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Re: T25 1.6TD Alternator not charging battery

Posted: 19 Jan 2015, 12:36
by Oldiebut goodie
I think that excitation will still take place with as little as 9v so the bulb resistance shouldn't be a factor.

Re: T25 1.6TD Alternator not charging battery

Posted: 19 Jan 2015, 12:54
by ghost123uk
Oldiebut goodie wrote:I think that excitation will still take place with as little as 9v so the bulb resistance shouldn't be a factor.
Ah, no, I meant the resistance inside the alternator. As in, if one was to feed 12V directly ,via a plain cable, into the sense terminal, what is the resistance inside the alternator. Thinking about it, I guess that input is feeding a set of coils to produce the initial magnetism required for the alternator to work. I am also guessing the resistance of those coils would be sufficient to prevent high currents flowing. Does this sound right?

Re: T25 1.6TD Alternator not charging battery

Posted: 19 Jan 2015, 15:50
by Oldiebut goodie
I've just got a spare alternator out of the workshop - there is a 2.6A drain when I feed 12v into the terminal with around 25k of resistance. I think that it was a fully working 45A alternator.

Re: T25 1.6TD Alternator not charging battery

Posted: 19 Jan 2015, 15:59
by uladk84
Thanks for all the input guys.

I connected everything back up, and the results are the same. Exciter terminal always has 12V, in the OFF, ON, and RUN positions, with or without the exciter wire plugged in.

I'm ordering a new alternator here. I'll be buggered if I'm limping home, staying in Italy!