Mavic Pro Motor Mod

[chazz]

How bout an IMU calibration? Does that even do anything? maybe i do that. Never done one of them before.

 

[lolo780]

Red is +
Green is -

18/03 biult Platinum ESC board for interest.

PWM is requested power %. Left front power must be dropping and the flight controller is commanding more to compensate.
Try adding + and - jumpers to those board locations.

Mavic Pro:
AON7544 Alpha & Omega Semiconductor Inc. | Discrete Semiconductor Products | DigiKey

Mavic Platinum
http://www.onsemi.com/pub/Collateral/NTTFS4C08N-D.PDF

P4P:
AON7418 Alpha & Omega Semiconductor Inc. | Discrete Semiconductor Products | DigiKey

Another problem with the Mavic is heat buildup on the ESC board. The MOSFETs sit upside down with no heat sinks of any kind and basically zero airflow. Try thermal pasting a square of aluminum on and see if that helps.

 

[beanbubba]

There are some setting in the fw that have PWM min and max in the name that have to do with each motor i might mess with them, WTH.

Probably not related, but while I am waiting for my new motors I rotated the motors and the problem followed. I rewired everything to eliminate a wiring issue, then rotated the motors back and problem followed again. Current issue is the the front motors will spin and the rear will not and the Go4 app quickly errors out with "check props" error. If I rotate the front to back motors, the same issues follows.

 

[beanbubba]

Red is +
Green is -

18/03 biult Platinum ESC board for interest.

PWM is requested power %. Left front power must be dropping and the flight controller is commanding more to compensate.
Try adding + and - jumpers to those board locations.

Mavic Pro:
AON7544 Alpha & Omega Semiconductor Inc. | Discrete Semiconductor Products | DigiKey

Mavic Platinum
http://www.onsemi.com/pub/Collateral/NTTFS4C08N-D.PDF

P4P:
AON7418 Alpha & Omega Semiconductor Inc. | Discrete Semiconductor Products | DigiKey

Another problem with the Mavic is heat buildup on the ESC board. The MOSFETs sit upside down with no heat sinks of any kind and basically zero airflow. Try thermal pasting a square of aluminum on and see if that helps.

Just morbid curiosity, how did you get a board completely clean with no solder residue??

 

[beanbubba]

Finished the build and ready for the new motors to jack into the micro banana adapters. This thing is super stiff and I have no worries that the frame/arms will be the weak link in this mod. I carefully extracted a factory antenna and coax (a serious pain in the a**) and have it routed to the front left rotor arm.

 

[lolo780]

Just morbid curiosity, how did you get a board completely clean with no solder residue??

It's a factory new part, that's how they come out of the package now without tinning or coating. The older Platinum ESC boards came pre tinned.

DJI fixed the design flaw that left tiny SMD components on the edge of the board for motor #2 which are susceptible to damage.

 

[beanbubba]

WHOOORAAAA !!!!!!!!!!

Good and bad news.

Bad news is my theory that I might have had bad motors was wrong. I attached them to Mavic#8 and no-go. If I was a betting man, I would wager that I over heated the main board by soldering the motor wires at least a dozen separate times.

So I cracked Mavic#9 out of the box and the madness continues. I moved the new rotor arms to the never flown bird and she fired up the first try and I did a 30 second inaugural flight. The gps and compass freaked out, but taking baby steps here

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[chazz]

WHOOORAAAA !!!!!!!!!!

Good and bad news.

Bad news is my theory that I might have had bad motors was wrong. I attached them to Mavic#8 and no-go. If I was a betting man, I would wager that I over heated the main board by soldering the motor wires at least a dozen separate times.

So I cracked Mavic#9 out of the box and the madness continues. I moved the new rotor arms to the never flown bird and she fired up the first try and I did a 30 second inaugural flight. The gps and compass freaked out, but taking baby steps here

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View attachment 39230

Thats great man! couldn't wait to see you testing this...I wonder why the compass error? You don't really need that compass extender if your not using a lion battery.. The lion battery that i use interferes with the compass when its close to it is why i move it up with the extender. as long as your using the stock battery you should try without that to see if the compass error goes away.

 

[lolo780]

You need metal shielding under the GPS module, and positioning it more forward will help get it away from the motors. Note that the Phantom places the GPS high and centered with ample amounts of metal foil underneath.

 

[beanbubba]

You need metal shielding under the GPS module, and positioning it more forward will help get it away from the motors. Note that the Phantom places the GPS high and centered with ample amounts of metal foil underneath.

Good point, I removed the metal plate in the mod and forgot to put it back. I put the factory gps/shell back on and completed a 15 minute hover test with zero issues. Fingers crossed.

 

[lolo780]

Good point, I removed the metal plate in the mod and forgot to put it back. I put the factory gps/shell back on and completed a 15 minute hover test with zero issues. Fingers crossed.

Good to hear! Try some foil tape under your GPS extender and compare compass noise vs stock. High rear motor load will make a lot more noise back there so test thoroughly before flying beyond LOS.

And test at lower voltage towards the end of the packs when the current is highest. Exactly the time you don't want to have yaw errors when you're coming home on 0%.

 

[chazz]

I've never had a compass error even with all the lipo 4s batteries i've ever tested except with the lion battery underneath the gps. That is the only reason i need that extender...

 

[beanbubba]

Hmmm... just completed another hover test and landed as usual. The second the bird landed and the motors cut off, all 4 props came loose and flew up a couple feet.

I don't have p3 prop experience, am I doing something wrong??

 

[beanbubba]

Good to hear! Try some foil tape under your GPS extender and compare compass noise vs stock. High rear motor load will make a lot more noise back there so test thoroughly before flying beyond LOS.

And test at lower voltage towards the end of the packs when the current is highest. Exactly the time you don't want to have yaw errors when you're coming home on 0%.

Aye aye sir! After hearing chaszz's issues, I am taking my sweet time for once on this mod.

 

[chazz]

you should get a full flight in with the stock battery without going far with it then after that maybe try with a ms5200 as a carry on.

 

[chazz]

Hmmm... just completed another hover test and landed as usual. The second the bird landed and the motors cut off, all 4 props came loose and flew up a couple feet.

I don't have p3 prop experience, am I doing something wrong??

Ive never heard of such a thing. that is very odd.

 

[chazz]

your motors would have had to spin backwards i think

 

[chazz]

Maybe they worn t tight?

 

[beanbubba]

Ive never heard of such a thing. that is very odd.

Well, these appear to be reverse threaded props and self tighten during flight. It appears that the mavic shuts the motors down hard and fast and the forward momentum is enough to unscrew them all the way when the motors stop???

EDIT: I twisted the props a tiny bit tighter on the next flight and this did not happen again.

 

[beanbubba]

I just did another test flight and stayed very close. Put in sport mode and did non stop full throttle up/down/left/right for about 10 minutes. Zero issues.

I also took note of the factory battery temperature and it was warm to the touch, but nothing I haven't seen on a factory bird.

EDIT: one very noticeable difference was the flight control responses. They are noticeably more sluggish (but not in a bad way). It's like moving from a sports car to a heavy duty pick up truck. You can feel the power/torque improvement, but controls are less sharp. Hopefully this results in a much larger towing capacity