SL/R230: Need battery drain help please
Thread Starter
Member
Joined: Apr 2012
Posts: 179
Likes: 4
Sl55 2003
Need battery drain help please
Anyone ny area that is handy with the r230 I have 2003 sl55 battery drain tried everything need a fresh perspective.
Available anytime if you want to take a look. Much appreciated thank you thank you in advance.
On Long Island NY replaced bcm,
alarm removed , pulled fusds
relapced alternator and both batteries
Anyone pleasehelp!!!!!!!!!!!!!!!!!!
Available anytime if you want to take a look. Much appreciated thank you thank you in advance.
On Long Island NY replaced bcm,
alarm removed , pulled fusds
relapced alternator and both batteries
Anyone pleasehelp!!!!!!!!!!!!!!!!!!
Newbie
Joined: Jun 2019
Posts: 7
Likes: 0
W 211, 2003, E-320
10222022-BAttery Drain- No one has the right Solution except keep on changing batteries. - It seems there is no real answer to Battery Drain except the video showed in UT to cut the constant current wire for seat adjustment module both sides and Alternator regulator. It works, yet too many issues either BCM, Break switch under the driver side, suppose to be a cheap fix, then so many other messages like, Visit Dealer, Reduced Breaking, functions not available and similar sings. I have spent hundred of hours on my Comp., U Tube, Articles and I am really afraid to go to a dealer who may give me a bill for more than the E-320 of 2003. I kept Mercedes since my childhood of age 15 and now 64, never had such a serious issue. My batteries are almost new. Auxiliary shows 12.14 and back 11.5 after just a little charge. I can drive and can start next day. If I only turn the ignition on few times w/o starting, battery would drain right a way, sign will come and would not start. I will look for BCM again and last hope is Battery Relay K57. If you or NAYONE Finds a real answer, please share houstonbn12gmail. Good luck, Thanks
Super Member
Joined: Sep 2018
Posts: 746
Likes: 185
From: Melbourne, Australia
2005 SL 500 R230
Woah there. Step back and do a bit of measuring and analysis (if you haven't already). There's always a reason for current drain beyond what the car should take in its quiescent state.
You need a few special tools with this car; one is a clamp meter that can measure DC milliamps. Just measuring the voltage after the batteries have dropped is only part of the picture. Let the car go completely to sleep and measure the current drain from the rear battery. (You might have to remove the bulb in the boot light - I don't know if that goes to sleep after a while or not)
The Command radio can continue to draw current for some time after the car is switched off I believe.
One circuit or more will be drawing parasitic current.
There should be zero current drawn from the front battery.
You need a few special tools with this car; one is a clamp meter that can measure DC milliamps. Just measuring the voltage after the batteries have dropped is only part of the picture. Let the car go completely to sleep and measure the current drain from the rear battery. (You might have to remove the bulb in the boot light - I don't know if that goes to sleep after a while or not)
The Command radio can continue to draw current for some time after the car is switched off I believe.
One circuit or more will be drawing parasitic current.
There should be zero current drawn from the front battery.
Newbie
Joined: Jun 2019
Posts: 7
Likes: 0
W 211, 2003, E-320
W 211, E-320, 2003, Thank you for taking the time to respond to my issues. Now, I really don't have a low battery draw. Car runs fine, starts next day as long as Drive every day. However, if I turn the key on and off few times just to check the voltage or trying to see other functions, voltage suddenly draws where it would not start the car. Sometimes even with low battery , convivence functions not available, longer stopping Distance etc., car starts, have good voltage but then suddenly dies and battery is low. A car starting and running few minutes earlier now has the low battery. I will do what u said, will take out the trunk light bulb, let it sit for an hour and will see. If you know, can I bypass the BCM Battery Control Module in the trunk. Thanks again. 10.24.22
Thread Starter
Member
Joined: Apr 2012
Posts: 179
Likes: 4
Sl55 2003
OK Im the orig poster . I have a 2003 sl55
Both batteries seem to drain ,the rear one really fast! 2 amps draw on the meter.
I have pulled all the fuses gets down to 1.7amps at times.
bcm has been replaced. alternator too . both my batts dead now cant even start car. will replace both when back in NY .
I really need a local set of eyes to take a look . maybe see something i am missing.
thanks for all the advice please keep it coming.
Both batteries seem to drain ,the rear one really fast! 2 amps draw on the meter.
I have pulled all the fuses gets down to 1.7amps at times.
bcm has been replaced. alternator too . both my batts dead now cant even start car. will replace both when back in NY .
I really need a local set of eyes to take a look . maybe see something i am missing.
thanks for all the advice please keep it coming.
Super Member
Joined: Sep 2018
Posts: 746
Likes: 185
From: Melbourne, Australia
2005 SL 500 R230
What's the current draw on the front battery?
It should be zero.
If it's not then I would suspect relay K57 or the BCM.
Pull relay K57 and see what happens to the current draw on the front battery. Flip the cover off the relay and see if the armature is stuck (pulled in).
Then disconnect the BCM and see what happens. 2A is a lot of current; that's your issue. You should be able to track this down yourself. Sounds like the BCM.
Relay K57 should be normally open. Looking at the battery control pdf (you do have this don't you ? - search R230 Dual Battery On-board Electrical System) if relay 57 or the BCM is faulty then the front battery could drain through the BCM or whatever is the underlying issue.
It should be zero.
If it's not then I would suspect relay K57 or the BCM.
Pull relay K57 and see what happens to the current draw on the front battery. Flip the cover off the relay and see if the armature is stuck (pulled in).
Then disconnect the BCM and see what happens. 2A is a lot of current; that's your issue. You should be able to track this down yourself. Sounds like the BCM.
Relay K57 should be normally open. Looking at the battery control pdf (you do have this don't you ? - search R230 Dual Battery On-board Electrical System) if relay 57 or the BCM is faulty then the front battery could drain through the BCM or whatever is the underlying issue.
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