Drone just rolled left after connecting two 4 cell battery in parallel

I connected two 4 cell battery in parallel and did a flight test. There was a sudden roll to the left, the reason of which I cannot find. I am attaching the log file along with this. Kindly look it up and let me know if you can understand the reason. Also look for the RCin VS RCout graph for roll channel. Initially in the earlier two flight test that I did, battery fail safe got engaged even though the voltage was way above the failsafe voltage.


There was a sudden commanded roll.
Have a look at RCin

Maybe an RC problem.

If you had 2 batteries this flight, then one battery would not have cut it.
Have a look at your voltage sag in flight, especially when power is commanded.
The 2 batteries are barely keeping up.