Car alternator or voltage regulator?!

[RustyHill]

Hey all,

 

2009/2010 Skoda VRS MK2 FL 120000 miles petrol

Hoping someone can sanity check me;

Driving earlier today the AC was on full blast for 10min with no issues, then the fan speed dropped to 2/3^rd in output and on the display, 5 min later it dropped to ½ , 5min later 1/3^rd then finally off. Stopped for 20min and turned back on, AC came on no issues but started to drop again as I got near home. No warning on dash or anything.

At the same time the dash cam was coming on and off. It’s been doing this more and more recently.

 

So I’ve done a few checks and these are the results;

Tested battery voltage turned off             = 12.15v

Tested battery voltage turned running     = 12.37v

Gave it a good rev, back at idle                  = 12.70v

Under high load, full beams and full AC = 11.90V

 

 

I’m thinking it’s the alternator purely on the running idle voltage, however a friend said it was possibly the voltage regulator.

 

Anyone have an idea how to check regulator vs alternator? It’s not had a new alternator or regulator before but the battery is only 1.5 years old.

 

Or any other thoughts?

 

Cheers

 

Rusty

[TheClient]

They're usually in the alternator aren't now they?. I think you need a new or exchange alternator. 

[RustyHill]

Thanks TheClient, I hadn't even thought of that / looked into that but yes it would appear you are correct after a quick google!

 

Well that makes it easier, I'll swap the alternator and in the process be changing the regulator too!

 

Rusty

[J.R.]

The regulator and brush pack can usually be removed and replaced if the aftermarket has started manufacturing them, a hell of a lot cheaper than a new alternator and on many vehicles a lot easier to fit, on my MK1 Octavia it could be done from above (just) without removing the alternator and power steering pump involving grovelling underneath.

 

For an 09 vehicle I would be confident that the regulator/brush pack will be available.

[RustyHill]

I've had a look around and can find a few rebuild kits and tutorials, however this car is the work horse of the house, so I'm going to buy a new one to save time and any other issues popping up while rebuilding.

 

Depending on the condition of the case I may rebuild and sell on or keep as a backup in the future.

 

Cheers.

 

[J.R.]

In the situation that I was, away from my home workshop and my decent tools, trolley jack etc replacing only the regulator pack from above definitely saved me time and aggravation but were I fully equipped and working inside it would have been no great shakes for me to remove and replace the alternator.

 

As it was when the warning light came on on the A20 going to Dover I had to make a decision, carry on with my journey or return, I chose the former and reduced the electrical load to the minimum and did a further 140 miles and a couple of non avoidable starts at the customs shed and on the ferry.

 

Working from above I was able to remove the regulator pack and tease a bit more wear out of the brushes while waiting for the new one to be delivered, then and now in France you simply cannot buy most repair items.

 

I think you have nothing to lose by removing the regulator pack and you may even find and resolve the problem, a dodgy connector or sticking brushes, the rest of the unit is likely to go on for ever which you definitely cannot say about an aftermarket replacement unit.

 

 

Edited 9 July, 2022 by J.R.

[RustyHill]

Not going to lie J.R only just seen you reply!

I got a garage to swap it for me in the end. I could have done as you said above, and 5 years ago I would have, but in the end I just didn't have time/ could not be bothered to mess around! 

 

On the upside, the car has is charging at idle, the AC works full time and the dash cam isn't turning off randomly. The very slight mis fire i had at startup idle has also gone which when thinking about it does make sense so overall i know it cost more but it's worth it for peace of mind.

 

Will swap and sell on the old one though as the case just needs a wire brush, a bit of blasting and protection put on to fight another day, plus new parts obviously.

 

Rusty

[RustyHill]

Evening all, sorry to bump an old post but it turns out I haven't fixed the power issues after all 😞 and am a little lost on where to look.

 

So the car has been happier with a new alternator but I'm still having power issues, I thought maybe where the alternator was dieing it had damaged the newish battery so bought yet another but the problems continue. 

 

So a bit of a catchup;

It's had a new alternator (last 5 months) and new battery (1 month ago) but it's continuing to shut down systems while I'm driving.

 

Last night we were on a long drive ( 2 hours+ 80 miles) The car started fine, no battery lights or the audio warning of low battery. Drove for 1.5H with headlights on and then the dash cam turned off and wouldn't turn on again. A few min later the AC turned down from half blower strength to quarter then down to fully off and wouldn't turn on again. We got home with no dashcam or AC/heater etc on but headlights still working fine. I dumped the car as couldn't be bothered to look at it last night.

This morning dashcam turns on fine, AC and blower go all the way to full power and stay on with the headlights and everything else still on, I didn't charge it over night or anything!

 

I feel like it's not a battery drain issue while turned off as this morning it seems to once again have plenty of power but last night not enough, it's like there is a huge draw on the battery/alternator after a while and the car is turning stuff off to save power but once reset after a few hours it's all normal.

 

Does anyone have any suggestions on what to check?

 

I'll do a current draw test when I have a bit more time as per this guide below. The charge voltage at idle is 13. 57V and drops to 12.95v when idling with headlights, AC and blower on. 

