[solved] Reported AMPs used is too low?



I noticed my reported AMPs used ranges only from ~.5 A to ~0.8 A, never outside of this range even when I'm running all 3 motors full tilt.

I removed the batteries and attached their leads to a bench power supply set to 10V (so the OpenROV is powered entirely from the bench power supply, instead of batteries), and it reports the amps used ranging up to ~2-3 AMPs, or even higher if I try to run the motors without the propellors attached (likely not a good idea).

Has anyone else noticed under-reporting of AMPs used? Could this be a software issue?


Hi Mike:

If you download the controller board schematic from GitHub and study it, you'll see that we measure current draw at six separate places- the two battery tubes, the three motors, and a catchall point for all current that isn't going to the motors. I suspect that you're looking at that last point- I think it's called BRDI in the telemetry pane. That shows you the current draw of the controller board Atmega processor (Arduino), the BeagleBone, and the homeplug adapter.

If you want to see what the total current draw of the ROV is, you can add together the two battery pack telemetry points- I think they're called BAT1I and BAT2I or something like that.



Thanks Walt, indeed when I checked BAT1I and BAT2I (added with BRDI) the values match what my power supply said it was feeding. It seems like the big AMPs reported at the bottom of the UI should already be the sum of all of these (not just BRDI)?

However, I now have a much bigger problem: in testing the reported current draw, I seem to have broken something :(

I (once again, stupidly) was tested the motors without the propellors attached (I had pulled them off to let the water dry out), and the current draw became very high shortly, high enough that my bench power supply had to drop its voltage down meaning the draw was > 12 AMPs.

The UI froze, so I rebooted, but on reboot there is no power coming from the escs (the camera servo isn't running/humming, even if I jiggle the camera a bit), and I see no telemetry coming back, lights/lasers don't work.

I fear I just killed the controller board ... is there anything resettable on it? Or anywhere I can check for voltage to isolate what may have burned out? I tested PWR to GND on one of the escs and it's 0.


OK, phew, turned out I just had to re-upload the firmware! After that all is working again ... scary.

But I do think the UI should report the sum of BT1I, BT2I and BRDI (not just BRDI alone)?

closed #5