Mikrokopter Quadro-X strange Current readings

[Carcara]

Hello all,

I recently put together a new distribution board with 4 new BLCtrls 2.0, this is the setup:

Mikrokopter Flight Ctrl Board HW V2.0 / SW V2.08a
Mikrokopter Navi Ctrl Board HW V1.1 / SW V2.08a
MK3 Mag V0.23a
BL Ctrl V0.31
Axi 2820/14 motors
APC 14 x 4.7 slow flyers
Quadro X configuration

On all of my flights I get these strange current readings for motors 2 and 3, where they show much more current consumption compared to the other 2 motors. I know it´s not the motors that are causing the problem, because after swaping motor 1 and 2, the higher reading continues on motor 2 position. The weird thing is that the temperature after flight are all the same, regardless of motors 1 through 4.

I can send the last flight log file so you can take a closer look (could not upload a .gpx file at this post!)

Any help is appreciated.

Regards,

Marcelo.

Flight date: 20/02/2015 15:07:21
Flight time: 15:07:21.8 - 15:08:17.2 (55 secs, 00:00:55)
Batt. time : 60 secs, 00:01:00

Start Location : -30.0851704 / -51.0576908 @105,9m
Elevation(GPS) : 0 42,96 389,4 m (min/avg/max)
GPS alt. (raw) : 104,375 127 389,4 m
Altitude(Barom.): 0,5 5,12 9,8 m
Vertical speed : -0,76 0,11 0,74 m/s
Max speed : 10,1 km/h
Max target dist.: 0 m
Max distance/LOS: 228,7 m / 228,7 m

Sats : 0 5 7
Voltage : min. 14,3, max. 14,9 V
Current : 0,5 18 27,3 A
Wattage : 7 278 393,12 W
Capacity: 317 mAh

Motor1: 0,0 2,9 4,4 A Temp: 34 56 69 °C
Motor2: 0,1 6,0 9,0 A Temp: 32 51 62 °C
Motor3: 0,0 6,3 9,0 A Temp: 33 53 65 °C
Motor4: 0,0 2,5 4,3 A Temp: 35 51 61 °C

Magnet Field: 96 114 125 % (!)
Magnet Inclination: 46 48 55 deg

No errors found

 

[smartaerials]

Hi Carcara,
Motors 2 and 3 are placed on the starboard side of the MK Quadro X configuration.
Could it be maybe, that your payload is not centered or balanced with the battery ?
Regards

 

[stevemaller]

It is possible to calibrate the BLs’ current sensors.
Using the motor test in MK_TOOL, you can hook up a current sensor to your LiPo and run the motor at various power settings and adjust the "Current Scaling" parameter for each BL individually.
See here: http://wiki.mikrokopter.de/en/BL-Ctrl_2.0

I'd be concerned if two of them are off by that much. Are you seeing proper flight performance? Yaw authority, etc.?

 

[Carcara]

Hi Carcara,
Motors 2 and 3 are placed on the starboard side of the MK Quadro X configuration.
Could it be maybe, that your payload is not centered or balanced with the battery ?
Regards

Smartaerials, that is definitively not a possibility, because as soon as you startup motors, before taking off, the readings are way off. I even tried flying with the battery pack moved to the side, but nothing changed much.

 

[Carcara]

It is possible to calibrate the BLs’ current sensors.
Using the motor test in MK_TOOL, you can hook up a current sensor to your LiPo and run the motor at various power settings and adjust the "Current Scaling" parameter for each BL individually.
See here: http://wiki.mikrokopter.de/en/BL-Ctrl_2.0

I'd be concerned if two of them are off by that much. Are you seeing proper flight performance? Yaw authority, etc.?

Hi Steve, flight permormance is ok, and BL-Ctrs have apparently same temperature after flight, at least by fingertip sensitivity. I would imagine those two would be much hotter then the others, but not. What I really think is strange is the fact that 2 out of 4 displays same problems. I just bought these brand new BL-Ctrls at quadrocopter.com! Would you suspect of a problem at the Flight Ctrl Board?

I re-flashed Flight Ctrl software. Tried to re-flash BL-Ctrl firmware (0.31) but got an error. After reconfiguring everything I keep getting lots of magnet errors, did many flights yesterday. Free fly, GPS, Altitude Hold, RTH, all working ok. Before re-installing firmware, there were no errors at all.

I will look into the "currrent scaling" technique to measure each BL-Ctrl, that´s a great idea.

Regards,

Marcelo.

