Anyone know the real lumens per watt of a halogen bulb? Incandescent filaments are said to be around 15-18 lm/w but ive seen anywhere from 12-30 lm/w for halogen which obviously makes it hard to estimate the brightness of a halogen flashlight with any kind of accuracy. The lamp im trying to figure out is a 85w 12v halogen driven at 12.7v. I just use 20 lm/w as a rough estimate but if anyone has a more accurate number id appreciate it thanks 
