Cable size for 1500 W electrical windlass

[Sailorman97]

Originally Posted by motion30

What kind of boat was assigned to you? Did you do better than the one you currently have?

I was hoping to be assigned a better one than the current. I can't afford to rebuild another wreck.

[KWF]

Originally Posted by s/v Jedi

Here is what you do: buy a small AGM battery and install it near the windlass to run it from. Now install a Victron Smart Orion 30A 12V - 12V close to that battery to recharge it and run something like AWG 6 from a breaker or fuse to the input of the Smart Orion.

The savings on wire will easily pay for the Orion and battery.

Agree that placing a battery near windlass is often the way to go.

[kavw]

I’m not a fan of batteries at the bow if it can be avoided.
The one time expense of bigger cables is worthwhile.
I did not see it mentioned, but you can run two sets cables in parallel, that is two 1/0 of red and two of yellow/black. That is if running the thick cables are too difficult. Or you can buy in bulk the smaller cable and realize a savings.
I’ve cut into the boat a passage to carry 1.5 inch pvc to hold the cables in, protects them from chafe and supports them, a few small holes in the pvc pipe to drain any water. Avoid the bilge if at all possible.

[Lucky Lars]

Ahoy,

One way to deal with the cable sizing problem is to figure what voltage you
need at the windlass using an online voltage drop calculator:

https://www.calculator.net/voltage-drop-calculator.html

Use 'Estimated Resistance' tab.

Good Luck,

Uncle Larry

[Jammer]

Originally Posted by Goudurix

Hi ,
I'm about to install a QUICK 1500 W electrical windlass on a 37 ft Jeanneau.
The specs state 150A current draw but advise to install a 100 Amp magnetic jumper.
I have a 330 Ah gel battery park, and need 9,2 metres of cable run from battery switch and battery monitor shunt (one way so 18,4 m total both ways).
The supplier says for that length I will need minimum 50 mm2 cable (1/0 AWG).
Would this be OK for that length? 70mm2/ 2/0 AWG would become very unpractical and expensive.

Hello Jan.

Electrical threads draw lots of replies

The first fact to consider is that windlass current ratings reflect a hypothetical rated load rather than what the windlass will actually draw. When lifting the anchor and chain the windlass will draw considerably less than the rated load. When heavily loaded, as when breaking out the anchor or when pulling the boat up to the anchor, the windlass will draw more than the rated load.

The second fact to consider is the actual, specific effect of voltage drop on a windlass motor. Most of the posts upthread consider voltage drop as an inherent evil and advocate sizing the wiring based on some general percentage threshold that is held up as good electrical system design. I believe this is misguided and leads to oversizing the wiring.

Nearly all windlass motors in that size range are series wound. On a series wound DC motor with a windlass load, the effect of reduced voltage is reduced shaft speed while torque and current remain mostly constant. The reduction in shaft speed is proportional to the reduction in voltage: Reduce the voltage by 10% and the speed drops by 10%, reduce the voltage by 20% and the speed drops by 20%. On these motor and load types, voltage drop does not cause current to increase or cause more internal heating inside the motor (though operating the motor for longer times and slower speeds will cause proportionally more accumulation of heat over time).

If you run 1/0 cable, at nominal rated current, you'll have a 9% voltage drop at 150 amps. If you run 2/0 cable, it's 7.5%.

Lightly loaded, running say 50 amps (educated guess), the voltage drops will be 3% and 2.5%, respectively. Approaching stall at around 450 amps (educated guess) it would be 27% and 22.5%.

So the engineering question to answer is whether these voltage drops are acceptable in light of the fact that the only meaningful effect they have is to reduce windlass speed.

It's your boat, so the choice is up to you. On my boat I strive to minimize complexity, weight, and cost of electrical components where I can do so consistent with safety and performance, and am careful not to oversize components. If it were my boat I would probably use AWG 1 or AWG 2, which still meet the ABYC ampacity guidelines.

[De.windhoos]

Originally Posted by Goudurix

Hi ,
I'm about to install a QUICK 1500 W electrical windlass on a 37 ft Jeanneau.
The specs state 150A current draw but advise to install a 100 Amp magnetic jumper.
I have a 330 Ah gel battery park, and need 9,2 metres of cable run from battery switch and battery monitor shunt (one way so 18,4 m total both ways).
The supplier says for that length I will need minimum 50 mm2 cable (1/0 AWG).
Would this be OK for that length? 70mm2/ 2/0 AWG would become very unpractical and expensive.

