So exactly how much is lost in the spring any way? Is the resistance due to a lack of surface area or the mechanical properties of the metal the spring is made of? Do the electrons flow on the surface of the metal or through the core? Exactly how conductive is solder? how much pressure needs to be applied to the contact surfaces so that maximum conductivity is achieved? Would there be any advantage to making a flashlight body a positive conductor and rewiring the flashlight altogether. If power runs to ground then why not put the ground closer to the business end? If the body of the flashlight would act like a capacitor, would that overcome the loss? Or better yet what if the body of the flashlight were some awesome meta-material the could transform heat energy into electrical energy?
That is what we need. A super conductive host that acted like a peltier junction to reclaim the lost energy from heat.
Understand about maximizing run time, that’s what 7 levels are for. With ToyKeepers UI allowing a reverse action from the standard tail clicky the high drain modes need not be entered into. Mine always start on moon, off with the clicky, reverse down if a selected mode has been determined to be too high. Easy enough to manage cell life and heat, Turbo is there if/when needed.
I like little lights that think they’re far larger.
I am thinking more exotic. How about a phosphor bronze coated carbon nano tube with inlaid rare earth magnetic crystals weaved in a counter opposing position binding an electromagnetic energy field which propagates an electric current into a hyper excited state thus releasing copious amounts of free energy that blue shifts an LED into releasing a spectrum of light that……………………….
what you really think I am going to divulge my plans to take over the universe? NEVER!!!
My old RayOVac 2 x D incandescent from Ebay had a rusty spring so I shoved copper braid over the wire of it, following the helix, and closed the ends with solder.
:FACEPALM: 
With ToyKeepers UI allowing a reverse action from the standard tail clicky the high drain modes need not be entered into. Mine always start on moon, off with the clicky, reverse down if a selected mode has been determined to be too high. Easy enough to manage cell life and heat, Turbo is there if/when needed.