adapting my second hand speed pedelec to my needs?

[meesterkweepeer]

Hello,

Any hints on the best way to adapt my newy-bought second hand speed pedelec to my needs?

Specs:
• battery: 48V removable in-frame, 2 pcs, nominally 500 Wh each, old so presumably little capacity left
• motor: 48V 500W Bafang/8FUN rear hub motor (uart)
• display: Kingmeter SW-LCD
• controller: no idea. Probably lishui or kunteng, but could be anything decent really.

Use case. I need to bridge a 70 km distance one way twice a week. I figure about 2 kWh of battery capacity would be ideal: 0.02 kWh/km* 70km = 1.4 kWh +0.6 kWh optimal charge/discharge range 15-85%.

Battery options. Please shine your light on these. Which one would you go for, and why?
• option 1. keep the two existing batteries as they are. connect one ~1kWh new generic battery each in parallel to each old frame battery. something like https://enerprof.de/fahrradakkus/rahmen ... 1200wh?c=9 . switch mid-way. Once the frame batteries die, keep only the hull and try to connect these directly. the least intrusive/expensive, most incremental way. fast charging.
• option 2. get the two existing batteries recelled (600Wh capacity) if that can be done. connect one ~ 0.4 kWh generic battery in parallel to each recelled frame battery. mid-way switch required. aesthetically pleasing. lowes point of gravity. Leaves me dependent on both old batteries functioning after recelling.
• option 3. get one new >=2 kWh softpack battery in a case on the luggage rack. try to get it to work with the controller and lcd or replace those. no mid-way switch required. slow charging.
• option 4. gut the frame batteries. add a 1kWh hard case battery on top of the frame battery holder. add another on the luggage rack.

Speed. A nice to have feature would be to be able to ride the bike at the EU speed limit of 45km/h. It is currently limited to about 40-42km/h. Not the motor. Just firmware. Changing that would probably require fiddling with the controller and/or lcd or replacing them. That pleads in favour of option 3.

Motor replacement. The motor might be perfectly healthy or it might be close to dying. Is a replacement uart bafang 500w rear hub motor still easy to source, or are the newly produced ones all can bus based? Any hints on that?

Free and open source software/firmware. I love this. Any hints on how to open up my speed pedelec as much as possible?

Kind regards,

Meester Kweepeer