Power supply

I’ve an ongoing concern about the power requirements to run an RPi, IMU, Camera, LiDAR, WiFi, GPS, ESCs and soon the Sweep.

Today, I bit the bullet, and cut open a USB cable, split the red-wire, and attached my multimeter to the split wire to measure the current:

 This shot was taken during a passive flight with the RPi 3B running.  All but the LiDAR was powered by the snipped power line i.e. RPi 3B, IMU, GPS, WiFi, ESCs and camera.  When my code wasn’t running, it dropped to about 0.4A.  I was stunned at how low it was!  Adding the LiDAR and Scanse sweep (135mA and 650mA max respectively according to the spec) makes a grand maximum total of 1.37A drawn.

And that means I should be able to simplify the system significantly with just one 2.4A battery bank running everything.  I don’t quite believe it, so the next step is simply try it!

P.S. I couldn’t resist it and plugged the Scanse Sweep in and ran another flight; 1.07A was the highest achieved.  This wasn’t operating its LiDAR, just rotation, but it’s LiDAR is just another Garmin LiDAR-Lite V3, so the total with those two comes out as 1.34A, confirming the best guestimate above!

P.P.S. That went so well, I swapped PCBs to now everything is fed via the RPi micro USB cable from a 2.4A battery bank. I even attached the sweep, and it still only just touched 1A. Next step is to get the rain to stop, and try this for real.

P.P.P.S. I did a very short real flight and at all worked well, confirming each problem over the last couple of weeks was due to SD card corruption. I hope to get a video tomorrow (weather permitting), and then move on to add Scanse Sweep object avoidance.

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