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Ask Dodgerench Your Own Question
Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3407
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
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Nitro: have you ever seen a alternator short?

Customer Question

have you ever seen a alternator short?
Submitted: 2 years ago.
Category: Dodge
Expert:  Dodgerench replied 2 years ago.
Hi, my name is Ed. Welcome to JustAnswer!. Seen one? Replaced a few I have. I see you've replaced yours already, so what are you seeing?
Customer: replied 2 years ago.
Just that I never seen one and shouldn't there be a fusible link ? The battery also was damaged. Alternator was so hot you couldn't touch it. Anything else that may be bad?
Expert:  Dodgerench replied 2 years ago.
Yup, there should be a fuse link of some sort, but oddly, they don't usually blow. I've seen a couple of shorted diode heat-sinks in Wranglers already this year and they just drained the battery. It might have a bit to do with battery capacity when it comes to fuse link failure, since battery charge will go backwards through the alternator as well. A high capacity battery might stand a better chance of melting the fuse link (or replaceable fuse) than a weak one. And yes... the alternator gets so hot you could cook on it. I'll check the books to see if your Nitro uses a conventional fuse link or it has a 120 or 160 amp fuse mounted in the fuse block where your alternator dumps its charge.Is the system charging now?
Expert:  Dodgerench replied 2 years ago.
The wiring diagram does show an 8-gauge fuse link in the alternator output circuit. They're usually located within inches of the output stud at the back of the alternator and colored differently from the red charge cable. I think it's green in color.If you're not charging now, measure voltage at the alternator output stud with the engine running. Compare this voltage to what you find at the battery and it should be pretty much the same thing if nothing got burned up. An open circuit on your output circuit will push voltage WAY high, sometimes over 60 volts.
Customer: replied 2 years ago.
Thanks for the input. System seems to be charging. Will check outputs.
Expert:  Dodgerench replied 2 years ago.
OK, standing by.
Expert:  Dodgerench replied 2 years ago.
I hear your charging voltage is 13.9 at both ends and this is good news. While target charging voltage will vary from time to time (depends largely on ambient temperature), 13.9 is certainly a winning number. The similarity between testing points shows that current is freely flowing between the alternator and battery and the heat you're seeing on the alternator is normal when it's working. I think you came out of this situation with flying colors, considering the damage sure could've been greater! Cheers!Ed
Expert:  Dodgerench replied 2 years ago.
If everything has worked out OK, I'll bid you a great day and don' t forget to rate your JustAnswer! experience on the way out. Take care, Ed