Rollover after changing motor

[Andibody]

Hey everyone,

I am new to fpv and also to this forum. I am from Austria so also my english is not the best.

Just recently I bought an Eachine Wizard x220s to dive into drones and it worked great. After a crash I tried to fly again and one motor just burned through, only smoke and that was it. So I bought a new motor, replaced it (not an eachine but with same specs, 2205 and 2300kv flying on 4s), I just changed the motor direction in BLHeli and started again. At half throttle everything is fine, it hovers straight goes forward, backward, left, right and turns, everything is good. But when i go full throttle it rolls over and crashes.
So I thought the motor could not keep up with the others, changed it again, same issue. I didn´t change anything in Beta flight or BLHeli except the direction of the new motor. And i triple checked that the props are mounted the right way.

Any ideas what the issue could be? Sorry if it is a stupid question but I don´t find what i need in the internet.

Thanks a lot
Andy

 

[wafflejock]

When you changes direction using bl heli suite which option did you pick? You don't want bidirectional in there that is for 3D flight, you want just regular normal or reverse options. Also alternative to switching settings in bl heli can just swap any two of the three phase wires (between esc and motor) and will flip the motor direction.

 

[Andibody]

I just changed the motor to "reversed" nothing else. I think the direction is fine otherwise it would not hover so stable on half throttle. Only when I go full it flips over

 

[wafflejock]

Yah that should be fine the only other thing I can think of is the esc doesn't expect the low to high range that the FC is sending it, are you using d-shot or pwm for the signal from the FC to the ESCs? In any case can try doing esc calibration also bench test with props off and using motors tab see if power also cuts out on any of the motors when raising throttle with the slider vs controlling with transmitter.

 

[wafflejock]

Good way to get more info is activate and download the blackbox logs and use betaflight blackbox viewer app on your computer to see the input vs gyro info etc when it bails out. I've also heard of motor desync which this sounds like it could be but I'm not really sure what params to tweak in blheli to fix that kind of problem if it is that the same glitching of motors should happen when using the motors slider in betaflight configurator.

 

[wafflejock]

After rereading your original post I'd also be suspect of just that esc or that part of the 4 in 1 ESC had some MOSFETs or capacitors burn out or get knocked loose and so in high throttle situations when pulling a lot of amps to the motor it could be pooping out. To check if it's a given esc or motor can always swap two motors. Personally I've stuck with individual ESCs for my builds still just because so much easier to replace a single esc than tear apart a whole stack if one part of a 4 in 1 burns out. I'm going to do a DJI digital build soon and will probably go 4 in 1 ESC on that one but will be the exception not the rule

 

[Andibody]

Thanks for your answer, i will try to figure out what it means and what I should do
In the first case I was thinking what can happen that the motor burns anyways? ot was 1/10 of full throttle so no overheating or anything else, maybei something with ESC I really don´t know. But with black box is a good idea to see. And i will try to figure out hot to test in betaflight and see the signals. thanks a lot

 

[Dugdog47]

I've been having fun on 2.5 version of cleanflight , haven't smoked any motors either lol.

 

[wafflejock]

I've been lucky enough to not smoke a motor myself but saw it happen on my buddies emax buzz. He was stuck in the grass and gave it some throttle and ended up cooking the motor. Personally I've always had the esc go first, in the case of my buddies the damaged motor was replaced and the replacement fried so we figured the esc must be shot, I replaced the 4 in 1 with some spare (individual ESCs) I had laying around and we got him back in the air.

 

[Dugdog47]

I've been hearing stories of motors getting smoked with bad tuned bf 4.xxx although I've not used it much the couple kwads I do have on it fly fine with cool motors lol.

Usually smoked motors are the result of operator error though.

 

[Andibody]

stupid question. is there a tutorial on how to change a 4in1 to a FC with single ESCs?

 

[Andibody]

and an additional question the Eachine 4in1 is a BHeli based with 30Ampere. Can I also use Bheli with 45 Ampere? Since the spare parts for eachine take around 6-8 weeks to deliver in my region.

BTW, thanks a lot for your support, really appreciated

 

[wafflejock]

Hey yup the amp rating on ESCs is a maximum limit above that much current and they cook. So going with higher amp ones just makes more power available if the voltage is high enough given the roughly fixed resistance of the coils, it's a bit more complicated than that because of how ESCs and bldc motors operate but in general a higher amp esc doesn't mean it is necessarily delivering extra power all the time just that at the top end of the throttle it could supply more current to get more torque out of the motors. The max rpm of a bldc motor is determined by the voltage the torque is limited based on the current, so fast changes in rotational speed require more current/electrons to flow, but the top speed/rpm is based on the KV and the voltage (kv is a constant determined by the windings, bearings, and magnets and other physical parameters of the motor).


Long story short should be safe to do.

If you use 4 individual ESCs the only "tricks" are you probably want a power distribution board or PDB or an FC that has pads for powering the motors through the ESCs since each of the four ESCs will need battery power hooked up to them. Then just need to find the 4 motor signal pads on the FC usually even if they are designed to work with a 4 in 1 they will have some pads or holes for soldering signal connections. Generic boards like the kakute f7 or 722 based ones will have through holes for the signal connections. If you mess up the order of the motors /signal wires can fix it with resource remapping in betaflight CLI. Admittedly it's easier to do this when just building from scratch since you end up doing disassembly and basically full reassembly but once done if one esc blows it's a lot easier to just replace it on the arm without taking it all apart again.