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Unread 02-06-2014, 05:39 AM   #1
georged
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low battery voltage

The battery in my 04 GCL 4L goes low (12.3 V) after few days of not driving. With temperature above 70 and driving the battery voltage does not go above 13.7. Is there a way to get it to go over 14?
Also I believe I read there is a way to bypass the BCM and use an external alternator - any comments?

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Unread 02-06-2014, 06:22 AM   #2
bessyboy
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Just get a bigger alternator. Mine runs right around 13.8-.9 with the stock one which is plenty
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Unread 02-07-2014, 03:57 AM   #3
86cj74.2L
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Is your voltage still 13.7 at idle with everything on? AC on high, all lights, rear defroster?
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Unread 02-07-2014, 04:46 AM   #4
georged
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Voltage stays there unless the temperature is lower than 50. Battery is new and tests better than rated.
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Unread 02-07-2014, 05:39 AM   #5
Matrixxxx
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i would check your voltage with a multi meter, the meters are not usually very accurate. its your voltage regulator which determines the voltage, the alternator will go to high volts when charging as the battery charge increases the voltage will get lower.
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Unread 02-07-2014, 06:10 AM   #6
bessyboy
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What exactly should the output be? I'm sorta curious now, I put a multimeter across the battery and before starting it read 12.23 and after starting it was 13.8. I also put this other tester on I'm pretty sure it was for amps and it read right on the boarder of "OK". What is the amps supposed to be I will be testing it later
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Unread 02-07-2014, 09:58 AM   #7
rep-tile
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Anything 13.5-14V is normal. The output voltage is controlled by the PCM. Your battery voltage does sound low. How do your battery connectors look?
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Unread 02-07-2014, 10:45 AM   #8
86cj74.2L
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Quote:
Originally Posted by rep-tile
Anything 13.5-14V is normal. The output voltage is controlled by the PCM. Your battery voltage does sound low. How do your battery connectors look?
If you in this range at the battery with all accessorys but the rear defrost on I'd say your ok.
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