Windlass Battery - deep cycle or starting?

[Wotname]

Originally Posted by Frankly

One little side but related issue comes with my new Rocna anchor. After a good blow the bow on Cbreeze will dip almost a ft pulling that bugger out of the bottom. We have tripped the 70 amp breaker a couple of times. The old SL Anchorman would never even grunt pulling the old Delta out of the bottom. Using the boat to break her out once the chain is vertical is becoming a common recovery technique. The Rocna brings up a good chunk of the bottom but she tows very stable and 60 seconds of 2 or 3 knots will wipe her clean.

Bottom line is get a good windlass and a stiff power supply if you are starting from scratch. There is no free lunch in this new class of "high holding power" anchors.

If we are expecting a quiet night I no longer pull very hard setting that thing. Just enough to make sure the chain is not fouled and let her be. Life is easier the next morning.

Good point!

Maybe the windlass manuals will be getting re-written sometime in the distant future to reflect these anchors

[mcarling]

Originally Posted by ramblinrod

Hmmmm, I have yet to find a windlass manufacturer who recommends pulling the boat up to the anchor via windlass. Every one I've seen mandates using the vessel engine to move up to the anchor location, and only using the windlass to raise the anchor.

I learned to sail on a boat without an engine, so still use sails when possible to avoid disturbing other people in an anchorage. Not always possible, but sometimes it is. I've always had mixed feelings about having diesel onboard.

[donradcliffe]

Originally Posted by roland stockham

I remember at school when we where learning about AC & DC electricity doing an experiment where there were a set of power lines about 20ft long down one bench with a bulb at the end to represent the power grid. If you put 12v AC into the lines the bulb lit, if you did it with 12v DC nothing happened, same voltage, same load but DC just does not like to travel. So even if you can afford the cost and weight of all that copper it will still work better if you run it off a battery.

I you think DC doesn't travel as well as AC, I suggest you read this.

https://en.wikipedia.org/wiki/Pacific_DC_Intertie

[donradcliffe]

Originally Posted by TheThunderbird

54' boat 75lbs anchor.
Windlass 1500W
Bow-thrust 5300W !!!

Currently there are big wires coming from engine batteries 2x200Ah
I use them always with engine on.

In the future, an intelligent upgrade could be a LiFePO battery dedicated to bow-works

As cranking is the issue, I was told of approx.20Ah battery being enough with that technology, which allows the highest discharge current rate!

Thus...

Lower battery weight, shorter connection, smaller cables (fuse now is 400+A)

Note: Lithium batteries are quite expensive (approx. 4X lead acid ones, even considering that you need power installed capacity...).
But they make much sense when you consider the practicality of
- size/weight
- high discharge currents
Although.... considering the control system for just one battery sounds impractical for now...

You were told wrong. LifePO batteries have limits on their discharge rate, which are coming down with experience. To drive a 150 amp windless motor you need more like a 150 amp-hr LiFePO battery.

[Reefmagnet]

Originally Posted by donradcliffe

I you think DC doesn't travel as well as AC, I suggest you read this.

https://en.wikipedia.org/wiki/Pacific_DC_Intertie

AC is also described with RMS (root mean square) voltage values which, long story short, means 12VAC is in someways closer to about 17VDC when it comes to overcoming line resistance.

Sent from my SGP521 using Cruisers Sailing Forum mobile app

[ramblinrod]

Originally Posted by Reefmagnet

AC is also described with RMS (root mean square) voltage values which, long story short, means 12VAC is in someways closer to about 17VDC when it comes to overcoming line resistance.

Sent from my SGP521 using Cruisers Sailing Forum mobile app

RMS is used to express AC in the equivalent power of DC. 12Vdc is equivalent to 12Vac RMS which is actually 17Vac P-P. When alternating current is expressed as Vac, it is assumed to be RMS unless implicitly expressed as Peak or P-P.

AC is actually harder to push down a wire than DC due to skin affect. (The magnetic flux causes electrons to tend to run down the surface of the wire rather than equally across its cross sectional area as with DC.

[ramblinrod]

Originally Posted by btrayfors

The way you use your boat can determine how you wish to power your windlass. I often like to come to anchor while under sail, and leave the anchorage under sail, i.e., without starting the engine.

