Battery module

[meeDamian]

This one should probably belong to a "case" repo, but we can move it there after @BTCln creates it.

@hitchcott has suggested this as our UPS solution. I think it might be perfect, but I also think we should try to find it cheaper somewhere.

(screenshot in case Amazon listing gets deleted/changed)

[nolim1t]

That looks cool. Maybe @noaho might be able to find something when he goes to Shenzhen.

[meeDamian]

Yeah, I strongly believe that if we find it for a good price, it can be a really great and useful addition.

Paging @BTCln as including it in a box design as early as possible might be a good idea - ideally in a way that's optional.