Returns current in mA

def battery_discharge_current(self):
        """ Returns current in mA """
        msb = self.bus.read_byte_data(AXP209_ADDRESS, BATTERY_DISCHARGE_CURRENT_MSB_REG)
        lsb = self.bus.read_byte_data(AXP209_ADDRESS, BATTERY_DISCHARGE_CURRENT_LSB_REG)
        # 13bits
        discharge_bin = msb << 5 | lsb & 0x1f
        # 0 mV -> 000h,	0.5 mA/bit	1FFFh -> 1800 mA
        return discharge_bin * 0.5