'15 charger alternator issue

diymirage · Feb 17, 2022

hey guys

i took the wife out for dinner in her new charger today and something odd happened
its about a 10 mile drive to the restaurant and when i left the house there was a slight tic under the hood
way to slow to be engine related but i wasnt sure what it was

about 2 miles into the drive the low battery light came on
i switch the dash over to the voltmeter and it read 11.2
by the time we got to the restaurant it was down to 10.8

i decided not to let it ruin our night and just hoped for the best, so we went in and ate

after dinner i got ready to leave and she fired up just fine, and the voltage was sitting at 10.6
now from here, it got to drop quickly and about halfway there i didnt think id make it home, as one by one the systems started to shut down
when it dropped below 10, i lost traction control (great fun in the 2 inches of fresh snow)

around 9.5 the radio and dash lights went out and i guess by 9 the entire dash and all gauges went dead

then there was a squeak, you know the kind, like a accesory belt slipping
then a squeal and one by one the lights and systems came back on

she squealed for a little while as she crept back up to 14.2 but when i came home she idled at 14.1 volts

now, the entire time, the coolant did not get past 190

so what in the world happened?

i know the belt tensioner was replaced recently but no idea what else
if the belt was slipping, id imagine to see the coolant spike too, right?

my wife took the car to work, so it has sat outside for a while but it didnt freeze hard so i cant believe that has anything to do with it

thoughts?

Killer6 · Feb 17, 2022

A lot of modern alts have an internal clutch at the pulley, sort of like a fan clutch, a possibility...or You have a poor connection/wire somewhere. Worn brushes, etc., any DTC's?
Edit: of course there are/should be, what are they? Lol...

royslead · Feb 17, 2022

I've seen those alternators intermittently have brushes stick, and have issues (if equipped) with the over-running clutches- though I can't remember if your car would have one - I'm thinking it does not. Most likely the brushes were stuck, and when they finally loosened and made contact, the squeal you heard was from the alternator being under load. The loss of sub systems is a completely normal operation, when enough voltage is lost. It is a designed in feature, to conserve as much battery as possible. If it happens again, try knocking the alternator housing with a hammer or rock or similar. The idea is to just jar it enough to dislodge the brushes, not beat the crap out of it. Ideally, though - I would replace the alternator.

Dana67Dart · Feb 17, 2022

Clutch type alternator pulleys look like this at the pulley, a cap of sorts.

If it happens again you could prove it is the issue by backing off the tensioner and seeing if it free wheels in the direction of travel.

Oldmanmopar · Feb 18, 2022

Could a wire be loose . The squealing was the belt slipping because it was charging instead of maintaining the battery. My truck did the same thing . It was one of the smaller wires on the battery cables because the nut was left loose after I had it off. I used my battery in another car and just twisted the battery cable on and never tightened the nut which left a wire loose.