Since it is for a car, then these trip points are useless. First, for modern cars, the normal charging voltage (with engine running above 1500RPM, engine warmed up), is 14.2 to 14.5V....
Thresholds are 11.5, 12v, and 13.5. The 12v threshold should really be 12.6 to 12.7.
Yes, but it depends...Since it is for a car, then these trip points are useless. First, for modern cars, the normal charging voltage (with engine running above 1500RPM, engine warmed up), is 14.2 to 14.5V.
This condition is usually indicated by the ALT "idiot light" on the dash. However, if there is a partial failure in the diode trio (older GM vehicles) the idiot light is lit very dimly, and is hard to see during daylight.If the alternator quits, you would like to know that. This means it is your battery that is holding up the bus voltage (for now). The battery almost immediately drops to ~12.65V, and then discharges downward from there with no alternator on line.
In the schematic I've posted, the yellow LED is turning off and the green is turning on at 12.7v.If the voltage regulator shorts, applying full-field excitation to the alternator, the voltage shoots up held down only by the battery, you cook the battery, then damage appliances, so you would like to know that.
Vbat >14.7V, light the RED led, you have a runaway alternator.
Vbat < 12.7V, light the AMBER led, your alternator is not charging.
Otherwise, light the GREEN led.