@Stefanj about programming card for MAX6. I think it’s this card But i am sure there are many alternatives.
About your battery and charging system. I see you going for 4x4S batteries. Probably, 2x in series, and 2x parallel, so you will get 8S, 12Ah. It’s nice, but you have two/three options regarding charging it.
1 option - Pain in the ass you have your 4x batteries, you have to open the box each time, and charge every battery with 4S charger separately. One after another. It takes time, and you have to disconnect parallel and series wires each time. you have to buy charger with integrated power supply, but 4S balance charger is rather cheap.
2 option - less pain in the ass, but still you have your 4x batteries. you have to open each time box to charge it. you connected, all the balance wires into one plug (there are some threads regarding how to do that), so you have to connect one plug to the balance charger, and all power wires to one plug, same it goes to the charger. you got one big 8S battery, and you probably need 8S, charger. It’s not that cheap, and usually needs power supply (the charger is only charger, and that charger needs DC power supply to work)
3 option - best, but needs BMS - battery managment system. you connect all the balance wires to the bms, Power wires also ( this setup is the best with the 2x batteries. If you go with 8S i suggest to use 2x 16 Ah 10C Turnigy Multistar Battery) i don’t know about voltage sag with max6 esc, but i have those two batteries in my Trampa twin motor setup with VESC contollers, and i have no voltage sag. I have 6364 motor’s, and i am heavy as hell, and all working fine.
Anyway, you have your batteries, connected to the BMS. Pluses: BMS protects the ESC from too much current in case something go wrong, or motor short. You dont have spark, when you connect esc to battery You have charging port on the battery case, so you dont have to open the box all the time. You just connect XLR plug to the port on your box, and wait for the battery to auto charge. It’s the easy mode system, most commercial boards use these BMS prottects and balance each cell, from overcharge, or too much discharge.
I think 120 A BMS is enough for the ESC, but i am not sure, since i use 2x VESC
BMS - an example from Aliexpress
Charger - i can’t access the site from where i am, so not sure if the link is correct, anyway you need 8S 33,6 V BMS charger, 4-5 Amps.
You can look at my build thread, to see how i did my trampa boards, with BMS/LiPo batteries.
I want to add, that although i am heavy(120 kg), and i use pneumatics, My board have a range of about 18-20 km, with this 16 Ah, 378 Wh battery.
Ofc, that’s my opinion. Some will say, that if you go BMS, it’s best to use Li-Ion 16850 cells, like LG HG2, but that’s more expensive.
I suggest to get some information’s on this forum, mainy about batteries, cos rest is fairly easy
Good luck!