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Bad Raven:
02 Dec 2019 20:03:50
Only if the battery is fully charged, leak a few volts and it'll be fine.......
Andy7:
02 Dec 2019 17:19:55
If yo fly a Mavic Mini and get over a gramme of mud on it, do you have to register it?  :rofl:
hoverfly:
02 Dec 2019 08:38:56
Not a problem i've had a body mod, I think of Jean Harlow naked on a trampoline  and the new antenna  extends automatically..   :whistling:
Andy7:
29 Nov 2019 17:17:37
That'll play hell with your FPV signal. :rofl:
hoverfly:
29 Nov 2019 17:10:20
Won't get me i'm wearing my tin foil hat... :wack0
Andy7:
29 Nov 2019 14:19:03
Because GOVERNMENT SPY DRONES are watching us! :frantic:
hoverfly:
29 Nov 2019 11:41:22
BBC News this am ..only 50% of people have registered  for the  CAA  scheme.. If people haven't registered  how do they know it's 50%.. :shrug:
ched:
28 Nov 2019 20:16:14
Very very quiet. I am missing chatting :-( Must be the weather....
Gaza07:
25 Nov 2019 08:28:26
Forums very quiet  :shrug:
ched:
18 Oct 2019 11:25:16
Sounds good yama. Would love to see some images. 3d models sound cool too
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3d - Printworx

Printing 3d Forum

New to this

Started by tipsy trucker, Sunday,December 09, 2018, 19:38:51

Previous topic - Next topic

tipsy trucker

Myself and ched999 have brushed onto this subject earlier and it may be something I end up needing to try

I've got a problem with motors not doing more than about 10%  even at full throttle. The f.c. and escs were both used on my previous quad without any trouble but they're certainly giving me some trouble now.

I've checked everything I cant think of, recalibrated several times etc etc but still not getting anywhere. I've come across a bit of info though; a screenshot of the blheli suite that came with the escs and the motor timing is marked as "medium" (REV 16.5 A-L-40 multi)

the old motors were sunnysky 2212 980kv

the new motors are Gartt 5008 400kv

both on 4s

I can get the motors to 6500rpm (measured with a lazer tachometer) with no load but only 650rpm with their 18" prop's on - I'm wondering if timing might be the issue, perhaps such a slow motor needs different (slower) timing.

I've downloaded the blheli suite and ordered a usb interface, just in case. It looks a relatively simple job but I thought I'd ask for your views for a start and is there some sort of chart that tells you what timing for what motor/setup?

Cheredanine

it Is likely that the timing may need to be different between such dramatically different motors as well as demag compensation. But that is not your problem

Couple of questions/points;
1. What esc protocol are you running on the fc?
2. ESCs are generally chosen for their amp capacity, that is a dramatic change in motor, it is likely that it needs different rated ESCs, you sure these are man enough?
3. The esc version appears to be blheli_s - be very careful, there are three flavours of blheli - the original, blheli, the second gen, blheli_s and the latest, blheli32, use the right configurator and software.

Now most of that has no bearing on your problem,
You are using blheli_s so you should be able to use dshot (as opposed to pwn, oneshot of any flavour or multishot), this is a far more resilient protocol, and does NOT need calibrating, I would strongly recommend using it if you are not. The specific version of dshot depends on the ESCs, blheli_s supports up to dshot600, however the hardware may not if has too much capacitance on the signal line, I would start at dshot150 to be safe and then try dshot300 and dshot600. If they don’t work go back to the previous one that did.

I’d i am reading right, the motor has a full range without load, but under load only does about 10% yes?



tipsy trucker

I was hoping to avoid the subject for the simple reason the fc and escs worked together absolutely fine last time (the very same ones, rescued from the wreckage - prop flew apart 70m up), I didn't want to muddy the water....

I'm using naza fc and the escs were sold as blheli dshot but i don't know any more than that (I may have got the revision wrong, I'll confirm when the interface arrives).

The escs are apparently 28A continuous and 38A "burst". Ecalc reckons around 20A peak so all should be well there.

I've measured with a tachometer and get 6500rpm without the prop and only 650rpm with it - the screws are nowhere near interfering with anything but I tried shorter ones anyway and it made no difference

Cheredanine

Ok so the reason I wanted dshot is it removes calibration issues
The fact the motors spin at full speed without load (props) means the basics work fine (in terms of commands, timing, back emf etc)
The fact they don’t spin up under load suggests, given the other factors, only one thing - power to the motors is being throttled.
(The command clearly works when there isn’t much power needed, they don’t when there is)
It could be a number of things, bad connection, short, on more advanced ESCs, limitation on amp draw given the nomaclature of the esc software (even if you have it slightly wrong, it is blheli_s, I don’t think, although it has been a few years, blheli_s has ampage limiting capability. So my money is on one of the first two

tipsy trucker

I don't have anything to hand to measure over 10A but what I do have is an electronics engineer/lecturer of ~ 55years experience (my dad) I don't do too bad with the physical side of things, my soldering's reasonable - I used to be a mechanic so learnt back at college but these things rub off on you as well when you have a resident expert.

