Mk1 Golf GTi Alternator Query

Hi all,

Mk1 Golf GTi 1.8 DX

Need some assistance please.

Over the past 4 years, I have replaced the battery 3 times.

Most recently after 10 months (not driving regularly) the battery was toast. I managed to get a replacement through warranty.

I have checked for parasitic drain and there is hardly any draw. I know the alarm and the radio use some current, but not enough to destroy the battery.

I tested my alternator and even changed it with another one I have but I get the same results.

With car off, the voltage of battery is 12.5v. When engine started I am getting 13.5v at the battery. When I put on the ancillaries such as headlights, heater motor, spot lights etc, I get a screeching sound from both alternators.

The alternator states 14v on the decal…….should I be getting 14v with the car running?

I check both my other cars and confirm they show 14v running.

Appreciate your help and assistance

Thanks


 

 

Depending on the year, and the AMP.  You can have a 55A alternator that is putting out 14V.

Turn on a few things and that can drop it.
Add Resistive cables and bad grounds…..

I know that when I run my 93 with 90amp  I have 13.85 volts at the alternator.

when I turn on everything that is a/c full use the power windows crank the radio up, and highbeams… I still get 13.85 at the battery.

Relaying the headlights, and changing grounds if needed is a good thing, you can upgrade your alternator and get it to a rebuilder….

The battery should be 12.6v so your 12.5v sound ok.

When charging 13.5 is a little low, nearer14v would be ideal.

Whats the charge rate with everything switched on?

Batteries don't respond well to being flattened, do you use a trickle charger if the cars parked up for more than a month?

Are you using well known brand name batteries or £30 ones from the local under arches parts shop?

Thanks for the feedback.

The standard alternator is the 65 amp.

I also had upgraded to a 90 amp.

With both alternators fitted with new voltage regulators, I am getting 13.75 volts when I measure the voltage from the B+ point and the earth stud of the alternator.

The battery is showing 13.5v when running…..when I put the blower on full, headlights, spot lights, voltage drops to around 12.5v and I hear screeching sounds on both units…..when I turn everything off then it goes back to 13.5v.

I noticed that the blower on full power knocks the voltage to around 12.5v.

Either way, I am not achieving the preferred charge rate of around 14v.

I have relayed the headlights with an upgraded loom kit with relays.

Not using a trickle charger…..I tend to disconnect the battery if parked up long term……I noticed that even if the battery was installed it definitely would go flat in a month.

I checked the continuity of the earth cables and I am getting around 0.1 to 0.3 resistance, which I think is ok.

The battery is Yuasa brand with 5 year warranty. £75 from GSF.  Very good brand as I have on my other cars.

Ref the grounding points, I know there is the alternator to body and the battery to body straps and the alternator to the starter motor to the battery. The blue wire is ok as when I start the car the battery sign illuminates and voltage is around 12.5v and when I tap the throttle the light disappears and the volt meter shows the 13.5v.

Something just doesn't seem right especially the fact I have been through 3 batteries, two being warranty claims. Prior to that the car was off road for 17 years.

I think something could be draining the charging system / battery hard while the engine is running hence I'm getting a low voltage.

When the car is stationary with ignition off (key out) …I tested with a volt meter and confirm fuses 1 to 4 are live showing 12.5v.

BRINZ said

Thanks for the feedback.

The standard alternator is the 65 amp.

I also had upgraded to a 90 amp.

With both alternators fitted with new voltage regulators, I am getting 13.75 volts when I measure the voltage from the B+ point and the earth stud of the alternator.

The battery is showing 13.5v when running…..when I put the blower on full, headlights, spot lights, voltage drops to around 12.5v and I hear screeching sounds on both units…..when I turn everything off then it goes back to 13.5v.

I noticed that the blower on full power knocks the voltage to around 12.5v.

Either way, I am not achieving the preferred charge rate of around 14v.

I have relayed the headlights with an upgraded loom kit with relays.

Not using a trickle charger…..I tend to disconnect the battery if parked up long term……I noticed that even if the battery was installed it definitely would go flat in a month.

I checked the continuity of the earth cables and I am getting around 0.1 to 0.3 resistance, which I think is ok.

The battery is Yuasa brand with 5 year warranty. £75 from GSF.  Very good brand as I have on my other cars.

Ref the grounding points, I know there is the alternator to body and the battery to body straps and the alternator to the starter motor to the battery. The blue wire is ok as when I start the car the battery sign illuminates and voltage is around 12.5v and when I tap the throttle the light disappears and the volt meter shows the 13.5v.

Something just doesn't seem right especially the fact I have been through 3 batteries, two being warranty claims. Prior to that the car was off road for 17 years.

Only points I'd make is that shouldn't be draining within a month. My understanding is that after that they never achieve full capacity again and each flattening get worse.

Test the drain and remove the fuses one by one and see which circuits are drawing power, clean up all the contacts you can find.

Get the battery speced for a Diesel Golf and a CTEK charger

Thanks.

Yes I went for the 60amp Golf Diesel battery which died and I just for the same replacement under warranty.

The drain when everything is off is the clock and radio which isn't much.

I just need to figure out why the voltage drops drastically when the heater fan is on full and when other ancillaries are on…..there shouldn't be such a large drop. Unless something is shorting. I need the fuse for the dash as I need the alternator blue wire circuit to work.

I'm thinking tomorrow I will pull fuses one by one during engine run and see if the voltage increases nearer 14v. I have a suspicion that they could be issue with heater blower.

Will update tomorrow

More than likely you have a burned ground wire in the blower plug.  passenger side of the heater box. high.

