Alternator Problems?

[DougJones]

Hi everyone,

Over the past few months my ammeter on my Seat Alhambra 130 1.9tdi has started "drifting" from 14v to 14.4v every 4/5 seconds at all engine speeds.

When the engine is cold you can feel the extra load at low speeds.

If the engine is switched off, then on many occasions the fault disappears. Is this a sign that the alternator is on its way out, or that something else is happening that the voltage regulator can't cope with. I have the "home" version of vagcom but no fault codes show up.

Battery was replaced a few months ago.

I have tried switching everything electrical off, and switching everything on ie heated windscreen, seats, lights etc. but this makes no difference to the apparent rise and fall in voltage.

The car is a 53 plate & has just done 45000 miles.

Any suggestions would be most welcome.

Many thanks

Doug Jones

[Bigjeeze]

Hi everyone,

Over the past few months my ammeter on my Seat Alhambra 130 1.9tdi has started "drifting" from 14v to 14.4v every 4/5 seconds at all engine speeds.

When the engine is cold you can feel the extra load at low speeds.

If the engine is switched off, then on many occasions the fault disappears. Is this a sign that the alternator is on its way out, or that something else is happening that the voltage regulator can't cope with. I have the "home" version of vagcom but no fault codes show up.

Battery was replaced a few months ago.

I have tried switching everything electrical off, and switching everything on ie heated windscreen, seats, lights etc. but this makes no difference to the apparent rise and fall in voltage.

The car is a 53 plate & has just done 45000 miles.

Any suggestions would be most welcome.

Many thanks

Doug Jones

 

You'll have to wait for the more knowledgeable on the site but I think it seems quite normal. I don't think that that amount of fluctuation is a problem. What if any other issues or problems do you have? If the alternator is on the way out then surely you would notice other faults. One thing does spring to mind. Check the alternator pulley - that may be starting to sitck. Do a search and you'll see what I mean.

[DougJones]

Many thanks for the reply.

The pulley seems to "freewheel" fine, what seems strange, is the regular rise & fall of voltage, and the fact that most times after switching off the voltage remains stable.

Many times when starting, the voltage remains stable at 14v with no indication of a problem.

[seatkid]

The voltage should be stable and only rise slowly to about 14.3 - 14.4v max when the battery is fully charged. Check the main fuse/power distribution box in the engine bay (in front of the battery) for signing of overheating terminals. Faulty crimps on the main power leads are a common problem and can lead to fuse box melt down (literally) and burnt cables. The fluctuating voltage may be a symptom that a crimp is on its way out. Also check your battery terminals are tight. The battery may be on its way out is another possibility. Edited January 1, 2012 by seatkid

[DougJones]

Many thanks Seatkid, will check out those points in the morning.

[DougJones]

Many thanks Seatkid, will check out those points in the morning.

Checked out these points this morning, distribution/fuse box under the battery cover seems fine. Disconnected the main feed power cable to it & no signs of overheating or corrosion. Reconnected the battery cable as well.

Started up and the problem is still there, starts at 14v and rises to approx 14.4/14.5v then falls back to 14v again after 4/5seconds does the same thing again :rolleyes:

Previously checked the alternator pulley for "freewheeling" and seems fine.

On the unlicensed version of vagcom will alternator faults show up? as when I run a scan no faults appear on my laptop readout.

Any further thoughts would be appreciated.

Edited January 2, 2012 by DougJones

[popeye2755]

Have you put a DVM on the battery to check the "real" voltage when the fault occurs? That would be interesting...

[DougJones]

Thanks for thoughts, was going to try today, but the weather got the better of me.

Will try in the morning to see if I can get a sensible reading.

[DougJones]

Checked the battery voltage this morning with engine running - 14.2v

Went to local garage to get battery & alternator checked, both came up as good. no problems identified, will just keep monitoring the situation to see if anything fails completely.

Many thanks for the suggestions posted, will keep forum up to date if anything drastic happens as it may be a help to others.