Dead Windlass Battery. Replace, or run cable?

[Tooluser]

S/V Nobody has a bow windlass. Historically (and stock for the E38) it was powered by a lead-acid battery located in the bow. This battery can be ganged to the house bank (and thus the alternator, theoretically) by a switch for charging over a long (~50’ round trip) pair of relatively thin (#8 or #10 AWG) wires.



Current situation, with a dead windlass battery.

The battery in the bow is currently dead. How should I replace? The dollar cost ends up approximately the same. Anything I'm not considering?

A few salient facts:

• I have run this windlass over the AWG 10 cable, gingerly, even with the ‘dead’ battery. It worked fine! I was a bit surprised. Yes it has OCP. It’s possible it’s #8 or #6. But still not ideally sized for full-time running off the engine/house.
• The windlass should be considered a 100A load. Seawolf.
• The anchor has a significant amount of chain, but an AGM battery is 80 pounds so don’t be telling me this battle doesn’t matter.

Options are:

1. Replace battery in situ with AGM. Potentially add DC-DC charger to keep it topped up rather than just ganging them all together.
2. Replace battery with Lithium, add DC-DC charger for the purpose.
3. Remove battery, replace small cables with #2s.

Options Detail​

Replace with fresh AGM​

This wins on simplicity. Toss the old one, get a new one.

Cost: $250-300 with a DC-DC charger.

Time: 5/5

Pro: Sail more.

Cons: Stay heavy in the bow. Replace the AGM every N years. Will a charger do a good job over that distance/voltage drop? Probably, with reasonable fiddling. (I'd buy an Orion.)

Replace with Lithium​

Lithium batteries capable of the necessary cranking amps do exist. A 50Ah battery would be plenty. That said, this is a slightly experimental approach.

Cost: $350 with a DC-DC charger

Time: 5/5, easy

Pro: Lose a lot of weight (70lbs, and up high) in the bow. Battery lasts much much longer.

Con: Lithium hassle.

Replace with #2AWG cable​

Cost: $225 worth of cable

Time: 3/5 pulling fat heavy cables

Pro: Lose all the weight in the bow, no battery to wear out

Con: All that work. Gods know what else I’d find, too.

Decision Matrix​

Option	Cost	Time	Pro	Con
New AGM	$350	5/5	0/5	4/5
New Lithium	$350	5/5	2/5	2/5
Pull the cables	$250	2/5	3/5	3/5

 

[Tooluser]

Anyone who says "BOTH!" will be invited to come pull cables in Blaine, WA.

 

[bsangs]

Can only provide you some insight to my windlass setup. It runs to a small bow breaker located in the V-berth, then back to the battery bank, where it connects to the battery with a 200 amp fuse block. That small breaker in the bow is basically useless as a breaker, but I feel the previous owner installed it instead of putting a fuse block on the battery. That breaker does have a flip switch, which allows me to disconnect it from the battery, which I do when I know I won't be using the windlass. (My windlass only operates in reverse, so there is no solenoid in this equation.) The previous owner did not have properly gauged wires installed, so I had to do that and it honestly wasn't that daunting. Ran nicely under the v-berth panels - to the port side of the front water tank - through the head, along the walls of the settee and into the battery box. Hauling an 80-pound battery into that area is probably the easier job, though it does not seem like an enviable task. Good luck.

 

[Tooluser]

That's good insight and makes me optimistic. Mine goes down the starboard, I believe.

I should say that I'm planning to run the windlass directly to the 'hot' bus, shared with the alternator, which is connected to the house bank. I can flip it to the starter battery or both with the bonding switch.

(Wort noting; I left out the breakers & fuses - I think the breaker is there to protect the windlass itself. And handy to prevent accidental usage such as tearing apart the bow roller when the 'up' switch is stepped on accidentally.)

 

[bsangs]

That's good insight and makes me optimistic. Mine goes down the starboard, I believe.

I should say that I'm planning to run the windlass directly to the 'hot' bus, shared with the alternator, which is connected to the house bank. I can flip it to the starter battery or both with the bonding switch.

(Wort noting; I left out the breakers & fuses - I think the breaker is there to protect the windlass itself. And handy to prevent accidental usage such as tearing apart the bow roller when the 'up' switch is stepped on accidentally.)

And by "reverse" I of course meant "up." Why I brain farted on that, I'm not sure.

 

[Nick J]

Option 3, you already have a 10 awg pull string in place. other than the cable pull, it's the simplest option.

