S class battery keeps going dead - do you know the solution

[dj_factor]

Hi guys, i have a s320. I dont know but since last month it is giving me problems, i would park the car and not drive it 2-3 days and it would go dead(battery). Dont know why. I then have to jump start it. Took it to a local garage last month and he said that the battery is going, so got a 91 AMP brand new Bosch battery and have it installed since 22nd April and yesterday the car went dead again. I had last driven it on tuesday 12th and when i tried to switch it on - on sat 16th the car went flat dead. Wont open the doors or anything. had to jump start it again and let it run for a few mins. Do you know what might the problem be.

For hints, I have a service exceeded by 4 days and SRS light on since last month (since i vacumed the whole car). Would the SRS light cause any problems. Now that i have a new battery, dont think it should do this.
Cheers

 

[Diesel Benz]

I doubt the flat battery is from the SRS fault (that would need to be fixed anyway). You must have some quiescent current that should not exist. Old posts should tell how this can be diagnosed. Basically once the car electronics are supposed to be sleeping, you should measure the quiescent current. If too high, pull out fuses until you find out which one helps (you should find potential candidates from old posts).

 

[Gawdi]

I had a similar problem with my 300D - and I asked on here. I was advised to check on the boot light - which I did and hey presto it wasnt going off when the boot was shut..

How do u check? Because its like the fridge door conundrum - I put my video camera in the boot and shut it...

 

[robertjrt]

Dead battery

My S500L had exactly the same problem back in 2005. Mercedes-Benz Chelsea told me it was the ignition switch which required replacement.(keyLessGo)

As you may have read elsewhere, MB fried the electrics and wanted me to pay a bill of £6,800. The main fuse melted!

I have yet to discover the cause of the original fault as far as I can see on all the invoices. At the trial the MB witness told the Court that if the car was left for more than two days all the CPU's required re-booting.

I am please to read that you are able to jump start your car without causing damage.

If you discover the cause, please let me know.

Hi guys, i have a s320. I dont know but since last month it is giving me problems, i would park the car and not drive it 2-3 days and it would go dead(battery). Dont know why. I then have to jump start it. Took it to a local garage last month and he said that the battery is going, so got a 91 AMP brand new Bosch battery and have it installed since 22nd April and yesterday the car went dead again. I had last driven it on tuesday 12th and when i tried to switch it on - on sat 16th the car went flat dead. Wont open the doors or anything. had to jump start it again and let it run for a few mins. Do you know what might the problem be.

For hints, I have a service exceeded by 4 days and SRS light on since last month (since i vacumed the whole car). Would the SRS light cause any problems. Now that i have a new battery, dont think it should do this.
Cheers

 

[dj_factor]

Thanks guys, I will work on it straight away. I have tried to search for old posts but cant find anything relevant. - DEISEL BENZ, can you please direct me to the right path as to what exactly should i be searching. I have searched for Battery Flat, Flat battery, Current drawing, etc terms but cant find anything relevant.
Thanks

 

[Matt45]

I had similar faults on my SL. Not every time but common enough to get a new batter [2 in fact] and a lot of diagnosis at the dealership. Fixed it myself after reading reports of here. Fistly try checking if you have 'locator lighting' switched on. If so switch it off as there seems to be a common drain in the lighting sensor and this can drain the battery even if the lights are out. Secondly, never switch off the car and leave it if you've only had the engine running for a short time, ie, you start it, back it out of the garage to wash it and turn it off. You need to let the wake up circuits wake up fully and then go off. Thirdly I charge the battery about every 3-4 weeks on a 3.5 charge rate for about 4 hours until the battery full light comes on. Following these rules I've had not one failure since. Have a look in the search for battery faults, the one I found that led me this way was from an S Class owner with a similar problem. matt

 

[Diesel Benz]

