battery light on idle

Hi everyone,

Just starting out with my golf really, I'm keeping her in the garage at the moment and letting the engine tick over for 30 mins a week, but the other night I noticed after about 25 minutes, the battery light came on as if the alternator was not charging the battery. As soon as I blipped the throttle, it went out completely.

Is this normal? Any ideas if I need to be checking stuff out here?

Cheers!

Would say that your alternator is on the way out. Turn your lights on and see if they brighten when you rev - sure sign that the alternator is going.

If you have access to a multimeter you could check that voltage across the battery when idling is more than 13V.

Check the charging belt is not loose….

Good luck
 

not quite, read here on this forum that its normal, there is a diode or something that makes the light come on when the car first starts and goes away, happens on most mk1's from what iv herd, definatley happens onmine hth

check your voltage regulator on your alternater

Totally agree. The red light does come on when you first start the car, then goes out once you blip the throttle. However, the problem here is that the light cones ON AFTER 20 minutes.

Does dound like alternator/regulator. Change the voltage regulator - only costs about 15 quid and easy to replace. If you can, check the voltages across battery before and after starting the car.

Good luck
 

Cheers guys, I've got a multimeter from work , so I'll check the battery voltages before and after starting the car. I'll also try revving the engine a bit and see what happens to the lights, and get back to you with the results

The alternator is the bosch 65 Amp version- if it's the voltage regulator, I can replace this part directkly right? Where to find one?

Cheers

bytor said

Totally agree. The red light does come on when you first start the car, then goes out once you blip the throttle. However, the problem here is that the light cones ON AFTER 20 minutes.

Does dound like alternator/regulator. Change the voltage regulator - only costs about 15 quid and easy to replace. If you can, check the voltages across battery before and after starting the car.

Good luck
 

i had this before and the LED stayed on for 40min as i was working on the car but didnt touch the throttle. come on every moring like clockwork and off as soon as i hit the gas. nothing to worry about IMO as my Alt is fine. HTH

haha u made the same mistake as me, re read the post, its 40minutes into when the car is being driven, which obviously means the alternator isnt chargeing properly or is slipping, one or the other!

ioboy said

Hi everyone,

 letting the engine tick over for 30 mins a week,

Not a major point but why are yopu just letting it tick over? Why don't you go for a spin once a week? I read in my VW owners manual that it's a bad idea and it should be avoided.

Tian :dontknow:

The regulator can be removed from the alternator and the brush lenth chekced, before forking out for a replacement. Haynes should detail min brush length.

I read in my VW owners manual that it's a bad idea and it should be avoided.

This is because at idle revs the top of the head can be starved of oil and the cam not adequately lubricated. Think this is more of an issue with small blocks with the overhead oil spray bar and also when starting from cold when oil has dropped to the bottom of the engine and is thick and slow to move.

Cheers

Hi everyone, cheers for all the replies.

So, I had a bit of a check through the electrics. Before I start the car, the battery voltage is about 12.4v. When I first started it, it went up to just over 16v, then dropped over the next 30 mins to steady out at 13.75v. Once the engine was switched off, the battery voltage went back to about 12.5v. This seems ok to me, based on the things I have read here, so I think the alternator itself is probably working ok. Also, as per bytor's recommendation, I checked the brightness of the lights when I rev'd the engine. All the lights stayed a constant brightness.

The red battery light does indeed come on (and stay on) as soon as i start the car, and go off when I blip the throttle. If I leave the car ticking over for a while, it comes back on, but goes off again as soon as I blip the throttle. Maybe it would be good to check and clean up the earth connections?

So is it possible the regulator needs adjusting/replacing but not the alternator? I presume the diodes will be arranged in the regultor so that if the regulator o/p drops below the battery voltage, the light comes on, but if the regulator o/p is higher, the light stays off. I'll check the regulator tonight.

Tian: Yes, I know keeping it garaged is not totally ideal. There are a few reasons for this though. 1. It had a rusty fuel filler pipe, which I changed this weekend. 2. My hovercraft's in the way, stopping me from getting it out of my drive (It's going to a new home this week). 3. I live in Cumbria, which is the wettest windiest place on earth! 4. It has embarrasing Halford's finance 16" Fox rims, which are being changed with slots that arrived this morning.

As soon as the hov's out of the way though I'll start giving her a proper trip out once a week instead!

Have a nice day chaps!

Hi,
Had a read through your note. If the voltage is going to 16V, that's WAY TOO HIGH! I had this problem some time ago - the acid in the battery will start to boil!

I would say that the voltage regulator is gone in that case. I had mine changed and it sorted out my issue. I have a voltemeter in the car and when I started the car it would sit well below 12V and once I revved it a little would suddenly swing above 15V - too high. The confusing thing is that the voltage stabilises at 13.75, which is spot on????

My advice would be;

1. Check the wiring between the alternator and the battery.
2. Take the regulator out of the alternator. From memory, there are two screws holding it in place. Be careful as you take it our as the electodes can easily break. An new unit is about ?15.

The issue with mine was different in that the LED would NEVER come on. By changing the loom and putting in new regulator, it worked fine.

Good luck, you'll sort it in the end, keep us posted though!!

Adios

Hi bytor cheers for the advice. I'll try what you suggest and cleaning up the loom can only help.

Where do I get replacement regulators for my alternator? It's a 65A Bosche one. VW garage?

I've got 3 vdo displays inside too, although none of them are working (I presume none of them are connected). I'll attach the voltmeter ASAP which will let me keep my eye on it.

I'll keep you guys posted on my progress

Cheers

Tian: Yes, I know keeping it garaged is not totally ideal. There are a few reasons for this though. 1. It had a rusty fuel filler pipe, which I changed this weekend. 2. My hovercraft's in the way, stopping me from getting it out of my drive (It's going to a new home this week). 3. I live in Cumbria, which is the wettest windiest place on earth! 4. It has embarrasing Halford's finance 16" Fox rims, which are being changed with slots that arrived this morning.

Hovercraft, it can't be that wet in Cumbria, can it?

Hope it all goes well for ya.

Tian :wink:

Hmm. Getting the regulator may be tricky as to my knowledge you will need to match the alternator rating to the reg. If it's a VW original you shouldn't have much of an issue…..

I would suggest writing down all the details of the alternator and then taking the regulator with you and going to a auto parts shop. VW can only help if you have the original alternator on there (or replacement was original part). Not sure if G&S sell them?

Cheers

hmm, GSF sell what the describe as:

VOLT.REGULATOR-BOSCH ALT.
G1 8/81 >

for ?9.50 (p/n: 91030).

I will have a look for the model # of the alternator and gove GSF a call. If it matches I'll grab one, clean up the elctrics and see what happens…

Cheers all!