Lucky

For about two years now my 08 I noticed that when coming to a stop the alternator stops charging for a sec. It go's to about 12 volts Then jumps back up to 14.7.

You can see the head light dim down and hear the change in the blower motor.

Lately it has been doing it more often some times it's stops charging for about 3 sec. Then returns.

Today I decided to investigate some and tested the battery and alt. also checking wiring and connections.

When testing the alternator output I have 14.7. If I load the engine down a little with the clutch I can get it to act up for a sec or two.

I ended up with a strange result. At idle it will charge at 14.6 if I unplug the voltage regulator from the alternator the voltage will only drop to 13.5 and remain there until I shut the engine off. With the engine off the voltage will read battery voltage. About 12.3

Now I am a bit sleep depraved lately but I'm thinking that my alternator may have an internal short keeping the field energized.

Any other thoughts. This would be the first alternator that I have come across that would charge with the field wiring unplugged.

843de

Hmm...scratches head, eats another Christmas cookie. Going from memory dating back to the days at the Firestone store where we actually worked on alternators.

What is happening could he one of several things.

Either one brush insulator is broken, and/or one brush is shorting to ground, or the field itself could be shorted to the frame internally.

A continuity check might narrow things down.

Oldblue

I Think a bench test at AZ or your other local parts store is in order to verify this. Sounds like time for a new alternator!

hhr11

I would test that alternator as Old Blue says.
In the old days I remember pulling the battery cable off alternator equipped cars and the cars kept on running due to the alternator being self excited.

Oldblue

That worked prior to all the computer control equipment added to new cars, never remove the positive cable first running or not as you may touch the ground or the grounded bodywork and blow the battery or more expensive computers

Lucky

Yep I going to do some more testing as soon as I get a chance. I will keep you guys updated.

843de

Thanks Lucky, you know these mysteries that never get updated just drive us nuts, and for some of us...getting to "nuts" doesn't even require shifting out of Park.

donbrew

Where did you find a voltage regulator?

Accidentally open the hood on the 71 Plymouth parked next to the HHR?
I know you meant the control connector.

Lucky

There two alternators that can be on the hhr. A Bosch from 06 to 07 and a valeo 08 to 11. Both of them have a. Internal regulator.

The internal regulator controls output voltage but also responds to commands from the PCM to increase or decrease voltage output as needed.

843de

Now if Lucky was in the Christmas spirit, he'd have changed the Ballast Resistor on that Plymouth and left a tag on it "From Santa".

Anyone who had a Chrysler/Dodge/Plymouth of a certain vintage, always kept a spare Ballast Resistor in the glove box, because when they failed...you weren't goin' nowhere.