 

 

 

 

One other thought someone at work said was a Power management relay failing.... anyone know where this is and how to test it? 

 

Cheers once again all

 

Rusty

[J.R.]

58 minutes ago, RustyHill said:

someone at work said was a Power management relay failing.... anyone know where this is? 

In his imagination!

[RustyHill]

1 hour ago, J.R. said:

In his imagination!

Ha I'll take that as a very unlikely possibility then!  Oh well something to cross off the list

[SuperbTWM]

Have you monitored the voltage while these strange things are happenning?

[raf300]

I am no expert as I have been researching alternator issues. 
 

what happen checking the ground wire of alternator and that sort of thing? 
I would expect garage May have checked it but worth asking maybe. 
 

Others on forum may know more. 
 

[Breezy_Pete]

If you can get sufficient access without risk of shorting, try measuring charging voltage right at the alternator; positive probe on output stud, negative probe on alternator body. I'm thinking your 'at idle' numbers for charge voltage are very low (do those numbers rise much if you rev to say 2000rpm?). On a car without start/stop I would expect to see nearer 14.5V unloaded, and not dipping much with the loads mentioned.

Testing at the alternator may reveal bad connections/cables if the numbers are much higher there. 

[RustyHill]

21 hours ago, SuperbTWM said:

Have you monitored the voltage while these strange things are happenning?

 No I haven't to be honest, I will next time the issue crops up. 

 

11 hours ago, raf300 said:

I am no expert as I have been researching alternator issues. 
 

what happen checking the ground wire of alternator and that sort of thing? 
I would expect garage May have checked it but worth asking maybe. 
 

Others on forum may know more. 
 

As you say I would hope that the garage would have cleaned up the earth and all connections however I will find time to get in and check them. If they are corroded that could explain the dropping power. Especially if they are over heating over time.

 

11 hours ago, Breezy_Pete said:

If you can get sufficient access without risk of shorting, try measuring charging voltage right at the alternator; positive probe on output stud, negative probe on alternator body. I'm thinking your 'at idle' numbers for charge voltage are very low (do those numbers rise much if you rev to say 2000rpm?). On a car without start/stop I would expect to see nearer 14.5V unloaded, and not dipping much with the loads mentioned.

Testing at the alternator may reveal bad connections/cables if the numbers are much higher there. 

Yes I agree the charging voltage is low, it wasn't when first installed but does seem to have dropped a lot. I've not tested 2k RMP charging since the new alternator. I do find it strange that even at motorway speeds/revs (3K ish) though it seems to be dropping even then which does tie into a bad connection. I have a logging multimeter somewhere so I may hock that up across the battery and see what it is there during a run then find a way to secure it carefully around the alternator and record it there on a run too.

 

 

Thanks all it's given me a few other thoughts, unfortunately I'm away till Friday so can't test any of these now, but the Mrs has been using it all day today and has reported no issues at all.   

 

[RustyHill]

So a quick update,

 

I went for a long drive with a basic logger attached to the battery, started off charging at 12.9v from the off, within 30min it had dropped to 12.2v, then things started turning off with it reading 11.9v.

 

I checked connections and earth and all good. Between neutral on the battery and the alternator case is 2 Ohms resistance, between positive battery and positive output of the alternator was floating between 200 Ohm and 500 Ohm but I'm guessing that is normal with capacitors, switches and what not in the way. 

 

I've totally forgotten to do the direct voltage output of the alternator when the issues are showing but when it's running 'fine' it is putting out 13.2V which to me says the alternator is dodgey and it's just coincidence that 2 alternators in a row have been bad... 

 

I've contacted the garage that did it again and they are having the car back to investigate

 

Rusty

Edited 24 November, 2022 by RustyHill
Spelling

[RustyHill]

A final (hopefully) update.

 

Garage found a very corroded earth point on the started motor which when they cleaned it up seemed to solve the charging issue. I have no idea why this would cause the charge voltage to drop as i can't see it being used once running.... however it seems to have worked so I'm not going to complain. 

 

Anyway while driving with everything I can find to turn on I still have 14.1v so I am very happy to say the least! 

 

Moral of the story, before I start looking at ECU's, alternators etc check the basics better; check the earth points of things that don't even seem like they could be causing issues!

[J.R.]

Does the starter motor have an individual earthing lead? My memory (which is fallible) is telling me no but the main battery cable and alternator cable are connected there.

 

I'm sure someone will either confirm or correct me.

[Breezy_Pete]

32 minutes ago, RustyHill said:

I have no idea why this would cause the charge voltage to drop as i can't see it being used once running

I'd expect that to be the main engine-to-chassis earth connection, so highly relevant.  Localised to starter body area for minimum resistance when cranking.

Edited 6 December, 2022 by Breezy_Pete
sp

[RustyHill]

On 06/12/2022 at 11:50, Breezy_Pete said:

I'd expect that to be the main engine-to-chassis earth connection, so highly relevant.  Localized to starter body area for minimum resistance when cranking.

Ah well that will be it then! Makes far more sense!

 

Thanks again everyone