Welding cable or battery cable for windlass

[sheyes]

Is it ok to use welding cable for wiring up the power to an electric windlass? The length would be about 10 meters from the leisure batteries (through a circuit breaker) to the windlass. I assume the alternative is battery cable but this looks expensive.

Steve

 

[neale]

Is it ok to use welding cable for wiring up the power to an electric windlass? The length would be about 10 meters from the leisure batteries (through a circuit breaker) to the windlass. I assume the alternative is battery cable but this looks expensive.

Steve

As long as it is rated for the current shouldn't be a problem. Just seal the ends up well against moisture.

 

[prv]

What matters is the cross-sectional area of the conductors, not the notional use of the cable. Do your volt-drop calculations and then pick any stranded cable with enough copper in it.

For what it's worth, the "intermediate" cable in my refit (for charging, and main incomer to panel, but not engine starting or individual domestic circuits) appears to be exactly the same stuff as on my welder.

Pete

 

[greenalien]

10 metres is quite a long run, so you need to use 40mm2 cable to avoid excessive voltage drop. At present, this costs around £10 per metre, so you're looking at a couple of hundred pounds for the wiring. This is assuming you are using a 12v winch - if it was 24v, the voltage drop would be less, and you could get away with 25mm2 which is about £6.50 per metre.

What many people do is to rig up a second battery nearer to the winch - that way, you can keep the heavy-duty cable to a minimum, and run lighter cable from the new battery to the charging system.

 

[KellysEye]

>What many people do is to rig up a second battery nearer to the winch - that way, you can keep the heavy-duty cable to a minimum, and run lighter cable from the new battery to the charging system.

Agree, that's the best way to go. Our anchor battery is in a raised box at the aft end of the front berth, no more than two meters from the terminals.

I have no doubt welding cable would work fine, it also makes significantly better jump leads.

 

[VicS]

As said you need to choose cable with a cross sectional area that will give a voltage drop within acceptable limits .

You can look up suitable cable size in tables or even calculate it but you need to know not only the length of the cable run but the current draw by the equipment as well.
70 amps flowing through 20 metres ( You have to measure the distance there and back again) of 40mm² cable will result in a volts drop of approx 0.6 volts

 

[Rafiki]

I used cable which was notionally for welding purposes. I bought it from someone on ebay specilaising in welding equipment. I also bought from teh same source some nifty cable lugs - basically the end fittings for the cable which used a pair of bolts to clamp onto the cable. It would have been impossible to have used crimp-on lugs without a special crimper. Total cost for cables and lugs £80 in 2007 for a 32foot boat.
Just one other point. I looked at various options such as a sepertae dedicated battery and finally decided to keep it simple and run the winch from the engine battery. I deliberately went that route rather than the leisure battery since by the time it comes to anchoring the chances are the battery will be well charged up through engine use. When you come to pull up the anchor you will have already started the engine and tehrefore tehre is no risk that the winch will have drained the battery so taht the engine can't be started, motoring away from the anchorage etc then puts juice back into the battery.

Andrew

 

[greenalien]

As far as current carrying capacity is concerned, there's no difference between welding cable and battery cable of the same cross-sectional area - the welding cable is designed to be flexible, and therefore has many fine wire strands in it, and usually has a rubber sheath - battery cable is designed to be bent into shape and then left there, so it has less strands, but they are thicker; it also usually has a PVC sheath. Welding cable is usually a bit more expensive than battery cable. However, the main consideration these days has to be the cost of copper, which has gone through the roof lately (hence all the crims pinching railway wiring cables!) so keeping the length of high-current cable to a minimum is a worthwhile exercise.

 

[pvb]

What many people do is to rig up a second battery nearer to the winch - that way, you can keep the heavy-duty cable to a minimum, and run lighter cable from the new battery to the charging system.

Many people might do that, but to do it properly isn't necessarily any cheaper. Unless you use a special "echo charge" unit to charge the dedicated windlass battery, you still need fairly meaty cables, as considerable current will flow when operating the windlass with the engine running (as is often the case). And you need to fuse the cable at both ends, rather than just at one end. And, of course, the battery in the bows needs to be properly contained and, ideally, properly vented.

It's easier just to run big cables.

 

[pappaecho]

If you want good quality cable with 100 amp rating go to an electrical wholesaler, and buy " meter tails", which is sold by the metre, and which are double insulated and colour coded. You can get 16 sqmm, 25 sqmm and 35 sq mm. I would have thought 16 mm would be enough dependent on the current draw of the thruster

 

[pvb]

I would have thought 16 mm would be enough dependent on the current draw of the thruster

Nowhere near big enough!

 

[greenalien]

I would have thought 16 mm would be enough

If the windlass takes 80 amps, you'll get approximately a 2 volt voltage drop over 10 metres if you use 16mm2 cable...use 40mm2 cable, and you'll only lose around half a volt.

 

[prv]

Nowhere near big enough!

They're also made of a few (7?) very thick "strands", because they're meant to be bent into place and then left alone with no vibration etc. On a boat, I'd rather use welding or battery cable that's properly stranded.

Pete

 

[VicS]

I would have thought 16 mm would be enough dependent on the current draw of the thruster

Since we have not been told what windlass or what its current draw is You cannot say that!

My guess is that a windlass chosen for a 34 ft boat will take about 70 - 100 amps,
In which case you will drop 1.75 - 2.5 volts over a total 20m run of 16mm² cable

 

[vyv_cox]

In my case the decision was made for me by the design of the boat. Siting an extra battery forward would be completely impractical due to space restrictions, especially low down. Threading heavy-strand battery cable through a Sadler 34, a design apparently designed to thwart any attempts to install additional wiring, would have been a nightmare. Threading flexible welding cable through was not easy, but achievable. It's been in for 10 years now, running fine and no evidence of corrosion.

 

[JimC]

Since we have not been told what windlass or what its current draw is You cannot say that!

My guess is that a windlass chosen for a 34 ft boat will take about 70 - 100 amps,
In which case you will drop 1.75 - 2.5 volts over a total 20m run of 16mm² cable

... and if the engine is running, which will probably be the case, there is likely to be 13.5 to 14.5 volts on the battery which will mean the voltage at the Windlass will be very close to the nominal 12 volts.

 

[savageseadog]

I will only say, very simply, the bigger the better. There is the potential stall situation to consider where the current will try to increase massively under load (just when you need maximum grunt). The thinner the cable the more likely it is the windlass will stall, 35mm sq minimum.
Remember to secure the cable well as movement and vibration will break the strands. Welding cable is better as the conductors are flexible and less prone to damage, the insulation is usually more robust and flexible too.

 

[VicS]

... and if the engine is running, which will probably be the case, there is likely to be 13.5 to 14.5 volts on the battery which will mean the voltage at the Windlass will be very close to the nominal 12 volts.

Provided the engine alternator is large enough to supply the windlass current in addition to any other load there may be

The engine may not be running if the boat is to be sailed away. The question relates to a sail boat not a motor boat.

It would be poor installation if the engine had to run to boost the volts because the cable to the anchor windlass were not heavy enough to power the windlass without

 

[G12]

Nobody has mentioned that welding cable isn't tinned. Tinned cable is much better in the marine environment as it resists corrosion considerably better than it's untinned counterpart.

 

[VicS]

Nobody has mentioned that welding cable isn't tinned. Tinned cable is much better in the marine environment as it resists corrosion considerably better than it's untinned counterpart.

ITYWF that tinned welding cable is available if you want it