1.5V LED boost circuit board project

[Lynx_Arc]

One other forgotten thing is lights are typically rated at OTF lumens (out the front) vs Emitter lumens. I've read that from about 25% to 35% of the emitter lumens are lost in reflectors, lenses, and optics in LED lights. If you assume 30% loss to get 100 lumens out you would need about 140 emitter lumens. This is very substantial as most lights these days are ANSI rated and that is OTF lumens.

 

[olo]

One other forgotten thing is lights are typically rated at OTF lumens (out the front) vs Emitter lumens. I've read that from about 25% to 35% of the emitter lumens are lost in reflectors, lenses, and optics in LED lights. If you assume 30% loss to get 100 lumens out you would need about 140 emitter lumens. This is very substantial as most lights these days are ANSI rated and that is OTF lumens.

Good point. And while I doubt that batteries will improve by 20% in my lifetime, reducing 25% light loss to 5% is trivial - smartphone camera modules are like $25 and have glass optics with AR coating in addition to the sensor. So a good lens is like what, $10?

 

[Lynx_Arc]

Good point. And while I doubt that batteries will improve by 20% in my lifetime, reducing 25% light loss to 5% is trivial - smartphone camera modules are like $25 and have glass optics with AR coating in addition to the sensor. So a good lens is like what, $10?

I agree that it is unlikely we will see any breakthroughs anytime soon that will make it to market at a cost effective price as I've seen a lot of reports about battery tech in the last dozen years or so that never manifested itself.
As for the loss I was saying total not each item that was that much loss but the combined set of items with each contributing a portion of the loss and upgrading the items to better quality items may still end up with a 15% or so loss in lumens at best the only way around it is to do away with any focusing additions and no lens at all. Perhaps a lens of high quality AR coated etc only loses 5-10% I'm not really sure what the number is but I recall several people long ago replacing lenses and reflectors in Mag lights to get a few extra lumens but also to deal with heat from high output incan bulbs.

 

[DIWdiver]

I spent some time looking for a constant power discharge graph for any AAA NiMH - couldn't find anything. But based on AA graphs I remember seeing I wouldn't be surprised if NiMH has double Wh of alkalines at 500 mW. And I don't see any lights producing 100 lm for 1,5 hours on a single NiMH AAA, even though that should be easily possible, since NiMH spends more time at higher voltage, where converters are more efficient.

I didn't look beyond that one DS for a constant power curve, because the one I wanted had to lie somewhere between the 1000 and 200 mA constant current curves, and those aren't that far apart for NiMH. For alkaline they are dramatically different.

At fairly low currents, the alkaline actually has higher capacity. At high currents, considerably lower.