C32 AMG, C55 AMG (W203) 2001 - 2007

What is the typical charging voltage?

Old Oct 17, 2010 | 12:56 PM
  #1  
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2004 C32, 2006 Honda CBR1000RR, 2007 Harley NightRod, 2013 Harley Road Glide Custom
Question What is the typical charging voltage?

I don't think my problem is with the seat contoller. I replaced my battery like a year ago and my car is slow to start if I leave it outdoors for a couple of days at a time. If I leave it indoors, I don't have any issues. Here is what I know:

1) With the car running, the voltage across the battery is 14.12 volts.

2) With the car not running after the first day and inside the garage, the battery reads 12.38 volts.

3) With the cst not running after the second day and inside the garage, the battery reads 12.41. volts.

My question is, what should the running voltage be? And, could I have received a less than perfect battery? If the running voltage is low, does that mean the alternator or voltage regulator is going bad?
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Old Oct 17, 2010 | 07:26 PM
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Originally Posted by trbo2nr
I don't think my problem is with the seat contoller. I replaced my battery like a year ago and my car is slow to start if I leave it outdoors for a couple of days at a time. If I leave it indoors, I don't have any issues. Here is what I know:

1) With the car running, the voltage across the battery is 14.12 volts.

2) With the car not running after the first day and inside the garage, the battery reads 12.38 volts.

3) With the cst not running after the second day and inside the garage, the battery reads 12.41. volts.

My question is, what should the running voltage be? And, could I have received a less than perfect battery? If the running voltage is low, does that mean the alternator or voltage regulator is going bad?
With the engine running and your lights & a/c at about 1100rpms it should read between 13.5 to about 14.2 give or take.
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Old Oct 17, 2010 | 09:00 PM
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2007 GL450 2005 C55 2002 C32 sold 2001 ML320 sold
While the engine is on, mine reads between 13.6 to 14.4 depending on accessories on and engine speed. With engine off - my battery reads 11.9 to 12.0v after a few hours sitting.

This is all using the info in the instrument cluster rather than reading it using a voltmeter.
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Old Oct 18, 2010 | 01:49 AM
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Your voltage readings are within spec. There's something else going on that is causing the vehicle to hesitate during crank. Do you wait a few seconds after going to accessory position two before clicking over to start the engine?
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Old Oct 18, 2010 | 04:37 PM
  #5  
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Originally Posted by gt4awd
Your voltage readings are within spec. There's something else going on that is causing the vehicle to hesitate during crank. Do you wait a few seconds after going to accessory position two before clicking over to start the engine?
Thanks all for the replies. No, I generally just turn the key without waiting much in that accessory position. I will try that. What does that do?
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Old Oct 19, 2010 | 12:52 AM
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Prime the fuel pump/lines.
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