As a disclaimer, I've not bought a or sold any controller yet.
1. Battery costs can easily out pace the controller/display cost. Thus far, beyond the supplement diagram, there is no BMS or battery system construction guidance from Adaptto.
- When using JST splitters, there's reports of blowing the controller due to either intentionally or unintentionally disconnecting the BMS/mains in an out of order fashion. So to do it safely, it'd seem you're limited to one balancing board per 4s.
- Should you go beyond the 7 balancing boards the BMS comes with, the bar graph display does not cleanly show the additional balancing boards and there seems to be quirks such that they're not being analyzed properly. From the supplement, they mention a BMS channel B that is to be used when the number of balancing boards exceeds 16 but there's no mention of any best practice usages or upper limits for board counts.
- The boards are 4s boards and without guidance, a safe and limiting bet would mean use of only 4s cell groupings. The supplement mentions that it's easy to swap but the reality is that you must solder the intra-BMS board connections (beyond 4 boards). Adaptto needs to make intra-board connectors and for goof proofing, I wouldn't use JST connectors and would recommend connectors that lock.
- As is, there's no real cost savings here with the number of boards needed and high the cost for each.
- The documentation around battery maintenance and preservation is non-existent. Until this has been fully fleshed out, I'll assume that battery safety and longevity will be better served by the Satiator with the charging done offline from the Adaptto.
- Charging & design considerations seem problematic. Without a full charging solution with charger, one has to guess as to the relative safety and proper handling of differing battery chemistries. Along with this comes the need to remember to exit charging mode on the display such that things don't break. Oh, and don't forget, per the supplement, exploitation is strictly forbidden in charging mode, whatever that's to mean.
2. There's still a guessing/troubleshooting cost that exceeds others. There's only two sources (a duopoly, if you will) from whom you can order Adaptto. Neither offer full kits or any guidance on what extra parts (e.g. throttles, brakes, sensors, chargers, connectors, circuit breaker etc.) work without undue experimentation.
3. Right sizing is still a wild guess. True, there are resources out there we can use to model (thanks, Justin) but I could not locate the information needed to create a custom controller. Nor is there any easy or readily available indicator of optimal matching of controller to motor and to battery properties.