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0-609-05
Plastic panel indicator light supplied with a 12v 2w incandescent bulb for use with alternator charging.
When you turn the ignition key, before the engine is started, a small current flows from the battery, through the incandescent bulb, to the alternator's field windings. This current is essential because it creates a weak magnetic field that is needed to "excite" the alternator and allow it to start generating its own power once the engine is running. The incandescent bulb's filament provides the correct amount of resistance for this process.
Once the alternator begins generating power, it provides voltage back to the other side of the light bulb. With the same voltage on both sides of the bulb, the current stops flowing, and the light goes out, indicating that the alternator is working properly.
