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Weird quadcopter throttle issue.

#1
Ok so I have a bit of a weird issue with my quad now. This piggybacks on my battery selection thread and I thought I fixed the issue when I got a bigger battery. I also went with a traditional quad instead of deadcat which the crius seems to like better.

I took my new quad build on a ATG 650 frame for a short flight yesterday at my father's river house. It went good but I didnt have my FPV system setup yet. So, when it got too close to some tries and was facing me I inadvertantly flew into the tree when attempting to fly away. Anyway, the gembals and gps stablized it nicely but I couldnt see where it went and cut the throttle. A minor crash insued and I bent a prop. I even straightened the prop out afterward and flew it again without any issues other than vibration. I then replaced the prop today.

With the only changes to my quad are the one prop and the FPV transmitter, small battery, and wire connecting to the goprp. I attempted to fly today and the thing will not take off. It simply got off the ground about a couple of inches at full throttle. This happened after flying for about 5 minutes last week at home also and I chaulked it up to low battery.

I have the following setup.

DT700 motors
Turnigy 9x tx set with efsky module.
Hobbyking 20a escs
3000mah 40c lipo
10/4 props.
ATG650 frame.


Options I have considered.

-motors are underpowered
-one esc is bad
-crius megapirate software needs RX calibration after any changes (today I added home as here so it wouldnt to fly 90 miles home and changed failsafe to RTL removed loiter mode and replaced it with auto mode.)


Is there any options I have missed? I am really thinking hard on replacing the motors with some NTMs and the escs with plushes. However, I think first I want to build a smaller quad like a 350 to learn more with prior to flying the big one. It is still plenty big to use a gopro.
 

xuzme720

Dedicated foam bender
Mentor
#2
Options I have considered.

-motors are underpowered
-one esc is bad
-crius megapirate software needs RX calibration after any changes (today I added home as here so it wouldnt to fly 90 miles home and changed failsafe to RTL removed loiter mode and replaced it with auto mode.)
I doubt it's underpowered, I mean it flew well until it hit the tree. I also doubt it's a bad ESC. One bad one would only tip the copter in that direction or flip it. I'm leaning more to calibration or endpoint issues. Does it sound like it's still hitting the same rpm's as it did when it flew?

This is all of course assuming you have given the battery a fresh charge, just to rule that out...
 
#3
Yeh I have been charging it each time before flight. As for the RPMs I dont know but it cant be if it isnt lifting off. I know the props arnt slipping because I have the ziptie mod on all four motors so not to lose the props.

I had this issue before it crashed once too and I am not sure why. Maybe I need to look more into the calibration problem. I dont know why it would start and stop having the issue though. I checked all the connections to everything but that really shouldnt be the issue either if the thing is reving up high enough to slightly lift off.
 

xuzme720

Dedicated foam bender
Mentor
#4
Check the throttle setting in your "stick scaling" on the menu. It needs to be set to as close to 100 as your esc's will allow. I think the stock is around 85...? Also check your transmitter settings. If, like most of us, you use the radio for different models, it's easy to be using the wrong model with different settings. It's getting harder to do that now, but it used to be pretty easy with some of the older radios.
 
#5
Tried it again today now that I am back home. I went in and recalibrated the radio in the APM software. Took the thing out and flew it around for a bit. After about a minute or two I started to have the same issue again and the copter was getting caught on grass as it was hovering along the ground. None of the ESCs felt warm and the motors were slightly warm. Funny part was that when the thing started out I was taking off at 50% throttle. After a few minutes the thing was not bairly hovering off the ground at 100%.

I checked for stick scaling on the 9x and it only has throttle curve. That appears to be setup right. One thing is that the ESCs are calibrated but not flashed for use with a quad. I am wondering if they might be getting out of sync? New ESCs are not very expensive. I also want to build a small 350 size copter. So I am tempted to buy 4 hobbywind 40amp ESCs and put on 4 bigger motors. I could also get some smaller motors for the 350 and use my current ESCs since the throttle needed to lift a smaller copter will be so much smaller.
 
