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Some help needed with DIY bait-boat

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Some help needed with DIY bait-boat

Old 02-05-2015, 01:21 AM
  #1  
Maniakkk
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Question Some help needed with DIY bait-boat

Hello everybody,

I'm kinda new to the RC World, and i could use some advice. I'm going to build myself a bait-boat, and there a few questions which i have unanswered and maybe you guys have more experience then me and can help out. I'm planning on using 2 brush-less motors (which are being delivered as we type) with 2 Li-po batteries . I have an older, but decent, remote control E-Fly 100C, 6ch 27Mhz.

1st Question : I have no idea how to make the boat go in reverse. How can i do that ?
2nd Question : Anybody have a boat wiring diagram which i could use ? 2 motors, 2 esc, 2 batteries.
3rd Question : This is a budget project so i`m trying to keep everything as cheap as possible. I saw transmitter/receiver upgrade kits from 27Mhz to 2.4Ghz. Whats the cheapest out there ?

I hope what i wrote makes sense to you.

Thanks in advance.

EDIT: I searched the forum a bit, but couldn't find anything, if you know any posts please link them, and sorry if double posted.

Last edited by Maniakkk; 02-05-2015 at 01:23 AM.
Old 02-05-2015, 02:24 AM
  #2  
mfr02
 
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Reversing motors. Buy ESCs that support actual reversing, rather than "can be reversed". Some manufacturers sell forward only ESCs that can have the motor run the other way if two of the ESC-motor wires get reversed. ESC - Electronic Speed Control.
Wiring. It basically plugs together like electric Lego. If the ESCs have BEC, one of the plugs to the RX will need to be modified by having its red (center) wire winkled out and taped back. BEC - Battery Elimination Circuit. Provides a supply of 5 volts for the receiver and anything else plugged into it as well as the ESC internals. By repute, more than one feeding the same rail do not play well together.
2.4 conversion. If its a budget project, why bother? In lumpy water, an upright 27MHz aerial works much more reliably than a 2G4 stub, plus, if you get a cheap conversion, there is a good chance that it will be a "park flyer" job, with a lack of range.
Old 02-05-2015, 02:54 AM
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Maniakkk
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i`m having trouble understanding something about the reversing motors. i know that for a boat with 2 motors, 1 should go clockwise and the other counterclockwise , in order to achieve that, switch 2 wires and it should work. but thats not what i was asking. when on water, i want the boat to be able to backup just like a car getting out of the garage.

hope it makes more sense now.
Old 02-05-2015, 08:53 AM
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mfr02
 
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Thats what I meant. With brushed motors, two wires, reverse the polarity to reverse the rotation. A marine reversing ESC does this under direct control of the stick with the boat out there.
However, you did mention BRUSH-LESS motors. The ESCs for these are different, and only a few do reversing as you would like. Boats are a minority interest, the size of the market means that unit costs are higher than with the much simpler requirements of the fast and the flyers. There are some brushless ESCs that do proper reversing, but I don't have any information about how good their low speed control might be. Reversing brushless motors consists of reversing the phase order that the power pulses are fed to the three wires to the motor, which is done in software but can also be done by transposing any two of the three wires. Not many programmers have thought how to do reversing without trouble and fuss.
Old 02-06-2015, 12:18 AM
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Maniakkk
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ok now i get it.

like i said, this is a budget project, and some parts (most of them) come directly from China. being my first build of this kind, in case something fries, i dont want it to be too expensive to replace.

i checked the ESCs and in the product sheet it says that they can also go in reverse which is great.

now i have another question, about power consumption, cause im not sure if i chose the right type of motors :


[TABLE="width: 1"]
[TR]
[TD]Motor[/TD]
[TD]C3530/08
[/TD]
[TD]
[/TD]
[TD="colspan: 2"][TABLE]
[TR]
[TD="colspan: 2"]Size
[/TD]
[/TR]
[/TABLE]
[/TD]
[/TR]
[TR]
[TD]KV(rpm/v)[/TD]
[TD]1700
[/TD]
[TD="colspan: 2"]
[/TD]
[/TR]
[TR]
[TD]Power(W)[/TD]
[TD]460
[/TD]
[/TR]
[TR]
[TD]Wire Winds[/TD]
[TD]8
[/TD]
[/TR]
[TR]
[TD]Resistance(m)[/TD]
[TD]42
[/TD]
[/TR]
[TR]
[TD]Idle Current(A)[/TD]
[TD]2.2
[/TD]
[TD]Shaft diameter A(mm)[/TD]
[TD]4
[/TD]
[/TR]
[TR]
[TD]ESC(A)[/TD]
[TD]30
[/TD]
[TD]Motor length B(mm)[/TD]
[TD]30
[/TD]
[/TR]
[TR]
[TD]Cells Ni-Cd/Ni-MH[/TD]
[TD]6-12
[/TD]
[TD]Motor diameter C(mm)[/TD]
[TD]35
[/TD]
[/TR]
[TR]
[TD]Cells Li-Po[/TD]
[TD]2-4
[/TD]
[TD]Basic length D(mm)[/TD]
[TD]13
[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD]Total length E(mm)[/TD]
[TD]49
[/TD]
[/TR]
[/TABLE]

those are the specs for the motors, i will have 2 x 11.1v 3cell 2600mAh Li-po batteries, they will be wired in paralel so even if they discharge diferently , both motors will spin the same way.

do you have any ideea how i could find out how much the bateries will last ?
Old 02-12-2015, 02:10 PM
  #6  
mfr02
 
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do you have any ideea how i could find out how much the bateries will last ?
A bit like asking how long a piece of elastic is. You know the energy stored, 2.6A/H. A motor pulling 2.6A will run for 1H. More current, less time.
Old 02-20-2015, 01:51 AM
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Hi Maniakkk
What size it the boat??
Check out Hobbyking.com for parts.
They have ESC's with reverse in water cooled and fan cooled.
If your going to use reverse a fair bit, go for solid shaft prop drives.
Flex drives do not like a lot of reverse!!!
Setting up two prop drives require a bit of work.
First you require a left and right hand turning prop.
The standard prop to setup the ESC is the centre wire connects to the centre wire of the motor(brushless motors have 3 wires) the other two wires cross connect to get the motor to run correct for the prop.
For the other prop the motor connections are without the cross over.
You motors with handle a fair size boat, one of our club members has a 40 inch cabin cruiser with a bit small motor and it goes very nicely.
It's no speed motor but well over scale speed!!!
Batteries you may get 45-60 minutes out of them but get a couple of Lipo battery alarms fro Hobbyking (very cheap but they work).

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