Rize Fixie battery

[martiboy]

Thinking of getting a Rize fixie and mainly concerned about two things. https://rizebikes.com/products/fixie
1. Is the battery easily swappable? I don't mind some unscrewing with a screw driver for 5 minutes.
2. Is it possible to wire in a second battery in parallel? (Just curious, won't do it if 1 above is easily doable)

 

[martiboy]

Would something like this with matching voltage work? https://www.alibaba.com/product-detail/Mini-water-bottle-ebike-battery-pack_1600096976016.html