Low Power with new Quad Copter

Derekh1968 · « **on:** July 05, 2017, 01:04:45 am »

I have tried to configure a couple of times in Libre Pilot . with props off everything works well. with Props on quad lifts to 24 - 36" then seems to loose power lowering back to the ground. Batteries fully charged 12.6v on multimeter. Voltage drops to 12.36v after a few attempts. It will do the same thing over and over again arm and disarm between attempts have tried two different Batteries (S3 11.1V Lipo). was wondering if there is a voltage limit in Libre Pilot that would limit power or something else that would be causing this. Any thoughts appreciated.

Brian · « **Reply #1 on:** July 05, 2017, 02:12:35 am »

How much does your quad weigh, and what are the props/motors? I don't know of anything in the software that could cause this.

Derekh1968 · « **Reply #2 on:** July 05, 2017, 04:45:57 am »

160mm frame
Weight: 350g Complete
Motors 1306-3100KV
Battery 11.1V 1300mah 25C
ESC: 6A SimonK FW
Props: 4" 4045
Flight Controller: CC3D

Brian · « **Reply #3 on:** July 05, 2017, 05:47:33 am »

My best guess is that you're overloading your ESCs. Are they getting hot at all?

I couldn't find exact specs, and I don't know exactly what motors you have, but I found specs on these motors:

http://www.myrcmart.com/rcx-h1306-3100kv-micro-outrunner-brushless-motor-efficiency-racing-p-7937.html

They show a max of 7 amps at 3S, and the maximum thrust at that amperage is 278g. The thrust should be okay, but I would run them on at least 10 amp ESCs.

It could be that the initial ramp up is overloading the ESCs and they are then limiting the current.

ernstock · « **Reply #4 on:** July 05, 2017, 09:24:51 pm »

Or perhaps the motors could be a bit small / the battery a bit big ( heavy ) , and rather low C rating , props too big / aggressive.

I fly 4045 props on a 180 frame , similar battery , but 60c ( important ) and 2205 motors

Have a feeling that 1306 motors tend to be used on 100 size frames with 2" props ?

Edit - for clarity I should add that my set up is 4s

Edit #2 - also my escs are around 20a

Derekh1968 · « **Reply #5 on:** July 05, 2017, 09:40:16 pm »

Thanks to both of you for feedback. 4" props are what it came with they just fit 1mm clearance. I was thinking of trying 3" 3 blade but was afraid of loosing lift. May be a combination of everything ESC's to small Props to big. It was as supposed to be ready to fly quad.

I am still grounded!

Brian · « **Reply #6 on:** July 05, 2017, 10:12:49 pm »

It came as a RTF kit? Do you have a link to the quad?

Derekh1968 · « **Reply #7 on:** July 05, 2017, 10:35:19 pm »

http://www.rchobbiesoutlet.com/rc-racing-drone-quadcopter-rtf-kit-u01004-l160-2/

Specs are pretty vague

Brian · « **Reply #8 on:** July 05, 2017, 10:54:03 pm »

Thanks. That explains why it seems heavier than expected. That's a pretty heavy frame.

That said, if they sell it in that configuration, you would expect that they would have tested it. I would contact them, tell them the problem that you're having and see what they say.

Derekh1968 · « **Reply #9 on:** July 05, 2017, 10:57:55 pm »

I am Talking to them. Are saying others are flying so was hoping for simple configuration solution !!

Mateusz · « **Reply #10 on:** July 06, 2017, 04:27:54 am »

Just reading this thread. On my ~150mm quad I have 20A ESC and 3045BN Props.
I would think 6A ESC are for sub 90mm quads. Also battery 1300mah and 25c that is berly 32A of current giving you max 8A per motor. 4" props and sams kv motors as mine eat WAY much more. I think what happens is that you draw more current than your low C battery can provide. If you do that then voltage on battery drops immediately. Voltage and current should be visible if you have sensor hooked up. I think you draw too much current which cause battery to stall and temporarily drop voltage to zero.

TheOtherCliff · « **Reply #11 on:** July 06, 2017, 07:23:04 am »

My Tarot TL150H1 came assembled and has 6A Tarot ESCs, brushless 1106 3800KV motors, and 3 inch props. Stock battery is 3s550 45C. I fly it (non-racing) with lower C rating 3s500 to 3s1000 battery. It lifts the 3s1000 battery just fine, but I would not use it for racing, just long term sight seeing

.

Still, even a good sounding battery might have been abused. NEVER let your battery go dead. Never let any cell go lower than 3.4V resting and more like 3.6V or 3.7V is what you should work for.

The smaller 120 and 140 Tarot quads use 1105 3000KV motors.

(FlightTime counts the number of seconds since the battery was plugged in.) Use a Lipo alarm for a test to see if the battery voltage drops or delay takeoff to allow FlightTime to increase and check Firmware -> FlightTime before and after the flight, without unplugging battery after the flight. You can see if FlightTIme got restarted and that will tell you that FC got reset.

It's been a few months since I flew my Tarot 150. Now I have an itch...

Brian · « **Reply #12 on:** July 06, 2017, 05:30:43 pm »

Cliff, how much does your Tarot 150 weigh? I bet it's half the weight of the OP's quad, which I think is the root of the problem.

TheOtherCliff · « **Reply #13 on:** July 06, 2017, 10:16:28 pm »

Tarot 150 takeoff weight with 3s800 lipo is 163 grams.

He is running 1306 motors with 4 inch props. I am running 1106 motors with 3 inch props.

Looks like his is about twice as heavy and so it would probably take about twice the current to lift off (both are 3s). That 3s1300 25c could be a bit weak, especially if it has been discharged too far. We gave some tests to try to see if it was a bad battery, but no response so far.

Derekh1968 · « **Reply #14 on:** July 07, 2017, 03:25:59 pm »

Cliff
I am getting the same results with two Batteries, Both new (They could both be bad)
Supplier it saying others are flying same configuration. They are saying they will replace Quad and batteries.

From answers and youtube videos I think both motors and ESC's may be undersized for weight of Quad.
This is my first real quad am trying to step up from Syma toys. Do most flying in warehouse space after hours and thought enclosed props may prevent some crashes.

is Flight time you are talking about the Scope tab in Libre Pilot?