Upgrading Windlass Wiring

[SV Demeter]

Originally Posted by h20man

I believe one has to also look at the length of the cable...

and the second image (which I now managed to show in the post...) shows how amperage decreases over length.... 90 feet in a 4 drops down to about 13 amps....

Umm Im not so sure you are reading the voltage drop table correctly but it has nothing to do with sizing fuses. For that you need to use the ampacity table. Ampacity tells you the maximum amount of CURRENT you can safely put through a particular gauge wire. You want your fuse to protect the wire so you never want a fuse to be rated higher than the ampacity of the wire it is trying to protect. 4 AWG in theory can handle up to 160 amps but I believe the OP stated his windlass was maxed out at 80 amps. In that case a 160 amp fuse would protect the wire but at the expense of the windlass. A better fuse would be 80 amps although maybe 85 or 90 to avoid nuisance trips.

Voltage drop tables such as above tell you what size wire to use to stay within an acceptable range for the device you are running. Motors typically do not take kindly to low voltage and will die a premature death if subjected to them. In this case the OP would likley be looking at a 90' circuit that will carry 80-90 amps. There are no wire sizes on the table you posted that meet this requirement if the goal is not to exceed 3% voltage drop. A look here could help:

Voltage Drop Calculator

Im certain there are more qualified electrical guys who can chime in here if I have mispoken.

[Cheechako]

Just brainstorming here.... What if a small gel or sealed(gr 24?) battery were installed in the bow at the end of the existing cables. If installed in parallel, it wouldnt interrupt the current from the main bank, but would it avoid needing the larger cables? Electricty follows the path of least resistance, so the battery would take the main load until it got fairly depleted right? It would likely be enough for most anchoring without overstressing the main cables...????

[Oyvind]

The point of a separate battery up front for the windlass, (and bow thruster, too, if you have that,) isn't just to be able to use smaller cables, but perhaps more importantly to ensure max voltage to the windlass motor. What SV Demeter said, there's nothing that will kill the windlass motor faster than too low voltage.

You don't need a fancy marine deep-cycle house battery for this. A regular automotive starter battery will be just as good, and probably better, since it will both be able to give off higher amps and recharges much faster than a deep-cycle battery. In all events, remember to always run the engine at a fast idle when you operate the windlass. As others have said, the battery will need all the help it can get.

[GordMay]

1. For a number of good reasons, NEVER parallel conductors of unequal size or length, nor of differing insulation, termination or manufacture.
2. Ypou cannot simply parallel fuses.

Sorry - I'm currently unable to participate fully.

[janders]

Originally Posted by GordMay

1. For a number of good reasons, NEVER parallel conductors of unequal size or length, nor of differing insulation, termination or manufacture.
2. Ypou cannot simply parallel fuses.

Sorry - I'm currently unable to participate fully.

That gets right to heart of what I was asking. Very interested in the "why"...

[daddle]

Originally Posted by janders

That gets right to heart of what I was asking. Very interested in the "why"...

In theory separate wires are just fine. But GordMay is the go-to guy for what works in practice. The problem probably stems from it being difficult to balance the load in the separate wires. What with the marine environment, corrosion, lax construction standards, etc. In the pristine environment of hi-tech electronics we wouldn't worry about it other than for possible noise effects. But heavily loaded wires are a different problem. A fire would be a bummer.

My recommendation: select the proper wire based on the manuals. Buy it. Install it properly. Skip the goofy forward battery trick for the reasons above. I have a candy-ass lightweight performance boat with properly sized (heavy) wires running the about 40 feet. It's just not that big of a deal - except the hit on the wallet.

[Blue Stocking]

Originally Posted by GordMay

1. For a number of good reasons, NEVER parallel conductors of unequal size or length, nor of differing insulation, termination or manufacture.
2. Ypou cannot simply parallel fuses.

Sorry - I'm currently unable to participate fully.

1. A horse and a pony teamed up to pull a wagon can't share the load 50/50 because of their different abilities.
2. Same size traces from the collar to the wagon for both animals with not break at the same time because the work they are doing is not the same.

Am I close Gord?

[SV Demeter]

I think its the load balancing. How do you determine how many of the amps go through each wire?

[zeehag]

i upgradedmy electric lofrans 100 windlass to a manual and i LOVE my manual windlass--is reliable is fre of electrical gremlins nd always WORKS. have fun and goooodluck!!!
most cruisers who really cruise who i have met use manual as is a lot mor ereliable in a pinch than is electric ... mine does not work and i will trade up for a manual any day of week. there is no reason for me to have an electric windlass, as they always break when most needed. is a lofrans 1000. make offer with your manual and i will respond.(as long as the manual is a burly one i can use it)

[osirissail]

Originally Posted by janders

I'd love to do that but I don't think I would really save much on wiring size. The way I understand it, you have to size the charging wire to that fwd battery to the size of your alternator. When the engine is running and the windlass is going, that battery is going to want all the current available to it which means the full output of the alternator is running through that charging wire. In our case, we're sizing that wiring for an 80A alternator which is a little less than the windlass draw. But the difference is probably not enough to justify installing a battery forward.

