Motor balance issue in Auto Analysis of MP

I recently tested a newly assembled S500 quad with Pixhawk running on Copter 3.4.1

The Log Analyzer indicated following :–

" Test : Motor balance = WARN – Motor Channel Averages = (1559, 1497, 1431, 1415)
Average motor output = 1475
Difference between min and max motor average = 144"

Pls advise what has gone wrong and what should I do to rectify this.

I notice in bench testing, the props on the right hand side, ie. motor 1 and motor 4 stop first, followed by motors on the left hand side (motor 2 and 3).
When I did ESC calibration, I used All At Once Calibration, instead of one by one. I also calibrated my radio before ESC calibration.

Pls see the data flash log in the following link :–

Appreciate any help.

I’m seeing the same error on a new build (tbs discovery, tbs bulletproof 30a escs and tbs 900kv2 motors), have never seen it before and can’t see any information on likely causes etc online. My specific error is:

Test: Motor Balance = FAIL - Motor channel averages = [1635, 1533, 1690, 1604]
Average motor output = 1615
Difference between min and max motor averages = 157

Running mission planner 1.3.41 build 1.1.6110.31287, ArduCopter
Firmware Version V3.4.1

My log file… 2016-11-11 14-29-56.bin (3.2 MB)

Any input appreciated!

The difference IS there, if you graph your RCOut you can see it clearly.

1: Check the CofG of your copter.
It will have a big effect, so you may need to move things around to get it more balanced centrally.

2: Motor and arm alignment.
Not as critical to motor balance but more visible in consistent flight characteristics, a twisted motor or out of alignment arm can have an effect on motor power.

3: How consistent are your motors, props and ESC’s?
Not all are created equal, so how confident are you that they are of consistent quality?

4: After checking everything redo ESC calibration.

Hello, I’m having the same problem (with Copter 3.2 but still…) and checked everything (expect CofG, how do you precisly check that, apart from balancing it on your finger…) you mentioned above!
Do you have any news ?
(My ESCs are all the same, just one is starting 2% lower than the others but I can’t change this by calibration weirdly …)
Cheers, Antoine

Hi Mike,

  1. C of G — Visual check reveals that when reducing throttle to minimum
    on bench test, the 2 motors on the right hand side (Motor No. 1 and 4) on
    quad (x configuration) stop first, then followed by the 2 motors on the
    left hand side. If this relates to motor balance, then C of G has nothing
    to do with this issue, as the copter did not take off.

  2. All motors are new and not crashed. Arm and frame are also new, though
    the S500 frame from HobbyKing is plastic arm, but not twisted.

  3. Not sure of my confidence level on the consistency of quality of those 3
    components you mentioned…ESC are Emax 30A with BLHeli firmware, motor
    and prop are DJI Phantom 3 clones.

My best guesstimate is : before I did ESC “all at once” calibration, I am
not sure if I messed up with the timing parameter of one ESC when I tried
"one by one" calibration. After successful “all at once” calibration, I
could not program the parameters using transmitter. Suspect the timing
parameter of 1 motor is different from the other 3.

PS : I hate programming the ESC using Tx, as the sound emitted never follow
the instruction manual for most ESCs, incl Emax. And I could not find a
vendor selling Emax programming card. Let me know if you find one.

Please see my reply to Mike. If you can’t see it, let me know.

To summarize, my guesstimate is my messing up of the timing parameter of
one or more ESC during "one by one " ESC calibration, before I was
successful calibrating all the ESCs using “all at once” calibration. After
that, I tried to change individual parameter of each ESC, but was not

I am now looking to buy a Emax ESC program card. Let me know if you find
one online. Thanks

The CofG is not much a factor, as the CofG of my previous quad (now flied
away) was out of balance and I did not get such warning message.

By the way, how do you check to find out one motor is starting 2% lower
than the other ? Probably this is due to the timing parameter of one motor
being different from the other 3.