I had similar faults on my SL. Not every time but common enough to get a new batter [2 in fact] and a lot of diagnosis at the dealership. Fixed it myself after reading reports of here. Fistly try checking if you have 'locator lighting' switched on. If so switch it off as there seems to be a common drain in the lighting sensor and this can drain the battery even if the lights are out. Secondly, never switch off the car and leave it if you've only had the engine running for a short time, ie, you start it, back it out of the garage to wash it and turn it off. You need to let the wake up circuits wake up fully and then go off. Thirdly I charge the battery about every 3-4 weeks on a 3.5 charge rate for about 4 hours until the battery full light comes on. Following these rules I've had not one failure since. Have a look in the search for battery faults, the one I found that led me this way was from an S Class owner with a similar problem. matt

To me it sounds like you still have an issue with the car, the current drain is just not high enough to make the battery run flat before you charge it again but it should be fine when parked for weeks, if everything is right.

 

[Diesel Benz]

Thanks guys, I will work on it straight away. I have tried to search for old posts but cant find anything relevant. - DEISEL BENZ, can you please direct me to the right path as to what exactly should i be searching. I have searched for Battery Flat, Flat battery, Current drawing, etc terms but cant find anything relevant.
Thanks

I tried a search with the magic word that was already mentioned in this thread: "quiescent". But you have to search from the electronics forum. I don't know if this link works:
http://www.mbclub.co.uk/forums/search.php?searchid=2187744

An example: http://www.mbclub.co.uk/forums/electronics/64185-battery-keeps-going-flat.html

Example control units that have problems entering sleep mode are memory seat control units, Comand, overhead control panel control unit etc. Note that the current may be mostly from one device when the faulty one actually is another one that is connected to the same CAN bus and keeps all devices on that bus alive.

 

[robertjrt]

Re-charging battery.

My S500L was starting fine for 10 months before the problem. Although I did not drive the car far, in London it can take an hour to go five miles, surely, the heavy duty alternator should have been able to recharge the battery?

 

[tromppost]

Not quite on topic but I leave my car dumped in the drive for weeks on end and found that a solar trickle charger works well. Its way easier than having to find the time at the weekend to run the engine to charge the battery.

 

[dj_factor]

Amazingly chaps, I used to switch this on after 5 days and sometimes even 6, but never let it go on the 7th. all in all used to switch it on after a few days and all seemed perfect. its just that recently it has sparked these problems.

I have now been picky on things and have discovered something new. on the climate control panels, there is a tiny vent just next to the EC, REST button and it has some noise coming on from it - when i switch on the car or switch off and it settles down. Maybe it is to detect the inside temperature. Can it be the offender too.
Thanks

 

[Diesel Benz]

I have now been picky on things and have discovered something new. on the climate control panels, there is a tiny vent just next to the EC, REST button and it has some noise coming on from it - when i switch on the car or switch off and it settles down. Maybe it is to detect the inside temperature. Can it be the offender too.
Thanks

It must be one of those AC interior temperature sensors. A small blower helps it sense the air temperature at the area close to the sensor. Probably some dirt that you could try to clean out, or the motor has worn out. But this noise should not be causing a flat battery if it goes away when ignition is switched off. On some models however a similar sensor at the overhead control panel remains on, that being a symptom of the related CAN bus remaining alive. This causes significant power consumption, not from the blower but the control units remaining alive. Looks like not your problem (not sure if I should say "unfortunately").

 

[dj_factor]

Guys I have just noticed that my center brake light (the one behind passengers head rests) blinks for 1 sec every 15-20 mins, when the car is off and locked. I dont know why this is happening. Can this be the problem. Please let me know what you think and what would the remedy be to it.
Thanks

 

[mr. shr]

Well this is definitely not right.
I'd say you get yourself to an indy with a STAR machine.
Explain the issue with the blinking brake light as that could be their starting point.

But hopefully, a quck test on STAR will reveal what and where the fault might be.

 

[saorbust]

Is the boot closed properly ?!

 

[dj_factor]

Hi guys, the boot is closed properly. Its also a soft close boot, so i know for sure that it is closed properly. Im trying to look for the multimeter, once i get it, will start with the process to check the fuses.

guys by anychance, would you have any idea of a Star diagnoser in west yorkshire or Manchester area.
Thanks