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Byron

Any Electricians Here?

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I have a 12 volt out board motor.

The controller sits on top of the motor. I want to move the controller to the front of the boat so I need to lengthen the wires by about 4 metres.

Two of the wires are 5 sq mm. Two are 1.5 sq mm

I have received conflicting advice as to how to join them.

An electrician says to use crimped terminals and not to use solder.

Another says that solder and shrink tube will be better.

It is not possible to gain access to the actual motor as it runs underwater and I don't want to break the seal. So I have to insert some wire in the run between the actual motor and the controller.

All advice greatly welcomed.

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I'm an electrical engineer, but I cannot solder underwater! I'm not a Mason!

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I have a 12 volt out board motor.

The controller sits on top of the motor. I want to move the controller to the front of the boat so I need to lengthen the wires by about 4 metres.

Two of the wires are 5 sq mm. Two are 1.5 sq mm

I have received conflicting advice as to how to join them.

An electrician says to use crimped terminals and not to use solder.

Another says that solder and shrink tube will be better.

It is not possible to gain access to the actual motor as it runs underwater and I don't want to break the seal. So I have to insert some wire in the run between the actual motor and the controller.

All advice greatly welcomed.

An extra 8 metres of cable in a 12V system running a motor might be a problem, you will get substantial losses from it. Do you know what the current draw of your motor is? If you can find out I'll calculate your losses for you.

On a boat you should be using stranded wire, not solid, and 5mm2 is a strange size cable, not very common. As the diameter of the wire increases, it becomes more difficult to solder it properly, especially stranded, as the heat does not conduct into the inner strands. IF you've got access to a good crimping tool, crimp the 5mm, if you want, solder the 1.5mm.

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I'm an electrical engineer, but I cannot solder underwater! I'm not a Mason Satanist/Lucifer Worshipper!

Fixed it for you. Just been on the Who Do The Elite Really Worship thread :lol:.

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Fixed it for you. Just been on the Who Do The Elite Really Worship thread :lol:.

I dont do alien reptile stuff either! No warp coil bypasses! :huh:

Just normal building and industrial electrics!

I didn't know you could get electric boats!

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I have a 12 volt out board motor.

The controller sits on top of the motor. I want to move the controller to the front of the boat so I need to lengthen the wires by about 4 metres.

Two of the wires are 5 sq mm. Two are 1.5 sq mm

I have received conflicting advice as to how to join them.

An electrician says to use crimped terminals and not to use solder.

Another says that solder and shrink tube will be better.

It is not possible to gain access to the actual motor as it runs underwater and I don't want to break the seal. So I have to insert some wire in the run between the actual motor and the controller.

All advice greatly welcomed.

i changed a plug about 5 years ago and it worked, i was walking round the house like charlie big bllocks that day i can tell you

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1 It is 12 volt, not mains

2 The maximum draw is 40 amps.

3 The odd wire sizes are because it is made in Korea. The nearest I can buy will be 6 sq mm and 1.5 sq mm

4 I take the point that solder might not get properly into 5 sq mm.

5 I'll either buy a good quality crimping tool or get it done professionally.

6 Oddly, the ends of these wires are ordinary car size spade connectors that fit onto the control switch. The control switch has 9 discreet positions, 5 forward and 3 back together with an 'off' no power setting

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1 It is 12 volt, not mains

2 The maximum draw is 40 amps.

3 The odd wire sizes are because it is made in Korea. The nearest I can buy will be 6 sq mm and 1.5 sq mm

4 I take the point that solder might not get properly into 5 sq mm.

5 I'll either buy a good quality crimping tool or get it done professionally.

6 Oddly, the ends of these wires are ordinary car size spade connectors that fit onto the control switch. The control switch has 9 discreet positions, 5 forward and 3 back together with an 'off' no power setting

If you're going to extend the wiring by 4mtrs I'd use 16mm sq cable to minimise volt drop for a 40A draw. If I were doing it, on a boat, I'd use a screw terminal block and "pot it" in a plastic potting box using epoxy potting compound. No special tools required.