 

[Carcara]

Using the motor test in MK_TOOL, you can hook up a current sensor to your LiPo and run the motor at various power settings and adjust the "Current Scaling" parameter for each BL individually.

Steve, as I press "ctrl + settings" to go to adjustment dialog box I get this error: "Bl-Ctrl hardware has no configuration support". Should I connect each Bl-Ctrl indiviadually as if I was updating firmware as described here? http://wiki.mikrokopter.de/en/SoftwareUpdate

Thanks,

Marcelo.

 

[Carcara]

Using the motor test in MK_TOOL, you can hook up a current sensor to your LiPo and run the motor at various power settings and adjust the "Current Scaling" parameter for each BL individually.

Steve, here are the readings from each motor/bl-ctrl:

Motor # / Slider Position / Current Value
1 / 34 / 1.9A
2 / 34 / 1.8A
3 / 34 / 1.9A
4 / 34 / 1.8A

1 / 70 / 5.2A
2 / 70 / 5.0A
3 / 70 / 5.2A
4 / 70 / 5.0A

1 / 120 / 14.3A
2 / 120 / 13.8A
3 / 120 / 14.3A
4 / 120 / 13.9A

Well, it looks like they are OK, so the next step will be calibrating the current sensors.

Regards,

Marcelo.

 

[stevemaller]

Steve, as I press "ctrl + settings" to go to adjustment dialog box I get this error: "Bl-Ctrl hardware has no configuration support". Should I connect each Bl-Ctrl indiviadually as if I was updating firmware as described here? http://wiki.mikrokopter.de/en/SoftwareUpdate

I've never actually done this with the BL2.0 boards. The MK wiki says it should work, but I have no idea. I know it works quite easily from MKTOOL with the 3.0 BLs. Don't connect directly to the BLs or you'll be unable to run the motor test, right?

 

[Carcara]

I've never actually done this with the BL2.0 boards. The MK wiki says it should work, but I have no idea. I know it works quite easily from MKTOOL with the 3.0 BLs. Don't connect directly to the BLs or you'll be unable to run the motor test, right?

Steve, I managed to make it work. As we launch MK Tools, the first connected board is Navi Ctrl. I was trying to press "ctrl settings" from the Flight Ctrl board, and the error messages persisted. When I switch back to Navi Ctrl and press "ctrl settind" it works fine.

I calibrated the current scaling as precisely as I could, comparing the values from the meter and the values given by MK Tools at the left column after mouse clicking it to give current reading (the current always oscilate there, and I used the average value that I could read).

After calibrating, flying and re-calibrating again, all seems much better now. I noticed the high temperature at the capacitors, much hotter when comparing to the mosfets. This was made by finger touching, not with any temperature gun or probe. The log files give me BL-Ctrl temperatures between 90C degrees and 100C degrees. Do you think its possible to solder an extra capacitor to lower the overall temperature? I was reading the Elko Capacitor datasheet and the temperature limit is 105C degrees.

What is the normal average temperaure one should expect from the BL-Ctrls / Capacitors?

 

[smartaerials]

What is the normal average temperaure one should expect from the BL-Ctrls / Capacitors?

MK Bl-Ctrls get very hot easily under stress, specially if they are where they should be, in the dom.
The only way I could get good temps when running with heavy payloads was placing BLs under the propwash..
Whats your AUW?
Regards

 

[stevemaller]

BL 2.0s were notorious for being able to get your english muffins a toasty brown under load.

Heat sinks glued to the MOSFETs help a little, as does a small fan. Placing the BLs out under the prop wash could help, but be aware that there are potentially serious issues with extending the LiPo wires that far (possibly requiring changing the capacitors).

The much easier and better solution is to ditch the BL2.0s altogether and move to the BL3.0s, which are considerably better at dissipating heat, and can run 6S, as well.

 

[Carcara]

Whats your AUW?

Smartaerials,
the AUW on this setup is 4,2kg.

 

[smartaerials]

the AUW on this setup is 4,2kg.

Hi Carcara,
I think you may be pushing those BLs to the limit with 4,2 kg. They are designed to run with MK3638 for heavy lift, and 3638 take the Bl Ctrl to the limit at 750-800grams, you are pulling 1050gr there so you may be crossing the red line..Could we se a photo of your setup?
I´ve burned several MK BLS without pushing them that hard, but on a octocopter, if you loose a bl on a cuadrocopter while airborne it s going to be a hard crash.
Regards

 

[Carcara]

I think you may be pushing those BLs to the limit with 4,2 kg.

