I am still struggling to find a battery that can output at the Amps that I need it to. This is not an issue of capacity: i.e. how much power the batter contains, but actually an issue of discharge rate (measured as "C"s). Some batteries hold huge amounts of power, but can only discharge at very low rates (useful for applicants like battery storage), while other batteries hold less power but can output it much faster without disintegrating (useful for EVs or hybrids). The problem is obvious when doing the maths: 3Kw motor running at 48V requires a constant output of 62.5A from the battery (w = va). Even worse, at its peak of 5Kw, it will be pulling over 100A. All of this on top of (say) 5a for the BOS (lights, controller, etc). I had thought it might be possible to retrofit an e-bike battery, but many of them claim to only be able to output 50A continuous - not enough for what we want. I will probably need a custom battery then, and that means either I have to learn how to build a battery - or I hire someone else to build a battery for me. I have found these high capacity cells, which claim up to 3C (i.e. they can discharge themselves at three times their capacity - in this case 120A CC). I'm not sure if I would need to BMS these together or not - as I can specify high/low voltage with my controller. That would, however mean adjusting my wiring diagram to have it charge through my controller or an external BMS somehow.