Wobling copter after loading 4.0.2

Last weekend I decided to upload copter 4.0.2 to my testing quad and do a few testing flights.
Batteries fully loaded.
Lifted it from the ground, but after only half a meter the copter started wobling like mad and was difficult to even land.
Looking at the dataflash logs, it looks like a sudden batery sag going from 12.2 to even 9.94
When landed the voltage goes up again.
The same happened with two batteries, experienced the same behavior.
Worn up batteries or something else?

Here is the link to the log: Dataflash log

Well, the battery appears to be shot but what size is this craft?

Definitely not a battery.
Tried with a new set of batteries and I get the same violent woblling effect.
My motors are working like mad, just look at the RCOUT…
ESC failure?
Should I try with 3.6?

Any hint would be appreciated.

It’s a RoboCat 270 with PixRacer, been flying it for almost 2 years without problems.
2200Kv motors, 5" tri props, 3S battery, GPS, FPV.

I have a somewhat similar 5" on 4S. I think you should run through the Tuning steps in the following link. Particularity INS_GYRO_FILTER. I have mine at 80Hz.

Are you saying that 4.0.2 messed with my settings?
It was a fine tuned craft, very responsive and stable.
Will check tomorrow (as I already locked my workshop) what the params are now as I remember I set them as per recommendation for small quads.
This is the first time I have problems when uploading a new fw version so I didn’t even consider a configuration problem. Well, shit happens…

If I had the Gyro filter set at 20Hz it would be a wobbling mess. I have a Pixracer also. After following the new recommendations also take a look at the notch filter. It helped on a quad that was already flying pretty well. If you have ESC telemetry it will work even better but not required.

Couldn’t wait till tomorrow…
You were right! The Gyro was at 20, and so were the other params messed up, brought them back to what they should be. Now I cant wait to test it tomorrow :slight_smile:
I was lurking the notch filter, but didn’t had time to really look into it, maybe now it’s the right time.
The forecast for tomorrow is strong winds, hope not all day.
Thanks Dave! You were very helpful.
Will keep you informed how things went (if weather allows).

Although the wind was a little bit too strong I couldn’t resist to test my craft.
It flies like a charm with the changes I made yesterday.

Big thanks Dave!

Ok, let me try the notch filter now…

Happy to hear it’s flying well again Igor! After applying the notch filter you may be able to tune it even tighter. There are 2 other related advancements that Mr. Piper has produced. Double Notch filter (which is a PR not yet merged) and in-flight FFT tracking (which is Master). Good things coming!!