Hello Smartaerials,
what I cannot understand is how am I pushing the limit on the BL-Ctrls 2.0 if they are rated to 35A continuous, and the setup is not even taking 15A? Take a look at one of the last log files:

Flight date: 26/02/2015 13:45:55
Flight time: 13:45:55.0 - 13:49:56.2 (241 secs, 00:04:01)
Batt. time : 240 secs, 00:04:00

Start Location : -30.0853423 / -51.0578848 @106,9m
Elevation(GPS) : 106,912 107,14 106,912 m (min/avg/max)
GPS alt. (raw) : 106,912 105 106,912 m
Altitude(Barom.): -5,15 3,72 9,75 m
Vertical speed : 0 -0,01 0 m/s
Max speed : 0 km/h
Max target dist.: 0 m
Max distance/LOS: 0 m / 9,8 m

Sats : 0 -1 0
Voltage : min. 13,1, max. 15,1 V
Current : 0,5 35 45,2 A
Wattage : 7 498 596,64 W
Capacity: 2408 mAh

Motor1: 0,0 8,2 10,6 A Temp: 35 97 112 °C
Motor2: 0,0 8,8 12,1 A Temp: 34 95 111 °C
Motor3: 0,0 9,1 11,9 A Temp: 36 96 112 °C
Motor4: 0,0 8,6 11,2 A Temp: 34 88 100 °C

Magnet Field: 17 50 123 % (!)
Magnet Inclination: 11 34 68 deg

No errors found

I bench tested these motors with 30A Escs and got 1,5kg with 50% thrust on each. Here are some photos as you asked.

View attachment 23582 View attachment 23583 View attachment 23584 View attachment 23585

 

[smartaerials]

Hi Carcara,
Woe, what are you doing with the drone??It s the first time a see the flash on a drone ahah! Is that an industrial oven/mine??
Regarding your log.. I know thats the theory , MK says:

• By high-performance MOSFETs 35A and 40A peak period are possible. (with appropriate cooling)

And they must do the test in a super lab, with extraterrestial conditions..I´m sorry that I can t give you the cientific explanation but think that the max recomendet payload for a MK Quadro XL is 1kg, so maby 2.5 AUW , you are using bigger motors and drawing much more power through the Bl to keep that 4.2AUW in the air, so it doesn t come as a surprise to se those temps.
I wouldn t keep flying with this setup, you have no chance if one Bl goes,it will start spinning and it will make a mess.
Bl V3, or Abusse mark PWM converter and use standart ESC I would say. The other option would be to set the Bl right under the prop wash, I had it like that on a Hex and it cooled it down 30C, but 112C is very very hot.
Regards

 

[Carcara]

Smartaerials,

do you happen to know how the temperature on the ESC is measured, I mean whe the sensor is placed?

This setup was used to inspect a boiler, totally dark inside. Got great results with the flash, but we are working on other solutions as well.

It cannot be bigger or wont fit inside, so I needcto work on other solutions, bigger ESCs are an option.

Regards.

 

[Carcara]

Hi Carcara,
Woe, what are you doing with the drone??It s the first time a see the flash on a drone ahah! Is that an industrial oven/mine??
Regarding your log.. I know thats the theory , MK says:

• By high-performance MOSFETs 35A and 40A peak period are possible. (with appropriate cooling)

And they must do the test in a super lab, with extraterrestial conditions..I´m sorry that I can t give you the cientific explanation but think that the max recomendet payload for a MK Quadro XL is 1kg, so maby 2.5 AUW , you are using bigger motors and drawing much more power through the Bl to keep that 4.2AUW in the air, so it doesn t come as a surprise to se those temps.
I wouldn t keep flying with this setup, you have no chance if one Bl goes,it will start spinning and it will make a mess.
Bl V3, or Abusse mark PWM converter and use standart ESC I would say. The other option would be to set the Bl right under the prop wash, I had it like that on a Hex and it cooled it down 30C, but 112C is very very hot.
Regards

Smartaerials,

do you happen to know how the temperature on the ESC is measured, I mean where the sensor is placed?

This setup was used to inspect a boiler, totally dark inside. Got great results with the flash, but we are working on other solutions as well.

It cannot be bigger or wont fit inside, so I need to work on other solutions, bigger ESCs are an option.

Regards.

 

[smartaerials]

Hi Carcara,
Sorry but I don t know where it s located. Maybe SteveMaller would know how to explain it technically.
Regards