You are making the simple, very very complicated. Forget the ripple, forget checking dfm whatever that is. For the last time, connect it all up, start the engine and check the alternator can keep 14.3±0.2 volts at the battery terminals when you load it up.

 

35 minutes ago, xman said:

You are making the simple, very very complicated. Forget the ripple, forget checking dfm whatever that is. For the last time, connect it all up, start the engine and check the alternator can keep 14.3±0.2 volts at the battery terminals when you load it up.

 

@xman Just did what you said and I was wrong about the AC ripple cause the meter which i was using was a cheap $10 meter which shows AC readings in a battery even if u connect that to a DC battery. (Ive learned it the hard way by turning off the car and still the meter showing AC reading from my battery).

Coming to the readings the battery was 12.47V when the car is off.

13.4 when the car is running (Ie alternator is working) 

Ive tried to rev it upto 2000rpm it never reached 14V. What may be your guesses? Will post the reading pics shortly.

Is it very hot where you are? In that case 13.4 volts may be ok.

 

https://www.aa1car.com/library/charging_checks.htm

 

How sure your $10 meter is accurate, you already said it doesnt measure ac correctly, so chances are its rubbish at dc too.

DFM is a  (PWM) signal from the alternator which tells the engine ECU how much electrical load is on the alternator output, as a percentage of what it can supply at that rpm. 

Can be ignored in this investigation.

The other thin wire to the alternator is the exciter connection, which supplies current to the rotor winding to help the alternator start up. After it has started to generate current, it uses its own output to supply this. It will typically read one diode drop less than the terminal 15 (ignition 12V) voltage.

Again, as the alternator does seem to be starting up, probably not relevant.

 

25 minutes ago, xman said:

Is it very hot where you are? In that case 13.4 volts may be ok.

 

https://www.aa1car.com/library/charging_checks.htm

 

How sure your $10 meter is accurate, you already said it doesnt measure ac correctly, so chances are its rubbish at dc too.

Yeah it is 28Celcius here in south india which i would say a nice weather it gets too hot than this upto 35 in sunny days. But the link says that it shouldbe 13.9V least but in may case the output is 13.4V Just one volt higher than battery voltage is it acceptable?

 

Regarding the meter it reads 12.47V while its not running maybe it’s reading little higher say 0.5V  Variation(Not sure) just guessingv it may be still reading a 13V which is 1V higher than battery voltage. So it just gives us a rough data.

EDIT:Just tested the multimeter with apple usb charger it reads 5.07 volts so I think there wont be much of reading eroor i think.

 

Im totally confused. :(

Edited 8 October, 20187 yr by Vigneshwaran
Removed unneeded quote and added my climate info

@xman  @Wino 

Guys Today morning ive tested the voltage reading from the Bluetooth ODB adapter with Android phone.

I inserted the adapter And turned on the ignition and using the torque app the voltage reading was as follows.

At moring before starting :12.4V

After starting the car :13.5V~ 13.6V(Max) even revving upto 2500RPM. 

While riding the car I’ve kept my phone in phone holder with the torque app runnning to know the values.

When I turned on the music system it drop 0.1V ie(13.5v).

When i turned on AC it dropped 0.4V  ie(13.0V~13.3) I suspect the AC clutch(Electromagnetic clutch) which must be drawing some current.

If i turn on headlights(25w*2 =50w Retrofitted led h4 bulb) it looses about 0.2v ie(13.3V~ 13.4V).

So if turn  them on all together (AC/Stereo/Healamp) the voltage drops even lower to 12.8V. 

So it could be a Sign of weak alternator or a weak battery?(Ive recently upgraded the battery 65Ah Amaron) 

 

I think your alternator has a failed diode. This would explain the low output and also the sparking when reconnecting the output wire with engine off.

 

Please confirm that you did try this disconnect/reconnect of the alternator output cable with engine not running and still saw sparking?

1 hour ago, Wino said:

I think your alternator has a failed diode. This would explain the low output and also the sparking when reconnecting the output wire with engine off.

 

Please confirm that you did try this disconnect/reconnect of the alternator output cable with engine not running and still saw sparking?

Yes @Wino I checked for the spark while the car/Alternator is not running and saw a little spark. 

Can you guys help me with finding the part number of fabia Alternator rectifier and voltagevregulator? Or should i change the whole alternator?

 

2 hours ago, Wino said:

I think your alternator has a failed diode. This would explain the low output and also the sparking when reconnecting the output wire with engine off.

 

 

^^^ Agreed

 

There's so many different alternators and part no's fitted, try 7zap.com

 

Edited 9 October, 20187 yr by xman

53 minutes ago, Vigneshwaran said:

Can you guys help me with finding the part number of fabia Alternator rectifier and voltagevregulator? Or should i change the whole alternator?

 

I'm fairly sure there isn't a removable 'rectifier' module, the diodes are soldered into the main structure of the alternator during manufacture.

So iff I'm right about a diode having failed, it's either a specialist alternator repair workshop, or a replacement alternator.

The voltage regulator is combined with the brushpack on these and that is reasonably easy to remove and replace. They aren't very cheap, but cheaper than a new alternator.

Is it a Valeo or Bosch alternator, or another brand?

A quick look on 7-zap.com confirms rectifier is not a replaceable module, only voltage regulator. So you need a new or refurbished alternator. Part no and rating is usually printed on the plastic rear cover.

12 minutes ago, Wino said:

 

I'm fairly sure there isn't a removable 'rectifier' module, the diodes are soldered into the main structure of the alternator during manufacture.

So iff I'm right about a diode having failed, it's either a specialist alternator repair workshop, or a replacement alternator.

The voltage regulator is combined with the brushpack on these and that is reasonably easy to remove and replace. They aren't very cheap, but cheaper than a new alternator.

Is it a Valeo or Bosch alternator, or another brand?

 

Ok then i will replace the alternator. Not sure about the manufacture @Wino will check and update.

 

5 minutes ago, xman said:

A quick look on 7-zap.com confirms rectifier is not a replaceable module, only voltage regulator. So you need a new or refurbished alternator. Part no and rating is usually printed on the plastic rear cover.

Okay I am going with a new alternator.  

The people from the local service centre asking 5000Rupees(80$) for an alternator with exchange of my old alternator.

Not sure whether its an refurbished or new one. 

Will visit them on evening and update you both guys.

Thanks a lot for your inputs. It did really helped.

THE REAL PROBLEM AND SOLUTION:

Okay now after a while( yeah its too late) but thought this would bring out how we will miss out very basic things.

The big cable( maybe 2 or 4awg ) which sends the 12v power generated from the alternator to was  broken in the middle poorly connected replacing the cable with other cable fixed the issue. Actually there was no parasitic drain. Since we use headlight and all lights and ac it draws more power from batter than what the alternator can put(Due to the resistance in the broken and improperly twisted connected cable) so it looked like it was draining in the night and didn’t start at the morning. Now it makes sense why the car was stopped and power steering and everything else was cutoff twice.