A few weeks ago when I was doing piro tic tocs I experienced two crashes. Before that I have trained tic tocs in all direction as well in circles, no issue at all with that.

Case 1: Goblin 380, HW 60A bec 7A, kst mg215ds, tail savöx SH-1257MG. I have done few piro tic tocs in each direction when I was doing another few Piro Tic tocs, suddenly heli drop like a brick with motor running. No reaction to rescue and sticks . Log say: low Voltage.

Case 2: T rex Cf 600, ds610/ds650, HW 100A bec 10A exactly the same ending, very bad crash, no log saved.

I also do piro tic tocs with T rex 700, ds610/ds650, Yep 130A external Bec Turnigy 8A running on 2S lipo, everything OK, no crash, rescue was after several Pirotictocs not perfectly straight but I dont need it anyway.

Can it be that Piro Tic Tocs are more demanding on servo power than tic tocs? On bench bec tester in spirit software was always no problem. Maybe HW internal bec dont deliver enought power ? 7A and 10A sounds like plenty so I'm confused. Both crash looks like system reset in flight. All cables were in places. No mechanical issue.

I always added some low esr capacitors
to my big heli in parallel to bec power
to avoid voltage drops

here there are some test that was made on different bec brands
https://www.vstabi.info/en/node/1327

turnigy is marked "to not use"
https://www.vstabi.info/en/node/1328

Hello,

the problem could happen if there is a position at which servos are binding with mechanics.
BEC tester might not reveal it, but if you will use pitch stick and give full collective pitch to a negative and positive and add full cyclic throw in all possible directions then you can find that something is not good and BEC could shutdown.
Another thing is that during fast movements under load there are much higher currents. It depends on how BEC is connected to the unit too, because some servo connectors are unable to deliver higher currents than 2A, usually maximum is 3A for continuous current. But peak current can vary a lot depeding on how firm the connection is.
So even with 20A BEC it could work as 5A BEC for example.
Capacitor can help in any way, but it could be enough to change connectors.

I believe you are using 2 leads from the BEC, right?

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Spirit System developer