Battery charging issues

I recently bought a 2000 cherokee sport. voltage meter dropped a couple hours into first trip with it. was able to drive it back to the trailer ok. windows and radio not working due to low power. replaced the battery and tested the alternator. it failed. replaced it and getting 14v across battery. 30 mins into second trip. voltage meter drops. jeep ends up dying and after getting a jump it is cutting out so back i can make it back. swapped batteries with a buddy and drove back fine. pulled alternator and bench tested. it failed. bench tested new alternator twice and installed. battery still isnt charging. checked wiring from Alt to batt- ok checked field plug on alt getting 5v and 0v thinking i may have a bad PCM. Any advise or help thanks guys

An alternator often has a difficult time charging a fully discharged battery.

A guy in my Jeep club works for one of the big name auto parts stores and he says between 10 -20% of the rebuilt alternators are DOA.


When the voltage meter drops, almost always the alternator is the root cause.

i think i figured it out. 15 amp fuse was bad.