Windlass wiring

[SimonD]

I'm planning to fit a Lewmar Pro Series 1000 winch. Despite the name, it draws 700W. I intend to fit a battery in the forepeak to drive it. My question is: what type and capacity of battery? I'm guessing some sort of sealed battery (an AGM?) that is designed for a starter motor application would be best, but I'm not sure how to size it.

Also, what size of cable do I need from the alternator (or more practically, the house batteries) to the windlass battery?

Thanks in advance.

 

[pvb]

Ideally, you need a DC-DC charger to charge the windlass battery from your house battery. This will have a maximum charge current, which you can use to calculate the required cable size. You should have cable which only has a voltage drop of about 3%.

Alternatively, you can just connect the windlass battery to the house battery. In this case, you need quite substantial cable, as there could be a significant current flowing if you operate the windlass whilst the engine is running (and the house battery has a higher voltage).

If you have a windlass battery, you need to fuse the cable next to the windlass battery as well as next to the house battery, so 2 substantial fuses are needed.

At the end of the day, it's usually cheaper just to run heavy duty cables straight to the windlass from the house battery (with a fuse next to the house battery).

 

[Talulah]

pvb is right.
Whilst it is often easy enough to locate a battery in the forepeak for the windlass and consequently have 2 relatively short bulky cables you have to think about how it's going to get charged.
The process of charging requires some thought.
If you just connect it up to the domestic batteries it is in effect just an extension of the domestic batteries. The current draw from the other batteries could be significant.
If you want to isolate the battery so it charges off the alternator but is disconnected from the house bank under normal conditions then a voltage sensitive relay would do it. However, if you operate the windlass with the engine now running the VSR is closed and your are back to large currents being drawn from the domestic bank.
Personally, big cables from the domestic bank but increase the capacity if needed by adding an additional battery in parallel.
I have no experience of DC to DC chargers.

 

[Gordonmc]

I plan to replace a manual windlass with an electric one following some adventures last season. Recovering 10mm chain and a humungous anchor with a F6 blowing a 15 ton boat was no joke. Especially as I was single handed so couldn't use the engine.
Anyway...
The plan is to install a battery under the forepeak bunk in an unused second anchor chain locker, complete with controller etc.
The battery would not be connected to a charger in situ. To do so would mean running substantial cables from the house bank at the other end of the boat, about 30 foot.
I would remove the battery to charge it periodically using a hefty solar panel array (installed).
As the windlass would only be used three or four times a season I reckon I could live with that.
I would use a spare 115 AH leisure battery which should stand up to 40% discharge.
Thoughts?

 

[Talulah]

My immediate thought is that your leisure battery will have self depleated when you come to use it.

 

[maxi77]

My immediate thought is that your leisure battery will have self depleated when you come to use it.

I solved that by fitting a VSR to ensure it was always charged when the other batteries were charged

 

[nimbusgb]

My feeling is that a lot of these fancy forward battery systems are total overkill.

A 700watt windlass draws about 60 amps.

Even if you run it continuously for 5 minutes at full load ( and it survives that ) you only use about 5 amp hours from the battery. ( 60 amps * 5 minutes = 300amp minutes or 300/60 = 5 amp hours ) Not exactly a huge drain even on a medium sized car starter battery.

What you need to be sure of is that the battery wil supply 60 amps for 5 minutes and that your charging system will put it back in time for the next useage.

Anchoring once a day as one does in the Med with a 100% contingency a 95 Ah car starter battery could even be charged off a solar panel but the engine alternator will put the 5 Ah back in 15 minutes anyway.

 

[pvb]

Even if you run it continuously for 5 minutes at full load ( and it survives that ) you only use about 5 amp hours from the battery. ( 60 amps * 5 minutes = 300amp minutes or 300/60 = 5 amp hours ) Not exactly a huge drain even on a medium sized car starter battery.

You've ignored the Peukert effect, which means that the capacity of a battery reduces rapidly if it's discharged at a higher current than its 20-hour rating. A typical 100Ah battery would be 50% discharged in only 20 minutes if you take a 60A current from it.

 

[nimbusgb]

You've ignored the Peukert effect, which means that the capacity of a battery reduces rapidly if it's discharged at a higher current than its 20-hour rating. A typical 100Ah battery would be 50% discharged in only 20 minutes if you take a 60A current from it.

I did say --- 'What you need to be sure of is that the battery wil supply 60 amps for 5 minutes' I had no intention of ignoring Peukert!

20 minutes on a 700w windlass at full load, I'll bet it's a smoking wreck long before then.

