VW Golf V 1.9 TDI: Examining Fluctuating Battery Charging Voltage (13.9-14.8V) & Possible Causes

Hello
I noticed such a problem in the car, namely the battery charging voltage of 13.9-14.8v is waving at idle speed. with no receivers turned on, it is similar with turned on, but the upper limit is up to 14.7v
Previously, it was perfect 14.5v with the lights off and 14.4v on.
What could it be?
Regulator or rectifier, or how to check it.

The regulator fell valeo or bosch?

now I measured and the voltage at idle without receivers fluctuates in the range of 14.1-14.35v
Altek is a bosch 140A

What made you interested in voltage fluctuations? Are there any symptoms of this hesitation?
Measure the voltage with another meter. Where do you measure this voltage? Battery or alternator?

You write that it used to be perfect? When was it?
Have you checked how with the voltages on a cold and hot alternator? Do you measure right after firing? How is the battery in? Did it manage in the cold?

He just checks the condition of the car every now and then so that it is always operational.
Voltage measured on the battery.
And the battery is new, it is only two weeks old, and the old one was the same. At -25 tdi he fired without any problem, the battery also falls off.
It makes no difference whether it's cold or warm.

patryk44gks wrote:

voltage at idle speed without receivers varies in the range of 14.1-14.35v

Then measure the current drawn from the alternator. This is the basis of anything.

Probably the problem lies with the voltage regulator, or in addition to irregular voltage, you do not have a kind of flashing lights at low speed, such as diodes, but replace the entire bridge, do not replace a single diode, because the weaker ones will sit down soon

Candle lights do not flicker well.
And will I say a 20A meter is enough to measure the alternator current?
I also have a module for heating candles for PLN 140 for replacement. I will replace the refularor immediately, but it's for the next month.

patryk44gks wrote:

And will I say a 20A meter is enough to measure the alternator current?

No, expect a consumption of 20A, 50A and 114A. It depends.

when it comes to GOLFA 5 WITH THIS engine you have an alternator that he gives you
14 V 140 A with a meter up to 20 A you will not succeed, the wires in the meter will heat up after a while as if they were to melt if it is a meter from a supermarket, they are not accurate if you do not have pulsating lights at idle speed, the meter indicates you wrong. Do the following on the turned off engine, see the battery if the voltage is flashing, if not, it means that the meter is ok then start the engine, see what voltage you have on the alternator and what is the difference on the battery, how is the difference, is the weight on the engine as there is no difference, and the alternator is still pulsating with voltage diodes replace the entire bridge see what condition the brushes are probably working unevenly clean the commutator and possibly replace the voltage regulator it is together with the brushes if there is still voltage fluctuation after this treatment, you will probably have to replace the alternator sometimes regeneration will do nothing but new

I have a meter in working order for PLN 70, and I also have a second car and the tension is not waving there.
Just measure the tension directly on the alternator. And tomorrow I will disassemble and cause something to help, and how not to replace the regulator or the rectifier system first?

If you unscrew the regulator and find that the brushes are worn and the brushes work unevenly, press them and check whether they slide out smoothly or are even, because maybe the spring was pressing unevenly, then after finding out the wear of the brushes, the first regulator and at higher revolutions there is also voltage ripple

I just measured the voltage coming directly from the alternator and it is the same.
And the voltage fluctuates in the range of 14.2-14-45v regardless of whether it turns on all the lights. For now, I guess I'll see what happens. But it seems to me just like you wrote that it is brushes, i.e. together with the regulator, and it should be calm.
Tomorrow I am replacing the glow plug heating module, and this regulator will control the voltage every now and then, but it will also be replaced soon.