ESC or Motor issue? Pulsing, stuttering?

[Keith Newman]

Hi, test flew a model today here in the UK.

Used to be a IC engine model. (Chilli Breeze)

Now it is has:

Mega Motor 22/30/2 Brushless Motor
Saker 80amp ESC
4s 3200mAh Lipo
APC Electric 10 x 6 Prop


Anyhow, i forgot to test it with a 'watt-meter'

It flew fine and took off of the ground very fast. Plenty of power.

Problem was, about 2-3 minutes into the flight, I lost motor power.

Landed and checked model over.

ESC was warm
Motor was warm
Lipo's were fine.

[Keith Newman]

Motor was now stuttering, pulsing, certainly now spooling up at all.

Anyhow when I came home. I I stripped motor & esc from the model, removed prop and re-tested.

Motor seemed now to spool up fine and go to full speed. (this is without prop on)

I have not programmed the ESC, will check that perhaps?

Any idea what my issue may have been?


Many thanks

[Steve Hargreaves - Moderator]

I would check for a poor connection between the motor & the ESC Keith & maybe re-solder the connectors. It can be quite difficult to get a good solder joint here & it sounds to me like one of the joints is intermittent ...

[Malcolm Fisher]

Hi Keith,

I had a similar happening with one of my electric set ups and the rudder and elevator controls were erratic. Back home I checked everything over and discovered that the connector from the ESC into the Rx was not fully home into its socket and the other "plugs" could also be suspected not to be connecting properly. After making sure that all connections were sound, everything worked fine.

Could you have something similar?

Malcolm

Edited By Malcolm Fisher on 21/05/2017 20:40:13

[Mark a]

Definitely a dodgy connection between motor and esc check all the soldered joints.

[Dave Bran]

The manufacturer website states that motor type is 2-3S. You have it on 4S. Are you sure it is rated OK for 4S??

Check this first!!

Running the motor on no load won't really tell you anything useful, After the no load run you could have restrained it and well away from prop and possible shed blades tried a brief static load run to check fault still evident.

You might have a timing issue with the ESC not set up well enough to cope, it's only a 6 pole 2 wind. Lots of things it COULD be!

[Chris Bott - Moderator]

I'd put my money on a temperature issue. An ESC that's warm on the outside could be very hot on the inside. Most ESC's will reduce or cut power to the motor if they get too hot. Or worse, the BEC might cut power to the Rx.

2-3 minutes into the flight could be how long it takes to get too hot.

Working once you get home could mean it had time to cool again.

[Keith Newman]

Dave Bran.

Unless I am missing something, The motor is okay for more cells that you write, 2-3S

http://www.megamotor.cz/v4/script/default.php?&sid=3a10de999f61f2b7fcf0c9ecb6016022&page_id=lang_eng

http://www.icare-rc.com/mega_acn2230.htm

https://www.rcgroups.com/forums/showthread.php?1856304-NIB-Mega-Motor-ACn-22-30-2

You do have me thinking now, I do usually use a Watt meter to check everything, but I didn't do that this time. Which annoys me as I may have then some better answers in my head.

You maybe right though, 3s maybe the max for this motor.

Like I said, back home, cooled down, all seems to be working okay, (touch wood)

But I did test in back home with a 3s 2200mAh Lipo as the 4s was needing charging.

[Former Member]

[This posting has been removed]

[Keith Newman]

Not yet, tried it on the work bench WITHOUT prop on

with a 3s 2200 mAh lipo and it spools up fine.

Fitted prop back on, now has stuttering / jittering,

99% sure it is not the soldering or connectors as it spools up fine without a prop

[Piers Bowlan]

Keith, do you have another suitable ESC to substitute and give it another test with the Watt meter. An 80A ESC should be fine but it may have developed a fault which won't show up unless it is under load. No point testing it without a prop. If no change, try substituting another motor if you have one. As has already been suggested, it may have overheated and caused some damage to the motor or ESC which shows up under load. Stuttering is sometimes a timing issue but I cannot see how that can change after two or three minutes of flight.

Looking at the spec. of this motor I would say that a 10X6 prop is too much on 4S as it is a 1920Kv motor and it could have exceeded the capabilities of your 80A ESC. Hope I am wrong!

 

 

 

Edited By Piers Bowlan on 22/05/2017 09:53:02

[Dickw]

Posted by Keith Newman on 21/05/2017 20:10:29: .........

Mega Motor 22/30/2 Brushless Motor
Saker 80amp ESC
4s 3200mAh Lipo
APC Electric 10 x 6 Prop

Anyhow, i forgot to test it with a 'watt-meter'
.............

