I'm assuming you mean that the warning light stays on when the engine is
started and revved, and know that with the engine stopped the warning light
*will* remain on while the switch is on.
What is more important is the voltages when running. Remove the wires from
the F and D terminals of the dynamo and link them together. Connect a 20v
voltmeter between the link and ground. Start the engine and slooowly
increase the speed. The voltage should rapidly rise towards 20v. Do NOT
rev so the voltage goes above 20v, and it should reach this by 1000rpm. If
you only see 0.5 to 1v the field winding may be faulty. If you see 4 to 5v
the armature winding may be faulty.
With the connections to the dynamo restored and the voltmeter connected to
the D terminal start and run the engine slowly increasing the voltage. At
between 12.7 and 13.3v the cut-out relay should operate (this is the one
with the normally open contact, the other two have normally closed contacts)
and the ignition warning light should go out, this should happen by about
1600rpm. The dynamo is now charging the battery and powering the cars
electrics. Further increase in engine revs should increase the voltage
reading to between 14.3 and 15.5v. This depends on ambient temperature, the
higher the temp the lower the voltage. As the battery charges the voltage
regulator relay (at the opposite end of the control box to the cut-out relay
if you have three relays, or the 'other' relay if you only have two) starts
to do its stuff, and it works by operating and releasing very quickly in
very small movements. This can be felt as a small vibration if a finger is
placed lightly on the armature, and you may see a continuous small spark
between the contacts.
The warning light usually glows by having 12v connected one side from the
ignition and 'seeing' a ground through the dynamo armature on the other. If
the light glows when turning on the ignition it implies the continuity of
the circuit through the wiring, brushes and armature is good. On a working
system when the engine is started and the engine revved to about 1600rpm the
dynamo is outputting 13v or better, the cut-out has operated to connect that
voltage to the battery, so the warning light has this same voltage both
sides which is what extinguishes it. If it stays lit when the engine is
running at 2000 rpm or higher it implies the generator isn't outputting any
voltage, which could be a break in the field circuit. This could be in the
dynamo itself (revealed by the tests in para 1) or somewhere in the control
box.
PaulH.
----- Original Message -----
>> I would like to know what some of the "normal" voltage readings should be
>> for a system in good operating condition.
>>
>> I'm having charging circuit problems - the Ignition light remains
>> illuminated as long as the switch is ON.
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