanta)
2003 S500 2007 GL450
If it is practical for you, the best answer by far is to keep a good battery maintainer attached.
If you use the correct battery (not the cheapest one that you ca find), and if your car doesn't have too much current draw, so that the battery doesn't go flat in two weeks, five to ten years seems pretty reasonable. Every time that the battery goes dead, you lose battery life. The longer it sits dead, the more battery life you lose. If you have high current drain, and the battery stays low a lot, two or three years life is probable. If you let it sit flat for seeks, six months to a year...
If you use the correct battery (not the cheapest one that you ca find), and if your car doesn't have too much current draw, so that the battery doesn't go flat in two weeks, five to ten years seems pretty reasonable. Every time that the battery goes dead, you lose battery life. The longer it sits dead, the more battery life you lose. If you have high current drain, and the battery stays low a lot, two or three years life is probable. If you let it sit flat for seeks, six months to a year...
Senior Member
Joined: Dec 2010
Posts: 282
Likes: 66
From: Virginia Beach
2005 S600 2005 SL600
Batteries in this car are big, AGM and expensive. They last for 8-10 years - IF they're not allowed to go flat.
Honestly, if you don't drive the car every few days, then it's going to be unhappy. You can park it for a week, perhaps two, but that's it. I've installed a battery maintainer on mine, from just this experience, which cost me a battery. $200 and a headache if the battery goes flat, or a $35 charger that I plug in when the car sits for a while...
If you completely discharge the battery, then I would put it on a good charger. Driving it helped, but even an hour might not be enough to bring it back up.
Honestly, if you don't drive the car every few days, then it's going to be unhappy. You can park it for a week, perhaps two, but that's it. I've installed a battery maintainer on mine, from just this experience, which cost me a battery. $200 and a headache if the battery goes flat, or a $35 charger that I plug in when the car sits for a while...
If you completely discharge the battery, then I would put it on a good charger. Driving it helped, but even an hour might not be enough to bring it back up.
