6T battery/charge warn light but showing14V on charge gauge?

[Johnny G Pipe]

Hi, a quick white flag wave - I am a fair way from home and on my way here had my 996T battery/charge warn light came on (and stay on). It will be raining, dark and busy when I head home and I don't want to get stranded.

After the warn came on, the dash voltmeter was still steady at 14V, and the wipers were all normal speed etc, so I am guessing my alternator is still working..?

Also, although the battery is only a couple years old, it was TOTALLY flat last week when it was minus 4 degrees, and it took the CTEK a couple of days to get it charged back up again.

So this is all pointing to a dying battery, yes? I think I am going to have to try and find a motor factors over lunchtime :-/

Thanks for any advice.

Edited by Johnny G Pipe on Thursday 8th January 13:39

[Storm996]

Dying battery. For sure. Taking into consideration that it went badly flat last week.

Remember to ctek the new one when the temp drops. Mine is on 24/7 on the drive recently.

[Johnny G Pipe]

Storm996 said:

Dying battery. For sure.

You'd think! New Bosch S4 from Eurocarparts fitted and its just the same.

It also started doing a subtle up and down rev thing at idle, with the voltmeter swinging from 12-14v, then back to normal (steady at 14v but still showing the battery/charge warn). Despite the battery light being on it drove an hour with heat and xenons on with no sign of a charge problem - albeit with a brand new battery.

Still - I'm hugely confused, Ted.

[Bennachie]

Alternator diode pack faulty. Alternator is not charging the battery fully....

[pete]

I would bet on the diode pack - exactly the same symptoms for me. It will eventually start to fail to charge when the alternator gets warm; mine would pump out 14v cold, then drop to under 11v when the car was warmed up. A replacement voltage reg was about £40 from Woods, took a couple of hours to fit myself as it's tricky to get the alternator out.

Cheers,
Pete

[Johnny G Pipe]

Cool, thanks. Diode pack is in regulator then..?

[tr7v8]

Johnny G Pipe said:

Cool, thanks. Diode pack is in regulator then..?

Yes inside alternator.

[NJH]

Definitely.

Most cars will drive for sometime on the battery alone and its common for the alternator charging fault to cause the light on the dash, what confuses people is that they think its OK because the car still drives when they are in fact just running off the battery. I made this mistake once many years ago and managed to coast into a petrol station when the engine eventually died, light was on the dash for about an hour before that.

[Johnny G Pipe]

Yep, my 356 didnt charge for about a year until I finally converted to alternator, it would run all day on the battery alone if I didnt use the electrics. OTOH I broke my alternator belt in my scoobie when it was dark and raining end of last year - and with wipers and lights it lasted about 20 minutes before expiring - and it wasnt happy before that either, wipers were super slow etc.

I think for my 6T to manage an hour of fast driving with full electrics on and 14V on the meter there must have been some charge getting through. Something is perhaps dying, rather than already dead, methinks.

[tr7v8]

Very often you on;y lose one leg of the 3 in the diode pack which is the one that triggers the alternator light on. If this is the case you'll get a reduced charge through the other two. Some alternators pull all three together so the alternator is a true charge indicator.

[Johnny G Pipe]

TR7 thanks, helpful info. Has a diode 'blown' in my efforts to start a dead car with jump leads I wonder?

tr7v8 said:

Johnny G Pipe said:

Cool, thanks. Diode pack is in regulator then..?

Yes inside alternator.

Whilst you are here can you confirm diode pack in regulator or alternator? :-) Is it replaceable on its own?

[tr7v8]

Johnny G Pipe said:

TR7 thanks, helpful info. Has a diode 'blown' in my efforts to start a dead car with jump leads I wonder?

tr7v8 said:

Johnny G Pipe said:

Cool, thanks. Diode pack is in regulator then..?

Yes inside alternator.

Whilst you are here can you confirm diode pack in regulator or alternator? :-) Is it replaceable on its own?

Could be but unlikely unless you get the leads the wrong way round. Modern alternators are a lot better than the old ones for this.
Not 100% sure on the 996T alternator but normally the regulator is in the alternator as is the diode pack. Some have reg & diode pack combined others have them separate. But the parts are changeable individually by an Auto electrician. Most garages & especially OPCs don't they just replace the whole alternator.

[Pugley]

If the alternator is getting old and has done a few miles it may be more cost effective to buy an exchange unit as the bearings/rings/diodes etc etc may be past their best.
It will come with some form of warranty and a diy repair wont.

[pierslofi]

Sounds like the regulator, which is attached to the back of the alternator. They are about £20, very easy to replace once you have the alternator off.

[Johnny G Pipe]

pierslofi said:

Sounds like the regulator, which is attached to the back of the alternator. They are about £20, very easy to replace once you have the alternator off.

Thanks for this and all. I need to get a balance between diagnosing-by-replacing parts and just giving it to a man who knows! I am already down 90 quid for the battery.

[ArcticGT3]

There's a good DIY here to remove the alternator, if your able to remove it yourself just drop it off with someone who recon's them and they'll do whatever needs doing and usually warranty it as well

http://www.dakingrulez.com/porsche_996_turbo_Gt2/d...