Aftermarket alternator?

[Whaler27]

My 2019 JLUR with the 3.6 just killed it’s second pair of batteries since I installed the Genesis dual battery system less than 10,000 miles ago. The jeep has less than 15,000 miles on it, so it’s spent most of its life in my shop on a Noco smart charger.

Last week the check engine light came on, so I connected a diagnostic tool to the OBD port to read and clear the code. The code was insignificant and unrelated to the electrical system, but I decided to do a full diagnostic run while I was hooked up. One of the diagnostic routines is an alternator check. The code reader tracks the jeep at idle for a while, then it instructs you to bring the RPMs between 2000 and 3500 rpms for about 30 seconds, than back to idle. The report said my alternator is in bad shape.

The OEM alternators are stupid expensive. Anybody had good luck with Napa alternatives? They have worked great in other vehicles, but some say Wranglers are too finicky. Thoughts?

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[Left Field]

A failed alternator at 15k miles is a bit unusual indeed. I wonder if the OBD diagnostic takes into account the 'smart' charging algorithms that our Jeeps use, which move the voltage level around anywhere between the mid 12's to the mid 14's however they see fit.

What voltage range do you see on your dash display while driving?

You might consider taking your alternator into NAPA and have them bench test it. That might give you a better indication of its health by taking the Jeep's 'smart' functions out of the equation.

Other follow-on possibilities might be parasitic draw or even a problem with the NOCO charger.

LF

 

[THAW]

Which diagnostic tool?

With JScan you can track alternator duty cycle, target voltage, and sensed voltage to see what's actually happening with the alternator.

MODULES -> Powertrain Control -> LIVE DATA ->
Generator Duty Cycle (%DC)
Target Charging Voltage (V)
Voltage Sense (V)

 

[mwilk012]

Dumb old tools can’t be used to properly diagnose an alternator anymore. Half the time they’re not charging and that’s intentional operation.

 

[ChoSunJuan]

Mean Green alternator are pretty good.

Jeep Alternators https://share.google/aGI1qP8nWiuFrPSjC

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