Problem ESC or Motor

[Bob Merrett]

Hello Everyone,

After two days of trawling different forums, sites and searches, and trying various suggestions I am still no better off.

My particular problem is that as my throttle stick ( Futaba 6XAs) get to 3/4 position the motor (EMP 3536/08 1000kv) hesitates. The power just drops right off and then surges back into life at the expected revs/power band at full throttle setting. I liken it to a fuel starvation problem on a normal engine. With no propeller attached it sounds just like a "knocking" noise. Thought the outer casing was catching on something, but no. The ESC is Hobbywing Pentium 40A. It is a twin set-up of the above, and happens to both motors at the same point, regardless of which ESC they are wired to.

Is it just bad equipment!?

All thoughts graciously and humbly received.

Sorry If I have missed any postings on here, but I have looked , honest! My brain is now fried with frustration!

Thanks,

Bob

[PatMc]

Bob, have you tried changing the timing of the ESCs ?
Outrunners are usually OK with "medium" but if running at high RPM sometimes the timing needs to be set to "high".

[Bob Merrett]

Thanks Pat. I have just changed the timing to high, they were on medium, but will need to wait until my Lipo charges up to test. My other one wont and keeps shutting off the charger! Something else to buy!!!!!

[Mal Quelch]

Bob,

another thing you could try is another Transmitter, your problem seems to be affecting both motor systems, could it be a dirty or bad track on that stick axis? Maybe try driving it with a servo tester or from a different channel BUT be aware you will have to make sure stick is held low when switching on or the motor may start up - but I think the hobbywing series have safeguards to prevent it.

Mal

[Biggles' Elder Brother - Moderator]

Its unlikely to be duff equipment - that would require both ESC's or both motors to have the same fault.

I'd agree with Pat that timing is most likely to be the issue. The only other thing I can suggest is have you "taught" the ESC's the throttle range? That is unlikely to be the problem but you can never be 100% sure how an ESC will react to finding a throttle setting beyond what it expects to see!

BEB

[Dave Bran]

A few observations:-

I have used HobbyWing ESCs extensively for quite a few years, even using them in installations where the previous ESC has given problems, to instant and permanent correction.

That motor is rated at Imax =30A for 60 seconds. Presumably at 3/4 stick its therefore running out of sync at maybe only 20A??

A 40A ESC is therefore likely to be cruising and getting hotter through doing more switching.

You say about testing "with no prop attached", which is, with no load at all, bound to push any timing issue nearer to the cliff edge and isn't the way to check. You don't state prop size, or if you have had a wattmeter on the setup and the results, and IMO that data you and we need to go any further.

[Gary Vinten 1]

Hi Bob

Change the timing to high this may work

[John Privett]

Bob, does it behave this way if you just plug-in one of the ESCs and completely disconnect the other one?

I'd also try plugging a servo into the throttle channel on the receiver and see if it also jitters as the throttle stick reaches the 3/4 position.

[Bob Merrett]

First and foremost thank you so much for all your replies.

Pat/BEB/Gary - I have now tested with the timing HIGH, throttle stick at full throw, waited for my cell count, then two bleeps, stick back down registered as normal. Still no difference I'm afraid.

John - Just ran my West Wings hawker Hunter EDF with a lovely smooth response all the way up with not the slightest hint of hesitation. Did test a servo prior as suggested too, again with no fault showing. The set up is one battery/esc per motor and a Y lead into the receiver with one red wire disabled.

Dave - saved your until last! I must admit than when I ordered the motors, these were sent as suitable replacement, as no stock of the others. information at the time said 35A 2-3S, now I see information shows 25A 2-4S.

On a fresh battery and when I get to "hesitation point" watt meter shows 210W, 17.7A, timing HIGH. Move to full throttle and it blips to 350W and shuts down. The ESC resets itself and I am able to move the throttle again with a smooth pick up until roughly 3/4 point and history repeats itself.

Other setting are 250W, 22A timing MEDIUM, before shutting down, 240W, 21A timing LOW, before shutting down.

The propellers are GWS EP1060 3 blade (for counter rotation)

The attached photo shows my set up. I have even disabled the other red ESC wire (on the Y lead) and powered the receiver separately, still the same. Aaaaaargh!

Thank You All,

Bob

[Mal Quelch]

Bob, thats a big aerial you have there! 35Mhz. Could it be interference from two switch mode bec`s? Sometimes one is enough to cause problems and you have doubles of everything.Trying to keep maximum separation may be difficult for you.

[Bob Merrett]

Mal, I will do some testing later on by swapping bits around with the two other electric models that I have and see how the individual motors and esc's perform then. Thanks.

[PatMc]

Bob, I'm not clear if you've had this problem when no props are attached as well as when they are.
It may be worth trying a single motor with a smaller prop in order to keep the current down but the motor not over-reving.

Another thought is that if both motors are behaving the same at exactly the same time it suggests it's more likely to be the Tx than the ESCs. Is there any chance that you have some sort of power curve or expo programmed to the throttle channel ? Perhaps inadvertently or left over when the memory was used for a different model. Might be worth trying the motors using a different memory that you know works with another model or trying this memory with a model that you know works OK.