Motor overload. Aircraft will decelerate to ensure safety

DamesNY · Jan 20, 2017

when i fly with single battery, i get the error. when i fly with the aux battery and main battery, no error UNTIL the battery goes under the 30% mark.
I don't think its a bearings issue, more a power issue and maybe the age of the TBXX's.
Mine tend to have 70+ cycles each and their capacities are a lot lower than a year ago.

Bob Stekeur · Jan 20, 2017

Besides the warning, do we notice any difference?

The_Learning_Curve · Jan 21, 2017

I don't notice performance limitations after getting this message. But it's also very rare for me to need max performance. I actually haven't been getting the message much lately. Possibly due to me being more attentive to the last time batteries were fully cycled. Having 10+ batteries is quite a burden when doing jobs and ending flights around 30%. That's a lot of hovering around to discharge completely at the end of a day or twos worth of flying. I also haven't updated to the latest firmware. I'm still on the 2nd to last update.

rbrdly · Jan 24, 2017

DVERichard said:
I have starting seeing this warning. It is not related to the gimbal motor.
The message reads:
"Motor Overloaded. Aircraft will decelerate to ensure safety."

I just started experiencing this myself after the latest update.
I think it's more battery related than motor.
I have a FLIR camera and my motors are all very close on temp - so I, like others, are leaning towards this being a battery issue.

I'm getting that issue with my batteries where it has sufficient power indicated, but then says the battery is critical and lands.
From my understanding, this bug was introduced when DJI updated the battery firmware with the new discharge update (after they borked everyone's batteries - I lost one of mine but I think the others are OK).

I "reset" all the batteries back then with a few discharge/charge cycles as instructed, but something is still borked, and is now giving me the motor overload issue as well.

Most of my problem, is that I am simply not using it enough...

Toan Doan · Jan 24, 2017

So basically no answer as to why it's happened and how to fix it, right? All seem to point to the new battery firmware update as the prime suspect. I'm getting it too. Has anyone spoken to Dji about this or is it just too hard to explain and go through the issue with them?

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bujaman · Jan 24, 2017

I just went through Chat with DJI tech support. They instructed me to do an IMU calibration. If the issue persists they said the next step is to reinstall FW. If I have a problem after that, then I will go back to tech support and report back.

The_Learning_Curve · Jan 24, 2017

Not sure how the IMU would contribute to a motor overload.. sounds like they're shooting in the dark. I feel as if the FW is just taking precautions according to the battery performance. If you're hovering and it knows you're just hovering, and the voltage drops abnormally it defaults to limited performance mode. If I calibrate a battery and fully charge it I don't get these messages. If I don't, these pop up a lot. But who knows.. just making assumptions, as bad as that can be

Toan Doan · Jan 26, 2017

The_Learning_Curve said:
Not sure how the IMU would contribute to a motor overload.. sounds like they're shooting in the dark. I feel as if the FW is just taking precautions according to the battery performance. If you're hovering and it knows you're just hovering, and the voltage drops abnormally it defaults to limited performance mode. If I calibrate a battery and fully charge it I don't get these messages. If I don't, these pop up a lot. But who knows.. just making assumptions, as bad as that can be

Yes I agree. Thought about this before too but not sure now you said it too. So I just calibrated a couple batteries and tested it yesterday didn't get the warning msg again. Not sure it's because I tested 30mins straight after the batteries were charged up (normally I charge overnight before or leave it for a day or two). My batteries are about 18 mths old. Anyway, will check out when I fly more next time. Will see if calibration is the answer. Thanks for the post![emoji1303]

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The_Learning_Curve · Jan 26, 2017

I flew down to around 20 or 30% on all my batteries last week and only recharged them without fully draining them. Flew today and it was super windy, got overload warnings pretty much on all 6 batteries that I used.

It's still hard to believe there isn't an official guide from DJI that explains all the possible issues that could throw up various warnings. Like you would get from the error code readers for cars.