Although I haven't had any issues with the Lewmar 1000 installed by the previous owner, the 2awg looks small to me. my 50-60' run (round trip) falls between the 2awg and 0awg recommendation in the manual. If I installed it or had to replace the cables, I would go with the larger size. Like you said, running the cable is the hardest part, so might as well do it once and never have to think about it. That larger size also gives additional flexibility in the future if you or a another owner decide to replace the windlass.

 

[ConchyDug]

Lithium all day long. Lose the weight the 38 is already a tank.

Pulling wire in a 38 isn't as simple as taping the old to the new and start yanking it from my experience. My 1980 38 has most of the wiring clamped every few feet or less. Everytime I've pulled wire to the bow it's a real PITA. Try not to be distracted by all the side projects you'll find along the way! I pulled out so much dead wire on my full lithium conversion it was comical.

 

[AlanO]

I'm an electric windlass neophyte, but suspect voltage drop could be a consideration in the battery placement? That's a long run, but proper cable size can mitigate.

 

[Tooluser]

my 50-60' run (round trip) falls between the 2awg and 0awg recommendation in the manual.

In general, I agree with oversupplying, but quoth Victron - #2 AWG is fine for even 65 feet.
(Ignore the green box, different issue).

FWIW, #1 is about $4/foot, and #1/0 would be $5. Woof.
That said, as you say, you do it once.

 

[Tooluser]

Lose the weight the 38 is already a tank.

No, I meant the Ericson 38, the sailboat.

I'm an electric windlass neophyte, but suspect voltage drop could be a consideration in the battery placement? That's a long run, but proper cable size can mitigate.

The battery can indeed; on the diagram, there's a fat cable from the battery, so it's bearing the brunt.
And yes, a larger gauge over a long run avoids the sag. That's the reason to replace the existing wire with #2 or larger.

 

[Tooluser]

Pulling wire in a 38 isn't as simple as taping the old to the new and start yanking it from my experience. My 1980 38 has most of the wiring clamped every few feet or less.

Ugh. Thank you.

 

[Nick J]

Lithium all day long. Lose the weight the 38 is already a tank.

Pulling wire in a 38 isn't as simple as taping the old to the new and start yanking it from my experience. My 1980 38 has most of the wiring clamped every few feet or less. Everytime I've pulled wire to the bow it's a real PITA. Try not to be distracted by all the side projects you'll find along the way! I pulled out so much dead wire on my full lithium conversion it was comical.

Couldn't agree more on lithium (LiFePO4), but for a solid house bank. no need for an additional battery at the bow.

I also agree on the wire pull for factory installed wires. However, a windlass was probably an addition by a previous owner which means all fasting points should be accessible. Nothing is going to help with the side project distraction though. I rewired my whole boat in the middle of changing out the shower mixing valve (the valve hole was the only access to that part of the boat), rebedded chain plates and built a cabinet at the nav desk while I was replacing the holding tank (removed plumbing made access to the chainplate bolts easer, and wanted to add a tank monitor), and I'm in the middle of reconfiguring the new nav cabinet and NMEA 2000 system while I'm installing a new VHF/AIS. "While I'm at it" can be a killer.

 

[Tooluser]

rewired my whole boat in the middle of changing out the shower mixing valve

Who says water and electricity don’t mix?

 

[southofvictor]

Go with the biggest cable you can pull. Voltage drop will be hard on your windlass motor. You might not need to go down to 3% but I‘d sure go for less than 10% rather than use that as a guide.

That said, I’d get the weight out of the bow. Either pull cable or go lithium if you do t mind the complexity.

 

[Tooluser]

You're right, @southofvictor. Sometimes you need to see things said out loud to think about them properly. Or I do anyway.

What I really want is a small, high CCA battery that can act as a capacitor up in the bow, and let me have more moderate cabling. I don't need to run the windlass for an hour straight, but when it runs, it needs some oomph. This seems like a reasonable use for lithium, but most of the 10C batteries are much larger capacity too. Looks like I can get a Dakota 25Ah that does 300CCA for $250. Maybe that's the solution?

Keeping the voltage drop to 3% would take 3/0AWG which is at the point where you're not pulling so much as hammering. So maybe I get away with 1/0. Hmm.

I need some more data. I'll go run the windlass with an ammeter on it, and I'll see how I feel. Thanks for the convo, y'all.

 

[Bolo]

This is why I installed a manual windlass on my boat. Simple, works every time and even my 70+ year old body has no trouble with it. Just teasing!

 

[Shawn Brooks]

The windlass manufacturer can probably tell you exactly what gauge to run given the amount of chain you have.