That’s odd. I have run 4S on 2212 920kv motors for countless flight hrs. What ESC’s are you using? I suppose you could try 8" props but I ran 9" and even 10" props.
I’m using these escs: nidici BLHeli-32 30A ESC 32bit Brushless Electric Speed 2-4s Controller for DShot1200 FPV Racing Drone（Pack of 4） https://www.amazon.com/dp/B07FD4G32J/ref=cm_sw_r_cp_api_i_ufyvDbR1H3W30
Could it be that your 920kV motors are able to handle this higher voltage and mine can’t? If so, may I ask what motors you are using? Thanks!
One one quad I was using these motors. They are very cheap but rated to 4S:
On another quad I used motors taken off an RTF quad that I know was only rated to 3S. I ran those until the bearings failed.
You might try using Dshot protocol instead of PWM. You have the ESC’s for it why not? It may provide better efficiency. Depending on what flight controller you have there are some considerations on outputs used. Info here:
I am pushing the Sunnysky X2212 980kv motors with 4S and 10x4.5 props without fail. Took a while to get the tune right. I think it came down to the crappy props I originally bought. I bought Xoar precision pair props and it flys great!
I’ve been looking at those motors myself, it’s good to hear that they are working well for you. I also liked that according to ecalc they will also accomodate 12" props in 3S, for a price that is quite reasonable.
Thanks! Seems like those motors are out of stock, but I’ve found a few others that are rated up to 4s batteries. I’m thinking of returning these motors and purchasing 4s motors. They should also last longer.
Still haven’t had a chance to fly the drone with this battery. I heard that if the drone actually flies there is less strain on the motors and there is air flowing through the motors which could cool it down. I’ll try to give that a shot soon and the Dshot protocol and see what happens.
Thanks for your help!
I got the new motors, calibrated everything and it seems to be flying better!! Thank you all so much! But upon looking at the logs, it seems like my motors are still working pretty hard for a loiter which doesn’t make sense according to ecalc. Any ideas? The thrust to weight ratio is 2.3
Here are the logs: https://drive.google.com/open?id=1YDKJeyPzPX1SeyNvbe8mRlmZ_YA2A0v2
- Hi you should change:
SERVOx_MIN from 1100 to 1000 and SERVOx_MAX from 1900 to 2000. At the Moment the Maximum output with your setting is 1900. With 2000 you will gain more thrust.
- Either your battery was not charged full, because fully charged 4s should be around 16.5-16.8V or you have not calibrated the voltage.
Based on what you have told us, you appear to be flying a typical F450 DJI style quad.
At 3.7kilos, this aircraft is 400 grams heavier than my Tarot 650 Sport that is carrying a 3axis gimbal with a GoPro and a 10000mAh 6S LiPo.
The only way you can fix this is to loose a considerable amount of weight.
As has been said, you also need to setup and calibrate the battery monitor.
A safer method to calibrate for current:
Start with a fully charged and balanced battery.
Fly for about 5 minutes or so, land, disarm, and disconnect the battery.
Using a charger that will display the total current charged, put the battery on CHAGE (NOT Balance Charge).
Connect the FC to Mission Planner and down load the latest data flash log
When the log is downloaded click Review a Log and double-click on the latest Binary log or DF log.
When the browser opens the log, in the right hand pane click on BAT. This will open the Battery branch.
Click on CurrTot. The browser will draw a plot of Total Current Used.
Right click in the plot pane. A menu dialog will open. Click on “Show Point Values”.
Hover the mouse pointer over the extreme right end of the plot. A pop-up will show the line number and the current. Write down this number as "Logged Current.
When the battery is charged, write down the total current as “Charged Current.”
Connect the FC to Mission Planner and navigate to Initial Setup > Optional Hardware > Battery Monitor and record the number in box #6 as Old Amps per Volt.
Using the attached spread sheet, enter Current Logged, Current Charged and Old Amps per Volt. The spread sheet will calculate a New Amps per volt. Enter the New Amps per Volt into box #6. Make another test flight and repeat this process. After a couple of iterations you should be able to get the Logged and Charged currents to well within ± 50mAh of each other.
Battery Monitor Calibration.zip (1.6 KB)
Thanks! I did the change to the SERVO_MIN and MAX and I calibrated the battery monitor. It seems to work better but the motors are still pretty high on the log. Any ideas?
Thanks! I actually meant that my drone weighs 3.7 pounds. I went ahead and did the battery monitor calibration but it hasn’t seemed to help. Any ideas?
Calibration of the battery monitor necessary was so we can get some accurate measurements.
How many calibration flights did you make? How low were you able to get the difference between logged and charged current?
