An AC charger is just a smart switch box - it tells the car how much current is available and confirms that the car is connected, but just switches on to pass power through - it doesn't regulate anything, or convert AC to DC, or change voltage. So yes, you need a charger, which is normally onboard the car; if you don't want to mount a charger on a kart, you need a DC charging connection to the cart instead of an AC connection.
I don't know if they're all set up this way, but an Orion BMS communicates with the charger by CAN to determine what the charging power and thus AC current will be, then negotiates with the EVSE (the Juice Box in this case) over J1772 to turn on the power.
I don't know if they're all set up this way, but an Orion BMS communicates with the charger by CAN to determine what the charging power and thus AC current will be, then negotiates with the EVSE (the Juice Box in this case) over J1772 to turn on the power.