generator / alternator

[kartone]

Buongiorno Alfisti!
Which is the quickest way with a multimeter to check whether the alternator is doing its job?
Buon finesettimana (weekend) 

[Duk]

Test the voltage across the battery when the engine isn't running and write the number down.
Start the engine and with the engine idling, measure across the battery terminal again. Write that number down.
Hold engine revs above 1500rpm and test again. write down again.
Now turn on the heavy current drawers like the headlights and radiator fan if you can do it manually. Measure and write down the battery voltage again.

Now compare the written numbers. Unless it's been upgraded, the alternator is probably of the older design that can't deliver much juice when the engine is idling. Newer (newer = last 20 odd years) alternators can deliver much more idle current than older ones.
If the voltage stays around the same when the engine has a few revs on board, then there is a problem. It should get to about 13.7 volts, or there abouts.
If the the voltage drops when you start to switch on the high current loads, then the alternator can't match the current draw and there is a problem, but make sure the system has good clean earths and power leads.

[kartone]

Ciao Duk, thanks for the assistance, will go through the procedure tomorrow and report, speriamo bene (hope for the best)!

[colcol]

I went through this a few years ago, the type of voltage regulator can affect your volts as well, had 4 second hand voltage regulators and used the one that made the alternator put out an extra volt at idle, but be carefull, as you don't want to fry your battery, if it starts using water, then your voltage is too high, Colin.

[kartone]

REPORT  CARD
battery voltage when:
engine off = 12.78
engine idle = 13.25
engine 1500 RPM = 13.74
engine idle + radiator fan + high beams = 12.20

[Duk]

So the alternator can't deliver much juice when idling, but that's no real surprise.
Do the last test again with 1500+rpm on board and see where you're at.