Strange voltage issue from Alternator

[HSV Listy]

My old alternator was charging and then not but it was a intermittant issue. One minute it would charge then next it stops. I put a new battery in first as it killed the original and installed a new aftermarket alternator.
After fitting the volts were fine for about 1 week sitting about 14.3. Now I have another issue where the volts are rapidly changing for 13 odd to 14 odd. Like really fast flicker (i guess 10 times a second). It is causing the dash lights to flicker and same with the head lights.

The faster I rev the engine the faster this flicker speeds up until it is too fast to see on a meter or the dash lights. It does not exceed 14 odd volts at full revs and at idle it seems to be around 14 but you can see the flicker in a multimeter

This happens stationary and on the move. Last time it took my mechanic 4 hours to change the alternator due to a number of reasons like my 8TB intake and the extra stuff I have in the bay that needs removing.

Any ideas or is there some on vehicle test I can do.

[blnls1]

What model car?? VX SS ,Avalanche V8???

[TommyVTss]

replaced the alternator and battery hmmmmm

its like an intermittent fault to earth,

hows the leed from the alternator to battery look? any shorts?

tom

[vuss383]

As stated what model ....

[ova400]

VX GTS

not to sure what could be doing but hope you get it sorted easily

[mustanger]

I dare say it would be on his VX ...........unless he put the 8 Throttle Bodies on his Avalanche :hide:

[clubbie]

Listy

Check the lead that goes from the alt to the battery. Mine was fritzed. $30 of cable and connectors fixed it when a reco alternator did not. Check that there is no corrosion on the plug in the alt.

Mine had the same symptoms as you described.

The alternator can be stuffed if you have had a powersteer leak and fluid get's in the alt.

Clubbie

[JuJu.Puff]

Definitely sounds like a connection issue. Check your leads +ve and -ve as stated above. Also check any fusible links and fuses in the line as a dirty or loose contact will aslo cause this problem. The fusible links can appear to be fine but they crack at the base where you can't see.

[JuJu.Puff]

Another thing to check is to see if you have anything leaking onto the alternator eg oil or coolant as either of these will get onto the slip ring and brushes and will tear them up.

[HSV Listy]

Sorry it a VX GTS.

Ok cool I will get to the terminals and leads first and go from there. It might be as simple as a loose lead and it does make sence being a new alternator.
I am not aware of any leaks but I did have a track day so I will have a look under there to see if there maybe a PS leak or something. Never even thought about that

Cheers and thanks for the advise.

[HSV Listy]

Chasing my own tail trying to find the problems. Seems to be a number of issues all combining to give a poor earth. Everything is tight and the connection seem good but you move the cables and the voltage flicker gets worse, then better. I am taking it to my mechanics Monday to get a bunch of battery and earth cables replaced and a sort out what is wrong with the battery isolator. The battery isolator switch even seemed to cause issues just by wiggling it.

PITA but hopefully a one day job and get the car sorted. My guess it is issues from running the engine so hot on occasions circuit racing. Not the first time I have had cable issues.

I dare say that is why the old alternator died from a high resistance joint and earth connections. Could explain why I was going through a battery every 12 months too.

[clubbie]

Listy

The main cable going from the alt to the batt degrades over time. Mine had a break about four inches from the alty. Looked ok but did the same thing high/lo/high when you moved it. Did our head in tightening cleaning checking contacts etc.

We decided to run a small cable parallel to the existing one (cost $5) and the problem went away. Then we knew it was the cable so we made a new one and that burnt out in two days (light guage). Went and got the correct guage cable and put the connectors on....no problems since.

Clubbie

[HSV Listy]

Listy

The main cable going from the alt to the batt degrades over time. Mine had a break about four inches from the alty. Looked ok but did the same thing high/lo/high when you moved it. Did our head in tightening cleaning checking contacts etc.

We decided to run a small cable parallel to the existing one (cost $5) and the problem went away. Then we knew it was the cable so we made a new one and that burnt out in two days (light guage). Went and got the correct guage cable and put the connectors on....no problems since.

Clubbie

I will give that a shot today. I have some cable lying around so I will see if it make a difference. By the sound it is a very similar fault.
Cheers

[Desertws6]

Have you tried to check for voltage between battery earth connection to car body and then engine block.

Use a voltmeter with the earth on the battery earth then touch the positive lead to body first and engine block second. (or vise versa)

If the voltage reads "0" the earth connection would be good. If it reads voltage, then a bad connection or dodgy cable.

Just something to examine.

,Steve

[nomad-kr]

Just curious, what would the average voltage reading be at... I start my car (VT LS1) and it reads about 14.2 - 14.3 and then after a bit of driving it is down to 13.7 - 13.9... Is this normal or should I be checking things?

[Desertws6]

Just curious, what would the average voltage reading be at... I start my car (VT LS1) and it reads about 14.2 - 14.3 and then after a bit of driving it is down to 13.7 - 13.9... Is this normal or should I be checking things?

Sounds normal.

Start car - draws from battery
Drive car for a while - What had been taken from battery has now been replaced.

[nomad-kr]

Sounds normal.

Start car - draws from battery
Drive car for a while - What had been taken from battery has now been replaced.

Sweet thanks mate.

I got the alternator replaced a few months ago as it had crapped itself... So was just wondering if this one was doing the job right... :)

Thanks for the answer

[HSV Listy]

While the tread I have not progress. THe alternator is a right pain to get to on my car as there is stuff in the road from above and below. I have the car booked in friday to get another spare battery lead put from the alternator to the battery and a second earth from battery to deck. This will be in addition to what is there now. I will get the battery isolator taken out of circuit just for a quick check too to make sure it is not that. Next week I will give them the car for a couple of days to get this and a couple of other niggling isses properly sorted.