Years ago I decided to put in a dedicated battery bank for my windlass. I have two Trojan 6V golf-cart batteries in series, total 225AH, located under one of the V-berths in the forward cabin. From there, the run to the windlass is quite short, about 8 feet. I use AWG 1/0 cable for this run. The circuit is fused and a Blue Sea Systems #6006 battery switch on the V-berth bulkhead allows easy turn on or off. The windlass (now a Lewmar V5) is quite happy with this arrangement.

This battery bank is charged in one of three ways using a dedicated battery charger (Iota DLS-55/IQ4):

(1) shorepower, when at dockside; or
(2) onboard diesel generator, providing 120VAC throughout the boat; or
(3) inverter when the main engine is running.

This system has worked pretty well for many years now, and doesn't require any wired connection aft to the main house battery bank, which would be about a 60-ft run roundtrip.

I can raise and lower the anchor multiple times without having to start the engine or generator.

Not for everyone, of course, but it works for me :-)

Bill

Attachment 117122
Attachment 117123

I actually don't care for your windlass battery selection.

First, you shouldn't need 220 A-hr of battery to run it. One small group 24 battery will easily handle it and requires less wiring (potential failure modes).

Secondly, if one of your 6 volts crap out, you are screwed.

If you wanted a redundant battery (though I don't feel it is necessary), two 12 Volt batteries in parallel would achieve this. If one of the 12 volts crapped out, you could just pull it out of the circuit and continue to use the other, until the bad one could be replaced to regain battery redundancy.

Additionally, 6 Volt golf cart batteries should not be located in an unventilated space.

For this application, I would recommend a single grp 24 AGM. It will only supply about 80 A-hrs, but if fully charged, would run your V5 fully loaded for 40 minutes, before depletion to 50% SOC. That's a lot of windlass running time at full load. At even 50ft /minute, that is 2000 ft or nearly half mile of rode.

[Reefmagnet]

Originally Posted by ramblinrod

RMS is used to express AC in the equivalent power of DC. 12Vdc is equivalent to 12Vac RMS which is actually 17Vac P-P. When alternating current is expressed as Vac, it is assumed to be RMS unless implicitly expressed as Peak or P-P.

AC is actually harder to push down a wire than DC due to skin affect. (The magnetic flux causes electrons to tend to run down the surface of the wire rather than equally across its cross sectional area as with DC.

What you say is true, except 12VAC RMS is ~34VAC p-p (negative sine) and I suspect the reason the AC vs DC light bulb experiment works (assuming no transformers were involved!) is because a cold tungsten filament is pretty much a short circuit which allows the higher AC voltage at peak levels to surge current to the filament to increase its glow across a fixed wire resistance.

[btrayfors]

Originally Posted by ramblinrod

I actually don't care for your windlass battery selection.

First, you shouldn't need 220 A-hr of battery to run it. One small group 24 battery will easily handle it and requires less wiring (potential failure modes).

At the high rate of discharge the windlass will cause, this is not a 225AH bank. It's more like a 150AH bank (the approximate C2 or C3 rate, not the C20 rate).

Secondly, if one of your 6 volts crap out, you are screwed.

This is no more likely than one of the cells in a 12VDC battery failing. Further, in a worst case scenario I could always pull one or two golf-carts from my house battery bank (6 golf-carts).

If you wanted a redundant battery (though I don't feel it is necessary), two 12 Volt batteries in parallel would achieve this. If one of the 12 volts crapped out, you could just pull it out of the circuit and continue to use the other, until the bad one could be replaced to regain battery redundancy.

Two 12VDC FLA batteries in parallel are no where near as robust as two 6V golf cart batteries in series. And, the parallel configuration requires one more jumper than does the 6VDC series configuration.

Additionally, 6 Volt golf cart batteries should not be located in an unventilated space.

But they very often are and I've seen no ill effects in more than 25 years of boating -- on my boat or on client's boats.

For this application, I would recommend a single grp 24 AGM. It will only supply about 80 A-hrs, but if fully charged, would run your V5 fully loaded for 40 minutes, before depletion to 50% SOC. That's a lot of windlass running time at full load. At even 50ft /minute, that is 2000 ft or nearly half mile of rode.

Understand your choice. But, I wanted a very robust setup capable of operating my windlass easily without running the engine. Further, it has been my experience that golf cart batteries are considerably tougher than are AGMs, and AGMs are "crankier" about reaching a full-charge state frequently than are FLAs. Still, either could do the trick.

