I put a couple of lights in my freezer for an hour, and compared their output before and after
there was indeed a drop in the maximum output when frozen, of about 20%
> I love flashlights as “things” as much as for light. But to keep my interest up, I need activities with them.
> This battery spreadsheet work is one such activity, and trying to understand how batteries effect light is another.
thanks for sharing your journey 
harmless fun with batteries…
I dont have a light meter recommendation… I cobbled something together that cost me $45, but you may prefer something more sophisticated… there is a good thread by djozz and Texas Ace is also a vendor for finished intergrating tubes…
and you can probably use ceiling bounce to get some idea of which light is brighter
as far as fun with throw… have you heard about the copper nano? 