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Since your lengethening the cables, and its a low voltage with a high load on the 5mm you will need to use a thicker cable, to be safe you could get some 25mm welding cable, best use crimped connectors, or large brass terminal blocks, unless you have some serious soldering equipment, this kind of thing I normally use a 2% silver solder and heatshrink or a resin joint, the 1.5 cables are probably signal cables, still probably best using 5mm just encase.

Car audio places sell cable and connectors

http://www.caraudiodirect.co.uk/phonocar-4-205-power-joiner.html

http://www.caraudiodirect.co.uk/accessories.html

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Twist the two bits of wire together then put some Sellotape over it. ;)

:lol:

You have obviously worked in India!

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If you're going to extend the wiring by 4mtrs I'd use 16mm sq cable to minimise volt drop for a 40A draw. If I were doing it, on a boat, I'd use a screw terminal block and "pot it" in a plastic potting box using epoxy potting compound. No special tools required.

I would go along with that.

Big bloody cable though :)

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If you're going to extend the wiring by 4mtrs I'd use 16mm sq cable to minimise volt drop for a 40A draw. If I were doing it, on a boat, I'd use a screw terminal block and "pot it" in a plastic potting box using epoxy potting compound. No special tools required.

Sounds a good idea.I take it that the screw block terminal is what I would call a domino block?

I've got plenty of epoxy for boat building.

I lashed up a system using jumper leads which can carry up to 250 amps for a short while and it seemed to work. Mention had been made of using welding cable 25 sq mm. What is your opinion?

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Sounds a good idea.I take it that the screw block terminal is what I would call a domino block?

I've got plenty of epoxy for boat building.

I lashed up a system using jumper leads which can carry up to 250 amps for a short while and it seemed to work. Mention had been made of using welding cable 25 sq mm. What is your opinion?

Any reasonable quality screw terminal block will do, they are sometimes called chocolate blocks, make sure you tighten the screws really tight, leave them for an hour or two and tighten again. If you can't find one big enough for your chosen cable, you can remove some strands so that it fits. You are concerned about resistance rather than ultimate current carrying capability and once it's potted it will be fine.

I was going to suggest 25mm cable, but thought it might be too bulky for a small boat, if you can fit it in, so much the better. You want as low resistance as possible so's not to degrade performance. Any flexible cable will do, I would use "Tri-Rated" but welding cable would be fine.

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1 It is 12 volt, not mains

2 The maximum draw is 40 amps.

3 The odd wire sizes are because it is made in Korea. The nearest I can buy will be 6 sq mm and 1.5 sq mm

4 I take the point that solder might not get properly into 5 sq mm.

5 I'll either buy a good quality crimping tool or get it done professionally.

6 Oddly, the ends of these wires are ordinary car size spade connectors that fit onto the control switch. The control switch has 9 discreet positions, 5 forward and 3 back together with an 'off' no power setting

I'm wondering how this setup works ..

I would think that the switch has a number of resistances within it to control the speed .. so Full Speed would be 0 OHMs (40 amp output) 1/2 speed would be X Ohms 1/4 speed X/2 Ohms etc .. It may be that as the speeds are reduced a number of resistances are put in series ..

Then there must be a double pole change over for forward/ reverse .. Probably the controller has two wipers inside that run on tracks that changeover in the Stop position ..

I suspect that the two 1.5mm wires are some sort of overload protection .. something like a Bimetalic preset thermostat in the bowels of the motor .. You can check this easily .. If there is no Resistance between the wires (Ie a Dead short) under normal conditions then I'm probably right .. It's possible that they might work the other way but unlikely ..

So the question you want to ask yourself is ..

Do I really want to extend the wires ? would not a remote be a better answer?

