MPPT SCCO v2.0

The SCCO v1.0 is a MPPT solar charger with multi chemistry battery support and a charging current of up to 4A based on the CN3795 IC.
The board features an adjustable output of up to 20V 2A. This device is mainly designed for low power applications such as IoT-devices.

  • 6,6V – 26V 4A (solar) input
  • Screw terminal, USB and USB-C Output
  • up to 20V 2A output, VReg has to be to lower then the desired output voltage
  • charge controller for single-or multi-cell Lithium ion, LiFePO4 or Lithium Titanate Batteries
  • up to 20V 4A battery charging current, input voltage has to be higher than charging voltage (VReg), set with external resistors
  • MPPT functionality, MPPT voltage set with external resistors
  • switch ESP12 and load manually
  • switch load digitally (to switch load digitally, manual load switch has to be in off position)
  • monitor input voltage, output voltage and battery voltage
  • programmable ESP12F (available Pins: 3.3V, GND, RX, TX, CS, MOSI, MISO, SCLK, SDA, SCL ADC, GPIO16)
  • LED status indication (if the LED is on, the battery is being charged, if the LED is off the charging is done or VIN is under VBAT or VIN is under 6.5V)
  • can be used as voltage source if battery is absent
  • overvoltage protection (no undervoltage or over current protection)

Resistor combinations:

External resistors for setting the VReg and VMPPT voltage are in 1206 package.

VReg resistor combinations:

  • 4.2 volts: R3 = 20.000 Ohms , R4 = 8060 Ohms
  • 3.7 volts: R3 = 20.300 Ohms , R4 = 9770 Ohms

VMPPT resistor combinations:

  • 9V: R1 = 2000 Ohms, R2 = 13.000 Ohms
  • 12V: R1 = 2200 Ohms, R2 = 20.000 Ohms
  • 18V: R1 = 2000 Ohms, R2 = 28.000 Ohms
  • 24V: R1 = 2000 Ohms, R2 = 39.000 Ohms

Charging current:

RCS\;value\;=\dfrac {0,12} {Charging\;current}

External resistor for setting the battery charging current (RCS) is in 2512 (1 watts) package.

RCS resistor values:

  • 1A = 0.12 Ohms
  • 2A = 0.06 Ohms
  • 3A = 0.04 Ohms
  • 4A = 0.03 Ohms

Efficiency: