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Author Topic: How to make it go,  (Read 4612 times)

surabaya

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How to make it go,
« on: May 27, 2007, 11:40:13 PM »

Hi, all.
I am pretty new to this. the building side of things,fine , :) but when it comes to the things that make it go, why are the wires all different colours,  ???, Well perhaps I`m not quite that bad.
My problem started when someone offered me a 50" motor cabin cruiser that needed restoration, Old and dusty with only the props and rudders left in.
I took up the challenge ( how hard can it be) and I`m doing fine,it is starting to look good. Now I need to think more of how it will move.
I have so far got an acoms  2 ch transmitter, 2 servos, rx with battery box, and 2 marbuchi RS540SH motors. Also while I was in singapore on the way back from Indonesia, I happened across a place brimming with R/C models and equip, and without too much thought, bought 2 Esc`s rated max 100amp for and 50amp reverse.
Now guy`s what do I do with all this and what else do I need( Cos just chucking them all in the boat does`nt seem to work)
I don`t know if all of these will match up and what wire goes where,
Any help would be much appreciated
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tobyker

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Re: How to make it go,
« Reply #1 on: May 28, 2007, 12:28:28 AM »

Welcome, mate. You will find the electric bits all explained on this site. Click on the "electric motors" bit on the home page. I suspect that  100 amp ESCs may not give you very slow running and you might do better with lower rated ones, but I don't know much about electrics - I'm building my first serious one at the moment, in between various sail projects. I suspect also that a pair of 540s may not shift a 50" hull all that quickly, but it will still be worth installing it all for the experience.

Good luck.
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Tug-Kenny

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Re: How to make it go,
« Reply #2 on: May 28, 2007, 11:50:03 AM »


Welcome to the club Surabaya.

You have all the 'stuff' you need.  The complete advice is buried here on our site, but my first thought is that you may need a 4,.8 volt battery for your receiver, and disconnect your middle wire from the  'powerful'  ESC's.

This wire is the  'BEC' control and sometimes causes grief.  ;)

The ESC's can be fed with the main battery for the motors (either 6 volts or 12 volts, depending on their rating ).

Hope this helps


Cheer...Ken
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malcolmfrary

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Re: How to make it go,
« Reply #3 on: May 28, 2007, 01:02:21 PM »

Assuming that the hull had a rudder fitted, or rudders linked mechanically, you need one of your servos to work that.
You could probably work both motors of the one ESC, connecting them in parallel.  If you two props are opposite handed, one of the motors will need to be connected in reverse.  A while age, a TV woodworker made a model tug and neglected that point, and was then puzzled as to why the thing could only spin in its own length.
To use both ESCs, you will need either a "Y" lead to feed the speed control to both, or a mixer, which plugs into both receiver channels, and has outputs for the steering servo and both ESCs, but performs the extra trick of altering the relative speed of the props when turning.
As Ken says, if you are using the RX battery pack, disconnect the red wire from the centre of the ESC plugs.  Some cut them, my preferred method is to winkle the female pin out and tape it back.  It can be re-used later if required.
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funtimefrankie

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Re: How to make it go,
« Reply #4 on: May 28, 2007, 01:50:10 PM »

On the ESC the red and black go to the drive battery and the blue and yellow to the motor.
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Re: How to make it go,
« Reply #5 on: May 28, 2007, 05:08:45 PM »

Hi, all.
I am pretty new to this. the building side of things,fine , :) but when it comes to the things that make it go, why are the wires all different colours,  ???, Well perhaps I`m not quite that bad.
My problem started when someone offered me a 50" motor cabin cruiser that needed restoration, Old and dusty with only the props and rudders left in.
I took up the challenge ( how hard can it be) and I`m doing fine,it is starting to look good. Now I need to think more of how it will move.
I have so far got an acoms  2 ch transmitter, 2 servos, rx with battery box, and 2 marbuchi RS540SH motors. Also while I was in singapore on the way back from Indonesia, I happened across a place brimming with R/C models and equip, and without too much thought, bought 2 Esc`s rated max 100amp for and 50amp reverse.
Now guy`s what do I do with all this and what else do I need( Cos just chucking them all in the boat does`nt seem to work)
I don`t know if all of these will match up and what wire goes where,
Any help would be much appreciated

Surabaya,

I created a webpage a while ago which explains a little about the basics of radio control setups (see below).

http://www.modelfireboats.co.nr/ue/new2boats.html

Hope this helps, I think it's what you are after. There are various other articles there which should help you sort out the electronics, just click the "Understand Electronics" link in the sidebar.