Either you can use a full controller .. Here is a great explaination of what I've just been saying and explaining how you could build a mosfet controller yourself ..

http://www.gifford.co.uk/~coredump/mosfetpwm.htm

But I'm sure you could buy a mosfet drive and then make up a remote variable resistance device .. (then pot the whole thing in Epoxy for marine use)

Or a simple way would be to make a little bit of engineering to control the whole thing from a Bowden cable ..

something like this ..

http://cgi.ebay.com/ebaymotors/UNIVERSAL-TOP-MOUNT-BOAT-CONTROL-W-24FT-THROTTLE-CABLE-/190479060513?pt=Boat_Parts_Accessories_Gear&hash=item2c596fce21

(just the first one I came across .. probably WAY too big for your needs)

That way the controls are where you want them and you don't have lots of heavy cable about ..

If you do need to extend the cables it's sometimes cheaper to buy the stuff at silly prices per meter from car accessories shops (they use it in super sized radio installations) than from the likes of RS as you don't have to buy a roll .. I got the cable for my inverters from a local non ferrous scrap dealer .. I probably paid 2x the scrap value .. but 1/4 of the new value :)

Be carefull with the clips .. make sure they can take the whole weight .. also it might be a good idea if you have a remote to wire an E-Stop button through the protecting circuit close to the motor .. (in case anyone falls in or something (like a scarf) is dropped overboard ..).

Have fun ..

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Shed dweller,

Thank you for your thoughts.

Having already installed a teleflex steering cable, I did think of something similar to control the 'throttle'

However, the batteries have to be in the middle of the boat (Its only 12 foot long), so either way, a long cable run is inevitable.

The shortest run I can manage with is 2.3 metres. If I use 25 sq mm jumper leads which are rated at 220 amps, I .think I should be OK.

Yes, the two 1.5 sq mm cables are a dead short.

The motor itself is more than powerful enough for its intended use, so a small voltage drop may not be a problem.

I shall try the terminal block embeded in epoxy. The cables from the motor will go to an MK commando plug and then on from there to the controller.

I suspect that the controller is a pulse type of some sort because the switch is quite small, no bigger than an orange, and there are no signs of any heat sink etc.

Thank you for your time.

Byron

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I shall try the terminal block embeded in epoxy. The cables from the motor will go to an MK commando plug and then on from there to the controller.

I would be inclined to use lugs rather than terminal blocks as you can be more sure of a really good connection and I think you would not have to epoxy them ..

Have fun :)

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Terminals are fine as long as you do them up properly and they have the advantage of not requiring a specialist crimp tool.

In this case, joining a 5mm sq cable to a 25mm sq cable, I'd use screw terminals even though I have the crimps and crimp tool readily available.

If you used crimps, you would need to use a nut and bolt to join the two crimps together and that would be a bit of a bodge.

Epoxy potting is not essential, but makes for a very reliable joint in a marine environment.

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NO NO NO normal screw blocks on a boat, even if the bodies are brass the screws are usually only plated steel and will rust through in no time at all. Potting it will NOT work as epoxy will not adhere to the PVC insulation (I've done this, it doesn't, you get a capillary which then draws moisture in). Don't use 2% silver solder, it has a higher melting temperature which your bog standard soldering iron will not achieve. If you want to do the screw block join, use an all-brass block, and they are not easy to find, and to do it correctly, you should tin the wire ends ("make solid"). Back to the problem of soldering large stranded cables.

Crimp them and insulate with heatshrink. Use multi-strand cables as thick as you can, auto cable is good and easy to get, 16mm was a good suggestion for 40 Amps, or multiple cables such as 3 by 4mm2. Your biggest problem will be finding a suitable crimp to connect between different size cables. One way round this is to crimp ring terminals on the end of the old wires, and the new ones, and bolt together with brass nuts and bolts, then get a couple of small plastic boxes to house the joins. Don't go cheap on the insulation of the joins whatever you do. Shorting a car battery on a small boat is not fun for those in the boat.

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^To be honest a bog standard diy iron wont manage anything more than about 4mm, I use a little silver in mines for added strength thats all. also another good way to seal the joint is a good quality self amalgamating tape, then heatshrinked or taped.

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