Does the fan spin freely if you flick it or is it seizing up causing it to overload the electrics?

So today I ran a few tests…..


Battery before start 12.5v
Running remains at 13.5v
Underload with lights, blower, etc drops below 12.5v

While running, I pulled fuses one by one to confirm if any short circuit but no difference.

So both alternators (90 amp and 65amp) for some reason under load do not charge the battery.

I removed the volt regulator, gave a good clean with sandpaper on the contact areas, and all the earth points (alt to body and battery to body to engine mount).

No difference……it's quite difficult to accept that 2 alternators have exactly the same issue.

Is there any device in the circuit which would send a signal to the alter alternator to crank the voltage up??

Running out of ideas.

Can you please advise what figures you can m are getting when engine is running and when under load with everything on?

Thank you

BRINZ said

So today I ran a few tests…..


Battery before start 12.5v
Running remains at 13.5v
Underload with lights, blower, etc drops below 12.5v

While running, I pulled fuses one by one to confirm if any short circuit but no difference.

So both alternators (90 amp and 65amp) for some reason under load do not charge the battery.

I removed the volt regulator, gave a good clean with sandpaper on the contact areas, and all the earth points (alt to body and battery to body to engine mount).

No difference……it's quite difficult to accept that 2 alternators have exactly the same issue.

Is there any device in the circuit which would send a signal to the alter alternator to crank the voltage up??

Running out of ideas.

Can you please advise what figures you can m are getting when engine is running and when under load with everything on?

Thank you

Put the volt metre directly to the alternator or run a wire directly to the battery see what you get

Sent from my SM-G960F using Tapatalk

BRINZ said

So today I ran a few tests…..


Battery before start 12.5v
Running remains at 13.5v
Underload with lights, blower, etc drops below 12.5v

While running, I pulled fuses one by one to confirm if any short circuit but no difference.

So both alternators (90 amp and 65amp) for some reason under load do not charge the battery.

I removed the volt regulator, gave a good clean with sandpaper on the contact areas, and all the earth points (alt to body and battery to body to engine mount).

No difference……it's quite difficult to accept that 2 alternators have exactly the same issue.

Is there any device in the circuit which would send a signal to the alter alternator to crank the voltage up??

Running out of ideas.

Can you please advise what figures you can m are getting when engine is running and when under load with everything on?

Thank you

Is the thick wire from the alternator B+ terminal to the main starter terminal and then battery +ve all good (not fraid or internally corroded) with shiney tight connections?.

Early-1800 said

BRINZ said

So today I ran a few tests…..


Battery before start 12.5v
Running remains at 13.5v
Underload with lights, blower, etc drops below 12.5v

While running, I pulled fuses one by one to confirm if any short circuit but no difference.

So both alternators (90 amp and 65amp) for some reason under load do not charge the battery.

I removed the volt regulator, gave a good clean with sandpaper on the contact areas, and all the earth points (alt to body and battery to body to engine mount).

No difference……it's quite difficult to accept that 2 alternators have exactly the same issue.

Is there any device in the circuit which would send a signal to the alter alternator to crank the voltage up??

Running out of ideas.

Can you please advise what figures you can m are getting when engine is running and when under load with everything on?

Thank you

Is the thick wire from the alternator B+ terminal to the main starter terminal and then battery +ve all good (not fraid or internally corroded) with shiney tight connections?.

So what is coming from the alternator

Sent from my SM-G960F using Tapatalk

Direct from alternator I am getting 13.75v without ancillaries on. Drops under load.

Took out and cleaned the alternator B+ cable. Still same results.

Does alternator output increase above idle speed?

No it remains steady....either 13.5v on idle or approx 12.5v with ancillaries on.....when I rev the engine no increase in voltage.

Dunno then,  the VDO voltmeters show green (ie good) 12v+ and above so 13.5 is prob OK?

You still have a problem if a new full charged battery is going flat after a months none use

It's ok on idle (13.5v) but the issue is with ancillaries on.

Appreciate if members can advise what volt reading they are getting on idle and when the headlights (main beam and dipped) and heater blower full speed is on.

If you all are getting above 13v, then I could have an issue with both the alternators I have (90amp and 65amp), not charging battery under load.

Just wanted to check with members what readings they are getting before dishing out money to get the alternators checked out.

Thanks.

I'd be tempted to replace the voltage regulator on your 90 amp unit, it should be an easy and relatively cheap swap out. I think you should see around 14-14.2v with no load and a little increase on rpm
What voltage are you getting across the battery with everything switched on, at idle and increased rpm.

It's been a long time since I earned my living on spanners and some things take a while to remember, but I'm sure by 2000rpm the regulator reduces charge generated

Thank you to everyone for their input.

Some positive news today……found 2 issues regarding battery drain and the alternator.

I had a LED bulb installed for the interior light, I didn't realise that it was faulty, didn't light up yet the component was hot. This probably was the cause of the drain. I removed it and replaced it with a normal filament bulb.

Regarding the alternator, I switched on the ancillaries (headlights, blower, rear window heater, spot lights) voltage dropped to 12.3v.

I carried out a resistance test on the cables @ 2000rpm
Battery negative to Alternator body = 0.07v
Battery positive to Alternator B+ = 0.65v

So issue with the B+ cable.

I plugged a jump lead to the B+ point and battery positive and immediately getting 13.06v under load. A jump of 0.76v so definitely issue with the B+ cable.

I would like to replace the cable with a high resistance one which can support high amps. Can anyone recommend best grade cable with the crimped connectors suitable for the alternator and starter motor. Or should I buy the cable separately and crimp them myself.

Thanks.