What I can tell you is I have battery voltage minus about 0.1v at the esc (which is about 420mm of 14g wire) which I consider normal and the voltage drops by about 0.2v at full throttle - the old man totted it all up in his head somehow and proclaimed there's no problem with the supply but I'm not too proud to experiment - if I get time Tomorrow, I'll put a second battery directly on the esc (in parallel) via croc clips and see what happens.

I wouldn't be surprised to find these escs are marked as 28 amp but are, in reality, much lower and just haven't got the oomph to get that big prop going but I've got little choice but to go on the info I have available for now

Cheredanine

Not disputing voltage, per se.
The rpm of the motor at max throttle should be kv (that is rpm per volt) x the voltage supplied.
This is clearly the case without load.

When load is applied (ie props on), the motors do not get over 10% assuming I am reading your description correct.

The above equation applies regardless of load, they should still be trying to get to the same speed, however, because the system has load, they require more power to do so.

As I am sure your dad will tell you (cos I am a dad and I would love to lecture my kids) P=IV
Whilst the voltage will sag a little if more current is pulled from the lipo, it shouldn’t go down to less than 10%, therefor the rpms shouldn’t, however that assumes the lipo can provide enough current to give the motor enough power.

Interestingly you don’t mention what lipo you are using, so that is a possibility but not much of one I would think.

ESCs rated 28 Amps, particularly blheli_s and later are common place, if they couldn’t handle the amp draw they wouldn’t restrict it, they would let the magic smoke out

Soldering - yes, many of us did degrees in electronic engineering 30 years ago, and solder regularly, no disrespect, but that doesn’t mean we don’t get dry joints or shorts, appeals to authority have no place in electronics.

My first thought would be the prop screws touching the windings, but you assured us that wasn’t the case, is there much heat in the motors?

Timing and demag are likely to produce stutter and desync rather than max 10% rpm, still have to go with something not getting enough power to the motors.

tipsy trucker

It's difficult to believe anyone with any sort of ability would have the same problem on 4 brand new motors though.

The old man figured it out in his head and it's a long time since I did any of this but a .2v drop on 16.5v is nothing like the expected current. We also measured the resistance (to get the final figure of about an amp) - I think in layman's terms what he was trying to say was that if there was a problem with the power supply this would have shown it up and the conclusion is that it's ok. I'll connect the second battery to the esc anyway though just to see what happens - if it solves the problem, we got it wrong and the supply is a problem, somewhere. Sadly, since retiring, dads not so keen to get involved (can't say I blame him) so all help is very gratefully received

The motors are stone cold (as is everything else) and the lipos I'm using are nearly new 6000mah 4s 35c

tipsy trucker

Monday,December 10, 2018, 12:59:59 #7 Last Edit: Monday,December 10, 2018, 13:10:20 by tipsy trucker
No, no difference- with a battery in parallel at the esc.

I reheated EVERY joint and added a little solder to any that looked less than perfect (more to get it flowing than anything) and tried again but still exactly the same 😕 I then put a brand new esc in, still the same. Did the calibration, still the same!

So, I should get a cheap servo tester from the Amazon man at some point today. I'll see if it does any different to the radio gear and if still no change, ill put one of the 980 motors on in it's place and see what happens then


Edit; just the same with servo tester so it's not a signal issue

atomiclama

Just a thought does the motor speed increase linearly through the throttle range or does it reach max speed  before the servo tester is at max?
Wasdale X, Ow that hurt

atomiclama

Where you based? Anyone near by ? take a fresh look at it?
Wasdale X, Ow that hurt

tipsy trucker

Without the prop it's very much linear with both sets of radio gear and the servo tester

With a prop, it's difficult to say - with the servo tester, it starts almost as soon as I move the knob but plateaus at the usual speed (about 650rpm) and turning any further has no effect at all. With the radios through the fc, it arms at whatever speed that is and doesn't do anything else until the stick passes a certain point (50%?) then speed increases as you'd expect but only briefly until it reaches its plateau. Directly to the receiver it does exactly the same as the servo tester.

I'm in Lincoln, anyone's welcome to have a look, there's even a beer in it 😉 I've had to give up for now, other things to do and work in a bit

Cheredanine

Hmmm, this is tough, all the usual suspects would effect unloaded as well as loaded or produce heat/magic smoke,

Have to wander if the fc is reacting to the current draw?

