I’m not having much luck finding any reputable sellers of LFP batteries. Anyone here have any recommendations? They sound to be slightly more stable and possibly more desirable to be strapped to my back.
https://www.batteryspace.com ← These guys are here in the SF Bay area. I may go swing by and ask them to prototype some LFP Batteries for me! 
@Pdwhite - Is there a convenient electrical spec info sheet somewhere that I can provide them to build from?