BETA RUN: BBB Beetleweight Dual Brushed ESC v2

More info about the ESC:

LED indicator light & beeps:
Start up beep = ESC has just powered on – it is receiving power and is connected to motor(s).
Solid LED = Powered on. Receiver ready, ESC is armed.
Flash & beep with short gap = Powered on. Throttle isn’t centred.
Flash & beep with long gap = Powered on. No receiver signal.

Driving & Mixing:
By default mixing is enabled on this ESC – the servo connectors drive the following:
– white wire is steering (turning left/right) – usually CH1 on 
– white wire is drive (forwards/backwards)
These match nicely with the defaults of the  FS-i6 transmitter + flysky receiver (CH1: AIL, CH2: ELE)
If your turning or driving is backwards on your transmitter, you’ll want to reverse the appropriate channel above.
If you want to disable mixing, there’s solder pads labelled on the back of the ESC – you want to create a solder bridge between them (and then re-heatshrink the ESC) Each servo connector will control one drive side and you’ll need to set up your own mixing – see our guide.

Programming:
Dual ESC Companion Software (Windows)  – these ESCs can be configured with a BBB ESC programmer or an arduino. Tutorial video here. More info  & video tutorial on the programmer page.

Wiring diagram for two or four wheel drive:

Components in this example: 3S or 4S Lipo, Beetle Safety Kit, Breakout cable, BBB dual ESC & as BEC, BBB 22mm Motors, and Flysky Reciever.
Image made by Team DSC.

Overvolting guide:

All motors are limited by the amount of current they can draw, as electrical current generates heat and eventually burns out a motor. Combat robot motors are generally rated so that they will draw a suitable (non-firey) amount of current at the rated voltage in practice. Key background:

• A motor’s speed is proportional to the voltage used (more volts = more RPMs)
• A motor’s maximum current draw is proportional to the voltage used (more volts = more amps)
• A motor’s torque is proportional to the current draw (if the motor is heavily loaded / stalled, its producing more torque and drawing more amps)
• Heat buildup is proportional to the current draw (more amps = more heat)

Simply overvolting a motor yields more speed, current and torque but also more heat, meaning an increased risk of burning out the motor. By overvolting using an ESC with appropriate current limiting, we can still achieve higher RPMs, but keep the current draw and torque consistent, preventing any excess heat buildup. This on its own, would yield higher drive speeds. If we adjust the gear ratio to the wheels, we can boost speed and torque together!

Theoretical case study:

• A robot with BBB 22mm’s direct driven and a 4S lipo, can move at 10mph and generate torque to push a 2Kg weight.
• The same robot with 8S (and ESC’s limited to ~3.5A) can move at 20mph and generate the same torque to push a 2Kg weight.
• The same robot with an additional (e.g. 3D printed) set of gears (with a 1:1.5 ratio) can move at 15mph, and generate torque to push a 3Kg weight.
• The same robot with an additional (e.g. 3D printed) set of gears (with a 1:2 ratio) can move at the same 10mph, and generate torque to push a 4Kg weight.

Key takeaways:

• Overvolting should only be done with a current-limiting ESC set to an appropriate current limit (the limit will vary depending on your motors!) – current limiting may only be effective when driving 1 motor from 1 ESC.
• Overvolting in this fashion increases the maximum RPM of your motor, but not its torque output
• Additional gearing can be added to trade some/all of the extra RPM for extra torque.