Alternator Query

Hi All,

Appreciate some advice please.

So my GTi (1.8 DX tin top) has inner spot lights fitted, I'm addition I installed new Hella 450 aftermarket front fog lights (55 watts each)

My concern is the load on the alternator. My current alternator is a standard 65 amps.

Let's say, in a very rare occurrence, I have the headlights, spot lights (inner and outer), Hella fog lights, heater, heated screen at back and radio on, then the voltage on my gauges drops to 12volts. With everything off, and only dipped beam and full beam or dipped beam and fogs it's around 13.5v.

Do you thing I should install a 90amp alternator?

Would an Audi 80, 90amp alternator fit my GTi (DX) or is there an alternative.

Appreciate your help.

Thank you.

Well the Cabriolet uses a 90amp, mine does, and you can buy rebuilt ones that are 120A.

Installing the fogs is a good thing, but the better thing is to relay the Headlights, and fogs to the battery direct.
You will use the headlight socket on one side to pick your relays, this off loads the current off the headlight switch shortens the run of wire increasing your  headlights and fogs by as much as 1 1/2 to 2 volts.

Your voltmeter in the car will barely dip.
Here is a kit that I used recently, cheap and easily installed.

https://www.ebay.com/itm/H4-Headlight-Relay-Wire-Wiring-Harness-2-Headlamp-Light-Bulb-Socket-Plug-Kit-12V/272458512251?epid=2076012739&hash=item3f6fcaf77b:g:pzEAAOSwB09YM746&vxp=mtr

You would relay your highs and lows….

Hi Briano,
Thanks for your input.
I forgot to mention, I have installed the head light / spot light upgrade kit which runs off the battery through relays and fuses. No doubt the lights are much brighter.
In the pic above I'm showing all lights in operation with engine running, but when I turn on heater in full, radio, rear window heater, rear fogs, the voltage drops to around 12.3v.
Will the Golf Cab 90amp alternator fit my DX Engine?
Can you please advise the part number?
Thanks mate, your always a help.

yes/no,

If your battery light isn't on, then everything is working correctly and you are slightly charging the battery.

With all the stuff you have on, you are adding or demanding more current or load to the circuits, so Ammeters are the better gauge of what is going on than a Voltmeter, butttt Voltmeters are more cost effective (cheaper) to install for the OEM or aftermarket. Ammeters have to run in series and that is a big hunky wire to run to the console and back to the battery….Also a bigger cabin fire hazard .

The upgraded Alternator will produce more amperage, and therefore give you more juice or higher voltage readings with all your stuff on.

Butttttttt in reality if your battery light isn't glowing, then you are still charging your battery just not as much, I would suspect that when your battery is marginal with all the stuff running, and you turn on your 4-Ways then I have seen a battery light flicker on the flash…..

Make sure that you have great grounds, Battery to frame and Frame to engine… as you can gain quite a lot of current flow,,, and I have seen as much as a volt added.

On one of my cars, I had 12.5V running…..
After I replaced my grounds  Battery to frame and frame to engine I had 13.75V.

I have seen folks wonder why after installing a gigawatt sub amp, and large woofers they run out of battery when they turn on the lights.
and the car slowly dims then dies…..because they were under powering the car with a 65 amp alternator.  Running a 90 or 120A alt cleared the issues up…



 

The battery light only lights when I start, when I tap the throttle it goes away. When everything is on, the battery light does not show so I guess that's a positive.

Ref the cabriolet 90amp Alternator, if I was to get hold of one, would I need to do mods to fit it.

How about a MK2 GTi 90amp alternator?

Just looking at options.

Thanks

Depends.

They made 2 styles of alternators (generally).

Those with plugs (Motorola style), and ones with 2 studs (Bosch).

The mk2 is along the lines of my 92 Cabriolet I believe and should have the 2 studs although I have heard of some mk2 golfs with the plugs. I don't know if the plugs are compatible, so you may need a newer style plug.

You can convert from Motorola Style to Bosch
by cutting the plug off, and attaching the 2 red wires to a large ring connector and the blue or black wire to a ring connector on the small stud that is in the same phenolic (plastic) bracket.

I actually think you are ok on the 65, until you put in the jigawatt sub.

It's not very often you will everything on for a long time, even high beam lights need to be dipped when a car comes the other way, rear heated windows only on for 5 mins or so…. if the battery light is not showing/glowing and you have a good quality car battery and not doing lots of short journeys with every thing on the standard alternator will be fine.
Is your car a daily drive?

Hi,

The connectors to my alternator are rings as the pic shows.

The car is not my daily drive yet as I need to get MOT etc. It will be back on the road after 17 years. A lot of work put into it. Just complete spray job left.

I found the earth from alternator to body is half broken as pic shows. I have ordered a new 35mm2 cable. This may also have an effect of the performance I think. The other earth from battery all looks good

Hi, I've been told you can fit a 90 amp alternator in place of the 65 amp without any alterations to wiring. Obviously if you get a replacement with the correct terminals. Kev

greavsy said

Hi, I've been told you can fit a 90 amp alternator in place of the 65 amp without any alterations to wiring. Obviously if you get a replacement with the correct terminals. Kev

Yep that is the same as the Cabriolet's and 90 is a good alternator.  I would caution you that  you will need to take your pulley off before leaving the store, and have it tested first. Some of the newer replacement alternators
don't have the pulley on it or the improper pulley for the alternator…

The power lead needs work or replacing.
Your grounds should run from the alternator case nut to the engine /alternator adjuster or block.

If you don't know how to change it out easily, there is a how-to in the archive how to's under Briano1234.

Thanks for the input.

I can get hold of a 90 amp Bosch 068 903 029 K

Is this the same part number as the Mk1 Cab?

should be, just look it up on your local car parts vendor.
Be sure that you have it tested prior to leaving the store, and the pulley.

So I finally got hold of a new ground cable, excellent deal on eBay for £7 and also sourced a 90A alternator and must say it's worth every penny! With the lights and accessories on it drops the lowest to around 13v with is great. Turn everything off and it shoots back to 14v.

Attached is a pic of the alternator I fitted and also comparing with the old one. The only alteration I had to make was on the tensioner bracket. I had to angle grinder the toothed plate as the alternator bolt hole was not lining up with the bracket slot.

You need to clean that thing....

Cosmetically??

BRINZ said

Cosmetically??

yes.  Unless your car's patina would be damaged but the installation of new bling.

I never install a new to me part unless it is shined up a wee bit.

Day i bought it.


2 months later.


Tis amazing what SOS (Steel Wool) and elbow grease can accomplish on aluminum.

 

Very Nice Brian !!  

Looks sweet. On my to do list...