I used to use that motor in an RC combat model with an 80A Hyperion ESC. It would pull in excess of 60 amps static and around 40 to 50 amps in flight on a 3s Lipo and a 9x5 prop.

I think 4s and a 10x6 is pushing it a bit.

I think there was originally a different version of this motor available with a lower kV (1770), but the current spec is here and the cell numbers mostly refer to NimH cells.

Dick

Edited By Dickw on 22/05/2017 10:02:32

Edited By Dickw on 22/05/2017 10:03:46

[Andy48]

That's a very low capacity battery for a motor that can draw 70amps. Equivalent to 25C, and if its drawing more than 70 amps ..... Even a 45C capacity battery may struggle on that given the variance between stated C rating and actual performance. Could be dropping the voltage too much and causing the ESC failsafe to kick in. Could also be ESC timing.

1. Set up ESC carefully checking all the settings.

2. Use a wattmeter.

[Piers Bowlan]

The spec. is here. On 3s and a 10x6 Cam Prop it draws 62A which is quite a bit for a 3200Ah LiPo but OK. If you run it on 4S you will need to prop down (9x6 or even 8x6?). If the motor did get too hot the insulation on the windings may be breaking down causing the stuttering you describe. However you say the motor was only warm, so hopefully the problem is something else.

[Andy48]

For a start, the OP said it was running on 4S.

Motor or ESC don't have to be that hot if the current draw is so much that after a short time the battery voltage drops below the set limit on the ESC.

[Geoff S]

The cell count isn't all that important. What is really, really, important is the current draw and checking it on a new, untried set-up is absolutely essential. I've found a lot of budget motors don't perform as the published spec implies perhaps more expensive ones are better.

I know a lot of people (even F3A competitors) never bother checking the current draw and rely on the fact they're using a recommended motor/prop/esc/battery combination and they get away with it but I like to know and always measure it.

Geoff

[Piers Bowlan]

Andy, I was pointing out that the published spec. on 3s is 62A on a 10x6 Cam prop. Therefore, on the 4S LiPo that Keith was using the current draw was likely to be well in excess of the motors published maximum 70A. The Mega Motors are good quality so I hope that there is an alternative explanation. I wouldn't expect the motor to stutter and pulse once the PCO cuts in but I am no expert.

[Former Member]

[This posting has been removed]

[Piers Bowlan]

You are right Andrew, some ESCs do do that when the BEC Power Cut Off activates. However Keith says he tested it on the bench with a 3S (he flew it on a 4S) and presumably freshly charged LiPo and it is still 'stuttering/jittering'. By the way Andrew, my precious post was aimed at 'Andy 48' by the way (note to self;- quote peoples posts to avoid confusion!).

Personally I doubt this problem is caused by a poor soldering connection as the problem cropped up after two or three minutes of flight but the only way to be sure is to test the circuit resistance with a meter. Keith could also check the motor windings too but trying another ESC would be what I would do next.

 

Edited By Piers Bowlan on 23/05/2017 06:21:32

Edited By Piers Bowlan on 23/05/2017 06:23:45

[Denis Watkins]

Keith, if you get time, prepare a lipo at storage charge 50 - 60%, then hook this up for the tests.

Does it run OK now?

[MattyB]

Whatever the root cause turns out to be the lessons here would seem to be:

1. Do some basic calculations on your powertrain before buying components to make sure they are in the right ballpark for your model, and;
2. Once installed always test your setup with a wattmeter before flying.

The fact the OP did neither is I suspect going to be a costly lesson...

Edited By MattyB on 23/05/2017 09:56:51

[Former Member]

[This posting has been removed]

[Old Geezer]

Just my tuppence-worth. Could this be battery related? I had a similar problem with an Eflite Sukhoi when trying to use a 20c LiPo, which went away when swapped to a nominal 40c - seemed that the voltage dropped dramatically, when the 20c was asked to produce more oomph than it was able - the ESC then pulsing to tell you that it thought you'd almost run out of electrons.

[will -0]

Hi, make sure you're using fresh electricity as leaving it in the wires over the winter can make it absorb water. Have you tried replacing the solder?

I'd love to see some pictures of your breeze, mine flies beautifully on an ASP 32.

[Andy48]

Posted by will -0 on 23/05/2017 15:08:42:

Hi, make sure you're using fresh electricity as leaving it in the wires over the winter can make it absorb water. Have you tried replacing the solder?

This has to be a wind-up, surely!