2006 Jeep Commander battery vs alternator

2006 JEEP COMMANDER
45,000 MILES • V8 • 4WD • AUTOMATIC
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RRANKINS
  • MEMBER
  • 2 POSTS
I parked my car yesterday and it had been running fine and when I returned a few minutes later it was dead. I got a jump and as soon as the cables were removed it died. We did this a few times and it would not stay running. I took it in and the dealer swears its the battery but in my experience if the alternator is working the battery could be bad and the car will continue to run after starting. I dont want to replace the battery and then the car runs for a few days until that battery is dead and then I am stranded again. Can it be the battery and not the alternator?
Jul 1, 2009 at 3:57 AM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 POSTS
To find out get both load tested, this will pin point which one is not doing its job.
Jul 1, 2009 at 4:02 AM
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RRANKINS
  • MEMBER
  • 2 POSTS
Are you saying that it is possible that a dead battery will cause this. I thought that the alternator would keep the car running even with a dead battery and you would not have a problem until you turned the car off again.
Jul 1, 2009 at 4:10 AM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 POSTS
I use to believe that 30 plus years ago not anymore-

Use a voltmeter read the battery voltage before you start the car up record it, Now start it and record the reading -The alternator is doing its job while the engine is running if the readings is over 2 volts from the reading before you start it up.

Good Luck
Jul 1, 2009 at 4:16 AM
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