AEKell@aol.com wrote:
> So what is the function of a Ballast Resistor?
> ( must have something to do with smoke regulation). Just disassembled a
> Unipart coil as supplied by Moss for MGA's. No sign of a resistor, just a
> coil, a core and some prematurely failed contact clips.
When you use the starter to crank the engine, it uses so much energy,
the remaining voltage only runs around 9 volts. Most car engines will
start and run okay on this 9 volts, but, just to make sure, especially
if the systems tend to become dodgy in time, some systems are designed
with a special 9 volt coil. These systems have to have a way to prevent
the 12 volts available when the starter *isn't* being used from burning
out the coil and points, so the system is designed so that the ignition
sees the full 9 volts available when the switch is in the START
position, but when it is relaxed into the RUN position, the 12 volt
energy comes through a ballast resistor, so the ignition still sees only
9 volts.
That's it in a nutshell: ballast resistor is added when the engine is
running but not when starting / coil is designed to run on 9 volts.
-Rock
--
Rocky, JJ Cale Band & Pratchett Books: http://www.rocky-frisco.com
Rocky's Mini Cooper Page: http://www.geocities.com/MotorCity/6437/
Mini Books: http://www.geocities.com/MotorCity/6437/rockboox.html
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