I’m installing lower KV motors on my 690-class quad - from 740 to 320.
I’m also going to go from a 4S to 6S pack - but the same mAh.
The props stay the same.
Of course I’ll need to repeat auto-tune - but I’m wondering if there are any other parameters I should consider before first flight.
The thrust-weight ratio was really high with the 740KV motors - hence the MOT_THST_HOVER of 0.09. I had to turn off LEARN to keep it from reverting back to 0.125. I suspect I’ll have a more normal value now as the thrust-weight ratio will be about half - and can re-enable LEARN for the hover value.
It seems like you are onto it - I think those are the things I would do too. Maybe set MOT_THST_HOVER back to 0.2 to start with, along with MOT_HOVER_LEARN,2
I’ve had some success with the change to 320KV motors and 6S battery.
MOT_THST_HOVER is now a more normal 0.29. And I adjusted the two parameters dependent on that value.
The copter was a bit mushy on first flight - to be expected because of the extra weight of the bigger battery. So I increased the pitch and roll PID’s by 20% - and that worked out well.
The efficiency is what I was hoping for - looks like a full 30 minutes with a 15% reserve. And I still have 16x5.4 props to upgrade to - which eCalc says adds another 2 minutes. Interesting to see less than 10A in flight.
I did another MagFit to adjust for the change in current flows. And updated amp-per-volt to get the amperage a little closer. All good.
I’m now getting a bit more vibe in Y axis - I’m guessing because of the HDMI cable that’s not perfectly secure - and in the prop wash. I have a plan for that.
I’m going to balance the props, just to be safe - and give auto-tune a try tomorrow.
If you’re interested - here’s the current eCalc, and log file.
