Quote:
Originally Posted by talljames
Hi, I have another thread but saw this one and it got me thinking. My running voltage using test 09 is varying from 12.3-12.6 on a 2005 e53 4.4i v8. Is this normal for these old cars? I thought it was supposed to be 13.8V. I will get a test done on the battery but could be a drain. My heating is not working but might not be related.
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What is the problem you are having that caused you to check running voltage?
I would do some troubleshooting before replacing anything.
Depending on the age of the battery you might want to get it load tested. Most auto parts stores will do a load test for free.
If alternator is OK the running voltage should max out at about 13.6-13.8 but can be lower depending on load. I would test the running voltage at the battery charge posts under the hood or the at the battery with a multimeter. Test with engine running with nothing that draws voltage off and again with everything on.
You can also check for a parasitic drain on the battery with a multimeter.
https://www.youtube.com/watch?v=zdIK...?v=zdIKNnwEjIs