Having problems with your 2005 Ford F 350 Super Duty ?
Ford f350 super duty 6.0 deisel. batteries fully charge during operation, or off charger, but left for more than 4-5 hrs, won't start. Havr replaced primary battery to no effect. Have checked the batteries charge to 13.8v. The output from the alternator reads 14. Could it be the alternator or a short. How do I proceed with diagnosis.
Hi well there is not anything wrong with the alternator, that is the correct charge, i would expect that with 1000 rpm at 14v, if that is on idle, it might actually be over charging the system, try revving it to 1000rpm or 1500rpm and take a reading then, if it stays the same there might be a fault with the regulator on the alternator if it drops below 13volts when revving the motor than you have an alternator fault it might be ok when on idel, but try some revv's and see what that gives you, also if after 4-5 hours you have a flat battery, try just leaving the volt meter on the battery and see how fast the drain is, it really could be allot of things, but a short is a good one to check for....hope this helps
Repair Help & Product Troubleshooting for 2005 Ford F 350 Super Duty
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