Battery light - advance warning?

[Linus Van Pelt 0]

Odd one this... When you start up the car, the warning lights come on and then go off (some kind of system test I assume). Just recently I've noticed that my battery light stays on (not flashing). However, as soon as the remotest amount of pressure is placed on the throttle, it goes out and all is well again... (I can move the car under clutch alone and it stays on).

 

Is this advance warning of an alternator or battery problem (or something else entirely)?

 

Cheers,

 

DtM.

[PhatVR6 0]

What's you're idle speed? it might be a bit low.

 

Check the voltage at the battery at idle.

 

Clean the terminals, make sure they are tight and greased too.

 

Either way, get it sorted, winters here, and it's no fun breaking down. My alternator belt snapped on my old Golf GL early this year. It was -3 outside, and I was stranded for 40 minutes........It took me 2 hours to regain the feeling in my toes when I eventually got home.

:cry:

[Linus Van Pelt 0]

Cheers bud, the idle speed is fine (usually about 900-950, a bit more when it's cold starting).

 

I'll do as you suggest and get the voltage checked (and clean the terminals), it was on my list of things to do, I just wondered if this was symptomatic of a common problem.

 

Incidentally, what sort of grease (graphite?) and in the worst case scenario, what breed of battery should I go for?

 

Cheers again,

 

DtM.

[G60Jet 1]

mine does it but i know my idle is low, but it ticks over fine so im not bothered

[PhatVR6 0]

You can get proper battery terminal grease. if not, vaseline will do.

 

Buy the best battery you can afford, the biggest that will fit. I always go for a battery off a diesel or at the least a VR6 one.

 

Try and stick with quality brands too, Bosch, Varta, Exide etc, no cheap sh1t.

[paulg60 0]

just rev it a bit when you start it :tongue: :wink:

[CaiosG60 PWR 0]

I've got exactly the same problem. I had it for ages though and nothing else seems to have developed.

[stevemac 0]

So far as I'm aware the battery is only used to start the engine. Once running the power supply should then supplied by the alternator. In addition to the above, I would be checking either the voltage regulator (mounted to back of alternator) or the alternator itself.

 

With your engine running at idle speed, the alternator is not supplying enough power (for whatever reason). Your battery will be making up the shortfall - hence the warning light coming on. As the engine revs increase, your alternator begins to supply more power & the battery is no longer needed - hence the light going out when you press the throttle.

 

Does your battery get "warm to touch" whilst the light is on, with the engine running ?

[dr_mat 0]

Stick a voltmeter across the battery terminals. It should read ~12.6 ish when the engine is off, and ~14.2 when the engine is running (whether the engine is idling or being revved, this shouldn't matter).

If the first figure is lower, replace the battery, if the second figure is lower, replace the alternator...

Unless there's something on somewhere that's pulling the voltage down, but I suspect you'd know about that with problems starting the car after you'd left it for more than a few days.

My suspicion is a knackered alternator.

[G60Jet 1]

Have you got a large stereo system running!! could be a drain on the system, try starting it without the stereo on and see what happens, Just a passing thought

[Phil K 0]

Used to have the same problem with my MK1 Golf.... never worried about it and it never got worse or caused me any grief. I'd also suggest the alternator but don't think you should lose any sleep over it :D

[Danger Mouse 0]

I had the same problem until last week when the alternator just decided to die.

 

Lasted about a day then.... no power.

 

DM

[Den_VR6 0]

I'd get the alternator checked - the regulator unit might be on its way out, it'll leave you stranded in the worst possible place if you don't.

[CaiosG60 PWR 0]

Sorry, I said that I had the same problem but its acctualy gone. Doh! I didn't notice.

 

Just like what everybody has been saying, it must have stoped when I got the alternator regulator unit replaced!! Its only a cheap part and easy to replace to.