It’s not a constant current.

The variable current supports the field winding of the alternator and is proportional (at a fixed RPM)

to the amount of current the Alternator must deliver to the buss.

It uses more current after initial start and tapers off when the battery recharges.

The minimum current is going to be a function of the load (number of other devices) that you are running.

 

So a better question might be to ask:

What is the regulator current draw when the Alternator must deliver a steady state load of 8A at cruise RPM ?

I picked 8A as a guestimate for nominal night IFR load. I have no idea what the answer is!

 

I am not sure it’s important to know the nominal current for the Regulator.

You typically want to know current loads so you can figure your endurance when the alternator does not work.

No alternator … than you can turn off the alternator field load. You want to know the max current so that you

can wire and fuse appropriately.

 

The LR-3 WILL short it’s input to ground on an over voltage detection to trip the alternator circuit breaker.

It is important that you properly fuse this.

 

 

 

Does anyone know how much current an LR-3 voltage regulator draws to drive a 40 amp alternator in a 12 VDC system?  Not how big a fuse to use, but how much current does it use?

Thanks in advance...

- Rob Wolf