Originally Posted by FireIslander
When I was looking for the alternator
I read so many different posts on this without any one being definitive. It was one of the threads I read about the bulb being a bulb and not an led. something with the ohm rating.
OK, here is the definitive answer.
Short version - If you are using a LED for the charge warning lamp you can add a 50 ohm 5 watt resistor in parallel
with the charge warning lamp. This will ensure initial excitation of the alternator
and perhaps more importantly, it will not cause any harm even if it is not needed.
The simplified drawing should be self explanatory but if not, please ask.
I am being conservative with the 5 watt rating, given the fact current
only flows through the resistor whenever the LED charge warning lamp is illuminated which is hardy ever and usually only for a short time. A 2 Watt resistor could be used but I would only do that if the physical size of the 5 Watt was problematic.
If you want the long answer of the why and wherefores of why the resistor is (or isn't) necessary and how it works, just ask.