>----- Original Message -----
>(My stock Lucas voltage regulator was set at 16 volts, and the shop
>manual seems to support this voltage. But this is way too high. I
>backed mine down to 14 volts.)
I don't recall who wrote that, but it is not exactly what the book
says, and it is misleading.
The book instructions call for disconnecting the cables from control
box terminals A and A1 and connecting them together while testing
voltage or adjusting the control box. Then the regulator relay
should be adjusted to make the dynamo generate "around" 16 volts
(depending on ambient temperature).
There is a sentence missing from the instructions in the book. It
should additionally say, "When finished testing, reconnect the cables
to control box terminals A and A1".
What that does is to disconnect the car's electrical load AND the
battery from the dynamo, so it will be running with zero electrical
load during the test or adjustment. Under those circumstances (no
load) it should be adjusted to make about 16 volts. However once the
load is reconnected to the dynamo it will not put out 16 volts. When
there is an electrical load the dynamo output voltage will drop
significantly, and the greater the current draw the lower the
voltage. Since voltage varies depending on a variable load, it is
best to test or adjust the regulator with no load so the results will
be consistent and repeatable.
When the thing is adjusted by the book, then reconnected and run
under load, the voltage will be substantially lower. When running
with only the ignition and fuel pump under power and the battery
fully charged, the voltage (at elevated engine speed) may be around
15.5 volts at the dynamo output terminal. With headlights and other
electrical equipment switched on the dynamo output voltage may be
around 14.5 volts. If the battery is significantly discharged and
drawing a lot of current during recharging, you might see only 14
volts at dynamo output, and possibly as low as 13.5 volts at the
battery terminals, depending on state of charge of the battery.
So if you are measuring system voltage with the cables connected
(normal electrical load), then 16 volts is too high, and 14 volts is too low.
My Mitsubishi 60 amp alternator will put out 14.52 +/- 0.02 volts
under any load circumstances with any engine speed of 700 rpm or
greater. Don't expect a generator to be that consistent. A
generator will put out far less current and lower voltage at low
speed, so it is intended to be adjusted to put out slightly higher
voltage (than the alternator) at higher speed and low load to make it
average out well enough to keep the battery charged with higher load.
You just have to get used to the fact that with a generator the
system voltage varies considerably with various load and engine
speed. Running with headlights switched off and battery mostly
charges, 15 volts at the dynamo output terminal is pretty good, and
it should never do 16 volts with the battery connected to the generator.
Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com
_______________________________________________
Mgs@autox.team.net
Archive: http://www.team.net/archive
Unsubscribe:
http://autox.team.net/mailman/options/mgs/mgs-archive@autox.team.net
|