Alternator charging problem

Hello mates.
Today i check my alternator charging and for my surprise see only 13V on idle rpm. That 13V was measured with maximum load on the charging system. I mean i switch on the head light ,air con ,heating for rear window ,sound system and more. Before the winter start i check the systems and everything was fine (on the same load between 14v and 14.3v). So i gees there is something wrong. All off the measurements was made directly on the back side off the alternator to eliminate any bad ground spots etc. There is no difference wen i measured on the battery. The multimeter says exactly the same volts like on the back off the alternator.
On the back off the alternator i see two numbers 037 903 025 F - 0 124 325 011 90A
Can some one help me to find replacement parts number for servicing my alternator. I thing i need a new pulley and new voltage regulator.
Any help will be appreciated.
 
Hello today i pull out the regulator. Here is a photo. Can some one tell me is that the oem number for that regulator BR14-M0 F 00M 145 225?
MID6ByF.jpg
 
Hello today i put new voltage regulator. But the problem is the same. Can someone explain me what are the two thin wires that are on the plug do.
On the blue wire i get + 7,80 volts when the ignition is switched on.
On the white wire i get only reading to ground (i mean the multimeter beeps between chassis ground and that white wire).
Can someone confirm that those two wires are fine?

Also when i start the car in the morning (fist start for the day) with new regulator , its charging 14,2+ volts for 3 4 mins. And after 3 4 mins voltage drops again ?

Any help would be greatly appreciated :)
 
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are you getting any other problems ?

I'm note sure that 13volts is bad, as the battery returns to full charge then the charging voltage should drop
 
On the blue wire i get + 7,80 volts when the ignition is switched on.
On the white wire i get only reading to ground (i mean the multimeter beeps between chassis ground and that white wire).
Can someone confirm that those two wires are fine?

Please can some one check those two wires on working system.
 
Also can someone explain to me the principle of alternator operation for a2 cars.
Does the alternator needs to output all the times 13,8-14,5v or only when the battery needs to be recharge.
I mean if the battery is full and the car no need much current can the charging voltage drops to 12,5 - 12,7v?
 
I had similar symptoms on my previous (petrol) A2 about a year ago. The alternator should always (also with full battery) produce about 14 Volts.
The extra wire is connected to the charging warning light in the instrument cluster.

I solved the problem by replacing the alternator (about € 125, refurbished), a rather simple job taking 1..2 hours.
 
Hello today the alternator was tested on test bench in alternator repair shop.
The gays from the shop says that the alternator is in 100% helt.
So they suggest me to inspect all the wires from alternator to the battery.
Can some one post some diagram or photos from where the wires passes from fron to the back off the A2 ?
 
I am confused (I often am)

You seem to indicate that you are not having any problems from the alternator, you have had it tested and everything is OK, so why would you want to start tracing wiring looking for faults?

There is a very old and wise adage, "If it isn't broken, don't fix it!".

And yes, the alternator output will vary depending on the state of charge of the battery and load it is under.

Steve B
 
Have you replaced the pulley yet?
The symptoms you have described can be caused by the clutch pulley failing. This happened to me. I was not convinced initially and it was only after a bench test (like you) showed no alternater problem that I changed the pulley, problem solved. I did have the added symptom if a noisy pulley though.

Geoff
 
Yes no problem from the alternator.
But on idle rpm it outputs some times under 13volts.


Your battery is 12 volts and so if it is charging at 13V it is adding charge even at idle.

I really don't know what you expect from your alternator, but it is working as it should and has been tested and your battery is not going flat.

Here are a few excerpts from knowledge based web sites

**********Alternator Output Supply and Demand

With all of that in mind, it’s also important to understand that the output of an alternator is tied to the demands of the electrical system in addition to its inherent capabilities and the speed that its input shaft is rotating at any given moment.
In essence, while maximum alternator output is dependent on the rotational speed of the input shaft, the actual output is load-dependent. That basically means that an alternator will never generate more current than is called for by the momentary demands of the electrical system.

***********

Normal Output

  • An alternator should put out between 13.5 and 15 volts of power. The alternator should be tested with the engine idling and electrical accessories, such as the radio and headlights, turned off. A reduced output may be a sign that the alternator is failing, but the drive belt and wiring should be inspected before replacing the alternator


***********

I really think that there is not a problem (unless there is noise from the alternator clutch)


Steve B
 
Hello all again. I guess i need to bump the tread a bit :D
So i have a question about my alternator output terminals connections.
My alternator looks like this lichtmaschine-14v-90a-referenz-nr-081625001-689-2.jpg
And i have a cable connection only for the B1+ that go to the battery.
My question is for what is B2+ ? Do i need to connect B1 and B2 for better output ?
 
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