S-Class (W221) 2007-2013: S 320 CDI, S 350, S 450, S 500, S 550, S 420 CDI, S 600

170 milliamp draw

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Old Mar 13, 2020 | 10:25 PM
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From: indiana
2008 s550
170 milliamp draw

Is a 170 milliamp draw on the consumer battery on a 08 s550 when off and locked normal?
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Old Mar 14, 2020 | 04:25 AM
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S500
no idea, quite a few other models have issues with comand not shutting down (but not heard of that on later 221 cars) and the rear door handles full of water on 211 (e class) is a common one to flatten the battery

all modern cars eat power with the thing's locked, alarms and can bus electronics doing strange stuff, what about keyless ? do the antenna's seeking out the key stay awake, don't see how the car can detect it otherwise? its why I wrote it should cope for three week's doing nothing, after that its always a gamble on any car post 1994. Some can't do 2 weeks, its why daily drivers have less issues

Last edited by BOTUS; Mar 14, 2020 at 04:29 AM.
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Old Mar 14, 2020 | 08:15 AM
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W221 S500 2010
I have read somewhere that the "magical" figure when everything is OK should be around 30 miliamps. According to that, yours looks a bit high, but people have reported much higher figures...
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Old Mar 15, 2020 | 06:08 PM
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From: indiana
2008 s550
I measured it again today and after siting for an hour It fluctuates between 160-320 miliamps. I'm on my 3rd battery from auto zone each of them only lasted a day but it doesn't seem to be the cars fault.
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Old Mar 15, 2020 | 06:22 PM
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'19 E63S sedan
Originally Posted by Will Hunt
I measured it again today and after siting for an hour It fluctuates between 160-320 miliamps. I'm on my 3rd battery from auto zone each of them only lasted a day but it doesn't seem to be the cars fault.
That's too high. It's 8 amp-hours a day. A few days of that will fully drain a battery. You might have a bad seat module preventing the CAN from sleeping, or some other issue. Someone who knows how to diagnose the electrical system needs to look at it.
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Old Mar 16, 2020 | 01:43 PM
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S500
why not unplug stuff or take out a few fuses and see where you are
the keyless stuff in the doors are another designed to fail headache, they stop things locking and many owners never notice, not sure if it drains current

if you can't wipe out faults its possible things are in a muddle and don't shutdown due to noise on the can bus. In earlier ones (S SL or CL) you should never disconnect a battery without nearly dealer level diagnostics or it'll never be happy (and if you have the "standard" damp puddle under the passenger footwell carpet you can spend 3 months on these fighting and get nowhere - till you resolve the damp and corroded connections).

The electrics are much better on the 221 and disconnecting the battery is OK, and I'm not sure if leaving faults there can cause an issue, but it would likely give you a clue as to what is playing up to look. depending upon spec you can have 56 modules complaining about nothing. If you don't have gear that can talk to all these modules then you should probably hand to someone who has, although you might get lucky. If its keyless I'd start there

Last edited by BOTUS; Mar 16, 2020 at 01:55 PM.
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Old Mar 16, 2020 | 02:23 PM
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W221 S500 2010
To find a parasitic draw, you will not find anything better than this:

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Old Mar 17, 2020 | 07:21 PM
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From: indiana
2008 s550
I have tried both pulling fuses and measuring voltage drop across the fuses pulling the fuses didn't change the amp draw and the voltage drop wasn't abnormal.
The series of events that lead up to this problem was that I drained the battery by having the ignition on for 2 hours without engine running, then I put in a Walmart battery I had sitting for 4 months and it would be at 11.5 volts after a day, so I put in a new autozone battery and after a day it was at 5 volts I got 2 other ones from warrant and they did the same thing. I've seen it go to 20 millivolts and stay but then I ran the test a few more times and it will only go down to 170 millivolts. Do I have to unplug the seat module to see if it's the problem or will pulling the seat adjustment fuses do the same thing?
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Old Mar 17, 2020 | 07:26 PM
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From: indiana
2008 s550
Originally Posted by BOTUS
why not unplug stuff or take out a few fuses and see where you are
the keyless stuff in the doors are another designed to fail headache, they stop things locking and many owners never notice, not sure if it drains current

if you can't wipe out faults its possible things are in a muddle and don't shutdown due to noise on the can bus. In earlier ones (S SL or CL) you should never disconnect a battery without nearly dealer level diagnostics or it'll never be happy (and if you have the "standard" damp puddle under the passenger footwell carpet you can spend 3 months on these fighting and get nowhere - till you resolve the damp and corroded connections).

The electrics are much better on the 221 and disconnecting the battery is OK, and I'm not sure if leaving faults there can cause an issue, but it would likely give you a clue as to what is playing up to look. depending upon spec you can have 56 modules complaining about nothing. If you don't have gear that can talk to all these modules then you should probably hand to someone who has, although you might get lucky. If its keyless I'd start there
I have scanned it with a foxwell nt520 and no faults were found other than low voltage after clearing that there none other that low washer fluid.
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Old Mar 18, 2020 | 01:15 PM
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S500
sorry don't know the scanner, might be good might just do engine management

around Europe MB enthusiasts all have good stuff to say about icarsoft MB||,
I have a great little Autel thing (europen only model MOT Pro EU908) that talks to everything but you can't do adaptions or any coding, if you want to get at the car or have a tutorial on how to fix the heavy users all go with a fake Merc STAR setup off ebay

but in the modern world that still leaves you short of flashing the right software due to merc SCN headache. Where its a 3k USD for something decent like Autel's new MS908S Pro or the online xentry toy at 12k a year rental and only works on Mercs.

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