6 motors with TB6612 driver + power requirements

Question

I am looking at the ServoCity Bogie platform - it comes with 6 motors.

The motor listed specs are:

• Suggested Voltage: 4.5 VDC
• No Load Current: 190 mA
• Max. Load Current: 250 mA

I was planning on using Adafruit's TB6612 based solution - it can handle "Power Supply current VM=15V max; Output current - IOUT=1.2 A(ave) / 3.2 A (peak)"

My questions are:

• Can I combine each side's 3 motors into 1 H-Bridge?
  • I assume so, and I would wire it in parallel. Is it then simply 3x250 mA = 750 mA draw?
• How do I calculate the battery voltage requirement?

A bonus question - The Feather board linked above has two of these chips; can I bridge the H-Bridge outputs to allow for a double amperage output?

H-Bridge => 2 outputs parallel => 3 motors in parallel.

If so, this would allow for slightly more powerful motors in the future.

Answer 1

1. Yes, You can combine each side's motors.
2. Yes, a parallel connection is proper one. Therefore, Your calculation of current drawn is also correct.
3. I don't see any strong need for calculation of the battery voltage. I'd rather consider calculation of battery capacity, as it will affect your working time, thus changing possible range of Your robot. I'd suggest using LiPo or LiIon batteries - these types of batteries offer slightly lower voltage than 4.5V, but have great energy density.

Bonus question: Yes, You can double Your H-bridge current by bridging its outputs. This is often used in minisumo category robots to drive more powerful motors. To do this, you should also bridge correct input pins: A_PWM with B_PWM, A_IN1 with B_IN1 and A_IN2 with B_IN2.