Strange Power Issue

[jassi 1 1 Cars]

HI all

 

Bit of a wierd one. I had to drive the car up to Birmingham last Saturday so as I was about to leave I thought I'd check fluid levels which were all ok. 5 minutes after setting off the car started sort of jerking / kangarooing. So I stopped and switched everything off, had a quick look under bonnet again as I kind of slammed it shut earlier in case I had done something but all was ok so drove off and car was fine all the way to Birmingham. Following day on the way back same thing started happening but was more pronounced so I stopped to get petrol and again the problem went away but came back again. So I ended up stopping and calling AA. Guy had a quick look couldn't find anything said battery and alternator were fine and the car was driving ok on test drive.

 

Over the last week the issue has been coming and going but this time I've noticed the battery symbol has been flashing but getting dim. It has been on /off intermittently previously since I bought the car but car has been ok. On Thursday the car would not start at all. When the AA guy did his checks he said the battery and alternator were fine (checked with meter).

 

Today I jump started the car and left it running for a while but when I tried to put the window down it cut out and would not start again. The battery seems to be ok i.e car lights come on / are not dim. I can hear the fuel pump / immobiliser when turning the key but it doesn't seem to be able to start the car.

 

I'm not sure where the problem is - battery, alternator, both, something else?

[jackherer 543]

A dim battery light can be caused by bad wiring or terminals. Was the battery light dimly on when the AA checked with a meter?

 

edit: http://forum.205gtidrivers.com/index.php?showtopic=80354

Edited June 25, 2016 by jackherer

[Paul_13 212 1 Cars]

Sounds like your alternator is dying

[Dizzee stuff 33 1 Cars]

Sounds more like a wiring fault, you need to check and clean all the connections around the battery inc earths & all connections to the shunt box.

[steve@cornwall 100]

As above and also check engine earth

[toolie72 67 1 Cars]

I had a strange alternator that would only charge at idle??!! I could put lights on etc and everything checked out at 12.1 (which is low)

Trying to start car I would get a french non! multimeter on battery terminals, try and start-drop to 2 volts

However I put multimeter to current (once I'd jumped car) and it was reading 2amps from alternator, putting loads onto it and it just dropped=dying alternator

 

Took it apart (as I now deal with motors etc) and found no obvious fault-swapped it out and I have had no battery light issues and the car (touch wood!!) has not done the dreaded clickclick in the petrol station since

 

Remember though-it is a circuit back to both terminals ie if you have no earthing then you will get strange readings (of course you can put jump lead from body of alternator to earth terminal to eliminate this-carefully!!)(and don't drive it like that lol)

[toolie72 67 1 Cars]

Oh and another thing-check terminal on starter that alternator feed through

[jassi 1 1 Cars]

I should've mentioned it's a gti6 conversion with battery in the boot so right ol pain.

 

I checked the voltage across the battery and it was 11.4v. Put it on charge and it went up to 12.4.

 

Whilst charging I cleaned the earthing point in boot and engine point.

 

With engine running (no revving) the voltage was 11.8. So starting to think it's the alternator.

[toolie72 67 1 Cars]

Measure on + from alternator to good earth-if readings are the same as at battery end then unless you have a short then you're probably on the right track

 

 

Mine when it was going was sporadic, no battery light sometimes, battery light coming on when booting it and going off on overrun, then it would be fine, then go in pooh again, it had a mind of its own

I live out of town so need my spots in the winter so I gave in and replaced it

[jassi 1 1 Cars]

This is getting confusing. I had a quick look at 306 GTI alternators and there seem to be couple available depending on whether the car had AC or not. They either produce 12V and 90Amps or 14v and 80Amps. I'm not sure which one I have and there doesnt seem to be any way to tell. But if I was getting 11.3v without revving and its only meant to do 12v then may be its ok?

[philmedomsley 0]

Unfortunately it sounds like a intermittent wiring fault, possibly a short. Good luck.

[jackherer 543]

12v is nominal, all alternators output close to 14v or they wouldn't charge a 12v battery.

 

11.3v is definitely NOT OK, as the battery is 12v you need the alternator to produce more than 12v in order to charge it.

 

An 80 amp alternator is plenty for a 205, it doesn't matter what a 306 would have fitted, the electrical accessories in the car are what determine the alternator you need.

What is the battery light doing when it is at 11.3v?

[jassi 1 1 Cars]

The battery light is on all the time but very dim whilst revving.

[dobboy 231 2 Cars]

Sorry just read last few posts.

 

What size of cabling have you wired the battery in?

[jackherer 543]

The battery light is on all the time but very dim whilst revving.

It does sound like the alternator has failed but there are so many oddly creative ways that I've seen people mess up battery relocations so you really need to double check all the wiring. You said you checked the battery ground and cleaned it up, what about the engine/gearbox ground? There must be a ground cable running from the bodyshell to the engine/gearbox, you need to check that too.

[jassi 1 1 Cars]

Tried cleaning and replacing several connectors but in the end had to change the alternator. Seems ok at minute.