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rbrdly · Jan 28, 2017

I flew 4 of my batteries down to 0%. Recharged two immediately. They don't produce the error any more.

I didn't have a chance to charge the other two for a couple of days, but it looks like I've left them over-discharged for too long, and destroyed them.

I was hoping they would be able to handle 0% for a couple of days, but looks like I was wrong.

2 more batteries gone to waste through bad battery management.

Poop

The_Learning_Curve · Jan 28, 2017

I don't recall any warnings about leaving them completely drained. I'm surprised I haven't made the same mistake yet.

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rbrdly · Jan 28, 2017

What I get with the three affected batteries is:

Plug into charger
Battery does a short health check
...
Nothing happens

If I do a long press to get the battery health, it shows all four lights.

They just won't accept charge.

Same experience whether I try to charge them individually, or on the hub.

If anyone has experienced this and recovered them, I'd love to know how you did it.

rbrdly · Jan 28, 2017

Actually, I might be out of the woods. I was using an inverter to try and charge them - was away, camping.

Just plugged one of them in at home and it looks like it's charging.

*chuffed*

bujaman · Jan 28, 2017

@rbrdly I was going to say have you left it on the charger for a while. Happened to me once, but it was not due to leaving at 0%. Not sure why it happened to me, but I left it on the charger for the better part of the afternoon and it started charging.

One question I have for anyone: I have about 40 cycles on a few batteries and I had not calibrated them (ignorance). After calibrating them for the first time, they are still not reaching the rated capacity. 4200 mAH for a tb47 (3900 mAH prior to calibration) should I calibrate it again or give it a few cycles?

Jonnyb333 · Feb 6, 2017

The Editor said:
The software can detect the amount of back emf coming from the motors as well as the driven pwm square wave from the esc's and the expected rpm. If the two do not correlate the software will assume a motor obstruction.

Sorry I am fairly new here, can you please speak English or at least translate emf pwm and esc? Errr electro magnetic force? I have had the same trouble last week.

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lake_flyer · Feb 8, 2017

Jonnyb333 said:
Sorry I am fairly new here, can you please speak English or at least translate emf pwm and esc? Errr electro magnetic force? I have had the same trouble last week.

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Electromotive force, also called emf is the voltage developed by any source of electrical energy such as a battery or dynamo.
Pulse-width modulation (PWM), or pulse-duration modulation (PDM), is a modulation technique used to encode a message into a pulsing signal.
An electronic speed control or ESC is an electronic circuit with the purpose to vary an electric motor's speed, its direction and possibly also to act as a dynamic brake.

Google is fast.

Jonnyb333 · Feb 8, 2017

Thanks! I don't think I am much clearer!! I was never one for physics. Is there something written somewhere in laymans language that would help me understand all this?

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Jonnyb333 · Feb 9, 2017

Ok my arty brain might have caught up. I am guessing that you are saying that the electricity is sent to the motors by pwm which acts as a code that can be monitored by the software. Any change in the code after going through the motors can be read by the software as a problem in the motor. Is that it?

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The Editor · Feb 9, 2017

Jonnyb333 said:
Sorry I am fairly new here, can you please speak English or at least translate emf pwm and esc? Errr electro magnetic force? I have had the same trouble last week.

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OK, to put it basically......
The motors are driven by the esc's by way of square wave pulses to accelerate/decelerate them.
Since all motors also act as generators, when the motors decelerate they produce a current (back emf) which can be detected. (It also assists in the rapid braking on the I1).
Since the flight controller knows what signal it is sending to the esc's and the esc's produce the drive pulses, if the firmware detects that the back emf isn't corresponding to the deceleration (or acceleration) commands being sent then the FW will throw up an error.
Unfortunately, the DJI coding chimps have overdosed on bananas again and made the algorithms a little over zealous in throwing up the 'error' message - this should be tweaked in the next FW release which is not too far away.