 

[Blueboatman]

Its all been done on here many times, but, couple of minutes to kill, here's ( yet another)suggestion.
Since the OP has to run cables routes anyway, just buy bigger cables and be done with it, simplest, forget the fancy chargers, second battery housings, secondary fuses ..
I doubled up on the engine start( cranking) batteries rather than hook into or add capacity onto the deepcycle domestics, for a 1200w windlass.

 

[snooks]

It's a case of either running thick cable up to the bow to power the windlass and not buying a battery, or run not-so-think cables to the bow to charge the battery.

I went for the former to keep weight out of the bow.

I rigged up a switch (BEP battery switch) and a 80A (or is it 90A) circuit breaker, and use 35mm2 cables.

I have a VSR, so the engine ploughs in the charge to the engine battery, usually within 5 mins of the engine going on, then it charges the domestic bank and the windlass is fed of the domestic back (2 x 110Ah) never had any problems with the system at all.

 

[SimonD]

Thanks Snooks et al. Big cables it is then. I had also intended to fit an engine battery to supplement the two 110AH house batteries, so I should be fine.

 

[Sneaky Pete]

Powering the windlass

This has saved me from putting a post on here it was weight of battery in forepeak plus all the other bits and pieces versus running cables from battery bank 8 meters up the boat, after the these replies I believe I will run heavy duty cable directly up to the windlass seems less complicated, thanks for the replies. Simples.

 

[pvb]

This has saved me from putting a post on here it was weight of battery in forepeak plus all the other bits and pieces versus running cables from battery bank 8 meters up the boat, after the these replies I believe I will run heavy duty cable directly up to the windlass seems less complicated, thanks for the replies. Simples.

It's cheaper and easier, and less to go wrong.

 

[lustyd]

If you're really smart about it, couldn't the really thick cables be used along the way with canbus for everything else on the boat?

 

[pvb]

If you're really smart about it, couldn't the really thick cables be used along the way with canbus for everything else on the boat?

Theoretically, but everything else on the boat probably already has its own cables.

 

[Finbar]

I have just fitted a Lofrans Kobra to my boat, running cable forward from the batteries. lofrans recommend 35mm sq cable for up to 10m run for my 1000w motor. I used welding cable which is bendy and not too expensive and ran it through the lockers in flexible conduit. All seems fine so far, and no more weight forward. Definitely much simpler than a dedicated battery.

 

[Puggy]

At the risk of repeating what has already been said, I have 150ah batteries for the bow thruster and windless located back in the engine compartment with massive 70mm2 cable to the bow (maybe 8 metres?). It all works a treat, and I think it is much better to have the batteries back where they can be properly charged with minimal voltage drop (both by the alternator and shorepower) so that they have a chance of longevity. Whatever voltage drop there might be to the windless or BT isn't noticeable in terms of performance.

 

[pvb]

At the risk of repeating what has already been said, I have 150ah batteries for the bow thruster and windless located back in the engine compartment with massive 70mm2 cable to the bow (maybe 8 metres?). It all works a treat, and I think it is much better to have the batteries back where they can be properly charged with minimal voltage drop (both by the alternator and shorepower) so that they have a chance of longevity. Whatever voltage drop there might be to the windless or BT isn't noticeable in terms of performance.

Are these batteries dedicated only to the thruster and windlass? Why not incorporate them into your domestic bank and have the benefit of them all the time?

 

[William_H]

At the risk of repeating what has already been said, I have 150ah batteries for the bow thruster and windless located back in the engine compartment with massive 70mm2 cable to the bow (maybe 8 metres?). It all works a treat, and I think it is much better to have the batteries back where they can be properly charged with minimal voltage drop (both by the alternator and shorepower) so that they have a chance of longevity. Whatever voltage drop there might be to the windless or BT isn't noticeable in terms of performance.

Comments on this thread suggest that volt drop in charging cables is a concern. This is not really the case.
A volt drop to eg a lamp means less power light from the lamp. But with battery charging a high current charging the battery if going through a resistive (small) cable simply drops the voltage a little which drops the current into the battery. So it becomes self leveling. yes the max current into the battery may be reduced but a battery naturally reduces the current it takes as battery voltage rises so actual time to full charge is not increased very much at all. Obviously the cables have to be reasonably heavy so they will not overheat or limit charge current too much but not as much concern as supplying current to a service.

If a battery at the winch is used and is charged by an alternator perhaps in parallel with a large battery then as the winch tries to take current from the cables and alternator the voltage will drop slightly reducing the current through the cables and so taking current from the local battery. So again not as much concern as you might imagine. I would not go for a battery to battery charger as these could not provide the large surge current so you might as well just chargee in parallel with engine battery or house battery.
Having said all that however I believe your best bet is large cables and run the winch from the engine battery. (assuming you will always have engine running. Who needs yet another battery that will need replacing after some years. good luck olewill