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Author Topic: Servo slows main drive motor?  (Read 2456 times)

Steven.T

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Servo slows main drive motor?
« on: December 22, 2013, 04:33:43 PM »

Hi guys,
Whilst running my Crashtender earlier today, I noticed the motor speed significantly drops when the steering servo is operated. Is there a reason for this?
There is a BEC on the speed controller, which I am using. However when I bought the boat, the guy had a 6v receiver battery wired in, although I couldn't see the need for it so have disconnected it electrically, but it is still in place.


Any ideas why the motor would slow down?
Cheers,
Steven
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Shipmate60

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Re: Servo slows main drive motor?
« Reply #1 on: December 22, 2013, 04:37:52 PM »

The servo could be close to the max current draw.
Try it with a receiver pack.


Bob
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cos918

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Re: Servo slows main drive motor?
« Reply #2 on: December 22, 2013, 05:27:15 PM »

Hi Steven
the cabel from the ESC that plugs in to the reciver. has the middle cable (normal red) been cut, dissconected etc?
Do you have a 2ch hand set or a 4ch hand set?

John
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Steven.T

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Re: Servo slows main drive motor?
« Reply #3 on: December 22, 2013, 06:01:33 PM »

Hi John, the red wire has not been cut or disconnected in any way.
My handset is just a planet T5, 5 channels I believe? It originally was an acombs techniplus, which I think was only 2 channel.
It's strange because I have exactly the same setup on my RTTL (different motor and servo) yet it does not have this problem.
Cheers
Steven
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cos918

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Re: Servo slows main drive motor?
« Reply #4 on: December 22, 2013, 06:18:43 PM »

With most ESC when you use the BEC you need the center wire. if you use  6v pack for the reciver you normaly dissconct the centre wire. Your sound like it is wired correctly.

Try plugging the servo of the other boat in to the reciver of the boat with the problem and see what happens.
If you are using a 5ch transmitter make sure you are not throteling back when you turn if you are using the one gimble for throtel and steering
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Steven.T

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Re: Servo slows main drive motor?
« Reply #5 on: December 22, 2013, 06:23:58 PM »

Forgot to mention, its the same receiver I use for both boats. As this one is only a recent acquisition I haven't had a chance to buy another receiver yet.
I'll try swapping the servos see what happens.
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grasshopper

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Re: Servo slows main drive motor?
« Reply #6 on: December 22, 2013, 06:28:00 PM »

Is there any form of channel mixing that you've accidentally added?
Some transmitters have the facility to mix channels so the flyboys can make their planes easier to fly, have you got rudder (aileron) and motor(elevator) channels interconnected?
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Steven.T

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Re: Servo slows main drive motor?
« Reply #7 on: December 22, 2013, 06:58:32 PM »

Not that I'm aware of, the only switches on the transmitter are for reverse functions, and another aux switch that retracts flaps on planes.
Could there be something to do with the boat can perform quite a tight turn, which could be slowing the prop down in some way?
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Leaky Bottom

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Re: Servo slows main drive motor?
« Reply #8 on: December 22, 2013, 07:04:28 PM »

Is there any form of channel mixing that you've accidentally added?
Some transmitters have the facility to mix channels so the flyboys can make their planes easier to fly, have you got rudder (aileron) and motor(elevator) channels interconnected?
The Planet T5 does not have any channel mixing capabilities so it will not be that
 
Hi Steven
the cabel from the ESC that plugs in to the reciver. has the middle cable (normal red) been cut, dissconected etc?
Do you have a 2ch hand set or a 4ch hand set?

John

It would'nt work at all if the red wire has been disconected and he's disconnected the 6v receiver pack as he says he has
 
What voltage and type of battery are you using?
Is there any binding of the movement in the rudder any where so the servo is pulling the voltage down in turns
 
 
 
 
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Steven.T

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Re: Servo slows main drive motor?
« Reply #9 on: December 22, 2013, 08:29:55 PM »

The battery is a 7.2v 3000mah Nimh.
The whole lot seems pretty free and smooth, it doesn't stick anywhere or seem to struggle.
As soon as the boat straightens out its right back up to full speed, seemingly as soon as the servo returns to center.
Cheers
Steven 
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Leaky Bottom

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Re: Servo slows main drive motor?
« Reply #10 on: December 22, 2013, 08:39:31 PM »

Does the motor still slow down when the rudder is applied when the boat is not in the water
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barriew

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Re: Servo slows main drive motor?
« Reply #11 on: December 22, 2013, 09:30:09 PM »

Is it the motor or the boat which slows down? Too much rudder throw will have the effect of slowing the boat even if the revs don't drop.


Barrie
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Steven.T

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Re: Servo slows main drive motor?
« Reply #12 on: December 22, 2013, 10:43:21 PM »

Leaky Bottom, I haven't tried it out of the water yet, I'll give it a go tomorrow night after I've finished wrapping presents!


Barriew, Obviously it's hard to tell when the boat is out on the water and at speed, as normally it's quite far from the shore, but it sounds like the motor slows down, thus slowing the boat.
Don't get me wrong, it doesn't slow down to a stop, it keeps going, but it's a noticeable drop in speed. If the rudder was overthrowing (which it does throw a good way), surely it wouldn't affect the motor speed?
Cheers,
Steven.
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malcolmfrary

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Re: Servo slows main drive motor?
« Reply #13 on: December 23, 2013, 10:14:13 AM »

If the rudder is putting extra drag into the system, slowing the boat down, then the prop will be trying to accelerate the boat.  Acceleration takes more power than running, so the motor is being asked to do more work.  Only being offered the same amount of power to do the extra work, it slows down.
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inertia

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Re: Servo slows main drive motor?
« Reply #14 on: December 23, 2013, 11:06:56 AM »

If the rudder was overthrowing (which it does throw a good way), surely it wouldn't affect the motor speed?
I'm inclined towards Malcom's suggestion but it depends upon how far exactly is "a good way"? 30 degrees each way is about optimum; more than that is slowly creating a drag anchor which will cause the motor to labour. Electronically it makes no sense with this radio (which has no channel mixing facility), but you could check that by replacing the ESC with another servo and seeing if that moves at all when you apply a rudder command.
DM
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