so I can answer my own question it’s not possible to run on only one battery/cell, tried it by cutting the wires/connections.
Regarding batterybar, does anyone know how it calculated the discharge rate? It’s just using the reported battery capacity and the capacity at a specific time to calculate right?
Anyways as of now I really discourage any one to get these: https://www.aliexpress.com/item/Free-shipping-5000-mah-lithium-battery-3-7-v-approx-8-inches-Sanei-N83-N86-AMPE/955308174.html?spm=a2g0s.9042311.0.0.3b2e4c4d9oFULd