Charging Weirdness

[cjmarsh81]

I have a slightly weird issue with my Navara. I have a D22 STR 3L Turbo diesel.

When I start the car, the red battery light comes on indicating low battery.( I know it is not low as I have tested this straight after charging with a ctek charger).

While the red light is on in the dash the alternator is not charging the battery. I put the meter on the battery and confirmed this.

If I give the car 2000 - 2500 revs the light turns off and the alternator starts working.

I thought it was the battery getting old as I have had a couple of issues with it. I put a new battery in the car yesterday and it is doing the same thing.

Has anyone else noticed this? I do not remember if it has always done this, it has definately been doing it for the last 6 months.

I assume there is a problem with the alternator.

Thanks

Chris

 

[superiorcruiser]

i get the same light when starting the car and as soon as i give it a rev the light goes out.
I never checked the battery though,since the light goes out..
weird..

 

[Leprechaun]

Yes, its sounds like an alternator problem.

 

[Old.Tony]

It could be the alternator. It could also be slipping belts, or a faulty regulator, or - and this happened on a friend's Falcon - a small amount of corrosion on the electrical terminals on the alternator. Couldn't pass any low current but once the revs got up it was fine.

 

[tweak'e]

check earths and connections.
also you might want to pop the belt off and check the pulley's one way clutch is working. they are known to fail.

 

[terryc]

+1 on the alternator being the place to look.

 

[cjmarsh81]

Thanks for the replies. I will check them out.

The alternator / corrosion on the terminals seems most likely.

If the belts were slipping wouldn't I hear them slipping?

Chris

 

[Old.Tony]

Not always, Chris. If the alternator's struggling to be turned over and the belt's not tight enough - and especially if there's a little glossing on the inner surface of the belt - it'll pass straight over it without giving a hint.

You could always try twisting the belt to take a look. It shouldn't be easy to do, the belts are on rather tight. Then get a good torch and shine it down further where you can see the underside of the belt. If it's a bit reflective (shiny patches) it might be slippage.

If it's slipping at idle, I'd be worried about the bearings in the alternator, because at idle it shouldn't load up enough. Slip the belt off and give the alternator shaft a spin and shake - if there's movement or roughness, the bearings aren't good. Hopefully they can be replaced.