Two-Six

Perhaps get one of these?: https://hobbyking.com/en_us/turnigy-180a-watt-meter-and-power-analyzer.html

It might not help much but good to have one anyway  :hmm:


Nighthawk Pro, Trex 450 L Dominator 6 cell *FLOWN*, Blade 450-3D, MCPX-BL, MCPX-V2, Hubsan X4, Seagull Boomerang IC .40 trainer, HK Bixler, AXN Clouds fly,, Spektrum DX7, Taranis, AccuRC

tipsy trucker

Quote from: Cheredanine on Monday,December 10, 2018, 16:53:03
Hmmm, this is tough, all the usual suspects would effect unloaded as well as loaded or produce heat/magic smoke,

Have to wander if the fc is reacting to the current draw?


It's doing exactly the same if I miss the fc out altogether though unfortunately- all I can think now is I either got 4 dud motors or the escs just don't "go" with them for some reason.

I'll try one of the old motors on it tomorrow and see what happens but I'm almost certain it'll be absolutely fine; they worked spot on with exactly the same setup on the old quad....

The USB linkup thing's due in the morning too so I'll try changing the timing up a notch and down a notch, just on the offchance

ched

I know it's shelling out more money but there has to be something weird going on but I would buy a cheapy SimonK 30A esc for about £2.5 on ebay (Check delivery times to get a UK supplier).
That would give you a 'spare' esc and your old motors to be able to determine where the issue is.

i.e.
new esc and new motor - if it works then old esc's don't behave as they should with new motors.
old esc old motor - if it works then issue is with new motors.

Have you checked the resistance between the motor screws and each of the 3 motor wires? Should be very high, this would prove no damage due to screws, well actually if screws now backed off might not prove anything (worth doing if you desolder motors to test old motor).
Also check the resistance between each of the 3 motor wires (when desoldered) they should be equal and the same as the specs.

I know it's silly but I assume that you have been testing not just 1 motor/esc each time?


As for when the FC (NAZA) is connected depending on what mode it's in you might get very little change of motor rpm till you get to 50% as it's not a linear throttle it is case of raising throttle over 50% to lift off and 50% should hover automatically.

I was hoping with this thread you would get some other ideas that I might have missed. Hopefully swapping motors, while a pain, might give you more clues as to what isn't working correctly.

Good luck and stay calm  :smiley:
I try :-)

tipsy trucker

Monday,December 10, 2018, 22:14:00 #15 Last Edit: Monday,December 10, 2018, 22:22:45 by tipsy trucker
Cheers ched

Just to clear that one up, the way the screws are on these motors, the screws can't touch the windings; at the top, all they'd hit is a bearing (if they were about 8mm too long) and the bottom's almost like s seperate base plate - the screws could possibly make it to something important but they'd need to be waaaay too long

I'll have a poke around with the meter though, just in case.

I think if we're no further forward tomorrow, a set of escs might be worth a try. I'm not sure what I'd get though apart from maybe 40A - I could flash the ones I'm using with simonk I suppose, just out of interest really

Cheredanine

If the screws were touching the windings the motor would get very hot very quickly (and would noticeably stutter, particularly under low throttle)

tipsy trucker

Still waiting on the postman  :waiting:

I've put one of the old motors on, with an 11x5 prop (which should be right at the limit of max current) and it's spot on, to the point that I was struggling to hold the arm it was mounted on (I needed a way to mount it but didn't want to remove the large motor so I mounted to a spare dji arm and held it at the other end).

The phase wires on the new motors are about an ohm between each and open circuit to the bell, I cant get at the bottom half of the motor while it's mounted.

At full throttle, each phase reads 8v between that and ground - I'm not sure what to expect there though. I can tell you without the prop and spinning flat out I cant stop the motor by hand (probably a bad Idea but sometimes these bits of info lead to the solution)

I've noticed two things today - the beeps when I connect the battery are sometimes different; they end in a double beep occasionally, is that relevant?

And, if I'm very gentle turning the speed up, the motor often stutters  :hmm:

atomiclama

Quote from: tipsy trucker on Tuesday,December 11, 2018, 12:44:22

And, if I'm very gentle turning the speed up, the motor often stutters  :hmm:


That's fine, the ESC has just has not sync'd to motor rotation, there's not a good enough BEMF to work with at low speeds.
Wasdale X, Ow that hurt

atomiclama

Quote from: tipsy trucker on Tuesday,December 11, 2018, 12:44:22
the beeps when I connect the battery are sometimes different; they end in a double beep occasionally, is that relevant?


So what's normal for your ESC compared to the 2x beeps.

I thought but maybe mistaken that the last sequence of beeps is the voltage detected so 3x beeps would be 3S 4x beeps 4S. I would expect 4x beeps for you.

