On 22 Mar 2016, DaveC wrote
(in nal-september.org):

Perhaps I am missing something. The battery terminals will be at the
battery voltage, no? So why would you use 4 volts which is at the
output? It would be 4 volts times the LED current or the battery
voltage times the input current.
Rick


Yikes! Of course youre right.

Thanks.


Just measured working light of same model: using power supply @1.5v (measured
at flashlight battery terminals), the current from the ps is 400 mA.
Estimating 75 percent efficiency that makes about 450 mW.

So a 1/2W replacement LED might be what Im looking for.

Thanks.