cs8 ice 50 too hot

One way to figure out if it is equivalent to the T-motor is by measuring the internal resistance you should see 30mΩ if the ohm meter is accurate. The amperage seems nominal for the battery voltage 5 to 5.5ish gives 120 to 132W of power which would seem like the normal power per motor expected for that kind of lifter. But that E-calc thing does show some weird anomalies. There are a lot of amp spikes in both on that data, which would also be normal depending on the maneuvering of the copter.

If it is a exact replica of the T-motor at 760kV, iare rated for 6S batteries. Even though they say they are rated for them that does necessarily those are correct for the application.

 

Hey Guys,
Here are my logs from today. This is Motor 1 and Motor 8. First flight it was 91*F outside and the second flight was 105*F. This was with a 5dMKII mounted and I did a decent amount of hovering to let it heat up. There wasn't any wind. 75*C is still well under the danger zone of the ESCs. Once you hit the 100*C range thats when you should start worrying. The actual Thermal shutdown would occur around the 120-140*C range. The motors were slightly warm after these flights.


A side note, the reason the Amps have a high spike are from doing Full Throttle Ascents. If I don't do that then I am seeing an average of 5-6amps per motor.

Josh

 

Castle Ice 50's, MT3515 400KV motors, 6s batteries, 15x5 TMotor CF props. Total flying weight is 19lbs with camera.

Josh

 

Compared to what my stock CS8 was running this is nice and cool! I flew my new X8 today and without camera it was hitting 100*C!

 

I am getting into 100C now. I can only fly in the mornings with a camera, stock CS.

 

That does look normal. I was wondering what the maximum current spike was going to be, and it looks like the highest spike was at 17A no where near what the E-calc was extrapolating. I ran a few E-calc runs, ond Jordi's model and noticed that for one it does not really allow you to model that motor 100%. I am not sure where they get the max power for 15 seconds on the motors they have listed. It contradicts the companies website that claim the T-motor can go 100 Watts higher for 180 Seconds. Secondly it is hard to get a good model for the propeller. Graunpner does not provide the P Constant for the prop. By looking at the pictures of the Graupner I factored in a -5 degree aerodynamic twist. When I ran his info with the 13.8 I get hover gas at around 6.24A. Of course I get all the crazy warnings that Gary got, but I take them with a grain of salt because it is my belief that the model is inappropriately extrapolating beyond known empirical values.

When I run a model for the motor at 760KV using 1A @ 10V and .03Ω. I just arbitrarily chose a max power number. The model claims that it will pull 68A per motor at 56C at 17.57V on the battery that's huge drop in voltage for 6S. Which I think is nonsense. Not knowing what the model assumptions are I think they are over exaggerated. You might see a bit of a current increase at full power with an aggressive pitch but I would have to venture that if someone were to fly the copter that way then they would be asking for a systematic failure of the battery and ESC's. Josh your data showed 17A at full power if you were maneuvering aggressively you probably could see a bit higher current draw, maybe in the mid to upper 20's but know where near 68A. And even with a higher KV motor there will be some increase in current for the torque required at higher speeds, I still think that reaching 68A is a bit of a stretch.

One of things the model does well is that it appears to predict through interpolation well. With his setup modeled as close I can get the hover gas is at 6A at 23V which is probably close to accurate from what the data showed on his VI curve graphs.

So I modeled this using 15X5 props and I get, the following for hover:

6S => 5.52 A at 23.05V for 127.24W.

5S => 5.63A at 19.2V for 108.1W

4S => 6.20 at 15.32 for 95W!!!



It is clearly evident to me that if we ignore the extrapolation of the data and only focus on the interpolation these motors are best suited for 4S batteries and 15 inch props for the best efficiency. Assuming the interpolated model is correct then you can see that between 127.24W and 95W there is a 25% loss of power probably due to heat caused by electromotive friction, the clanging and banging of electrons through the motor wires.

Either get new batteries or get lower KV motors that have a better power efficiency for lower current draws coupled with higher battery potential.

 

You will get there, at some point the more you are doing this stuff. There are a lot of aspects of multi-rotor that everyone on this board had to learn when first doing this.

I do want to clarify one more item. The 4S's show by the model that they will work for your setup, however there are limitations. Once you start adding an extra 2KG of mass to the system with the 3 axis gimbal and a camera. The 4S will be limited in the lifting characteristics with those motors. You will not have as much throttle response and you will probably expect to see the temps rise again. Also the 4S with those motors you will have very limited flight times. If I were to guess I would say you will only get about 6 to 6.5 min of safe flight time with a DSLR like a 5D camera with 10Ah. So I would probably stick with the 6S and go for bigger motors like the ones Josh has or something that is around 360 to 400KV range.

If local sources do not have these things, you may need to order from Asia, which is where most of this stuff is actually made anyway. Hint: Pay the extra for EMS shipping if it is available for Spain.

Being that you are new to this get extra props because you will most likely tip on a landing or two especially when there is no camera on the gimbal. You might want to get some sturdy props to practice with before going to the Xoars. Although the nice thing is when a good size camera is on the gimbal landings are much more stable even with variable winds.

Also, study the WKM manual and get a good understanding of the IOC functions, Heading Lock and Home Lock. These are functions that can lead to loss of orientation if you inadvertently turn them on or off. This a big reason why people crash. Home Lock will only work if there is a good GPS signal before takeoff. If you plan on using them you may want to test these out before every flight to make sure youdo not loose a 8000 Euro copter.

 

It does not look too bad. The wind probably helped cool the ESC's down a bit. It looks like average current was around 8A with a few spikes upto 11A. Your highest temp was around 70C. It does appear that the temperature curve starts to level off around 70 until you land of course. What you want to do is compare all of the motors. When flying with the gimbal without a camera, the CG is rearward so the back motors will work harder assuming no one is moving the gimbal, and the gimbal is oriented to the front. Once you put a camera on there you may see some higher temps overall something to be aware of.

Shaun