Is my alternator going bad?

[InnerBlueSkies]

Made a short video. Looking for feedback. I already have a Valeo arriving Friday. I don't know much about cars but one would figure the voltage would go with increase in throttle?

Car has died twice last weak with increased battery discharge warning. Noteworthy is I did a 3500 mile round trip, low RPM to MAX MPG, AC on 50% of time along with Dash Cam and radar. Shortly before this video ran it 10 miles with AC MAX, battery was 100% according to tender. OBD last showed a missing alternator.

[EJT86]

Well the alternator charges the battery. So when your car died how did you recharge the battery before it died again? How old is your battery? Usually when a car dies due to a dead alternator that’s it until it’s replaced.

[4130]

If you're getting a 278d, you need a new alternator. Mine showed no obvious signs other than car not wanting to start when it sat for a while. Otherwise it seemed fine and my voltmeter showed 14V + when running. I kept getting the 278d, so I swapped the alternator myself and the code hasn't come back.

[InnerBlueSkies]

Originally Posted by EJT86

Well the alternator charges the battery. So when your car died how did you recharge the battery before it died again? How old is your battery? Usually when a car dies due to a dead alternator that’s it until it’s replaced.

6 month battery replaced, was able to start with jump, died 10 miles down road, jumped and kept connected for 30 minutes, made it home 83 miles. That night went out and purchased battery tender so your seeing a battery which was fully charge prior to short run into town and back.

[InnerBlueSkies]

Originally Posted by 4130

If you're getting a 278d, you need a new alternator. Mine showed no obvious signs other than car not wanting to start when it sat for a while. Otherwise it seemed fine and my voltmeter showed 14V + when running. I kept getting the 278d, so I swapped the alternator myself and the code hasn't come back.

Thanks

[EJT86]

Originally Posted by InnerBlueSkies

6 month battery replaced, was able to start with jump, died 10 miles down road, jumped and kept connected for 30 minutes, made it home 83 miles. That night went out and purchased battery tender so your seeing a battery which was fully charge prior to short run into town and back.

Yea sounds like you got a bad alternator

[pbonsalb]

Could it be a bad engine ground? On drivers side between oil pan and frame rail at header collector level. Give it a tug.

[happydude]

Had same error code on my brother in laws e90 m3 it turned out the alternator was working but only intermittently. Your video showed it was working at the time you took the video. But I had witness his not working sometimes but working others. I ended up replacing it with a valeo last year and has not had an issue since. And all error codes gone.

[TX]

Check the voltage at the battery with a meter. Car off 12.5+ battery is OK. Anything less than 12V resting is a dead battery.
Car running charging around 13.5 to 14.4 alternator OK. AGM can be slightly lower charge voltages.


Side note, how did you get the voltage displayed in the dash?

if the battery age is approaching 5 years on an AGM, replace.

I had excessive discharge code thrown by a EDC shock controller that didn't shut off after the car was off and ran all night. That was expensive.

[InnerBlueSkies]

Originally Posted by TX

Check the voltage at the battery with a meter. Car off 12.5+ battery is OK. Anything less than 12V resting is a dead battery.
Car running charging around 13.5 to 14.4 alternator OK. AGM can be slightly lower charge voltages.


Side note, how did you get the voltage displayed in the dash?

if the battery age is approaching 5 years on an AGM, replace.

I had excessive discharge code thrown by a EDC shock controller that didn't shut off after the car was off and ran all night. That was expensive.

This is the process. If you encounter an issue, keep trying, didn't work on first shot for me, key is to count up digits, get to lock menu #19, enter in sum of digits (for VIN), should show UNLOCK.

[InnerBlueSkies]

Screenshot on the way to doctors appointment. I wonder how.long I can drive without an alternator 🤣

[pbonsalb]

Till the battery dies. Maybe 30 minutes given the draw of these cars, starting with a 12.6V battery?

[happydude]

Originally Posted by InnerBlueSkies

Screenshot on the way to doctors appointment. I wonder how.long I can drive without an alternator 🤣

Seems like you have same symptoms and codes my brother in law had. Sometimes car would be running for 10 mins before alternator would kick on and decide to start working again. Just replace the alternator you’ll be good. If you haven’t replaced your drive belts yet this would be a good time to do that too.

[ItsGary]

I had to replace my alternator to get rid of the 278D code also. I ordered a Valeo replacement from RockAuto


My car never died but the symptoms I experienced might have been coincidental. My car audio system didn't sound as crisp lack of bass. When I started monitoring the voltage I noticed I'd get more a thump from the bass when it was above 14v or above. Then I finally got the code for alternator missing which wouldn't go away