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ESC only works when increasing the throttle very slowly

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conrad taggart15/07/2019 01:22:32
99 forum posts
5 photos

I have an Overlander 80 amp XP2 Esc fitted in a Wot4 which only fires the motor up properly if I increase the throttle very slowly. If I increase it at normal speed the motor simply stutters. The Esc also work properly on a lower powered 3 cell battery but not the usual 4 cell battery ! Any suggestions as to what the problem is or, even better, potential fixes greatly appreciated.

Many thanks

Taggarc

Allan Bennett15/07/2019 03:53:58
1563 forum posts
43 photos

With the motor stuttering, I would say the first place to look is the connections between ESC and motor. Stuttering usually indicates a bad connection somewhere in one or more of the three wires -- usually the bullet connectors, but it could be anywhere including inside the motor or ESC. Obviously, check the bullets and their soldering first!

conrad taggart15/07/2019 09:03:53
99 forum posts
5 photos

Alan - I have checked it and can't see anything wrong. Plus would this problem not prevent it working properly at a lower voltage (3 cell as opposed to its usual 4 cell battery) or when engaging and increasing the throttle very slowly ... where it appears to work as normal. Thanks Taggarc

Nigel R15/07/2019 09:11:00
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3161 forum posts
486 photos

A bad joint is not necessarily visible to the naked eye, all the connections could well "look" ok.

The other possibility that comes to mind is that the ESC timing is or has become set incorrectly, for the given motor.

Chris Walby15/07/2019 09:30:03
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1024 forum posts
237 photos

....I had a twin that very occasionally one prop would kick back 1/4 turn and then pick up just like the other...only did it 1 in 10 times. Checked everything out and all looked okay so pressed on with the maiden.

Take off and all checks completed no problem so though I would try a fast medium low pass to finish off with so with 3 or so seconds at full power there was a short noise and the port motor stopped. Emergency dead stick landing and a lot of luck and it was okay !

Found under the manufactures heat shrink sleeving a very poorly soldered joint on the motor lead to ESC...Might be worth cutting all the manufactures sleeving off and inspection to double check (re apply post inspection!).

Failing that it could be something to do with the timing setting in the ESC

PS I have the same issue but no where near as bad with a ESC if I snap the throttle open (not yet sorted so interested what you find).

Chris Freeman 315/07/2019 09:44:51
282 forum posts
371 photos

can be a timming issue if the motor works when opened slowly. Take the prop off the motor and see what it does with the 4 cell pack.

Nigel R15/07/2019 10:38:28
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3161 forum posts
486 photos

"PS I have the same issue but no where near as bad with a ESC if I snap the throttle open (not yet sorted so interested what you find)."

As do I.

Once spinning, it is never a problem, so whilst airbourne and travelling, it never happens. As it is not fitted to a 3d type where airspeed could drop to zero, I am not minded to dig further.

I have put it down to the motor/esc combination; for whatever reason the esc cannot ramp up the motor speed, from a dead stop, with the prop load as is. Perhaps it is due to some parameter of the startup mode in the ESC. The only thing we can usually tinker with is the timing figure, and in my case that did not affect startup.

One fix for this scenario could be to program low throttle trim to be the very lowest amount needed to keep the prop turning, and use the the throttle cut switch to stop it completely.

Engine Doctor15/07/2019 10:44:29
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2331 forum posts
28 photos

Had this problem on couple of occasions and if not a faulty joint is usually a internal fault on the motor windings. Try swapping out the motor . Check / clean only one possible cause at a time then test. Good luck .

Martin Harris15/07/2019 11:19:12
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8948 forum posts
221 photos

As the motor runs OK on a lower voltage, I would start by checking/experimenting with the motor timing. According to the manual, default appears to be medium but the instructions state that most motors respond well to the low setting...

What motor are you using? Do the manufacturers specify a timing setting?

Alan H15/07/2019 11:58:47
77 forum posts
2 photos

I've had this sort of issue several times in the past and it has nearly always been timing or start up mode related. As has been suggested try the low timing setting and also try changing to a softer start up mode (but only change one parameter at a time)

conrad taggart16/07/2019 21:18:40
99 forum posts
5 photos

Thanks guys will give this a go tomorrow and let you know how I get on

conrad taggart25/07/2019 00:09:12
99 forum posts
5 photos
Posted by Martin Harris on 15/07/2019 11:19:12:

As the motor runs OK on a lower voltage, I would start by checking/experimenting with the motor timing. According to the manual, default appears to be medium but the instructions state that most motors respond well to the low setting...

What motor are you using? Do the manufacturers specify a timing setting?

Martin was on the money here. Tried changing the timing to the low setting as indicated by the ESC manual and it was the same. Then eventually tried the fast / high setting then hey presto worked like a dream. Odd to supply an ESC with a default fitting that is not typical (good old Overlander) or even worse where it is recommended as part of the standard setup for a Wot 4 and it doesn't run out of the box correctly with the recommended motor ! Once again thanks for the help and suggestions

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