Good Luck! ;D ;D ;D

surabaya

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Re: How to make it go,
« Reply #6 on: May 28, 2007, 10:20:33 PM »

 Hi, 1st Thanks for the welcome, I have looked in a couple of times before, but this is the first contact.
The clouds are parting and I can see some light, thanks for the info.
I did make a mistake in that the Esc`s are 50a fwd and 20a rev, could I use 1 for the pair of motors.
Also the link Fireboat gave is a wealth of help, Cheers.
Thanks also to funtime frankie, but where did the yellow wire come in, I only have a blue and red for the motor and black and red for batt. Am I correct that  the red is the yellow, and does the black go to the - red to the +
malcolmfrary, Yes yhe props do counter rotate, and yes , I had almost forgot :-[. Lastly, at the model shop, they told me that the BEC would allow me to do away with the batt`s for the rx, is this true? , How does it do it? and why is it not a good idea? . Just trying to learn from your experience ;D
Thanks again all.
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DickyD

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Re: How to make it go,
« Reply #7 on: May 28, 2007, 10:35:58 PM »

Red goes to +
Black to -
Blue and red for motors , wire one motor in reverse.
BEC does away with need for rx batteries. This is no problem and quite normal.
If your drive battery goes flat what good are seperate rx batteries ?
I have similar motors in one of my boats and use same esc as yours
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malcolmfrary

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Re: How to make it go,
« Reply #8 on: May 29, 2007, 12:15:32 PM »

The BEC does away with the need for separate RX batteries by taking the supply from the main battery, which must be normally at least 2 volts higher than the RX supply, and regulating it down to the RX voltage, nominally 5V.  You see a lot of receivers with "BEC" on the label - I have yet to see any specification as to what sort of performance can be expected from these, and so tend to ignore them.
If the main battery drops below this 2 volt headroom, the regulation becomes iffy, and control iscompromised, but as DickD says, at that point you have probably lost drive, so it makes little difference.  The obvious answer is that when a drop in performance is seen, bring the boat in. 
Flyboys dislike BECs because when their power stops, the plane doesn't, but still needs to have contrl to glide in, rather than plunge.
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Subculture

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Re: How to make it go,
« Reply #9 on: May 29, 2007, 06:04:37 PM »

That's true of BEC's that use linear regulators i.e. most BEC's that come built into ESC's.

However if you use a switch-mode BEC, they will operate reliably below the voltage they output. They are also considerably more efficient.

Worth considering, and especially useful for modellers running higher voltages i.e. 12-24 volts where linear regulators can otherwise run a bit hot.

surabaya

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Re: How to make it go,
« Reply #10 on: May 29, 2007, 09:06:36 PM »

Hi,
Thanks to you all. I think that I am going to try the two motors with the one 50a Esc protected by a fuse. Then I can see how it runs and if necessary upgrade to a better motor or try something like a Y lead or mixer.
One more thing, I have two 12v 12ah batteries ( each about the size of a motorbike batt) Obviously I only want one in the boat, but is the high ah going to cause a problem or will it just run for longer giving each motor about 6v. The weight is fine in the water, but should I sell or swap them for some a little smaller or with lower ah.
Tomorrow I dig out the solder ;D
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Tug-Kenny

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Re: How to make it go,
« Reply #11 on: May 29, 2007, 09:19:37 PM »


Hello Surabaya

The high amp hours only mean you have more time before discharge. I would go for a smaller one like 5 or 7 A/Hrs. It will cut down on the weight as well.

The motors will be getting 12 volts each  (not sharing 6 volts between them unless you wire them in series.  (in one and then to the next one and back to the battery,  if you see what I mean )

Hope this helps


Cheers...Ken
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Shipmate60

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Re: How to make it go,
« Reply #12 on: May 29, 2007, 09:26:49 PM »

surabaya,
If you want the boat to plane or have a good turn of speed you will have to get a lighter battery.
Try her first on your battery, then a Lot lighter battery of the same voltage.
Someone at the lake might be able to let you borrow one for a few runs.
Just ask STAVROS what difference a slightly lighter battery makes to a models performance.

