22 replies to this topic

[Seb.F]

So, got into the car last night at work to drive home and the battery light was on, has stayed on since then, and can't figure out what it means, the car was running perfectly and didn't cut out or stall or lose power, and I've drive it about 30 miles since.... so I didn't think it was the alternator as surely the battery would have run dead by now? Any ideas? As the battery is only 3k miles old, when I did the supercharger.

[siztenboots]

check earths

[Seb.F]

Where are the main ones to check, I was going to check the battery before I left work again today. Just seemed odd that it did it after a massive downpour, while the car was just sat still at work during the day!

[Zoobeef]

Use a multimeter and see what powers at your battery with the engine running. Should be 14+ volts. Then check at the altornator. Should be the same

[Seb.F]

Gah, not only do I not have a multimeter, I have virtually no time at the moment either, what a bloody time to show up... grr

[simsy]

Sounds like a cable to alternator is loose / damaged or the alternator is faulty. Light is driven by a trigger output from the alternator, saying the alternator is not working. I would expect the car to run for a couple of hours on a good battery, before desaster strikes. Measur ethe voltage at the battery with engine running. 14vdc ish.. Buy / beg a multi meter or run her into a garage quick.

[Zoobeef]

Light is driven by a trigger output from the alternator, saying the alternator is not working.

Not quite correct. The light is illuminated when you first turn the ignition on from the 12v from the battery. Once the vehicle is started the altornator sends 14v the other way down the wire with the light. 2 positives cencel each other out and extinguish the light.

Edit: good idea on the garage thing. Nip it into one and ask them nicely

Edited by zoobeef, 15 July 2010 - 09:07 AM.

[rsg]

either borrow a multimeter or scangauge can tell you

[_Dan_]

Hi Seb, Could any of the wiring near the alternator have got damaged when you fitted the charger? I know it get's pretty tight down there With the headlights on and the engine running, do they go noticibly dimmer when you switch the engine off, if so, the alternator is charging and hopefully the problem is trivial........

[Seb.F]

Edit: good idea on the garage thing. Nip it into one and ask them nicely

Will do that!

Could any of the wiring near the alternator have got damaged when you fitted the charger? I know it get's pretty tight down there

Shouldn't be, as I replaced the problematic wire

[simsy]

The red light is driven ( i.e. switched on and off ) by the alternator 'charging' trigger output. Yes, it uses a perminent ign feed to complete the circuit, as you state.

Edited by simsy, 15 July 2010 - 10:13 AM.

[Seb.F]

So why would it have only just come on now? Rather than coming on as soon as I did the conversion? Is something just loose you reckon?

[simsy]

How long ago was the conversion? But I bet the alternator has 1\ stopped working due to an internal fault, over heated or shorted out. 3/10 2\ has a loose or damaged cable, easy fix if you could see the connections, which is not easy with a sc vx... 5/10 3\ Poor earth cable some where maybe. 2/10 if belt had snapped you would know, right.... no power, no sc song, steam, red light , steering heavy, air con not working, etc

Edited by simsy, 15 July 2010 - 10:14 AM.

[Seb.F]

How long ago was the conversion? But I bet the alternator has

1\ stopped working due to an internal fault, over heated or shorted out. 3/10
2\ has a loose or damaged cable, easy fix if you could see the connections, which is not easy with a sc vx... 5/10
3\ Poor earth cable some where maybe. 2/10

if belt had snapped you would know, right.... no power, no sc song, steam, red light etc

It was a few months ago, and I've done over 3500 miles since that.

The belt definately hasn't snapped!!

[simsy]

I know, just messing.....

[Mangham54]

Seb it could easily be that the alternator has given up.... I managed over 50 miles when mine packed in, plus a dozen start ups on the charge in the battery only. If you (or someone locally) have a scanguage then you could checked the voltage on the battery ignition off and when running and see if the alternator is kicing out a charge. AutoVaux for an alternator... just over £100.

[FLD]

Did you trim back the black cover on the alternator and keep the suppressor part? Not being an electrical whizz I cant tell you wnat it does and if it would cause your symptom but just thought I'd check.

[Seb.F]

Cheers guys I will check later! Not wanting to spend another £100 on an alternator but I guess it can go down on the ad as a positive!

[Seb.F]

Battery light on, ABS light on, Airbag light on, 'oh sh*t'. Wiper went halfway across windscreen and almost stopped after I flicked it once. Got it to jamsport as I was about 15 minutes from home. 10.4 volts while running, surprised it actually was still running at that as well! In the 10 seconds I had it connected up it went to 10.2 so was dropping quite quickly!! They're checking it out as I have no time to be playing right now, way too busy at work. I'll know tomorrow morning whether it's alternator or just a cable.

[Zoobeef]

So next thing would be to see how many volts are at the altornator as that would tell you if its still working or if its a break in the wire