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2003 Mercedes C230 Kompressor, W203
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7 Posts
Discussion Starter #1
My 2003 c230 starts sluggish as if battery low. But battery is new. Cables clean and are tightly fitted.

It almost seems there is a battery drain. After each use the car won't restart. It just does one click when key turned. If after a drive car is turned off, it will restart if within minutes. If left for few hours it won't re-start.It Jump starts quickly

Every time I stop car it won't re-start so now I have to disconnect neg battery terminal to prevent battery drain. No matter how many times I use car in a day.
Upon re-connecting the neg terminal car will re-start quickly, albeit with sluggish turn of engine.

Sometimes (for weeks) it won't start following above steps. When key turned it will click once and NO engine turn. Automatically, all lights go off when key turned. After say 50 attempts at same turning the key to start engine eventually will show signs of minor turn and after "umpteenth" attempt engine starts up with barely enough battery power.

Most times, each day after use battery disconnected and the next day re-connect terminal and car starts within few turns but again with that worrying sign of not enough battery power.

I've read online, to check a starter relay but I can't find where it's located or ref letter in fuse-box diagram.
 

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2003 C320 coupe, 2000 ML320
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461 Posts
What's the battery voltage with the car not running ? What's the battery voltage with the car running ?.. Should be somewhere around 12.6v not running and 14.2v with the engine running..
 

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2003 Mercedes C230 Kompressor, W203
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Discussion Starter #3
Voltage not checked yet. Autozone said battery is good. It was replaced 7 months ago. Alternator unit less than year old - replaced as light on dash came up. Thanks
 

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2003 Mercedes C230 Kompressor, W203
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Discussion Starter #7
No multi meter but I'll buy one and post here after testing voltages.
Took car to Autozone for battery and alternator check up and they said it was working fine.
 

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2003 C320 coupe, 2000 ML320
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461 Posts
DO YOU HAVE AFTERMARKET STEREO UNITS INSTALLED.. like a power amp?


If so,.start there.. (it's not being shut down when the car is being turned off..)
 

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2003 C320 coupe, 2000 ML320
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It does sound like the battery is being drained down by a "parasitic draw".. or you've got some bad cables to the starter.. You want to take some reading right off the starter and battery, when it won't start.. Put your meter leads on the battery post (not cables) start car.. Wright down what the battery reads as As you're trying to start (not just with the key on but as you try to crank it).. Now you've got to get to the starter, put meter leads on the starter terminal post, (not the cables) try to start.. Take note of the readings.. You should not see a difference between the two readings of more than 1/2 volt ( give or take a bit).. Example .. On the battery, you try to start, it drops from 12.6v to 11.9v and then you do the same test on starter.. It's 12.6v and when crank it.. (let's say)..it's drops 6.7v.. Then you've got a problem with the cables and /or connectors.. NEXT TEST.. Pull the cable off the positive battery post,.. Put your meter on the milliamp scale,..place one lead on the battery and one lead on the positive cable.. With everything off, doors closed, lights off,etc.. you should be reading a very small current draw.. under 100 ma (.100 amps) and probable closer to 10ma.. (.01 amps).. Let's say your reading 745ma.. (way to high) and then you start pulling fuses one at a time.. when it drops down to that "under a 100ma" reading, that's where you need to focus on..

PS.. do the last test first,....It's easy and fast.. The one shown below.. Post how many milliamps you are pulling before you do anything..


2606937
 

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2003 Mercedes C230 Kompressor, W203
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Discussion Starter #11
Thanks for your post. I'll go buy voltage meter, read how to use it and then carry out above tests.
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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Do you have the power seat with memory option? If so, that's a common culprit for batter drain. The cheap solution is to require it so the seat is only powered with the ignition switched on.
 

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2003 Mercedes C230 Kompressor, W203
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Discussion Starter #13
Do you have the power seat with memory option? If so, that's a common culprit for batter drain. The cheap solution is to require it so the seat is only powered with the ignition switched on.
Yes, have power seats with 3 settings (1-2-3-) pwr door locks, pwr windows. If a separate fuse then, I'll take the fuse out for power seats and see if that makes a difference.
In a nutshell the problem is : When ignition switch turned it makes one click sound - no turn of engine no starter noise. So, I turn key back to OFF. Then I turn it back ON and it does one click sound again . This repeats for dozens of times and eventually starter engages and starts the engine.
Thank You, again
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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Check the voltage - you should have 12.5v at rest, no less than 11v when attempting to crank, and 14v at idle. If not, you have a power supply (battery, alternator, drain, etc.) problem.
 
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