Battery Draw - What's normal?
09-10-2022, 05:36 PM
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W203 C320 Wagon
Battery Draw - What's normal?
I've been working through some electrical gremlins on my new to me 2002 C320 Wagon.
I tracked down a bad parasitic draw to the seat control modules. I used a relay for passenger seat so it's only powered with ignition on and put in a 30a switch to control when the drivers seat gets power.
This took care of the biggest sources of battery draw, but I still see a 0.130 reading on the multimeter when everything should be asleep.
After going through every fuse again, the only thing that gets it down to 0.055 - 0.060 is pulling fuse 9 for the Overhead Control Panel control unit. My question is, does a 0.130 reading indicate a problem with the OCP or is this considered a "normal" battery draw for the W203's?
Thanks for the insights
I tracked down a bad parasitic draw to the seat control modules. I used a relay for passenger seat so it's only powered with ignition on and put in a 30a switch to control when the drivers seat gets power.
This took care of the biggest sources of battery draw, but I still see a 0.130 reading on the multimeter when everything should be asleep.
After going through every fuse again, the only thing that gets it down to 0.055 - 0.060 is pulling fuse 9 for the Overhead Control Panel control unit. My question is, does a 0.130 reading indicate a problem with the OCP or is this considered a "normal" battery draw for the W203's?
Thanks for the insights
09-10-2022, 07:27 PM
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This place is a joke.
Anything below 50ma is acceptable. You have more than double at 130ma. Make sure you are waiting at least 30 minutes, preferably 1 hour for the car to go to sleep. This time can be reduced by locking with the remote.
09-10-2022, 07:59 PM
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Thanks… I should have mentioned took as many steps as possible to make sure everything was asleep, including securing door locks and letting it sit.
Actually, the Klein multimeter went to sleep without the draw dropping.
I’m starting to wonder if it’s a fault in the overhead console fan that is causing the draw.
Actually, the Klein multimeter went to sleep without the draw dropping.
I’m starting to wonder if it’s a fault in the overhead console fan that is causing the draw.
09-11-2022, 07:47 AM
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2003 C230K Coupe Orion Blue
50mA is the magic number. I remember the car dropping below that value within about 5 or so minutes after locking the car.
I assume you're talking about the panel with the dome and reading lights. Are any bulbs there modified or replaced with LEDs?
I assume you're talking about the panel with the dome and reading lights. Are any bulbs there modified or replaced with LEDs?
09-11-2022, 09:00 AM
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Thanks. I thought 50 +/- was the magic number. I read on one of the forums that some MB’s stay around 120mA, but you can’t trust everything you read!
Yes, fuse 9 controls the overhead console with the reading lights. I doubt prior owner did any modes.
What I’ve read is there is a little fan in there that is somehow related to the interior temp control. I’ve also read this fan sometimes fails to fall asleep, but haven’t come across a conclusive solution. Usually locking the doors does the trick. This doesn’t seem to be my case.
Yes, fuse 9 controls the overhead console with the reading lights. I doubt prior owner did any modes.
What I’ve read is there is a little fan in there that is somehow related to the interior temp control. I’ve also read this fan sometimes fails to fall asleep, but haven’t come across a conclusive solution. Usually locking the doors does the trick. This doesn’t seem to be my case.
