Scirocco Register

ok well let me know how you get on when you fit the Alternator all so problems with Alternators here--

http://auto.howstuffworks.com/under-the ... oblems.htm

http://www.ehow.com/how_2210342_diagnos ... oblem.html

http://www.buzzle.com/articles/car-alte ... blems.html

Right, just to check this...

Fitted the new alternator today, and found that it had the old-style connections on the back, so had to crimp on spade connectors to get around this (the original has ring terminals). So that was the fat red wire to one of the larger paired 'B+' terminals, and the thin blue wire to the 'D+' terminal.

Start the car up, and all seems fine - then started measuring voltages.

Voltage across the battery reads +13.82V. Seems good.

Alternator body to the +'ve terminal on the battery - +13.87V. Good.

Then tried to measure between B+ on the alternator to +'ve terminal on the battery, and got a massive spark as soon as I touched the lead to the terminal on the alternator. Not so good. Held it there, and the spark died down - touched to the +'ve on the battery, and we only have +0.03V. Not entirely sure this is good Does this mean that no voltage is going from the alternator to the battery?

However, having had the engine running for about five to ten minutes, the voltage across the battery appears to be fine. Sitting around +13.80V, and going down but then climbing back up again, so seems to be charging. Also, no ignition light on the dash when running.

Does anyone know if this sounds normal? Not really sure what I'm looking for here.

Hi Mate,
PM'd u back.
Sounds to me like your alternator is working, I cannot explain the 0.03V problem, possibly becasue the terminals you chose belonged to seperate circuits? you could be picking a flux up from the alternator it's self, hence the very low V...I'm just guessing to be honest, I'm no sparky. The alternator seems to be working tho yes? if you test the voltage across the battery with the car off you should read around 12V yea? with car running again reading across the battery you should see around 13.6-14.4 V..which you are? HOpefully someone can confirm that. Anyhow, if it turns out that the Alternator isn't doing it's job, I will refund you matey, no problem.
Col.

I think you're right. Having read up on things a bit, the alt +'ve to battery +'ve apparently tests for a voltage loss - if it's anywhere above 0.3V it's actually a bad sign.
The main thing is the voltage across the battery I reckon, as you've suggested - as long as it reads above 13.4V I think I'm good. Thanks for the unit - and the advice!