#7
I dont have my voltmeter handy but I have tried several different batteries and they read 75-80% on recharge. Yesterday the things were at 100% and it wouldnt fly.
 
#8
Come to think of it yesterday's issue started right on takeoff but my first take off was foiled after some grass clippings caught the gear and made the copter flip forward. Today's issue started after I flew too low and caught some tall grass on one of the motors and went ahead and landed. Is it possible somehow that the issues are popping up because the resistance is somehow throwing the timing off on the ESCs?
 

xuzme720

Dedicated foam bender
Mentor
#9
Sorry, I was mixing this one up with a KK2 issue, but you are using an APM board I guess? Have you checked in the planner that you are getting full throttle to the board? What you are describing sounds like it's still a power issue, as in voltage loss or shortage.
 
#11
Well I ordered some bigger motors / ESCs and a 450 frame kit. The plan right now is to take this frame and install the larger motors with ESCs. I am then going to take these motors and ESCs and place them on a smaller frame. This way they will have no trouble lifting the frame and electronics. If that does not work I will first replace my current ESCs with a 4 in 1 hobbywing 25amp. If that does not work I will then replace the motors. The current motors and ESCs will then be reserved for a future Bixler FPV project.
 

kah00na

Senior Member
#13
I think you need to check all your solder points. Besides just your wiring harness, if your motors came with bullet connectors on them from the factory, I'd suggest reflowing the solder and adding some more of your own solder. I had one motor that just wouldn't behave correctly and then after one flight, I tugged lightly on the power cables and out came one of the wires. I tried to remove most of the original solder and added my own that I trusted a little more. Then I did the same thing on the other two wires. I haven't had the problem since.

Also, are you using a 2S or 3S battery?
 
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kah00na

Senior Member
#15
3S batteries. I am slightly wondering about the hobbyking 4way pcb board also. I have ordered another wiring harness as well.
If your soldering skills are descent and you have some shrink wrap, you can just make your own. I've made a 3 different ones for three different tricopter frames. It isn't a big deal. You just daisy chain all your ESCs together and run another pair of small wires to your flight board so it can monitor the voltage (if yours does that). I make mine out of 14 gauge wire.
 
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kah00na

Senior Member
#16
In this video starting about 9:42, he shows how he makes a wiring harness for a tricopter. It isn't that much different than a quadcopter. You just have one more connection to solder in.

 

Cyberdactyl

Misfit Multirotor Monkey
#17
One thing to remember making an "enclosed" harness is adding an auxiliary + and - lead for future use. I ran into this issue with my old quad, but of course I went WAAY overboard by attempting to add everything, including the kitchen sink. :eek:

 

kah00na

Senior Member
#18
One thing to remember making an "enclosed" harness is adding an auxiliary + and - lead for future use. I ran into this issue with my old quad, but of course I went WAAY overboard by attempting to add everything, including the kitchen sink. :eek:
That looks a little "overboard" to me. :)
 
#19
I was going to make my own but for $2 I could buy one. I really like my gas soldering iron but the thicker the wire gets the more of a pain that it is. I couldnt get the wire hot enough with the tip on one of my batteries so I ended up taking the tip off and using the torch to solder it HVAC copper stile. The wire is now fused perminantly to connector and the connector is slightly off color but it is a very good connection.

I am not really sure, if it is the connector, why this problem would come and go. I am still betting that it is an issue with the ESCs.
 

Cyberdactyl

Misfit Multirotor Monkey
#20
That looks a little "overboard" to me. :)
No, no, what I did was overboard. Adding an extra + and - lead coming off the harness is not. And it's maybe 3g exta weight, and well worth it for future lights, cam power, etc.

By the way, some have seen this already, but I got past the "attempt" and was successful. But it was a nightmare to change a broken boom once I had everything working.

https://vimeo.com/66983961