Thanks for your thoughts.

Bill

[a64pilot]

Originally Posted by Frankly

One little side but related issue comes with my new Rocna anchor. After a good blow the bow on Cbreeze will dip almost a ft pulling that bugger out of the bottom. We have tripped the 70 amp breaker a couple of times. The old SL Anchorman would never even grunt pulling the old Delta out of the bottom. Using the boat to break her out once the chain is vertical is becoming a common recovery technique. The Rocna brings up a good chunk of the bottom but she tows very stable and 60 seconds of 2 or 3 knots will wipe her clean.

Bottom line is get a good windlass and a stiff power supply if you are starting from scratch. There is no free lunch in this new class of "high holding power" anchors.

If we are expecting a quiet night I no longer pull very hard setting that thing. Just enough to make sure the chain is not fouled and let her be. Life is easier the next morning.

I learned a trick before I got my windlass and was pulling in the Rocna by hand, run over the anchor by quite a bit, boat will pry it out as it pulls the anchor backwards, then bring it in as the boat drifts back over it.
Now I have a little larger windlass than called for, a VWC 1500 and it will pull the thing out without a drop in RPM, but when I was hauling it aboard by hand, you had to use the boat to pull the anchor out.

[Maine Sail]

Originally Posted by donradcliffe

You were told wrong. LifePO batteries have limits on their discharge rate, which are coming down with experience. To drive a 150 amp windless motor you need more like a 150 amp-hr LiFePO battery.

The typical cells folks are using on boats have constant current discharge rates ranging from 1.5C to 4C and short duration currents as high as 20C+. We should not confuse el-cheapo "drop-in" LFP batteries, which are discharge rate limited by the cheap internal BMS contactor, with large prismatic cells such as the CALB CA, Winston LYP cells or Synopoly.

The 400Ah bank of LFP on my own boat can sustain a 1200A or 3C constant current discharge. Course my main contactor is only rated for 500A continuous so despite this bank being capable of a 1200A continuous discharge rate I am limited by my contactor to 500A continuous. A 100Ah drop-in battery may be limited to say 60A or 0.6C due to the internal BMS contactor..

[Maine Sail]

Originally Posted by ramblinrod

For this application, I would recommend a single grp 24 AGM. It will only supply about 80 A-hrs, but if fully charged, would run your V5 fully loaded for 40 minutes, before depletion to 50% SOC. That's a lot of windlass running time at full load. At even 50ft /minute, that is 2000 ft or nearly half mile of rode.

I for one would love to hear how a V-5 2000W windlass, which averages about 120A+ can run for 40 minutes on a single G-24 AGM..?

At a 1C discharge (80A on an 80Ah battery) with a Lifeline AGM, it will only deliver about 62% of its 20 hour rated capacity when new and just barely broken in. We can not forget Mr. Peukert......

120A is a 1.5C discharge rate for an 80Ah G-24 and if you ran that for 40 minutes the battery is beyond dead, forget 50% SOC.

The only way to attain 80Ah's from an 80Ah AGM is at 77-80F with a discharge rate of 4A.

With a discharge rate of 120A+ the usable capacity gets depleted very quickly and the battery simply can not deliver anywhere close to its rated 20 hour capacity, a 0.05C discharge rating, when it is discharged at 1.5C.

[evm1024]

Originally Posted by Reefmagnet

What you say is true, except 12VAC RMS is ~34VAC p-p (negative sine) and I suspect the reason the AC vs DC light bulb experiment works (assuming no transformers were involved!) is because a cold tungsten filament is pretty much a short circuit which allows the higher AC voltage at peak levels to surge current to the filament to increase its glow across a fixed wire resistance.

What you say is true... but lets not forget that the total swing of 12 v rms is ~34 volts but the total swing from the 0 point reference is ~ +-17 volts. And that is what counts.

And thus 12 v rms and 12 v DC going through the same non inductive resistance will dissipate the same power (and heat your coffee just as quickly).

[ramblinrod]

Originally Posted by Maine Sail

I for one would love to hear how a V-5 2000W windlass, which averages about 120A+ can run for 40 minutes on a single G-24 AGM..?

