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Discussion Starter #1 (Edited)
So, driving home from a friends I noticed the alternator warning was on, and when revving the engine the lights would go brighter and then dim again, whilst driving the alternator warning light 'alternated' between bright and dim, it was bright when I accelerated and went dim when I came to a standstill.

Back at base I checked battery voltage and it was down to 13.1 V

I've put my battery conditioner on it so will see if any lasting damage done in the morning.

Any thoughts on what this could be from symptoms above?

Ta

Sean
 

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First Q: what is the voltage across the battery at tickover and at about 2500rpm?
 

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Need to check if your alternator has the voltage regulator built in, later ones did, earlier ones had it as a separate unit.
If its just the regulator it will be cheaper than a whole new alternator, but if it turns out not to be (an if I'm honest i couldn't determine how to find out!) and you replace the alternator its probably better to switch it across to the later one.
Both my cars have had this failure, it seems quite common.
 

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Discussion Starter #5
I haven't had a chance to properly assess this as with my multi-meter its a two person job, I did a quick test this morning and across the terminals with the engine running and the hand throttle engaged a little to stop it stalling the voltage was jumping up and down between 13.9s and 14.5 it wasn't consistent.

I have no idea how to tell if my alternator has the voltage regulator built in or not.

i'll try to get a colleague to give me a hand at lunch time and get some proper readings after the car has warmed up and can idle constantly.

Sean
 

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Discussion Starter #6
Okay, test done

Battery Voltage (disconnected)

12.85

Battery Voltage (idle)

12.99

Battery Voltage (2500rpm)

14.95v

I have a clamp on my multimeter so I put this on the alternator feed at idle and it fluctuated around 80mV

Other things I noticed.

At idle once up to temp the Alternator warning light went out
If I held the rpms at a steady 1700rpm the Alternator warning light pulsed rhythmically

Hope this is useful.

I was planning on going to a meet in it tonight but not sure if I can trust it.

Sean
 

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ALWAYS trust your Alfa... that's the way I played it for 4 years (no breakdown cover) in my GT Jtd :thumbup:
 

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Discussion Starter #9 (Edited)
Thanks but are the readings I took normal? I have no idea about this stuff. :(
 

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Thanks but are the readings I took normal? I have no idea about this stuff. :(
voltage disconnected (12.85V) is good (healthy battery)
voltage at idle (12.99) is low....I'd expect 13,5V sorta
voltage at 2500 (14,95V) is quite high at almost 15V....I'd expect 14.5V

the fact that you said (earlier) it was jumping about is also not normal.

So what regulator have you got? if it is an internal regulator, pull it out (2 screws on back of Alt, and the regulator and brushes come out as a unit)and check the brushes are equally worn and clean....takes a few minutes to do, depending what's in the way on your car.
 

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From your readings it looks like the regulator - as the othrs said, check it and connections.
 

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Discussion Starter #12
voltage disconnected (12.85V) is good (healthy battery)
voltage at idle (12.99) is low....I'd expect 13,5V sorta
voltage at 2500 (14,95V) is quite high at almost 15V....I'd expect 14.5V

the fact that you said (earlier) it was jumping about is also not normal.

So what regulator have you got? if it is an internal regulator, pull it out (2 screws on back of Alt, and the regulator and brushes come out as a unit)and check the brushes are equally worn and clean....takes a few minutes to do, depending what's in the way on your car.
From your readings it looks like the regulator - as the othrs said, check it and connections.
Thanks guys, i'll have a poke around tomorrow and feedback :)
 

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Discussion Starter #13
I've taken a couple of pics, it looks to my untrained eye that this has an internal regulator.

Is it simply a case of undoing the two nuts and pulling it out?

ImageUploadedByAG Free1462522262.038153.jpg

ImageUploadedByAG Free1462522274.945492.jpg

Cheers

Sean
 

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Discussion Starter #15
ImageUploadedByAG Free1462541738.798916.jpg

Big grey box thing that looks a bit like the horn relay?

How do you get inside it?
 

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Discussion Starter #17
I bought a new one, it was only £20 and it came today, it looks almost the same as the old stock one except new and shiny.

Not had a chance to start the car yet to see if the problem is fixed.
 

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I bought a new one, it was only £20 and it came today, it looks almost the same as the old stock one except new and shiny.

Not had a chance to start the car yet to see if the problem is fixed.
Out of interest where did you get one? - the ones on CA are plastic boxes rather than the nicer metal ones
Cheers
 

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Discussion Starter #19
Out of interest where did you get one? - the ones on CA are plastic boxes rather than the nicer metal ones
Cheers
The picture bears no resemblance to what comes, I got it from ca, it looks exactly the same except without bosch stamped into it, I'd hazard a guess that if I sliced the tape holding the cover on my old cover would fit straight on.
 

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The picture bears no resemblance to what comes, I got it from ca, it looks exactly the same except without bosch stamped into it, I'd hazard a guess that if I sliced the tape holding the cover on my old cover would fit straight on.
Ah right - thanks
 
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