Thanks for your advice,

Jan
ON3ZTT
SY Goudurix

Why would you want a 1500W windlass on a 37ft boat? How much chain and what size do you have? I’ve got a Catalina 36 in the Med and we anchor 90% of the time. I have a lofrans cayman 1000W with 65m 10mm chain and a Rocna 44. I’ve never had any issues with raising my anchor.

[twofingerpoi]

https://abycinc.org/page/wiresizer

Circuit Wizard - Blue Sea Systems

ABYC electrician recently installed a Lofrans X2 1000W 12V windlass on my Beneteau 361 using Ancor 2 AWG and a BlueSeas 285 100A breaker.

Have yet to trip the breaker so working load is far below the max spec, which is 135A.

I have a 35 lb Delta Anchor but plan to replace with 45 lb Mantus/Rocna.

Voltage drop under working load is <7% and short duration so larger gauge wire would've been overkill. Goal of 3% is also overkill.

[Orin]

Jammer, I believe you’ve got the right idea here.
I would add to this, procedure matters too. When I leave an anchorage I always start my engine before pulling anchor. If my anchor is stuck in the much I stop pulling it up and wait for a few seconds for the wave action to wiggle it loose a bit before pulling more. It helps that I have an externally excited alternator with an alternator controller so I still produce juice at lower RPM. I will generally start my engine early to give me hot water, fully topped off batteries, plenty of juice for the windlass. It also serves as a function check of the engine / starting before I’m anchors aweigh. I believe this practice is quite common. Given that, the voltages are already elevated to around 13.5V depending on the temperature etc. I’ve had no issue. The batteries on my boat are undersized for the load, so it’s generally marginally harmful for me to pull up anchor without the engine running. That said it can be done, I just don’t like to. Granted in the case of 330Ah gel cells with a 150A load this shouldn’t be an issue.

I know some like to sail off anchor, when I do - it’s still with the engine running (lame right?)

Edit: My voltage drop is near 10% with #1 AWG over 60’ round trip… Which I think is totally acceptable.

[FlyingScot]

Originally Posted by Goudurix

Hi ,
I'm about to install a QUICK 1500 W electrical windlass on a 37 ft Jeanneau.
The specs state 150A current draw but advise to install a 100 Amp magnetic jumper.
I have a 330 Ah gel battery park, and need 9,2 metres of cable run from battery switch and battery monitor shunt (one way so 18,4 m total both ways).
The supplier says for that length I will need minimum 50 mm2 cable (1/0 AWG).
Would this be OK for that length? 70mm2/ 2/0 AWG would become very unpractical and expensive.

Thanks for your advice,

Jan
ON3ZTT
SY Goudurix

We recently upgraded our windlass from Quick HC3 1kw to same but 1.5kw. The contactor is inside the windlass and 1/0 cables were as big as would fit in the housing. We ran 4/0 to within a few fet of the winch and used a Blue Sea Power Post as the point to switch down to 1/0.
We haven't tested it yet.
The manual calls for a 100A breaker (12v). We installed 150A to prevent nuisance tripping. We have a large LiFePO4 battery bank (1320AH).

We recently upgraded our windlass from Quick HC3 1kw to same but 1.5kw. The contactor is inside the windlass and 1/0 cables were as big as would fit in the housing. We ran 4/0 to within a few feet of the winch and used a Blue Sea Power Post as the point to switch down to 1/0.
We haven't tested it yet.
The manual calls for a 100A breaker (12v). We installed 150A to prevent nuisance tripping. We have a large LiFePO4 battery bank (1320AH).


Don't skimp on wiring. Your house bank is small and not known for fast discharge.

[donradcliffe]

I'd like some links which show that reduced voltage means the same or lower current. All I can find on the internet is that lowering the voltage increases the current draw. When the contacts on my windlass wiring got dirty, it started tripping the breaker. When I cleaned them up, the trips stopped.

I have been on dozens of boats with 1/0 windlass wiring. They did not trip unless I overloaded the windlass. I would use 1/0 wire. If it proves to be a problem for the new installation, THEN run another set of 1/0 wires in parallel.

