Mikrokopter Double Quadro V3 BLC issue

[DKTek]

I have a SkyJib 8 with the newest hardware, 2.5FC, 2.1 Navi, 2.1 GPS and Double Quadro 2XL BLC.

The issue is, that the even motors(2,4,6,8) are running about 10deg hotter than the odd motors(1,3,5,7) and the GPX file is showing the even motors are 6-10amps more than the odd motors. The yaw moves around at times but holds heading most of the time. The remote compass solved my compass errors completely, but this issue remains.

I did add a second set of power leads for symmetry and convenience. I soldered the new wires to the original power wire protruding the top BLC. Could it be that I induced an electrical efficiency imbalance between the two BLC boards? Maybe a cold solder joint...

I added the second power leads because I have a hard time believing the the single power lead could handle the max amp load capable of this Double Quadro BLC. 480 amps is a lot for such small wire, even at a short burst.

Anyone else with similar issues?

GPX info...

MK Version: FC HW:2.5 SW:2.06a + NC HW:2.0 SW:2.06a BL:V3

Flight date: 4/19/2014 5:15:09 PM
Flight time: 5:15:09 PM.0 - 5:23:16 PM.6 (487 secs, 00:08:07)
Batt. time : 486 secs, 00:08:06

Start Lat./Lon. : 27.9611437 / -80.6750725
Elevation(GPS) : 0 0.04 4.825 m (min/avg/max)
Altitude(Barom.): -1.8 1.94 12.75 m
Vertical speed : -1.8 -0.05 3.86 m/s
Max speed : 12.9 km/h
Max target dist.: 3.5 m
Max distance/LOS: 13.4 m / 14.6 m

Sats : 9 10 12

Voltage : min. 15.1, max. 16.6 V
Current : 0.5 80 140.7 A
Wattage : 8 1261 2138.64 W
Capacity: 10744 mAh

Motor1: 0.0 7.0 16.9 A Temp: 35 40 45 °C
Motor2: 0.0 14.3 23.0 A Temp: 31 49 57 °C
Motor3: 0.0 6.2 14.9 A Temp: 32 38 42 °C
Motor4: 0.0 12.8 21.0 A Temp: 28 47 55 °C
Motor5: 0.0 5.9 12.3 A Temp: 32 40 44 °C
Motor6: 0.0 11.5 20.0 A Temp: 31 48 56 °C
Motor7: 0.0 5.2 13.0 A Temp: 31 39 44 °C
Motor8: 0.0 14.8 25.0 A Temp: 31 49 57 °C

Magnet Field: 99 102 107 % (ok)
Magnet Inclination: 54 55 61 deg

No errors found

 

[DKTek]

OK.... Is it possible to calibrate the upper and lower boards? Any suggestions at all?

 

[ovdt]

Can you post a screenshot of your Mixer settings in MK Tool?

The boards don't need to be calibrated. And also, can you please make sure that all the motors are level?

 

[DKTek]

First off, thank you for the reply and any advice offered.

The mixer settings are all default Okto 1. No changes. Motors spin in the indicated directions.

The SkyJib is easy to verify level motors by removing the landing gear, loosen the motor supports, and placing the airframe flat on table and retighten the supports. Also, the SkyJib has alignment pins molded into the motor supports. Although, there is a very small amount of play.

My PWMs are set to 200 which shows about a 31 amp draw at full throttle. Other than this and some channel assignments for switch locations, the settings are default.

 

[ovdt]

Hello DKTek,

That's a weird problem. I would say, the bottom BL Ctrl can get a bit hotter but this should not lead high current consumption.

I also use Double Quadro2XL PDB but I use it with 6s motors and lipo, and I don't see any temp difference. Maybe uploading the newest firmware for BL Ctrl can solve this issue.

http://www.mikrocontroller.com/files/upload/BL-Ctrl3_MEGA168_V1_02d_SVN799.hex

Changelog:
1. Improved motor-start
2. internal speed limitation
3. increased commutating speed (Max RPM is 200.000 devided by the number of magnets -> 16.666 RPM if you have 12magnets)
4. Prepared for redundant FC-Operation
5. Small bugfixes

http://forum.freeflysystems.com/index.php?threads/my-new-mk-heavy-lift-copter-project.3091/page-15

 

[DKTek]

Thank you, I will verify my current firmware and update if needed. I'll post the resulting GPX.

 

[DKTek]

BTW, I'm running 4s with 14" CF T-motor props.

 

[ovdt]

Which firmware are you running on your FC? I would also update the FC firmware to 2.06 and load okto2b mixer again and save the settings.

 

[DKTek]

"GPX info...

MK Version: FC HW:2.5 SW:2.06a + NC HW:2.0 SW:2.06a BL:V3" Although my NC is the new 2.1 with remote compass.

I'm not at the machine yet but will take another look at the firmware tonight.

Also, I followed your link to the other forum and thanks again. Good reading...

