Mark Chin
Published

Lithium Ion battery HAT for Raspberry Pi

Run your Pi remotely with a 18650 Lithium Ion battery.

BeginnerProtip15 minutes10,278
Lithium Ion battery HAT for Raspberry Pi

Things used in this project

Story

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Schematics

Pi18650 Block Schematic Diagram

Charging and Power Circuitry for Pi18650 HAT

Code

Pi18650 Code

Python
Python Script to Read Battery Status
def 	fuelguage_check_volt(self):

		#voltage is 14bit (reg's I and J) and temperature 10bit (reg's M and N)resolution 
		#convert I and J to 16bit variable, then (value / 65535) x 6V = Voltage 

		#read registers I and J (8 and 9 sequentially)
		voltage_msb = float(0.0)
		voltage_lsb = float(0.0)
		temp_msb = float(0.0)
		temp_lsb = float(0.0)

		all_regs = bus.read_i2c_block_data(FUELGUAGE_ADDR, FUELGUAGE_REG_ADDR_08, 16)
		status, control, acc_msb, acc_lsb, chrgthhi_msb, chrgethhi_lsb, chrgthlow_msb, chrgthlow_lsb, voltage_msb, voltage_lsb, voltth_msb, voltth_lsb, temp_msb, temp_lsb, tempth_msb, tempth_lsb = all_regs
		#print "all regs1: ", all_regs 

		
		#(voltage_reg_I_J) = bus.read_i2c_block_data(FUELGUAGE_ADDR, FUELGUAGE_REG_ADDR_08, 2)
		#voltage_msb = bus.read_byte_data(FUELGUAGE_ADDR, FUELGUAGE_REG_ADDR_08)
		#voltage_lsb = bus.read_byte_data(FUELGUAGE_ADDR, FUELGUAGE_REG_ADDR_09)

		#print "voltage_reg_I_J: ", voltage_reg_I_J
		#voltage_msb, voltage_lsb = voltage_reg_I_J

		#print "voltage_msb: ", voltage_msb
		#print "voltage_lsb: ", voltage_lsb


		voltage_16bit = float(0.0)
		voltage_msb = voltage_msb << 8
		#print "voltage_msb: ", hex(voltage_msb)
		#print "voltage_lsb: ", hex(voltage_lsb)

		
		voltage_16bit = float(voltage_msb | voltage_lsb)		

		#print "voltage_16bit: ", voltage_16bit


		#voltage at battery
		battery_volt = float(0.0)
		divisor = float(65535.0)
		multiplier = float(6.0)
		battery_volt = ( voltage_16bit / divisor ) * multiplier		

		print "battery_volt: ", battery_volt

		battery_capacity_percent = 0
		

		#battery capacity reference table
		if battery_volt >= 4.20:
			battery_capacity_percent = 100

		elif  battery_volt < 4.20 and battery_volt >= 4.15:
			battery_capacity_percent = 98

		elif  battery_volt < 4.15 and battery_volt >= 4.10:
			battery_capacity_percent = 95

		elif  battery_volt < 4.10 and battery_volt >= 4.00:
			battery_capacity_percent = 85

		elif  battery_volt < 4.00 and battery_volt >= 3.95:
			battery_capacity_percent = 75

		elif  battery_volt < 3.95 and battery_volt >= 3.90:
			battery_capacity_percent = 65

		elif  battery_volt < 3.90 and battery_volt >= 3.85:
			battery_capacity_percent = 55

		elif  battery_volt < 3.85 and battery_volt >= 3.80:
			battery_capacity_percent = 50

		elif  battery_volt < 3.80 and battery_volt >= 3.75:
			battery_capacity_percent = 48

		elif  battery_volt < 3.75 and battery_volt >= 3.70:
			battery_capacity_percent = 44

		elif  battery_volt < 3.70 and battery_volt >= 3.65:
			battery_capacity_percent = 38

		elif  battery_volt < 3.65 and battery_volt >= 3.60:
			battery_capacity_percent = 36

		elif  battery_volt < 3.60 and battery_volt >= 3.55:
			battery_capacity_percent = 34

		elif  battery_volt < 3.55 and battery_volt >= 3.50:
			battery_capacity_percent = 31

		elif  battery_volt < 3.50 and battery_volt >= 3.45:
			battery_capacity_percent = 29

		elif  battery_volt < 3.45 and battery_volt >= 3.40:
			battery_capacity_percent = 26

		elif  battery_volt < 3.40 and battery_volt >= 3.35:
			battery_capacity_percent = 24

		elif  battery_volt < 3.35 and battery_volt >= 3.30:
			battery_capacity_percent = 23

		elif  battery_volt < 3.30 and battery_volt >= 3.25:
			battery_capacity_percent = 21

		elif  battery_volt < 3.25 and battery_volt >= 3.20:
			battery_capacity_percent = 18

		elif  battery_volt < 3.20 and battery_volt >= 3.15:
			battery_capacity_percent = 16

		elif  battery_volt < 3.15 and battery_volt >= 3.10:
			battery_capacity_percent = 15

		elif  battery_volt < 3.10 and battery_volt >= 3.05:
			battery_capacity_percent = 11

		elif  battery_volt < 3.05 and battery_volt >= 3.00:
			battery_capacity_percent = 10
		else:
		      battery_capacity_percent = 0
		

		print "battery_capacity_percent: ", battery_capacity_percent


		#temperature conversion to celcius ------------------------------------------------

		#print "temp_msb: ", temp_msb

		#print "temp_lsb: ", temp_lsb

		temperature_16bit = float(0.0)
		temp_msb = temp_msb << 8

		#print "temp_msb: ", hex(temp_msb)

		temperature_16bit = float(temp_msb | temp_lsb)	

		#print "temperature_16bit: ", temperature_16bit

		#voltage at battery
		temperature_kelvin = float(0.0)
		temperature_multiplier = float(600.0)
		temperature_kelvin = ( temperature_16bit / divisor ) * temperature_multiplier	

		print "temperature_kelvin: ", temperature_kelvin

		temperature_celcius = float(0.0)

		temperature_celcius = temperature_kelvin - 273.0

		print "temperature_celcius: ", temperature_celcius

		

		return battery_capacity_percent, temperature_celcius, battery_volt

Credits

Mark Chin

Mark Chin

5 projects • 10 followers
Entrepreneur and Innovator of embedded systems, RFID and IoT.

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