Had three brown outs in one flight. it was scary

[coolgabsi]

Warp 360, flying very high.. saw the blades stall all of a sudden and lost control.. heli drifted away.. and then came back to life.. Scared I tried to get it to hover and I was still in ID up 2.

Tried to get the heli down, but figured if I could recreate it. yep I did recreate it, and the heli blades stalled. The heli drifted behind the tree line and dissappeared behind them. I panicked and wanted it to go higher so set to full throttle full pitch.

The heli was no where to be seen , and all of a sudden it appears rising above the trees!!!!!!! WOW that was a lucky break. very excited I brought it back slowly, and coming down, the heli tried to pitch up and stall again, with no input making any difference. the heli was dead. and all of a sudden AGAIn the stupid thing comes to life.. I land it.. take the battery off.. on the ground everything weas just fine. couldnt make it brown out again!!!!

It was nuts! I had heard these issues with MKS DS92A servos as they are power hogs and my BEC was 5A peak. (external).

Went through Castle logs, and found three drops in throttle input going to the castle ESC. The ESC never turned off or reset, I'll post the graph and let you see it too.

Bought Castle 10A BEC and replaced my current one. Hopefully this wont repeat. Made sure that the ESC was up to date with firmware but it really didnt show any signs of issues in the logs..

Scary stuff. Just wanted y'all to be careful too

 

[EyeStation]

Wow, that behind the tree line could have been bad if there were others over there. I bet you were thrilled beyond belief to see it rise from there though.
How you were able to bring it back after all those failures is mind boggling.
Congrats on no rebuild necessary and your cat-like reflexes.

 

[cml001]

Wow!!!

 

[murankar]

Good save, would have dumped it. What in store for the old BEC?

 

[pvolcko]

Scary stuff. Can't believe servos on a 360 size heli would draw enough power to brown out the system. Hope 10A covers it.

 

[coolgabsi]

yeah exactly.. These servos are power hogs. The old BEC is western robotics hercules. Its not being used Uri. Still good and working..

here is the log




You se "Throttle In" goes to "Zero" 3 times. Temperature readings are constant so ESC kept logging the whole time

Also Watt output (power output) drops to zero, but the voltage in (battery voltage) is still there and way above cut off (19.2 thick red line) ...

 

[Tony]

Someone is trying to tell you something. And that something is, "stick with the large birds" lmao. Lost the 450, lost the plane (can't remember what plane), and now the 360 tried it's best to go down so you could not find it. hehe

 

[treff]

WOW! The frightening thing, and it is the thing That lurks in the back of my mind after loosing heli in the tree tops is..................OTHERS. Not
the heli, that does not matter. What matters is where it's going to come down. Lucky this time but this is a very dangerous hobby and the need to think
and fly safe is paramount. Glad you got the heli back in one piece, more glad no one was injured. Those graphs are brilliant and tell the story Gaba. Very good
gear indeed to see what was happening. Cheers

 

[Ken Jackson]

My buddy had the same problem with his 700 shutting down intermittently. It ended up being the signal pin in the connector plug where it plugged into the Receiver. It was intermittent but once we found it it was obvious. The plastic retaining clip was broken and the pin could wiggle enough to cause the same graph. His only happened when inverted or coming out of inverted. Of course it happened the day he let my fly it and I auto rotated for my first time. In a panic but I did it. I was told you have to be an expert to auto a 500 so I never tried. All I broke was the front landing skid.

Just my thought,

Ken

- - - Updated - - -

I agree with Tony stick to the big birds. A 500 is my biggest and it is so much more comfortable to fly. 450/360 are just too small. OK for hovering and up close 3D. I losts tail orientation a lot with 450s.

 

[coolgabsi]

360 is closer to 500 than 450 lol just the way it is

I do love my big birds but this is my practice bird and so much cheaper to operate

Can't get rid of my warp. It's just a beautiful bird. A great design!!

 

[pvolcko]

The interesting piece on those graphs is the input voltage line on the second graph. It dips down quite a bit at each throttle loss, appearing to precede very slightly (second loss doesn't show it, but that is probably sampling/fencepost error, not sure what the sampling rate was for this graph). On the first and last drop out there is a massive wattage spike preceding too.

Did these occur on hard collective maneuvers?

There was an earlier throttle and power jump with associated voltage dip, but at the time the source voltage appeared to be around 23V and the dip hit around 21.5V. The later voltage dips hit when the battery was at 22-22.5V and dipped to 21 (First) and 20V (last).

