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Not holding charge

GTAye

New member
Location
The Dirty Jersey
09 GTI sitting long periods due to not driving much. Either slow crank to start or no crank at all. Car icon in MFD is faint and other electronics like radio and such won't turn on unless car is running. No indication of issue with alternator.

Put a jump charger with a voltage gauge on the battery and it showed battery at 13.5 volts. Took charger off and car still would not crank.

Thought 13.5 at rest is within expected value to start the car.

Put charger back on the battery and it started.

If it sits just a bit, cranks slowly again and car icon in MFD is faint in first two ignition positions. Other electronics won't come on until it turns over.

Any ideas on what is going on or other things to check?
 

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Last edited:

1131

Passed Driver's Ed
How old is the battery? Voltage isn't the same as amperage. A battery can produce 13.5V and still have bad cells. There are ways to test for amperage, but it would be simplest to just swap the battery with a known good to test.
 

GTI's

Go Kart Champion
Location
MD
09 GTI sitting long periods due to not driving much. Either slow crank to start or no crank at all. Car icon in MFD is faint and other electronics like radio and such won't turn on unless car is running. No indication of issue with alternator.

Put a jump charger with a voltage gauge on the battery and it showed battery at 13.5 volts. Took charger off and car still would not crank.

Thought 13.5 at rest is within expected value to start the car.

Put charger back on the battery and it started.

If it sits just a bit, cranks slowly again and car icon in MFD is faint in first two ignition positions. Other electronics won't come on until it turns over.

Any ideas on what is going on or other things to check?

Take your DVM and confirm that your old battery actual had 13.5 at rest, I think you will find that it was not. Test alternator output with DVM or Vcds.

If you do have a battery drain do a scan with Vcds and make repairs to any Dtc that might be causing a drain. If you need to do a Parasitic Draw Test you do not pull the fuse on a MK5 you need to follow the VW TB/TSB procedures or watch this video by HM
 

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Take your DVM and confirm that your old battery actual had 13.5 at rest, I think you will find that it was not. Test alternator output with DVM or Vcds.

If you do have a battery drain do a scan with Vcds and make repairs to any Dtc that might be causing a drain. If you need to do a Parasitic Draw Test you do not pull the fuse on a MK5 you need to follow the VW TB/TSB procedures or watch this video by HM
I like that method better. I have yet had a concern with mine...and only was aware of one way of detecting amp draw. Thanks for sharing that.
 
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