Robot-Sumo

Battery Managment System

Desired balancing current

Wh:

(I * V)*2 + 1

where I and V are the current and voltage of a motor at the highest efficiency

• I = 1.5A
• V = 12v

Desired battery capacity:

• 37w * desired working time = 37w * 0.5h = 18.5wh
  • = 1.54Ah (3 cell, 12 volt battery)

Desired balancing current

• For a 1.8Ah Battery
  • Assuming that the cells have less than a 1% charge-time difference at their end of life
    • 1.8Ah * 0.01 = 18mAh
    • With a balancing current of 10mA (internal cell balancing by bq40z80)
      • The cell can be balanced in 1.8 hour

Cell balancer and gauges

• Gauges with integrated balancer: Bq40z80

MotherBoard Design

• Low-level hardware control MCU: STM32f103c8t6

  • also could be used to run an onboard algorithm

• Customized Sensor module: I2C Fast Mode Communication

  • 400kbits/s
  • 3V3 powered
  • 3V3 SDA SCL GND
  • data flow: slave(sensor brd) to master(mother brd) only

• Motor Port: I2C Communicaation

  • 12V powered
  • VCC SDA SCL GND (Port)

• Edge Sensor

  • 3V3 powered
  • *Signal GND VCC 4

• 12V power port for charging or powering

• Battery: SMBus Communication

  • 12V battery pack power supply
  • SMBC SMBD
    • Remaining fuel
    • Battery state (Temp. Storage... etc)

• 12V->5V->3V3

  • 12V -> 5V

    • LM2596-5V buck converter

  • 5V -> 3V3

    • RT9193-33 LDO

• NRF24