Alternator options

cheechy

cheechy

A2OC Donor
Hello Not been on a great deal of late for many reasons, but 1 of which is in not using the A2 as much as I was.

Anyway I'm looking for suggestions please on what options I have with what appears on the have of it to be an alternator issue on a tdi90.

2 years ago I replaced my factory alternator with s refurbished unit due to a perceived voltage issue related an ASV issue. Turns out that there was likely nothing wrong with it but it had to be returned to the seller as it was a refurb / send back old service.

Due to the car sitting I was having start issues and I'm hooking up a trickle charger with great success. Kinda tells me that its likely not the battery...Issue is the battery is dropping even during a journey. Naturally I'm suspecting the barely used alternator had given up the ghost but could it be anything else like earthing?

If anyone has a working 140a alternator they might pay with I'd also be interested!
 
cheechy said:
Due to the car sitting I was having start issues and I'm hooking up a trickle charger with great success. Kinda tells me that its likely not the battery...Issue is the battery is dropping even during a journey. Naturally I'm suspecting the barely used alternator had given up the ghost but could it be anything else like earthing?
Click to expand...

Do you have a multimeter?
 
steve_c said:
Do you have a multimeter?
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Yup voltage not going up but I've measured at the battery... Which should be fine. If anything is going down.

I don't want to believe the alternator had failed given its likely done under 10k
 
And what was the voltage measured at the battery with the engine running. Also 20 minutes after running what was the battery voltage?

I take it the battery terminals are clean and tight and the auxiliary positive supply box is secure to the positive clamp and internal connections are clean and tight?
 
cheechy said:
Yup voltage not going up but I've measured at the battery...
Click to expand...

www.jdpower.com

How to Test a Car Battery with a Multimeter

When your car doesn’t start, often the battery is the culprit. Unfortunately, most vehicle owners do not check their battery until it fails. As preventative maintenance, the suggested best practice is to conduct a car battery voltage test regularly – at least twice per year – using a multimeter.
www.jdpower.com www.jdpower.com
 
Measured at battery with car running. It's under 13v with no more that base load. Think I just have to accept the alternator refurb was someone checking it worked and selling it on... New needed
 
Would expect in the region of 14.3v engine running at the battery. Is the over run clutch working on the alternator correctly. If it is slipping the alternator may not be able to produce the correct voltage. If you rev the engine doe the alternator push 14.3v to the battery then?
 
So voltage is dipping when the car is revved and returning back a bit when released. I've got the battery on trickle charger at present.
 
cheechy said:
So voltage is dipping when the car is revved and returning back a bit when released. I've got the battery on trickle charger at present.
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Surely any sound battery will hold a reasonable charge for a good while without continuous trickle charging.

Why not get the battery up to fully charged, then disconnect the charger and let the battery sit for a few hours before checking the resting voltage?
 
Did those last night and voltage wasnt to bad at all.

I did a 100 mile round trip with the fully charged battery from overnight and by the time I was getting near home (and I had to make a stop) the car was getting harder to start... With voltage dipping to 13v from 13.6v from stay point as reported by the colour DIS.

It sounds like it's working a little just not enough to significantly top up the battery
 
Ask now I guess is does anyone know of a place I can take the alternator to locally for reconditioning or do I just have to buy new? :(
 
It is worth considering a slipping alternator clutch! I had very similar symptoms (but accompanied by a screeching from the aux belt area) I was told that the alternator was on the blink but I had it bench tested but it was fine. What a lot of people fail to realise is how much demand there is on the alternator besides having to return all the charge used on starting the power steering takes a huge load, A/C (or worse the cabin heater) if the alternator is not supplying more than the total running demand then the battery is draining whilst driving.
on mine the clutch felt OK by hand but the real load when running was causing it to slip and hence power output could not meet the demand.
 
Yup I fitted a new pulley when this alternator went in 2 years back

Realty annoying but quite honestly I don't have the time or energy to spend on the car right now so will likely just need to get hold of another unit and get it fitted.

Pulley etc seems fine as air con was working fine today
 
The diode /brush pack is normally replaceable on it own. This is what normally wears or fails.

Your best bet would be to find an auto electrician locally and have them test both the charging system and the battery. They should be more than capable of repairing the alternator if needed.

Just because the air con is working fine does not mean the clutch is not slipping on the over run pulley. The pulley rotates at engine speed and the clutch takes the drive to the alternator shaft, so if slipping the alternator is not turning as fast ( or at all ).
 
That's the one area I likely need to check. I'm but guessing it's not just the point below the headlamp / and the alternator itself?
 
audifan said:
Engine earth bolts below left headlight onto the chassis rail and other end onto the STARTER.

Do not get the positive lead mixed up with the earth lead on the starter.
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Yup sorry meant starter just tired. Replaced the starter myself a couple of years back
 
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