Bob
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malcolmfrary

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Re: How to make it go,
« Reply #13 on: May 30, 2007, 11:08:32 AM »

Although wiring the motors in series to run two 6 volt motors off a 12 volt battery will work after a fashion, any imbalance in efficiency due to the motors or their loading will be exaggerated, usually resulting in a boat that is determined to circle.
The great thing with ESCs and running on a too-high voltage battery is that you dont have to turn the wick all the way up.  The speed stick has a lot of intermediate points between full off and full on, running at half means that although the motor is being presented with the full voltage, this is happening in short bursts, so the average voltage over time is within working limits.
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DickyD

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Re: How to make it go,
« Reply #14 on: May 30, 2007, 11:50:00 AM »

Isn't the mabuchi RS540SH motor the one that Tamiya use in their cars and buggies with the 7.2v NiCad packs
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surabaya

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Re: How to make it go,
« Reply #15 on: May 30, 2007, 09:26:48 PM »

Hi,
On thinking back, the guy I know who gave me the motors that he had left over is heavily into racing cars in his town, although he said that they would run on 12v and would be ok for a boat.
From what you say, it sounds like I may be better off buying a Y lead, a lower power battery and two better motors. Any reasonably low cost, but not cheap rubbish ( I have read the comments about these johnson motors) suggestions?.
Please remember that I may be about to burn out the lot by mistake :'(, but then with all of your help and knowledge I think I will have a successful, if not perfect first launching.
All I have to do is not be too impatient  ;D
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Re: How to make it go,
« Reply #16 on: May 30, 2007, 09:50:13 PM »

Dont know if this will help. http://deansmarine.co.uk/order1/accp/Untitled-4.jpg

You could get in touch with Bob [Shipmate60] He's made most types of boat and has a wealth of experience with motors etc.
You could send him a personal message. He's helped me out no end of times.
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malcolmfrary

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Re: How to make it go,
« Reply #17 on: May 30, 2007, 10:39:16 PM »

I think it was Colin Chapman who said "Add more lightness and simplicate" as his recipe for performance.  Lotus cars went well.
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catengineman

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Re: How to make it go,
« Reply #18 on: June 21, 2007, 10:31:12 PM »

That's true of BEC's that use linear regulators i.e. most BEC's that come built into ESC's.

However if you use a switch-mode BEC, they will operate reliably below the voltage they output. They are also considerably more efficient.

Worth considering, and especially useful for modellers running higher voltages i.e. 12-24 volts where linear regulators can otherwise run a bit hot.

Hi, subculture,

I have just read this and you have possibly come up with the answer to stop me pulling my hair out (whats left of it that is) please enlighten me on " A SWITCH-MODE BEC " I run 12 volt and 6 volt in my tug with the 6 volt supply also controlling the receiver system but lose control of the boat sudenly when the 6 volt system drops too low.

Richard,
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malcolmfrary

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Re: How to make it go,
« Reply #19 on: June 22, 2007, 07:27:08 PM »

If all that is being run off 6volt is the receiver and servos, a 7805 at about 35p will do a perfectly adequate job.  A switch mode convertor will certainly cost rather more, it will almost certainly be larger than a pack of 4 AA cells.  As long as the stuff running off 12volt is working OK, the radio will be working.  Also saves trying to remember to charge the radio battery as well as the main battery.
If you are running a lot off the 6volt supply, retain that battery, but run the radio off the 7805 from the 12volt.
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Subculture

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Re: How to make it go,
« Reply #20 on: August 18, 2007, 12:22:45 PM »

A switch mode convertor will certainly cost rather more, it will almost certainly be larger than a pack of 4 AA cells. 

I think you're a little out of touch-

malcolmfrary

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Re: How to make it go,
« Reply #21 on: August 18, 2007, 02:12:11 PM »

Such is progress.  Whats it cost?
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Re: How to make it go,
« Reply #22 on: August 18, 2007, 03:33:22 PM »

Paid about 8 for mine.

Granted, that's more expensive than a linear regulator, but when you factor in the cost of a servo lead(s), heatsink for the regulator etc. it's not too bad.

Plus I can run my radio at any voltage from about 3 volts to 24 volts.

Have a look at this site for a switch mode BEC that can go in as a direct pin for pin replacement for a 7805-

http://www.dimensionengineering.com/DE-SW050.htm

Andy

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Re: How to make it go,
« Reply #23 on: August 19, 2007, 11:52:29 AM »

When the DE-SW050 becomes easily available over here, it will probably take over from the 7805.  As the range also has a 3.3 volt regulator, this might be very handy for lighting circuit supplies.
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