I was hoping someone would answer this, perhaps they did and I missed it.
A quick and dirty explanation:
A generator uses mechanical power to create direct current. They tend to
require higher maintenance due to the commutator and brushes, which are
needed to make contact with the armature (rotating part of the device).
They usually need some external means of voltage and/or current regulation.
In order for a generator to charge the battery, it usually has to turn at a
fairly high RPM (Engine speed over 2000 RPM) so tooling around town "may"
cause you're battery to discharge even though everything in the charging
system is OK. This can be overcome by mounting a smaller pulley, but then
it may over charge the battery or fry the regulator when driven at highway
speeds. Finally, the armature uses copper for the windings which is
relatively expensive compared to alternators.
An alternator uses the same input power but creates alternating current
which is then converted to direct current using solid state electronics,
generally a diode trio. Like a generator, alternators also have a contact
with the armature; however, it is usually a simple "slip ring" that requires
little or no maintenance. Usually, they have the voltage/current regulation
built in. Alternators charge the system over a broader engine RPM band so
don't have the discharge/ overcharge problem mentioned above. They are also
usually induction machines, using a "squirrel cage" for the armature.
Typically, a squirrel cage is made from aluminum and is either cast, or
assembled from simple stock resulting in a lighter and much less expensive
device.
There are other differences as well; however, they are beyond the scope of
this course. The automotive industry has adopted the alternator because it
is less expensive to manufacture and is more reliable from a maintenance
perspective. I suspect these are both reasons that Lucas kept using the
generator for so long..... <-big grin->
-----Original Message-----
From: owner-spitfires@autox.team.net
[mailto:owner-spitfires@autox.team.net]On Behalf Of Patrick Bowen
Sent: Saturday, January 15, 2000 10:33 PM
To: spitfires@autox.team.net
Subject: generators vs alternators
OK, all this talk of generators has me wondering (through my ignorance)
exactly what is the difference between a generator and an alternator?
Patrick Bowen
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