Toked: a resistor does not regulate the current. It only partially limits it. Put in a better battery and it will be higher and put in a different load, and it will be completelly different.
Did you sell it to him with or without a diode? If you "regulated" the current on your diode, the current on his will be different. If you set the current on a dummy load, the diode may be severelly overdriven.
Like Dr_Lava said, it will be all over the place. A hard spike on power up, dropping later, not to mention the current ripple. Unregulated boost circuits can be worse than direct drive from a battery, through a resistor. If you set a current regulator to a certain current, it will be exactly that regardless of the type of the load. Without regulation it is actually harder to find a safe resistor. It has to be adjusted for each load separatelly, and takes a lot of time to make it safe for the diode, not to mention, that the current has to be lower.
With regulation, you can push the diode further and be safer at the same time.
These circuits are meant for LEDs, and even tho LEDs can take a lot more abuse, it wouldn't really hurt the manufacturer to make them regulated.
LEDs don't care about current ripple or spikes, they don't mind being overdriven ny 50% or more, they just keep on keeping on.
LDs are not NEARLY as sturdy as that.
I have a CREE Q5 in the above host (black), connected directly to a Li-Ion, and it's pulling 1.35A and dropping, but i would love to make it regulated, just so i would always have the same power untill the battery is empty. Still waiting for the parts tho. With an LD it is not just about always working at the same power, but also about surviving.