"We found out that there is a small part on the BL-Ctrls that is sensitive against moisture or dirt. We started to cover this part with a special isolating coating."

I wonder if liquid electrical tape is a reasonable substitute for the special isolating coating?

 

[DKTek]

OK, I did the BL firmware update. It was difficult because I was initially using the X3 side of the MK USB, the one intended for updating BL-Ctrl. I started a new thread with my issues.

The SkyJib uses the normal Okto mixer but I did reload it anyway and transferred the configs. I'll have to wait until this weekend to test fly it.

Now, I just need to find out more about this special isolating coating and exactly which "small part" needs it.

 

[ovdt]

"We found out that there is a small part on the BL-Ctrls that is sensitive against moisture or dirt. We started to cover this part with a special isolating coating."

I wonder if liquid electrical tape is a reasonable substitute for the special isolating coating?

That will work but it would look ugly and a bit pain to clean the board.

I would use conformal sprays (or commonly called "electrial insulation spray" ). They can be silicone or acrylic based. I'm using acrylic transparent insulation spray for all the boards (including the FC ).

To remove the coating, a spray like this can be used: https://www.techspray.com/p-146-conformal-coating-remover.aspx?referrer=/c-4-conformal-coatings.aspx

This one is popular and trustable spray: http://www.all-spec.com/products/2103-12S.html
You should find this kind of spray at any workshop markets.

Notes about coating process:

* Wait until it gets %100 dry.
* Don't spray over the mosfets, solder pads, molex socket, altimeter, buzzer, battery. You can use small pieces of electrical tape to cover over the areas that you don't want coating.
* I also would advise to spray the FC. Again, cover the solder points and socket headers. The rest can be coated.
* No need to coat the GPS antenna, but you can coat the bottom of the GPS.
* The same coating process for NaviCtrl.

 

[ovdt]

And this is the part that needs to be coated:

View attachment 17874

 

[ovdt]

A great guide on spraying the MK boards from Andy Laird Johnson:

http://rathergoodguides.com/document-guides/rgg_spraying_mk_boards_with.pdf

 

[DKTek]

Wow ovdt, thank you for the awesome replies loaded with excellent links and info. Living in FL means dealing with high humidity at times and we have our fair share of dirt to blow around, especially with the SkyJibs takeoff weight. Time to order some supplies and dedicate a weekend to some TLC for my three MK products. The SJ8 and two original Okto's.

BTW, I have a lot of flight time on those two Okto's and they have never failed me or done anything to alarm me. I would trust flying either one off a cruise ship in the middle of an ocean. They both carry RC Timer gimbals with GoPro's and Alex Moss black boards. 15 minutes flight time, every time. They have FW 2.04a loaded. No bling and they just work.

 

[ovdt]

You're welcome, hope to solve your problem asap.

MK electronics have been very reliable for me as well; once it's setup properly and maintained gently, it keeps working unless it is harshly used or crashed. I'd strongly suggest you to spray the boards if you live with high humidity. It doesn't mean nothing will happen since you had no poblmes until today. We better take the precaution.

What are you lifting with your Skyjib setup? Another note for your first message: Even each BL Ctrl 3.0 controller can handle 60A; all PDB can handle 240A continously (120A each Quadro2XL). Maybe you can move to 6S setup for a more efficient and less stressful lifting.

 

[darekbo]

Hi how can I check the number of firmware in BL 3.0 ? Where in koptertool this info is located ?

 

[ovdt]

It's not possible to see the BL Ctrl firmware version.

A new firmware released for BL Ctrl 3.0:

http://www.mikrokopter.de/ucwiki/en/BL_V3Update#Version_V1.04c

 

[DKTek]

It's not possible to see the BL Ctrl firmware version.

Except after the update....:tennis:

Hey ovdt, again I have to thank you for helping us keep up to date.

So far my issue still exist. How can I post the GPX file? The graphs show so much more to the trained eye than what I can try to decipher here. Yeah, I know it gives my exact location but I'm good with that.

What I "THINK" is happening... I'm starting to believe that the even motors are reaching the max temp, 100, and the protection protocol is cutting the power which might explain why the Jib yaws LEFT and full right rudder doesn't correct. Until I reduce the throttle slightly. I've been flying the Jib without a payload until today. I reduced my timers from 10 minutes down to 6 minutes until I get a good baseline for consumption. After my last flight, I did increase the max temp to 115 to see if the undirected yaw comes later in the flight. That's another test day.

I'm really considering your recommendation about changing my setup to 6S for more efficient lifting. There's a lot of choices for motors. Any suggestions for my all MK Jib rig? All of the boards are the most current and up to date. My Jib is the original V1 with the updated star center plate and roll cage. So, it only supports 14" props. I'm swinging the T-Motor 14x4.8 now. BTW, anyone notice that these props are labeled backwards, i.e. the clockwise prop is labeled 14x4.8L and vise-verse on the counter clockwise prop.