Hi all..

After several successfully flights with 3s lipo and standard PID settings i decided to change out my 3s with 4s 5000mAh batteries.

But something stranges happen during waypoint flight in AUTO mode.

It was set to climb 150meters in a 1km flight path. Everything started just fine, spot on and i was really happy with the result due to the wind and gust.

When the Hexa was almost at 150mtr height, it suddenly smacks the throttle to the max 100% and the copter goes to the sky like a rokcet.

i grab my RC and switch the mode from AUTO to Stab and was able to get it down without any crash.

My Gopro camera was also onboard. ;)

After i tried one more time, Set point of 100mtr .

When the copter reach 60mtr, same thing happend, it suddenly gives 100% throttle and goes like a rocket up in the sky,

Im not able to find the root couse to this problem.   Please help.. 

The log also showing 11sat count at all times.

Can this be becouse of 4s lipo???  or is this just a coincidence?

When using 4s, i ha to change my Rate P from 0.150   to    0.110.



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The battery should make no difference. Your copter will fly a bit more aggressive with 4S and you should tune down you P value. With my quad I switch between 3S and 4S with a little change in P value. You might want to reset and reload and recalibrate again and manually enter your parameter values. There is a chance of carrying bad parameter values from old parameter saved files.

Seems like there have been many instance of a runaway climb in Auto and Loiter modes that I have read on the forums (or seen personally). Is it possible that this is being caused by not setting the new tuning values as per Randy in the V2.9 / V2.9.1 release notes?

I will try to do a Reset from Cli, and do a full recalibration.

I have never used anything else than v2.9.1.


I cant understand why i had several trips( Maybe 20 flights) with 3s with same flight path and never had a bug.



But quite a few of the many strange runaways is happening after many successful flights and with no changes.

Add fresh battery, start mission as usual, and it takes off, or crashes.

This is happening more frequently now with 2.9.1 but as yet no pattern has emerged to indicate any commonality, other than running 2.9.1

Can you post here all the logs of this unwanted event?
I think is not related to the number of lipo cell.



1 event is with 150meter setpoint, it fails in approx 135meter height.( two logfiles)

2 event is with 100meter setpoint, it fails in approx 65meter height. ( one logfile ) 


Let me also add one thing..

Im using GPRS 3G for telemetry, but i dont think it should have any influence in this case.

As said, i have had maybe 20 successfully flights with this setup before this issue occured.



Video of second event.  100m setpoint and error occur at 65m


My guess is that it's because of vibration.  So we know that sudden upward acceleration can happen if vibration is bad (we've seen it with many people as they move to 2.9.1).  The situation here could be that it's borderline ok but it goes over the line when either the motors go to full power or when the copter leans over and the x/y axis becomes more important for altitude hold.  I was wondering if you could enable the RAW messages in the dataflash log, do a stabilize flight and post them here (remember to disable the RAW message when you're done).

Also you should modify your INS_MPU6K_FILTER to be 20 and you can turn off the ITERM message in the logs..that's a big message and it's not very useful.

That does make sense, if you have a 4s you have the engines running a little more aggresivly, causeing excess vbaration.

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