Thread: Alternator performance

Hi Mundy and where have you got the voltmeter connected.

EG, at the battery terminals or via a dash power socket?

Originally Posted by drivesafe

Hi Mundy and where have you got the voltmeter connected.

EG, at the battery terminals or via a dash power socket?

I have the positives connected to the terminals of both batteries and a negative to a localised earth spot. The positives go via a toggle switch to choose either the main or second battery.

Originally Posted by Mundy

Hi all,
I installed a voltmeter (40mm analogue) some years ago to monitor my dual and main batteries. I seem to have noticed lately that when the vehicle is cold, the alternator output (as shown on the gauge) is about 13.8V but as the engine warms up, it drops down to about 13V. I realise my voltmeter is not high precision instrument but 13V seems too low to me to adequately charge either the main or second battery. Is this performance normal? My 2004 disco's done 170k km.

If not normal, what is the likely cause, something simple or expensive?

Advice would be appreciated.

Mundy,


That sounds low. I have a Baintech volt metre connected to my aux battery which is located in the r/r storage box, so a fair distance from the main. Even with slight voltage drop the meter reads between 13.8 and 14.4 volts.


Cheers,


Franz

mine normally runs about 14.6-14.8 according to the nanocom

I had the same issue and decided on a re-brush and regulator kit.

Peopl said it was the diode plate the bearings would be shot the main shaft could be bent etc etc etc.

I was told by many people it was not woth it but i think it was the best thing I could have done..

I orderd it from the UK ............repairs kit . kom

And $80 later it took two weeks to arrive. With detailed instructions I did mine in a Saturday moring and I felt very proud of my self.

It now charges at 14.4 volts average..

Couldnt be more happy.... I learnt alot about my car in the process.

Cheers

Originally Posted by NWTASD2

I had the same issue and decided on a re-brush and regulator kit.

<snip>

And $80 later it took two weeks to arrive. With detailed instructions I did mine in a Saturday morning and I felt very proud of my self.

It now charges at 14.4 volts average..

Couldnt be more happy.... I learnt alot about my car in the process.

Cheers

Great stuff!
part numbers?
pics?
Tutorial?

Originally Posted by Mundy

Hi all,
I installed a voltmeter (40mm analogue) some years ago to monitor my dual and main batteries. I seem to have noticed lately that when the vehicle is cold, the alternator output (as shown on the gauge) is about 13.8V but as the engine warms up, it drops down to about 13V. I realise my voltmeter is not high precision instrument but 13V seems too low to me to adequately charge either the main or second battery. Is this performance normal? My 2004 disco's done 170k km.

If not normal, what is the likely cause, something simple or expensive?

Advice would be appreciated.

Before you do anything else, can I suggest you get a digital multimeter, and put it across the battery terminals, and then the alternator output, and check the readings again.

This will, at least, eliminate your voltmeter & wiring to it.

I'm really sorry Pedro and other forum members but I did not take any snaps but I have provided the link I used to buy the items.

Only complaint was postage was not very quick..

When they arrived it came with a step by step instruction page with photos and was simple as 123 to follow. In fact I got my 9 year old son to help.

But I will describe my experience the best I can.

Brush Box & Brushes

http://www.startermotorkits.com/?cat=73

I laid all parts on a table with a cloth. In order of disconnection.

Disconnected Battery.

Removed Inter cooler hoses from the manifold and inter-cooler then inserted a rag in both ends. To stop accidental ingress of dirt.

Removed fan belt. (It took some time to remember how to get it back on so I suggest if you are not familiar with fan belt just drop it off the alternator instead of removing it.

Disconnected oil hoses top and bottom of Alternator.

Used 50 or 55 Torx bit to access bolt.With a small extension Bar.

Removing the Viscous Fan would have made the job easier but I do not have a remover.

I then gently removed the power cable from the side of the Alternator.

Then came the multi plug at the back. NOT SO EASY. I went to SCA and bought some long nosed pliers with the bend at the end of the prongs. $11.95. Then got under the vechile and with my son that depresed the tab on top of the plug I gently wiggled the plug loose from back of the Alternator. (My alternator issues started with a broken WHITE GREEN wire so the unit was not getting excited. You need power to make power. At the time I made a temperary repair so while I had the plug out I extended the wire by 200mm.

I then removed the Alternator. And took it inside the garage.

It is here that the step by step instructions were used they inclue photos and couldn't be easier.

I removed the rear plate 3 screws. and a nut.

I removed the brush box 2 screws EASY and measured the remaing length of the brush's they were only just 6mm long. so I have kept them as a emergency emergency only.

Then the regulator and red silicone ring. EASY.

I took some emery paper and gave the shaft a good clean.. Steel wool would have been just as good.

I then charged up the compressor and with a can of contact cleaner gave the alternator and the external cover a good clean. Infact my son did this and I watched.

I then put the new regulator in and did up screws then the silicone ring it had an impression of the original side up so I made sure it went back the same way it came out.

Then the brush box also EASY 3 screws and the rear cover and small nut.

Stood back and smiled.

Re-installed into vehicle.

For the first three weeks I ran a multi meter with aligator clips and extension wire into the cab so I could monitor the voltage.

I then bought a cheap $3 plug into cigarette lighter voltage read out just to monitor any major change.

Oh yea I had a couple of cups of tea while I did this too it did'nt make any difference to the outcome but It made a very relaxing repair.

Hope this helps. Again sorry no pics..

I think I said this before this job improved my understanding of my car got me outside under the bonnet. Improved my collection of tools and most impotantly only cost me a fraction of the price of a new alternator.

This link may also help..
http://www.aulro.com/afvb/discovery-...lternator.html