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       Little Free Library, part 3
       January 15th, 2019
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       The batter test is complete. I picked up a solar powered battery
       pack off Amazon and plugged in the pi, then left it in the dark to
       see how long it took to drain. It lasted just over 80 hours with
       no external charging. That's fantastic! 
       
       The unit claims that it can fully recharge in about 7 hours of
       sunlight. Given various seasons and overcast days, rain, etc, that
       should be plenty of buffer to allow the pi to remain perpetually
       active.
       
       With that, there's only 3 things left to do:
       
       - Update the captive portal screen to indicate to users that they
         should: 1) disable their mobile data, and 2) browse to
         http://littlefreelibrary.  The actual domain doesn't matter, but
         that one seems easy enough to remember. The mobile data thing
         came up in testing as a barrier to IP rules running on the Pi
         that would normally redirect you to 10.0.0.5 and serve the web
         content. Captive Portal may trigger, but I need a real redirect
         of a real mobile browser for downloads. If you're reading this
         and making a project that doesn't need javascript or downloads,
         just do it IN the captive portal. It's much easier.
       
       - Build a weatherproof enclosure. The plan is to 3D print
         something that can hold the battery and pi, or just the pi glued
         on the battery, or a big glass box, or whatever. Something that
         will survive in the woods and not be blocked by snowfall.
       
       - Take pictures and "blog" the full build instructions so others
         can replicate and share it. This is a cool project and I hope
         others can build upon it.