Not a clue...but my guess is take the current going into the boost circuit and divide it by about 4 for an estimat as boost circuits are perhaps 50% efficient in older LED lights and red LEDs have a Vf about 2-2.5v if I remember. So if 50ma is going in you are perhaps getting 12ma to the red LED. I have measured the current into the boost circuit on a eled (white) uk2AAA before.... almost takes 3 hands and test leads to accomplish.