I have a 2000 Durango, 5.2L. After engine runs 30min. or more, check gauge light turns on and battery gauge reads about 9V, and engine struggles to stay on, have to step on gas paddle to keep engine running. Turned off engine and checked battery with Vmeter and reads 12V (battery is less than a year old). Started engine again and have to step on gas paddle to keep engine running. While engine is running, checked battery reading again with Vmeter and read 9V, same at alternator output connector. Suspected bad alternator – replaced. With new alternator installed, ran engine again for 30min or more and same problem, and this time battery gauge is all the way 0V when check gauge light lit. With engine still running verified battery with Vmeter and read 12.5V, same at output of alternator. Turned off engine and checked battery with Vmeter again and read same, 12.5V. Turned on engine again and battery still read same, 12.5V, same at alternator output. Is new alternator still bad and should I replace it again or is something else causing the problem? Any help is greatly appreciated. Thanks in advance.

 

I forgot to mention, the code is P1682 "Charging system voltage too low."

 

I would say the battery is dead and unable to hold any charge under load. Replace battery and let's trust for now that the new alt is actually good.

The old issues probably killed the battery.

IndyDurango

 

this same thing happend to a lady at my work a long time ago. check the wires from the alt to the fuse box under the hood. I am not sure what year it was but her gauge was reading low volts and it was the wires from alt to battery or alt to that fuse box check them all sounds like one wire isn't making a good connection.
hope this helps
Pizzo

 

Could very well do it. Load test the battery, check the connections, and test the output of the alternator. Most all this can be done at Checker or Auto Zone for free.

 

Follow up:
Early this morning, I put a charger on the battery and charged it for almost 4hrs. Battery voltage at 13V. Verified all fuses good. Started engine and read battery at 12.3V using a Vmeter with engine running. Decided to replace cable from alternator to fuse box, because it was getting pretty hot to touch after running engine about 15min (same size as battery cable). Started engine again and same result, battery voltage at 12.3V with engine running, indicating alternator not charging battery. Decided to go ahead and replace alternator again. Finally, it works, battery voltage at 14.3V with engine running. Ran engine for about 30min and drove around another 30min. So far it's good. I want to thank you guys for all the input, greatly appreciated...

 

14.3 is full output and charging your battery properly.


Glad to see you got it!