The battery appears to take a dramatic dump from the start of the flight through the first 40 seconds, going from 25.2V (full charge) to 23.5 by 30 seconds into the flight and 22.5V by 60 seconds into the flight. When you shut it down it recovers to 23V resting voltage, but during flight on the hard throttle hits, even at 30 seconds into the flight you're hitting 22V dips and 21V dips at 60-70 seconds in and 20V at the last dip at ~130s into the flight.

I'm thinking these things:
1) Battery is on it's way out. I would expect the decay curve to be shallower and the power spikes to not cause such dramatic voltage dips. That or it was an unusually cold day and the pack was cold, affecting power delivery capacity and causing larger voltage dips.

2) Too much collective pitch for the motor and power setup? What ESC is on this? What battery ratings? You're spiking upwards of 40A draw on the throttle punches, preceding the voltage dips and throttle cuts. Maybe you're running on the ragged edge of what your batteries can do (in the environmental conditions they were in) and ended up starving the BEC and Rx/Servos for power.

3) I'm not exactly sure how switching BECs work, but I'm assuming they chop voltage input on a time proportion basis into a filtering circuit to smooth the output. Higher chopping frequencies based on increased load (to maintain duty cycle and overall voltage output, but increase current availability). That would explain why they can't deliver high current with high voltage inputs (they get better with input voltages closer but still a bit higher that output voltage). I'm assuming there is some sort of initialization where they determine input voltage and guesstimate cell count and all that in order to select it's conditioning circuitry and chopping rates and all that. If the voltage is dipping that much compared to startup voltage maybe it is having to reset to a different conditioning parameter set. On those voltage dips and three cut offs, you dip to 21V or lower which would be interpreted as a 5S input voltage. If coupled with a high current load it may be having to reinit to a higher base duty cycle (lower input voltage) and higher frequency (high current demand).

Some combination of the three, perhaps.

I'm doubting the servos were drawing enough to put the BEC into current overload protection mode. WR BECs are renouned for being pretty resilient and able to deliver over rating, especially on a "punch" basis. Did you ever notice it coming down and being hot to the touch? I'd suspect that you are hitting what amounts to a sort of LVC on the BEC due to the main battery voltage dips being so low on throttle punches.

Maybe something is running tight? Bearing siezed? Putting undue load on the power system. Change in collective pitch setup? Or, like I said earlier, battery is on the way out or environment was affecting it so it was sagging heavily far earlier in the flight than normally occurs.

 

[coolgabsi]

You see that cause u had my throttle at full positive pitch.. That's 13degrees of pitch the fully stopped motor has to pull through.. I would see the blades almost stop before the motor would come up. The throttle would open, and the tail would whip like a couple degrees which basically was a sign of a high load

Notice when the voltage drops that same instant wattage is high.. So there is a lot of current being produced by the pack. When current demand goes up immediately, voltage would drop a little.

Even if the battery was dying, the rx is being powered by the bec so that is not causing it. Till the coltage drops below cut off that's not an issue

This is why I love to have this graphing feature

 

[coolgabsi]

No mks92a and 92a+ are known to run over 7A at high load. WR was peak at 5A

If you look at compass forums, this bird was coupled with mks 92a as a good setup, and many people saw brown outs. I just didn't think too much of it.

Bearings are all smooth.. Very smooth. I checked that.

Mks servos are seriously power hogs.

Ohh also if you notice, the voltage drop comes when the throttle shoots high and demand increases.

WR bec works at as low as 11.1V (3s pack) so that's definitely not the issue. The power loss happened not when I punched throttle but

1) when hit self level on the ikon

2) when I flaired up before landing

3) randomly (actually this was the first time)

 

[coolgabsi]

But I promise I am
Looking into what you said as I haven't flown it yet. If it doesn't get fixed... Battery will be checked. I'll go ahead and check the IR right now and reply back.

 

[coolgabsi]

Alright the batteries are at 11mili ohms/cell

 

[Graham Lawrie]

Lucky man Never had a brown out amd by the sound of it i dont want to either

 

[Graham Lawrie]

Love the graph features wish mine had that , so much information

 

[coolgabsi]

THE CULPRIT WAS FOUND

Brown outs of my Warp 360 - YouTube

I was not expecting to find this. I was checking for compatibility between my BEC and MKS servos. I read about some issues about it but the older version BEC's had that.

So while I was checking that out, I bumped the wire and saw the satellite flicker.. and thats when I discovered this! So glad this was found

 

[EyeStation]

Awesome catch there Gaba.

 

[Tony]

That is the EXACT same issue I had with the 600 nitro. I had two satellite wires that had a broken wire on them. For the Ikon install, I ordered 4 new satellite wires for it. Look closely at the satellite wires, you will find a broke wire right where it goes into the plug.