Alternator warning dash light

A little tech article for a simple idiot light. Pick up a two wire marker socket and the color bulb of your choice, or one of the flat bulbs but has to be two wire. Install socket in dash, lug one wire down on the ignition constant lug of your ignition switch. The other to the single wire to the alternator, this in no way involves the big wire on the charging lug. Wired correctly the light will light when switch to accessory on. Once started and if the alternator is producing at least 12v the light will go off once there is equal current on both sides of the light. If ignition switch is left on, without the engine running, this gadget will let you know, no more dead battery due to left on ignition switch. On a one wire alternator this is the ignition power source also, no additional wiring needed. And yes all kinds of things can be wired this same way like an alarm.
My dad was watching me wire this and said it is called an electrical shunt, sort of. An electrical shunt wired in line from source of power to destination with a resistor reduces power at its destination, here we could use a hugh bulb to reduce power but not what we are after. Pictures should be in self explanatory order with ignition on, light on. engine running light out alternator working and engine dies light back on ignition in the run position. Last should be just a look at the back of the socket I used. I am using this one on the cranking stand for my LS build. Hope someone was needing this. RTR

I use this to self excite the alternator so I don't have to rev the motor a little after cranking to get it to start charging.