[Eric Carnell]

A 60 foot run of cable for a 12v system will not be feasible for 125 amps. Even AWG 4/0 cable will cause 6.3% voltage drop. I like the idea of a dedicated windlass battery. If you can shorten cable to 10 feet, you could use AWG 1/0 cable for a voltage drop just slightly over 2%. A Victron Orion DC to DC charger is ideal to keep your windlass battery charged. It does isolate batteries and can be programmed to charge any type of battery you want. I use one to keep my start battery (FLA) charged from my house bank (LiFePO4). I would get their 15 amp charger. Even that low current will still require AWG 2 cable at a 60 foot length. You will need to step down to AWG 6 for a few inches to fit into the connector on the Orion.
Eric
SV Solstice.

[Orin]

I'd really like to know how some of you guys are arriving at your conclusions.

The manufacturer recommended wire sizing is fine here and installing a 'small battery' forward is not necessarily a better option.

If the smaller battery forward was a Lifeline GPL-24T you can see the internal resistance is 3.65mΩ with 150A load this would result in a 0.55V drop before you leave the battery terminals which exceeds the 3% (0.36V) some of you are trying for.

The lower resistance of the larger 330Ah battery bank means there will be more room for external resistance. The cables aren't that resistive.

[phorvati]

I run a 2000w ideal windlass with an old ups backup battery 90AH Agm. The kind that office desktops use. That's installed at about 12ft round trip from windlass motor. Workes well. No breaker but I use a fuse on the battery positive terminal. And I use a mechanical switch to switch this agm to the rest of the house bank to charge it.
No offgassing, worked well since 2018. We anchor about 20-30 times per year. Boat weighs 44k lbs.
Have another similar setup to start the lehman SP90 hp diesel. Small ups backup agm.
I would advise against non tinned copper wire. Corrosion finds a way to build resistance at the crimps.

[CarinaPDX]

On main batteries direct to windlass:

This is how I did Carina, with a 1000W S-L windlass and 65A circuit breaker, per instructions. I used 40mm2 (slightly larger than 2ga IIRC) cable, which was right at the limit for the distance. It has worked flawlessly since 1997 with no failures. I believe that using the main batteries is the best solution for smaller cruising boats. Running those large cables was a PITA, but running smaller ones would not have been that much easier - they both require tearing things up. I just used the manufacturer's wiring table for size, but if I were to calculate it myself I would have kept the drop to less than 10% and prefer better than that. A difference of a few percent voltage drop under full load conditions is just not that important, and should rarely be experienced and even then only briefly. N.B. I think the right breaker size for a 1500W windlass is going to be 100A, or possibly a little more. Putting in a much larger breaker is just wrong; the whole point is to kick off when the motor is drawing more than spec, not enable overloading.

On using a dedicated battery forward:

If, and only if, a direct wire run is deemed too difficult, then a system such as Jedi recommended early in this thread is the right way to go. A small AGM (perhaps group 24 or similar) is more than enough power and current for this windlass. AGMs got their start with the military because they are so vibration and shock resistant - perfect for the bow of a boat. And inexpensive enough if an automotive starter grade battery is purchased (no need for deep cycle). For a very long time batteries in the bow were dangerously wired to the main batteries, by not limiting the current to the wire's ampacity, but the modern DC-DC charger solves that problem. I disagree on one point: a 30A charger is not required; a 15A would be more than enough and would allow for even smaller wire.

Edit: On windlass usage

The proper use of the windlass is to lift the chain and anchor off of the bottom. It is not to pull the boat up to the anchor against the wind - that is what the engine is for. If doing this without engine, then use the windlass to pull in much of the catenary, then wait for the catenary to re-form and pull the boat forward, then repeat as needed. If the windlass can't pull the anchor out without overloading then pull the chain taut (vertically) and let the movement of the boat break the anchor loose. In extremis, secure the rode (not to the windlass) and motor slowly forward. Mindlessly making the windlass struggle is a bad idea. Also, once the anchor is set tie it off, preferably with a snubber, and never use the windlass to secure the rode. Using the windlass in this way you will rarely have much load on the windlass. Also, buy a chain counter, one of the truly useful accessories.

On netiquette and noobies:

It seems to me that those relatively new to the forum should at least try to not be insulting to those who have been contributing for years. After a while it becomes obvious who knows what they are talking about, and who doesn't. And I find that on practically every topic there are some folks who have professional level knowledge that exceeds my own. A certain amount of humility is called for. Anyone wishing to take on Jedi in his area of special expertise (electronics/electrical) is on a fool's errand. And yes, it is really helpful and considerate to put the boat type and actual location in the user info, to provide context.

Be nice.

Greg

[mainecoast]

This is how I did it on my GB36...Battery and charger within about 4 feet of the windlass. The two red cables go to the circuit breaker inside the access door.