It doesn't work that way in real life. The windlass battery in the bow, as others have posted, only needs to be large enough to handle the power needs of the windlass. Walmart auto or sealed marine batteries work just fine and are quite economical. These are liquid lead acid sealed or AGM batteries which will feed the windlass all it needs for the short time you are actually operating the windlass. It is wired to the windlass with heavy enough cable to prevent any significant voltage drop and appropriately fused/c/b'ed. Just like the engine starter, the windlass will use very little amp-hours to do its job - unless - you are in the habit of grinding away or overloading the windlass.
- - Wire voltage drop from a large load is a function of wire size versus wire length. Since the windlass is going to want it full rated Watts if the voltage drops then the amps will increase dramatically. This is where the danger of electrical fire raises its ugly head.
- - Also as others have posted you always use a c/b to protect the wire size/length if it is less than the load. What the alternator puts out is not a factor except in the wire from the alternator to the main DC distribution. Again here the alternator wire is sized to keep voltage drop to a minimum. The batteries will only accept the watts they need to re-charge. If you supply more, the battery voltage increases until you boil the battery - not a good thing to do. A "smart charger" will sense continuously what the battery needs and cut back the alternator output to keep the voltage within the "safe" limits.
- - The windlass will pull the power it needs from the dedicated battery. Only if you "grind" away with the windlass and deplete the battery will it want to suck excess power down the smaller "charging wire" routed from the main DC distribution to the windlass battery. This is where the charging wire c/b will trip if the battery wants too much power and protect the charging wire. So the windlass battery needs to be sized to fit the power requirements of the windlass for the time you will operating it.
- - In a multi-battery installation each battery will individually accept only what it needs to re-charge.
- - if you look at power yachts and large sailboats they all use dedicated batteries located very close to their heavy loads like windlass or bow/stern thrusters. Running extra heavy feed cable down the length of the boat, especially in large boats, is an invitation to an electrical fire. Not to mention the huge cost of those wires.

[Cheechako]

"i upgradedmy electric lofrans 100 windlass to a manual and..." I guess to save money if your electric is blown...maybe it makes sense...I do like simple too!....and the point is to "get out there" not try to make everything perfect! But for me....cant imagine going back to a manual windlass on larger boat. Had quite a few electric windlasses now, some of them were 15 years old when I bought the boat, went cruising and no windless ever failed on me (knock on wood!)

The other thing to keep in mind is your motor is probably what..80 amps locked rotor, meaning maximum when the windlass is stalled and you are (stupidly) trying to activate it. If you are using your windlass properly (motoring up to your anchor) all you are picking up is chain until the anchor. with the gearing in your windlass you are probably only drawing very minimal amps. In addition, when you first start your engine, you should be putting out about 14 volts or so. So realistically, you shouldnt be seeing a low voltage situation at the windlass. Let's say you are charging at 13.8 volts, and your cable size is per the 10% voltage drop chart, You're still at 12 volts at the windlass, and regardless, your alternator is going to sense voltage drop and keep the voltage high. I still say, if you've got 1/0 cables, try them with the 1000 watter, give it a good workout and see if any heat develops at all, or measure your voltage drop at each end with a VOM. You can melt the cables going to the starter on your engine with too much cranking too....you have to use horse sense sometimes...

[janders]

Thanks for all the input, y'all. Here's what I'm thinking right now. I took another look at the manufacturer's requirements and it actually looks the wire sizing chart I was reading was for their 1200W motor (although the documentation isn't entirely clear). I'm near the upper limit with 1/0AWG but within the acceptable range. However, I don't want the voltage to drop too much at the windlass. 10% voltage drop is pretty big.

So I'm thinking I'll run 2/0AWG off the primary house bank DC distribution post (which itself is protected by a 200A fuse) through the engine room and up to a 135A breaker about 12 feet down the circuit. I'll wire the existing 1/0AWG wiring into the breaker and run the windlass off the 1/0 wire. If the voltage drop is still too much at the windlass after that, I'll parallel the 1/0 wire with another run of 1/0. If some reason I can't parallel the 1/0 wiring (I'm not entirely sure 4 lengths of 1/0 will fit in some of the conduit), I'll pull it and re-wire with 2/0. I really hope it doesn't come to that though. The wire alone for 2/0AWG for this circuit is going to cost me ~$650.

[daddle]

The 1/0 may not be any big deal even at 10% loss. I use a long run of the minimum specified wire and the windlass can pull the bow firmly into the water...scary tension.

Technically, when the motor stalls, 90% of the loss will be in the motor windings and only 10% in the wire....that doesn't sound so bad.

[osirissail]

Just remember in DC circuits the current carrying capacity of a particular wire is determined by the size of the wire - and - the round-trip distance from the source of power to the load and back again to the ground source. Basically that means you enter the charts with the wire size and a wire length to the load that is double the distance between the power source and the load.

[Rhwins]

So, what did you choose? Are you happy with your choice?


I am facing the same dilemma on a 33' sailboat.