There is some protection in the ESC where it will back off driving the motor when the voltage drops, but this is usually turned off with multis, more of a plane thing I think.

Could be related, if for some reason the ESC is measuring 2S and you run the motor, the voltage drops and so the ESC protects and shuts down.  :shrug:

I had a similar problem to you, a motor would not reach full power, turned out one of the strands of the motor windings had broken. Would work fine no load but as soon as loaded it just couldn't handle it. But you are one new motors, I'm just waffling  ::).


Wasdale X, Ow that hurt

tipsy trucker

Quote from: atomiclama on Tuesday,December 11, 2018, 13:13:14
So what's normal for your ESC compared to the 2x beeps.
Without singing it to you, I'm struggling a bit; it goes up in three ascending beeps followed by a higher beep and a lower beep

if I remember right, when it's different, it'll do the three ascending - then the high beep - then two beeps close together at a slightly different tone altogether

Quote from: atomiclama on Tuesday,December 11, 2018, 13:13:14 There is some protection in the ESC where it will back off driving the motor when the voltage drops, but this is usually turned off with multis, more of a plane thing I think.


Funny you should mention that, I was just reading the blheli manual and came across this; "Low RPM power protect:
Power limiting for low RPMs can be enabled or disabled. Disabling it can be necessary in
order to achieve full power on some low kV motors running on a low supply voltage.
However, disabling it increases the risk of sync loss, with the possibility of toasting motor or
ESC."

Quote from: atomiclama on Tuesday,December 11, 2018, 13:13:14 I had a similar problem to you, a motor would not reach full power, turned out one of the strands of the motor windings had broken. Would work fine no load but as soon as loaded it just couldn't handle it. But you are one new motors, I'm just waffling  ::).


I tend to agree - they're new and I've not done anything that'd break any wires, and the resistances are all the same  :shrug:

It seems I'm on the postman's naughty list today so there's not much more I can try for now

tipsy trucker

So, back to the original question in a way; I'll try changing the timing and then disabling the low rpm thing

Failing that, it seems I can flash these with simonk firmware, any opinions about which version or anything else I might  need to know?

tipsy trucker

It worked!  :beer2: Thankyou all very much for trying to help  ~~

New settings:






Now to go crash it  :-/

ched

Well done.
What did you have to change?
It's always tricky getting older stuff to 'talk' to new kit.
It's great that you got to the bottom of the issue and managed to solve it.

I can see you building smaller fpv acro quads before long  ::) ::) ::)
I try :-)

tipsy trucker

Quote from: ched999uk on Wednesday,December 12, 2018, 15:39:09
I can see you building smaller fpv acro quads before long  ::) ::) ::)


Someone got me to watch a fpv race video a while back, I'm a lorry driver I don't get motion sickness but that certainly came close; I'm not sure it's "for me" to be honest lol

I turned the low rpm protection off and the timing up a notch (to medium high), I don't know which worked or if it was the combination though as it was the only thing I tried and I'm happy with the results. I also changed the throttle min and max to 1000-2000 (And mid to 1500) just because I'd read it works better somewhere but, if I'm honest, it was such a small change that I doubt it made any difference at all.

ched

Always good to read the solution as it's then here if anyone else has same issue in future.

FPV racing is, in my opinion a very young persons game. The reactions they have is stunning. I have watched an event through my goggles and I just can't comprehend how they manage to change direction so fast.

The FPV Acrobatics/Freestyle can be spectacular. Have a look here https://www.multi-rotor.co.uk/index.php?board=158.0 at the Wales/Snowdonia stuff. There are some spectacular flights.

Personally I am still learning to fly in Acro mode so I can just fly round and do a few tricks  ::) It is a great challenge. Being a lorry driver you might get to stop at some great locations round he UK. So if you had a small quad you might be able to get some lovely images  ::) Not that I am encouraging you you understand  :laugh:

Hope you have fun and post some vids when you get airborne, don't worry if you think they are not good or boring as we are all friends here.  ::)
I try :-)

tipsy trucker

Quote from: ched999uk on Wednesday,December 12, 2018, 16:45:50
Hope you have fun and post some vids when you get airborne, don't worry if you think they are not good or boring as we are all friends here.  ::)


It's already up  :whistling:

No no, if I go out and buy a 5" frame after christmas, it's all your fault   :laugh:

I've got more questions yet but I'll go back to my build thread for that  ;)


ched

Quote from: tipsy trucker on Wednesday,December 12, 2018, 17:04:07
It's already up  :whistling:

No no, if I go out and buy a 5" frame after christmas, it's all your fault   :laugh:

I've got more questions yet but I'll go back to my build thread for that  ;)

Doesn't need to be 5" anymore to get decent acro. There are some very good 3" quads about  ::)
I try :-)