SL/R230: FRONT BATERY CHARGING PROBLEM
Thread Starter
Junior Member
Joined: May 2008
Posts: 26
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2003 sl500 MB
FRONT BATERY CHARGING PROBLEM
hi, i just bought a 2003 sl 500 7,300 miles and i had problems with the alternator, therefore i made it repair, the problem is that the front battery does not get charge .... an the one in the trunk works perfectly, i change the front battery too and didnt help, what can be??
thanks a lot for your answers
HIRLEMANN1
thanks a lot for your answers
HIRLEMANN1
Senior Member
Joined: Jul 2005
Posts: 259
Likes: 1
2003 SL500
Take a volt meter and report back what the voltage is at the front battery and back battery with the engine off, engine running no load and engine running with heavy load (AC on, lights on) and report back. Did you replace the front battery with the correc MB battery?
Glenn
Glenn
Thread Starter
Junior Member
Joined: May 2008
Posts: 26
Likes: 0
2003 sl500 MB
YES, i did all that and also get a new MB battery, wich after two weeks get discharged, when the car is running the voltage mark 12.38volts and when i turn on all the electronics (lights, radio, a/c etc) still in 12.38 volts, at the time a start the engine mark 8.12 volts and once the engine is running goes back to 12.38 volts ,that is in the front battery, the back battery marks in the volt meter when the car´s engine is off 12.40volts , when the engine is running with and with out load mark 13.84 volts i took the car to the mb agency but i live in el salvador, and mine is the only one sl 500 in my country , and they where just guessing, they dont have experience at all in this car, they wanted to me to change the computer , to SEE if this solves the problem. do you know how can i get the wire electrical diagram for this car, cause maybe the problem is some relay or something simple, and thanks a lot for answering
HIRLEMANN
HIRLEMANN
Last edited by hirlemann1; May 21, 2008 at 05:34 AM.
Newbie
Joined: Mar 2008
Posts: 3
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SL 500
I am not a techy but I seem to remember there is an electrical control unit that controls charging to front and rear batteries and also when the Consumers Off Line kicks in. They replaced that unit in mine and bingo it what as good as gold for the next 4 years when I sold it.
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Member
Joined: Jan 2008
Posts: 154
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From: Sugar Land Texas
ML320
there is a control unit called a BCM it controls a relay that lets the frt battery charge, the frt battery only charges for a short period after the car is started i think it is about 14 minutes depending on battery voltage then it won't charge again until the car is re started. the frt battery on a sl is only for the starter motor and has no other function
