Vx Corsa alternator volts

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Sun 7 Mar 2004 21:04
Vx Corsa alternator volts - Cyd
I am servicing a friends Vauxhall Combo Van. It is a 1.7 diesel (non turbo) Isuzu engine.

When checking the charging circuit operation I found the following:

If I connect a voltmeter to the battery and then start the engine, the running no load voltage is 13.2 volts. After about 2 minutes (I haven't timed this exactly) the voltage jumps suddenly to 14.0 volts.
This isn't a fluke; I first thought maybe I had a dodgy connection, but I have repeated the test 4 times with the same result each time.
The battery is about 50-70% charged and so has plenty of room for more charge to be accepted.
13.2 is too low to charge the battery fully, but 14.0 is quite acceptable. Once the 14v charge is initiated the full load voltage only drops to 13.7, again quite acceptable.

Is this normal for this charging circuit? is there some device which limits the voltage initially? or is this indicative of some fault?
the Haynes is no help on this matter.
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Sun 7 Mar 2004 21:48
Vx Corsa alternator volts - 659FBE
All absolutely normal. What you are seeing is the regulator going into contol mode when the glowplugs have finished their post-heat mode. During post heat, the load exceeds the output of the alternator, so the voltage is below the regulated value.

659.
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Tue 9 Mar 2004 15:49
Vx Corsa alternator volts - Cyd
Many thanks, 659.
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