Question: Best method for stopping Teensy USB powering battery loads

Hi everyone,

I have a Teensy 4 powered from a 7.4V battery, that goes into to a 5V regulator. The 7.4V battery also powers 3 motors directly.

When I have the teensy powered by a USB I've noticed the motors are also drawing power back through the regulator from the Teensy. I understand I could add a Schottky diode at the 5V line of the regulator to prevent this or a mechanical switch.

Questions:
  1. Does anyone know a better method (lower voltage drop, less power lost when using battery) they could recommend?

Thanks for any tips or suggestions :D

battery.png
 
Well the simplest approach might be just to cut the solder trace that connects the USB and VIN. The pinout card (https://www.pjrc.com/teensy/pinout.html) shows where the trace that you have to cut is. IIRC, the first set of pinout cards did not have the backside printed, but the cards from the latest Teensy 4.0's now have it.

If you cut the trace, the Teensy will not receive any power from the USB. You will need to always power the Teensy with the external power. Given that you need that power to run the motors, I doubt you would want to run the Teensy just on USB power.

You could of course put a mechanical switch in there to manually set whether the Teensy draws power from USB or not.
 
Back
Top