LED Flashlight Efficiency

I was wondering is there any compromise in efficiency, when a manufacturer makes one circuit for a LED flashlight that can work safe-fully with all battery types (Li-on, NiMH, Lithium and Alkaline)?:thinking:

I believe that there would need to be a compromise to handle different types. Alas I'm no pro however, someone else needs to chime in.

Bearcat said:

I was wondering is there any compromise in efficiency, when a manufacturer makes one circuit for a LED flashlight that can work safe-fully with all battery types (Li-on, NiMH, Lithium and Alkaline)?:thinking:

Click to expand...

Unfortunately, yes there is, however, as opposed to thinking battery types, think input voltage versus output voltage. I.e. you can make a highly efficient regulator for when the LED battery voltage is above the LED voltage. You can also make a high (maybe not as high) regulator when the LED voltage is above the battery voltage. The issue is where you don't know whether the LED voltage is going to be above or below the battery voltage. In that case it is difficult to make a highly efficient regulator? With a bit of intelligence (I did this once for a non LED app), you can switch in a variety of regulator circuits dependant on the input/output characteristics. However, that is niether small or cheap.