I need a DETAILED EXACT list of EVERYTHING in your build. I need to know the battery weight, capacity, and cell count (3S, 4S) and C rating. I need to know the EXACT weight of the aircraft without the battery.
And post you current data flash log and post some pictures that show the motors and props…
When I have all of that data I may be able to figure out what is really going on.
Here is a list of the things in my build:
Flight controller: https://www.amazon.com/gp/product/B01N4KJEV4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Frame self printed
Weight without battery: 1300g (as accurate as my home scale can get me)
Here is a photo of my drone: https://drive.google.com/open?id=1FhzN94fs0jM8fEpenej3aE8T0yfOoWb7
Here is the latest log: https://drive.google.com/open?id=1vitY_CuWGpb1bsJBohvVtiP4yKel-EF_
I did 2 calibration flights and I got the logged and charged current to what seemed to be exact but it did bounce around a little bit.
Please let me know if there is anything else that I should provide. Thanks for your help!
The hardcase battery adds needless weight but I don’t see any problem with the performance of your craft. A bit of tuning is all you need but even that isn’t terrible as is. You might see a small increase in efficiency but using Dshot protocol. You have the ESC’s for it, no reason not to. If you do read the Wiki 1st because you will have to change the motor outputs to the Aux outputs and configure Arducopter accordingly. There are a couple other parameters that need to be set also.
I ran the numbers and they don’t look bad at all.
Each motor is pulling about 3 amps and you are getting a grams/Watt of 9.7. This works out to a flight time of about 20 minutes using 80% of the 5200mAh battery capacity.
Now that we have the battery monitor calibrated we need to make sure you have the low battery failsafe setup. Make sure the battery capacity is set to 5200mAh, and the reserve capacity is set to 1040mAh. Initially I set my warning voltage to 3.5v/cell, or 14V for a 4S.
Since you are running 4S, you might try using some 10" x 4.5" props, but before you do that measure the motor center to motor center distance between adjacent motors and subtract 1". This will give you the maximum prop length that you can run safely.
If you can run 10", this should bring the motor currents down a tad which will give you a slightly longer flight time. This will also bring Hover Throttle down and give the flight controller more head room for stability control.
To get the wobble sorted out try re-calibrating the accelerometers. You need a spirit level and some playing cards. Put the level on the frame and shim the landing gear with cards until the frame is level in roll and pitch. At that point connect to Mission Planner and run the calibration.
When you get the ACCs calibrated, take the aircraft outside and calibrate the compass using Stick Gestures. To do this you power up normally and when Pixhawk completes the boot process you hold the Left stick Up and to the Right. Pixhawk will make one long beep and then beep once per second. At this point pick the aircraft up and rotate it around each axis: Compass Calibration Stick Gestures. NOTE: If you go to a different location to fly, run the compass calibration again.
Another thing that will help is to make sure the aircraft is balanced in roll and pitch with the battery installed. When you get the aircraft balanced, take it out for a flight. When you arm the motors, hold the left stick in the arming position until the main LED cycles Blue and Red. This indicates that Auto Trim is active. Establish a stable hover and wait for the LED to turn Solid Green, and then land. Wait a few seconds for the settings to save and then take off. Hovering will be much easier…
I tried using the Dshot protocol and the drone felt more wobbly so I went back to the standard one. Do you think this is normal or may I have done something wrong?
Wow, thank you so much for the detailed response!
I have now calibrated the failsafe.
I put the 10 x 4.5 props into ecalc but it was giving me worse ratings because they were GemFan props. I was unable to find any better props on amazon. Do you have any suggestions for 1045 props for DJI style motors that I may be able to find on amazon?
I’ve recalibrated the accelerometers and I did the stick gesture calibration.
For the last thing, should I do autotrim when I do a hover manually or using loiter?
Do the AutoTrim in Stabilize. Pixhawk will “read” your stick values and save them.
For what its worth, eCalc is real picky about the data you enter. The first time I tried it the results it gave me were total crap. Then I found out I was making a mistake with the battery data.
For the props, you need to get something that is stiff enough to minimize “thrust bending.” I use GenFan 6030 Nylon/Glass fiber props on my 250 racer, and GemFan Flash Polycarbonate 3052-3 (tri-blade) props on my Tyro 79 3 inch racer. For the “big boys” I use "T-Motor style carbon fiber.
Its not normal. Configure for Dshot 150, switch your motor outputs to aux 1-4 (servo 9-12). You may have to turn off Low RPM Power Protect from BLHeli suite. Try it with default setting 1st.
I’m a big fan of APC props, these will fit a DJI hub