The battery normaly has a battery management system (BMS) that deals with balancing and cut outs. Like your HK charger works with lipo.
But the power displays seem a bit basic and don't factor in load droop.
And the reason I have just read and not got involved was... Personal insults and lack of reasoned debate.
Asking me what planet I live on suggests I am strange because?
Detail in federation or super state. It's not significant.
What is is common law, money and self interest. No war and freedom to live and work.
Most people just want tomorrow to be like today but a little better. We don't need a revolution.
Motobility scooters do 8 mph a 250 watt motor can do this easily.
One motor will suffice. Three batteries will give you the required voltage.
Range is dependant on ah the more the better, and weight and hills, less is better.
You already cycle at around 15 mph. Having the electric will make little difference. It's range that increases not speed. ( unless it's seriously hilly)
Torque sensor will give you the most natural feel. The other advice is test ride with test ride.
The only other way to increase the speed is to...