Alternator Charge?

[Cruz]

My van is a 1983 1.9DG with a new fanbelt that seems tight enough, and a new alternator regulator that was fitted in June when the alternator completely stopped charging

My problem is:

Starter Battery reads 12.8v with ignition off

When I start the van the red battery light does not go out and the charge to the battery does not increase until I give the engine a few revs

then I get around 13.2volts to the battery which rises to 13.5volts after about 5 minutes of driving and then rises to 13.8v after 20 minutes of driving.

What could cause the light to stay on until I rev the engine and for the alternator to not pump out as much voltage at first?

[Oldiebut goodie]

Some are just like that - my boat is exactly the same, have to give the throttle a bit of welly then the alternator kicks in, no matter what is renewed it remains the same - bit annoying as there is a high pitched warning buzzer to go with it!
My van takes about 45 seconds before the alternator kicks in.
I don't worry about it anymore and have suffered any ill effects with either.

[Cruz]

I think the light staying on is something to do with my immobiliser as I can hear a click behind the pod when I give it some revs

[kevtherev]

my 90 amp alternator did this too... as does my pals

oddly the 45 didn't

[CovKid]

I've got the 90, fine for three years, now needs a slight rev to spur it into life, after that its fine

[ghost123uk]

I've got the 90, fine for three years, now needs a slight rev to spur it into life, after that its fine

Same here

And your reading of 13.8 volts after a short time is spot on too = no worries

[Cruz]

13.3 with my lights on

[Simon Baxter]

That's just how they are.
The light tells you that there is a voltage difference between the battery and alternator.
All it means is that you have not reached charging speed, as noted a quick blip trips the alt over the speed it wants to start working at and the light will go off..
Nothing to worry about.

[Cruz]

Cheers Simon

[Red Westie]

Whilst I agree in part to some of these replies I cannot help but think they have missed some of the points on the original post ie:
I get around 13.2volts to the battery which rises to 13.5volts after about 5 minutes of driving and then rises to 13.8v after 20 minutes of driving.
Voltage regulators sometimes need a 'blip' of the throttle to switch and start charging but honestly...not this gradual increase in voltage over 20 minutes!
Bosch/Beru regulators are set to deliver from 13.9 to 14.2 volts and this should happen pretty much instantly...at least once off idle (more than 1200rpm) so taking the revs to 2,000rpm you should be seeing a charge rate in the late 13's straight away and not after several minutes.
My judgement would be...return the regulator bush pack as faulty but check the slip rings for excessive wear first.

My opinion
Martin

[CovKid]

It could be that the startup demands are greater during those first twenty minutes though and not sure how much the battery absorbs initially. Getting an accurate account of whats happening would need test gear in various places.

[Cruz]

My readings have all been at the battery posts so how would I go about testing the charge at the alternator? My alternator doesn't have posts but a plastic push in connector for the wires

[CovKid]

I doubt any of this matters really. Providing the battery isn't being boiled or its not charging at all, then it should all be fine. The fact I now have to blip the throttle whereas before it seemed to kick in without that, isn't of any concern since it does charge fine. The slight variation in voltage may not even be detectable on an analogue guage. I do know that before I changed my starter battery for a new one, the alternator was doing a lot more work.

If you've fitted the digital meter mod, you'll pay more attention to this side of things than you otherwise might, so there are pros and cons for the upgrade.

[Cafnod]

Easiest way then would b to use an inductive meter.
Or get another plug and fit in extra connections for test work

[CovKid]

Yep. At the end of the day its a very crude charging system and not even as smart as the LIDL battery charger. It does what it does I suppose but guess theres room for improvement in most things.