I have a race meet sunday so I can not afford to risk pulling things apart incase there develops more issues they can not fix. If I add stuff then it might make it better atleast.

[HSV Listy]

During the race day on start up the lights on the dash went flickery etc. I checked the headlights and they flikerd too as well as with a multimeter and the volts all over the place
I raced fine and the car went fine all day (other than running low on LPG where it changed back to petrol half way around the track) slight scare that chaging over at 7000rpm just before I changed gear. I just putted the last lap on petrol as it is not worth risking anything running on petrol and such a low tank without a surge tank.

I took the car back after the race meet and more time was spent without success. We decided instead of wasting money chasing this, the battery needs to go to the boot anyway so that was done on the weekend.
The old cables were not in good shape both insuralation and the cable itself presumely running the car around at 130 degree a few times a day racing before the cooling issue was sorted.
So there will be a couple more cables to be changed and the battery isolator is being bypassed to take all possible causes out of the equasion.
Then we will see what happens but hopefully it goes away. If not it will just stay there until another day.
Yes all earths were redone but there is a number of wiring things that need to be fixed as if the heat killed the battery cables most likly caused others.

Tough engines though LS1 that the wiring dies before the engine does running it to the edge of its life numberout times. Well done HSV.

[GMMAD]

have you connected the multi meter to the b+ on the alt?to see if the volts vary or are you just going off the battery?
if so try off the b+ on the alt to see if the volts are varying
if its fine there you know its in the cables some where
maybe try doing some voltage drops on the earth and power cables

connect the multi meter to the body of the car and the other to the battery
on the neg side up to .4 is expectable and .3 on the positive side

[HSV Listy]

have you connected the multi meter to the b+ on the alt?to see if the volts vary or are you just going off the battery?
if so try off the b+ on the alt to see if the volts are varying
if its fine there you know its in the cables some where
maybe try doing some voltage drops on the earth and power cables

connect the multi meter to the body of the car and the other to the battery
on the neg side up to .4 is expectable and .3 on the positive side

We did that and I even lent the mechanic a megger from work to put some current and big volts down the lines. The cables were disconnected one at a time and PCM disconnected too. It does not show up as low resistance at all but there must be some issue in there. Possible a short in the wiring harness that is failing ever so slightly but doubt that as it goes away.

I will know more tomorrow. I have a race meet this weekend so it would be nice to get rid of the issue before then. Surly it must not be good for the electronics and tuning to have this going on. That is what buggered up the final tuning when Oztrack was up here so in theory the GTS is still not properly tuned.
One day but not this year as hidden valley is shud down from the V8 supercars onwards for 6 months.

Plenty of time for some mods.

[GMMAD]

We did that and I even lent the mechanic a megger from work to put some current and big volts down the lines. The cables were disconnected one at a time and PCM disconnected too. It does not show up as low resistance at all but there must be some issue in there. Possible a short in the wiring harness that is failing ever so slightly but doubt that as it goes away.

I will know more tomorrow. I have a race meet this weekend so it would be nice to get rid of the issue before then. Surly it must not be good for the electronics and tuning to have this going on. That is what buggered up the final tuning when Oztrack was up here so in theory the GTS is still not properly tuned.
One day but not this year as hidden valley is shud down from the V8 supercars onwards for 6 months.

Plenty of time for some mods.
cable need to be tested with the engine running
have you checked the L and S wire circuits?
have you load tested the alt?

[HSV Listy]

cable need to be tested with the engine running
have you checked the L and S wire circuits?
have you load tested the alt?

What is the L and S wire
The alternator has been off and tested on a bench and it is fine.

The battey job will be done by tommorrow as nothing is easy on my car as we are avoiding runnign the cables near the gas lines. Not sure if it is nessessary bit for the sake of it why not.

[GMMAD]

the L and S wire are the signal wire and light wire
probably not so much the light wire more the signal wire
the signal wire supplies the amperage to the reg
not shore if the signal wire is controlled by the BCM in these models
(i dont think it is)but that may be something to look at as well
if it isnt supplying the right current your volts/amps can vary
if the alt and battery cable are fine it would have to be this

[HSV Listy]

the L and S wire are the signal wire and light wire
probably not so much the light wire more the signal wire
the signal wire supplies the amperage to the reg
not shore if the signal wire is controlled by the BCM in these models
(i dont think it is)but that may be something to look at as well
if it isnt supplying the right current your volts/amps can vary
if the alt and battery cable are fine it would have to be this

Thanks for that. Dont believe that has been done as yet but I will check

Cheers

[HSV Listy]

Well after the battery was moved and all cables replaced it is much better but still comes back every now and then. I am leaving it for now and put up with it.

Still dont know exactly what is causing it but there must be some loose connection somewhere. Either way I will get to it one day

[HSV Listy]

Well after replacing mains battery, alternator and several other from thealternator, earth etc and replacing the alternator again the voltage flicker is finially gone. Charging and voltage regulator is all nice and smooth
The alternator was under warranty so no cost for another one thankfully.
I guess it was a combination of high resitant joints from so much overheating during races I guess

Either way it has been a number of driving around and all is good.

Most of the work was needed anyway and the battery relocated to the boot to try and get more than 9 months out of each battery.