Dear friends:

Does Mercedes specify a maximum current draw (engine OFF) for old diesel cars (W123, 126 etc...) which don't have a car alarm system installed? How many milliamperes do the radio (station memory function) and the clock use? On my W126 300SD.
it's about 350 mA or less when the engine is OFF.

However, I've read that newer cars (no alarm) usually consume only a maximum of 50 mA.

I think 350 mA current draw is a little bit too high and that's not good for a battery.

Thanks for your info.

Eric

Hi Eric , that does seem high , does it spike and then go down to less than 50 ma ? The amp in the stereo will spike as it charges up and then drop to normal range . Try removing fuses and checking the draw, systematically eliminating each circuit will help you find which one is the culprit . I had a short inside the battery (drawing 2.5 amps ) that had me confused for a while , it was still drawing current with all the fuses pulled !The bad cell finally expired and so did the short .

__________________
Democracy dies in darkness, you have to kick at the darkness till it bleeds daylight

Kyle,

How did you measure the 2.5 amp short current inside the battery?

P E H

Hi P.E.H., I hooked up my DMM between the negative post and ground . I had an intermittent discharging battery on the CE , I was checking to see where the short was coming from and normally it was pulsing between 10 and 30 ma (from the clock) but if it was unhooked for a while I was seeing a spike to around 300 ma . This I assumed was the amp in the stereo powering up because it would settle back to the clock pulsing.Pulling the stereo fuse (always hot) confirmed it , but every once in while I saw a draw of 2.5 amps , when I charged the battery it went away , then finally the cell died during recharging and I put in a new battery , end of problem . This all happened over the course of a week , the car was fine sometimes and sometimes the battery was too low to start it , thankfully it always died in the garage at home.

__________________
Democracy dies in darkness, you have to kick at the darkness till it bleeds daylight