Electric motor control

[Maurice OzmondParticipant @mauriceozmond]

At 72 years of age its a long time since I played with radio control having built valve equipment and then only just entering the transistor era.  Having recently returned to model boat construction I find my construction capabilities are still excellent. I am in the process of scratch building a 32" PT boat based on John Drains Web site information but do not want to get involved in constructing elaborate control circuits. The hull has been double diagonal planked with Sapele Mahogany veneer and Zap a Gap which has proved to be both light and strong and looks pretty good as well.  I am grossly out of date with current control systems beyond the transmitter, reciever and servos.

I am looking for advice on how to achieve basic adequate speed control of three 400 size motors which I am considering fitting. Reverse is not important but would be an asset. Any assistance with component requirements and wiring arrangements would be much appreciated.

[Paul TParticipant @pault84577]

Hello Maurice

I have found that a 3 motor combo in a PT boat are best managed with 2 electronic speed controllers. The first to control the 2 wing engines and the second to control the center engine, with this set up you can maneuver the model at slow speed on one engine only but when you require some speed you can bring in the 2 wing engines and with ESCs you have the added benefit of reverse.

All the best

Paul

[Maurice OzmondParticipant @mauriceozmond]

Thanks Paul, I never thought of this arrangement. I was unaware that a single speed controller could control more than one motor. I presume the two motors would be wired in parallel and the controller would be sized to suit the double current reqiirement?

Regards

Maurice 

[Paul TParticipant @pault84577]

Hello Maurice

Yes that is exactly right, to establish the exact current draw I set the model up in the bath and ran both wing engines at full speed and measured the amps with a meter but when deciding on a speed controller I added a 35% safety margin to cover any unforseen problems.

The arrangement of having the center engine on a seperate controller from the wing engines gives you a saving in cost and weight and also has the added benifit of using less battery power when the boat is just "tootling" about.

All the best

Paul

[Maurice OzmondParticipant @mauriceozmond]

Hi Paul,

Thanks for confirming my thoughts but all is not yet fully clear to me. I have not purchased any radio or motor control equipment yet and would not expect you to specify any particular make or model.

Am I right in believing that a minimum four channel system will be required in order to provide the two separate speed controls using both forward/backward sticks in addition to steering. ie three channels required, and do you know of a general hookup diagram being available any where.

I have a copy of Dave Milburn’s article on setting up twin motor installations, at present I am assuming that figure 4 would apply excepting that one of the two ESC’s would control the out board pair of motors.

 Regards 

Maurice 

[Paul TParticipant @pault84577]

Hi Maurice

Sorry to be a duffer but I can’t recall Dave Milburn’s article can you point me in the right direction. (its probably in a recent issue and I just can’t find it)

Take care

Paul

[Maurice OzmondParticipant @mauriceozmond]

Hi Paul,

Sorry I should have given you more source information.

I picked up the article from the web site Modelboatmayhem. If you look at the electronics section there is a section on various type speed controllers and also Dave Milbourn’s article.

Regards

Maurice 

[Paul TParticipant @pault84577]

Hello Maurice

Sorry to have taken so long to reply to this question but I wanted to make sure that I was giving correct advice.

I would follow Dave Milburns directions but just make sure that the ESC for the twin motors is man enough to cope with the amps.

Good luck and please let us know how you get on.

Paul

[Maurice OzmondParticipant @mauriceozmond]

Thanks Paul, I thought I was on the right track.

It may be some time before I get there but when I do I will certainly let you know.

Thanks again

Regards

Maurice 

[Dave MilbournParticipant @davemilbourn48782]

There are at least four different methods shown on the website now. If you’re not sure which would be best for either your model or your pocket then just give me a ring c/o ACTion.

Dave M

http://www.action-electronics.co.uk/wd.php

[Maurice OzmondParticipant @mauriceozmond]

Thanks for your interest Dave, will contact you if I need further advice.

Maurice 

[Maurice OzmondParticipant @mauriceozmond]

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