EV Charger

Through research, one of the more affordable and easy to use chargers was the Elcon UHF series of chargers. They appear to be re branded versions of chargers available off AliExpress at similar costs, but as a Californian company, we should be able to get more support from them if needed. Balancing weight and power, the 3.3kW charger seemed like our best option. With 3.3kW charging our 16.3kWh battery pack, it is estimated that it will take up to 6 hours and 40 minutes to fully charge our battery pack. This is well within the expected charging time during night time. The datasheet and CAN specifications of the charger is attached below. 

Electrical Interface Specification

Use the pin on the charger that indicates if it is plugged in and direct it to a GPIO pin on a CAN<->UART<->CAN hardware setup - identical to the Solar Masters and Motor Interface configurations. 

Firmware Interface Specification

When the GPIO pin indicating a charge is plugged in is pulled high the Charger Board sends a CAN message to Chaos requesting a transition to the charging state. Chaos will attempt this transition. If the car is in "Idle" mode this will succeed and then once in "Charge" mode Chaos will respond indicating it is ready to allow charging. In the event Chaos is in drive mode this request will fail; the car will need to be put in "Idle" mode and the charger removed and reconnected in order to trigger charging to start. There is also a button in driver controls that sets the car into "Charge" mode from "Idle" which is an alternative to re-plugging in the car. If the car is already in "Charge" mode Chaos will immediately respond that it is OK to start charging.

On the Charger Board side once both the GPIO pin indicating a charger is available and Chaos has OK'd charging it will begin charging (assuming no BPS fault has occurred). This is achieved by sending Charge messages (with a predetermined current and voltage) to the charger at a fixed frequency of 1 Hz. Similarly, the Charger will send a status message at a frequency of 1 Hz. This message will be rebroadcast to telemetry. 

Required Parts

To interface with J1772 charging stations. we'll need to add a J1772 female connector to our vehicle. UWAFT (UW Alternative Fuels Team) has worked with the charge port off of a 2014-2015 Chevrolet Volt. Electrically speaking, the receptacles should all be similar but the volt receptacle can also be purchased with the door hinge assembly and seals. The part numbers required are listed in the table below.

Datasheets