Charging problem

[Superflan]

Hi,

I've been looking at fixing a charging problem on a Renault Grand Scenic III, R9M engine (1.6l 130hp).

Happened suddenly the car would display that there's a battery charging system problem, and my voltmeter would read something along 12.6V on the battery posts (and on the OBD connector). Starting the car after a night to bring it home made the charging problem disappear, until I give the engine a slightly faster acceleration and then it went bad. The day after, swapped the battery with a fully charged and brand new one. Idling cold, the alternator supplied 14V for 15 minutes and then the charging failure went on when I moved the car.

I checked and cleaned all the wires and connectors but nothing changed, I'm thinking of a bad overrun alternator pulley or a bad alternator. So I've got a couple questions for the BITOG crew

1- I wasn't confident jamming a tool through the alternator to try to move the rotor by pushing on the ventilator blades. I removed the belt and turned the OAP in both directions. One direction seems to lock and drive the alternator, and stops when I brake the pulley. The other direction... drives the alternator, and when I stop the pulley I can hear and feel the rotor continue to move for approx 0.5 seconds. Is this the wanted freewheeling move, or should it simply freewheel in one direction and not the other?

2- A remplacement "OE quality" (we know it's not OE quality) alternator is 300 bucks, OAP included. If the pulley isn't at cause, or even if it is, should we just replace this 130000km alternator because the wiring is looking cooked ? See pic attached.

3- Could someone give me the mental power to extract the alternator from there :

 

[Rand]

brushes worn out in alternator?

 

[Trav]

This should help you out.

https://www.gatestechzone.com/en/problem-diagnosis/accessory-drive-system/oap-function-tests

 

[Superflan]

brushes worn out in alternator?

Maybe, but brushes worn out usually make contact after a good rev ? I'm looking at extracting the alternator from the engine bay and slap another known-good used one, or a new equivalent one for 300 bucks. Replacing the OAP alone is more than 100 bucks. Given the coloration of the copper wires, I don't know if it's a good thing to do a one third value repair on this ?

This should help you out.

https://www.gatestechzone.com/en/problem-diagnosis/accessory-drive-system/oap-function-tests

Oh great thanks ! I learned something ; it wasn't clear as this on others manufacturers videos.

 

[Rand]

That is a nice writeup. Havent had to deal with that yet personally.

 

[Cujet]

It would be interesting to determine if the alternator is spinning as quickly as it should when charging fails.

 

[Superflan]

Y

It would be interesting to determine if the alternator is spinning as quickly as it should when charging fails.

Yes, I thought about it. To do this would require a small prop inserted in the central part of the pulley and a laser tachometer, I'll put the later one in my wish list

 

[ripcord]

Is your battery running down? Late model cars have ECU controlled charging circuits and use different charging strategies that try to minimize the power consumed by the alternator to maximize fuel economy. Many new cars will not push a constant 13.8 to 14.2 volts maintainance charge into the battery while you are driving like we are used to seeing. It will vary as the ECU determines what the battery needs to maintain it's charge.

Your car may be charging exactly the way it's engineered to. Try to verify before throwing $$$ at it.

 

[Superflan]

Is your battery running down? Late model cars have ECU controlled charging circuits and use different charging strategies that try to minimize the power consumed by the alternator to maximize fuel economy. Many new cars will not push a constant 13.8 to 14.2 volts maintainance charge into the battery while you are driving like we are used to seeing. It will vary as the ECU determines what the battery needs to maintain it's charge.

Your car may be charging exactly the way it's engineered to. Try to verify before throwing $$$ at it.

Yes, battery will discharge continuously when the alert appears. I've experienced it when it happened while driving and I had to get to destination with way below 12V left.

 

[el Nuke]

Are there any charging system related DTCs stored in the PCM? I’m thinking specifically of over-voltage or under-voltage codes that would indicate something happens and is recognized by the computer as being an adverse event.

Did you verify the B+ connection on the wiring harness that plugs into back of alternator is corrosion free and not losing connection intermittently?

I had a year-long charging system issue that was very random and seemed to go away after every major part replacement, only to return months later. The dealership kept it several weeks and couldn’t identify the (real) problem, opting to throw parts at it instead.

In the end, it turned out the B+ plug’s wires were corroded enough to lose connection sometimes and trigger the charging system errors. It wasn’t bad enough to do it all the time though, just every once in a while.

 

[Superflan]

Are there any charging system related DTCs stored in the PCM? I’m thinking specifically of over-voltage or under-voltage codes that would indicate something happens and is recognized by the computer as being an adverse event.

Did you verify the B+ connection on the wiring harness that plugs into back of alternator is corrosion free and not losing connection intermittently?

Finally got into reading DTC using the proper manufacturer scantool.

9210 - alternator
920F - voltage regulation

Since then I removed the alternator from the vehicle. All the sides of the stator have the burnt coloration that I posted earlier, and the B+ post and wire were clean. The pulley seems to be bad (hard overrunning direction and friction) too. The ground on the mounting points could have been faulty but I doubt it.

I decided to throw a new alternator at it and see what happens.

Pics.

 

[Cujet]

Any updates?

 

[Superflan]

Any updates?

Haha I felt asleep when writing the update post yesterday.

After replacing the alternator, the problem is fixed
Now after a couple hundred of kilometres, there's new noises like a slightly loose bearing (remanufactured alternator? Pulleys?) Or timing chain but I'll address this later after a couple short oil changes because this engine has been running low on oil (and too long on OCI) and makes a dry lifter noise a couple seconds on startup