Some random outsider thoughts. Most have probably been covered by others, and the rest impractical:
- Bluetooth is a nice whiz-bang feature, and a way to get a lot of info to display all at once via a phone app, but I don’t see it as essential Very Nice, but not essential.
- Adjustable charge rate and cutoff voltages - maybe based on a few canned profiles and x number of custom profile slots. Make sure the user defined profiles are hard to save/overwrite. Definitely do not autosave the settings when backing out or going to a new profile.
- Positive Action required to start a charge / discharge action (no automatic start by default)
- USB output/charge port - connected to either 1 slot or smart slot selection combining by cell voltage
- Input power - standard barrel connector or, preferably, a USB C PD port. (too bad POE is high voltage and low wattage - can you imagine plugging your charger up to a network port and controlling it from any web browser on your subnet?)
- Command port to connect to a PC via USB for control, reporting and updates - maybe make it emulate a network connection so the command interface can be browser based?
- Recording activities to an onboard SD sounds nice, but how can you match up a log entry to a particular physical cell after the fact?
- case color - why not. Original iMac colors? A nice clear, smoke, or frosted semi-transparent? This would make activity LEDs easy to place by each slot.
- Accurate mAh and internal resistance measures are a requirement
- Display - Color is a Nice To Have, but a large, clear display that shows all pertinent info for each cell (at the same time) is required. Maybe put in a mid sized phone type touchscreen color display and do away with most of the physical buttons too?
- UI - I don’t have experience with anything other than my Zanflare C4, but here it goes… Keep the one button under each slot. Make them a slot selector instead of a slot display cycle. Have it set so you can click one to select it, but if you hold down on it, you can click other slot buttons for a multi-select. Two control buttons. Use one to select the mode / data item for each selected slot, the other to modify the values for the selected mode/data item for the selected slots. I’m not sure if the Start function should be a selectable mode/option under the first button and enabled by the second button, or a separate, dayglo red warning sign recessed into the case so you can’t accidentally press it.
- Long Cell Support - Heck Yeah!
- Storage Charge mode - set the desired voltage and it will charge / discharge to that point then disconnect the slot
- incorporate an Android controller — while this is a nice feature, I’m not all that comfortable with it. It would allow for a rich application control and upgrade path, and a nice UI if paired with a color touchscreen, but I know someone will insist that it have a wifi connection and it will become yet another IOT device waiting to be exploited. Then there comes the cost…