LED current draw?

[GSS]

"difference in brightness" based on your subjective non-linear organic detectors (aka eyeballs), or something accurate? What is the current draw from their respective sources?

Could it be that your lights have a constant current driver? Or am I missing something obvious?

Yup just by eye
Pointing all five small Cree lights to the wall or ground in front of my feet in a darkened room with a variety of AA battery's and the 3 14500 trustfires.
Adding 2 different Efest's 14500 cells made it obviously way brighter.
Wouldn't a constant current driver not let that happen?

 

[Cyparagon]

Yes. If the circuit is a boost configuration (for instance, 1.5V alkaline powering a 3V LED), and the input voltage is higher than the load voltage (for instance, a 3.6V lithium cell powering a 3V LED using the same circuit), odd things can happen.