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EV-charger based on ESP32

This software is based on this code and is extended with MQTT support:

Required libraries

  • PubSubClient (MQTT)

Building the software

Copy the config.h.example file to config.h and change settings (WiFi / MQTT / pins / etc).

Open ev-charger.ino with Arduino IDE and compile/upload to ESP32 module.

ESP32-WROOM-32 Pinout

 3v3 to opamp _____________________
       3.3V--|*                   *| -- GND
 Jtag Reset--|*                   *| -- GPIO_23  
    GPIO_36--|*                   *| -- GPIO_22
    GPIO_39--|*                   *| -- GPIO__1
    GPIO_34--|*Analog IN          *| -- GPIO__3
    GPIO_35--|*Current sens       *| -- GPIO_21
    GPIO_32--|*PWM 1KhZ           *| -- NC / GND
    GPIO_33--|*230V Relay         *| -- GPIO_19
    GPIO_25--|*                   *| -- GPIO_18
    GPIO_26--|*                   *| -- GPIO__5
    GPIO_27--|*.                  *| -- GPIO_17
    GPIO_14--|*                   *| -- GPIO_16
    GPIO_12--|*                   *| -- GPIO__4
       GND---|*                   *| -- GPIO__0
    GPIO_13--|*                   *| -- GPIO__2
    GPIO__9--|*        Temp Sensor*| -- GPIO_15 <---> Dallas DS18b20 Temperature sensor
    GPIO_10--|*                   *| -- GPIO__8
    GPIO_11--|*                   *| -- GPIO__7
       5.0V--|*   EN  USB  BOOT   *| -- GPIO__6
             |____**__| |__**______|

Charging States:

State Pilot Voltage EV Resistance Description Analog theoretic (PWM 1khz)
State A 12V N/A Not Connected 3.177 V = 3943 of 4096 on ADC
State B 9V 2.7K Connected 2.811 V = 3489 of 4096 on ADC
State C 6V 882 Ohm Charging 2.445 V = 3034 of 4096 on ADC
State D 3V 246 Ohm Ventilation Required 2.079 V = 2580 of 4096 on ADC
State E 0V N/A No Power 1.713 V = 2126 of 4096 on ADC
State F -12V N/A EVSE Error 249.198 mV = 309 of 4096 on ADC

Calculation for PWM signal to charge @ x AMPS: (valid for up to 51A) AMPS = Duty cycle X 0.6 (duty cycle is in %) Duty Cycle = AMPS / 0.6

example: 6A / 0.6 = 10% PWM
        16A / 0.6 = 26.666% PWM
       10% PWM * 0.6 = 6A
       20% PWM * 0.6 = 12A
51-80A, AMPS = (Duty Cycle - 64)2.5

            
            Op-AMP circuit:

        
                     3.3V       Pilot to car (PP pin on EV charging plug)
                     |          | 
                     R47K       |--|<-| TVS diode-P6KE16A->GND
                     |          |
         GND---R68K--|--R200K---|
                                |                    
                                |                                  ____________________
                                Pilot -- R1(1KOhm) Output1 Pin_1  |*                  *| Pin_8 +VCC (+12V)_____________________
10K-10K voltage divider from 3.3V->inverting input(1.75V)  Pin_2  |*      LF353       *| Pin_7 Output2 (not used)              |
                                        From ESP32 GPIO_32 Pin_3  |*      OP-AMP      *| Pin_6 Inverting input2 (not used)     |
                                        -VCC ------- -12V  Pin_4  |*                  *| Pin_5 Non inverting input2 (not used) |
                                                |                 |____________________|                                       |
                                                |                                                                              |
                                GND---->|0.1uF|---|0.1uF|->OP_AMP_pin_8(+12V)__________________________________________________|