<VV> Bulb failure

[David B. Neale]

Frank is quite correct.  The highest voltage available on the Corvair, (other than from the ignition coil), is a nominal 12 volts; in fact, it can go up to just over 14 volts under certain circumstances.  The bulb, any bulb, cannot be forced to take more current other than by increasing the voltage across it ... or by lowering the filament resistance.  Since the latter isn't possible here, then we are back to applied voltage.

Wiring a bulb from a Corvair in series with the starter motor will merely result in the bulb lighting to near-normal brilliancy, because the resistance of the motor is so low.  The filament will therefore pass its rated current, or nearly so, and burn normally.  In the case of a 36 watt bulb, one can reckon that the bulb will draw 3 amps when 12 volts are applied to it.  The starter motor would draw literally hundreds of amps when 12 volts is applied to it ... but a bulb in series would limit the current.

In fact, the bulb would be "happier" when wired in series with the starter motor, because the (albeit low) resistance of the motor would limit the current to the bulb, (very slightly), such that the bulb would be slightly under-run; not quite so brilliant; and would have a longer life.

David




"Frank, try that! The bulb will explode!! GGGG

Matt Nall"