At a 1C discharge (80A on an 80Ah battery) with a Lifeline AGM, it will only deliver about 62% of its 20 hour rated capacity when new and just barely broken in. We can not forget Mr. Peukert......

120A is a 1.5C discharge rate for an 80Ah G-24 and if you ran that for 40 minutes the battery is beyond dead, forget 50% SOC.

The only way to attain 80Ah's from an 80Ah AGM is at 77-80F with a discharge rate of 4A.

With a discharge rate of 120A+ the usable capacity gets depleted very quickly and the battery simply can not deliver anywhere close to its rated 20 hour capacity, a 0.05C discharge rating, when it is discharged at 1.5C.

Hi Mainsail,

Yes, I didn't bother to do the actual calcs. What you say about the discharge rate A-hrs at higher than 20A-hr rating is absolutely true. BUT, we don't really know what the windlass will be drawing. I picked 66% of FLA, but most of the time it will draw much lower than this. On lowering, it may be only 10% of FLA, raising 40% FLA avg. (Wouldn't know without testing with that actual installation, as anchor, chain size, chain weight, bow roller friction, even freshwater vs salt water, avg flora and fauna on the anchor and chain, and avg. anchoring depth will have a bearing).

In reality, it will work out pretty close to 2000 ft of rode, maybe more.

Doesn't change any of my key points.

1. A single 12V GRP 24 DC is more than enough to power a V5 windlass.

2. A single 12V GRP 24 DC requires fewer electrical connections than 2 golf cart batteries.

3. It is safer to locate a 12V GRP 24 AGM in an unventilated space or a space ventilated to the cabin, than a golf cart battery.

4. If you want redundancy forward, 2 x 6 Volt golf cart batteries doesn't give it, 2 x 12V DC do.

5. If you want redundancy forward, you must use 2 x 12Vdc that will require one more cable connection than 2 x 6 Vdc (which the latter does not provide redundancy and requires one more connection than the single 12Vdc solution, that also does not provide forward redundancy forward.

6. If you have a battery failure with 2 Golf Cart batteries and you isolate the defective battery you have ZERO A-hrs available, because you simply can't run the windlass on 6Vdc. Whereas, if you had 2 x 12Vdc batteries (much smaller volume consumption BTW) you could still run the windlass but with reduced reserve capacity.

7. In response to boaters comment about moving 6 Vdc vs isolating 12Vdc batteries, on failure, disconnecting a failed 12Vdc GRP 24 of a pair and carrying on, is much easier than:

1. Disconnecting a 6 Vdc Golf Cart battery.
2. Removing the battery from it's mounted location.
3. Disconnecting a 6 Vdc Golf Cart Battery from the house bank.
4. Removing the battery from its mounted location.
5. Carrying the replacement battery forward through the boat.
6. Carrying the defective battery back through the boat.
7. Mounting the replacement battery in the V-berth location.
8. Connecting the replacement battery.
9. Securing the defective battery in the mount of the good one removed.

Batteries do not completely fail every day, but it does happen.

Some boaters have been sold a bill of goods that 6 Vdc golf cart batteries are the "Holy Grail."

6 Vdc golf cart batteries have their place, especially when installed in sets of 4 or more.

However, in my opinion, a pair forward under the V-berth to power a windlass, simply isn't one of them. It will certainly work, but not ideal. There are better AND lower cost solutions.

A GRP 24 AGM installed and used as I have prescribed, will last about 10 years, and will cost around half as much; or even less when one considers the cost of extra wiring, battery box, and consumed storage space of 2 x 6Vdc compared to 1 x 12 Vdc Grp 24.

Ramblin Rod
Marine Service Provider
About Sheen Marine

[ramblinrod]

Originally Posted by evm1024

What you say is true... but lets not forget that the total swing of 12 v rms is ~34 volts but the total swing from the 0 point reference is ~ +-17 volts. And that is what counts.

And thus 12 v rms and 12 v DC going through the same non inductive resistance will dissipate the same power (and heat your coffee just as quickly).

Correct, sorry I made an error in my prior post. In response to a poster claiming that 12Vdc was = something else Vac RMS, I responded correctly that it doesn't but then introduced another error.

12 Vdc = 12 Vac RMS (always implied unless otherwise stated) = 34 Vac peak to peak (P-P). 34 Vac P-P is what one would actually see, observing on a scope. One would only see 17Vac peak after rectification.