Wiring for bow mounted windlass battery.

[ash2020]

We have an old South Pacific windlass which I have always used by taking a Halfords jump start battery pack and clipping it on each time we go away. Not very convenient but I can't afford the £300 it will cost to wire back to the main batteries. I think it may be a good deal cheaper to mount a small 60 or 80 Ah battery up the pointy end and wire in a charging cable. Any ideas on the sort of circuit to prevent the accidental draw of big current down the charge wire. Would it be something like a massive zener diode or relay?
Thanks.

 

[Neeves]

I know I can lose touch with reality but why is wiring + big circuit breaker the windlass from the house batteries so expensive.

If you add a dedicated battery you will need to charge the battery which will need wiring and have a some means to control the charging.. The battery is single use, windlass, which seems inefficient as most of the time it will sit idle.

Jonathan

 

[Tranona]

We have an old South Pacific windlass which I have always used by taking a Halfords jump start battery pack and clipping it on each time we go away. Not very convenient but I can't afford the £300 it will cost to wire back to the main batteries. I think it may be a good deal cheaper to mount a small 60 or 80 Ah battery up the pointy end and wire in a charging cable. Any ideas on the sort of circuit to prevent the accidental draw of big current down the charge wire. Would it be something like a massive zener diode or relay?
Thanks.

You still have to charge the bow battery. The GH I have just bought did this by a combination of wind and solar. I have done away with those and will be charging from the engine start through a B2B charger which only needs 10mm sq cable rather than the heavy (at least 25mm sq) that is needed to use the house (ir start) battery direct. The bow battery is a 95Ah Leisure. Don't think a small battery such as you propose will cope, but it is the CCA that is important rather than capacity as windlasses draw high currents for short periods. Check with the data sheet for the windlass.

The cost of a dedicated battery and charger compared with wiring direct is about the same as the cost of the B2B offsets the extra cable costs.

 

[geem]

I know I can lose touch with reality but why is wiring + big circuit breaker the windlass from the house batteries so expensive.

If you add a dedicated battery you will need to charge the battery which will need wiring and have a some means to control the charging.. The battery is single use, windlass, which seems inefficient as most of the time it will sit idle.

Jonathan

I have the same view. Batteries fail. What do you do when the battery won't work the windlass? Connecting to the house bank must surely be a better engineering solution. The house bank will likely be a larger bank and happier to take the load of a windlass motor.

 

[Tranona]

I have the same view. Batteries fail. What do you do when the battery won't work the windlass? Connecting to the house bank must surely be a better engineering solution. The house bank will likely be a larger bank and happier to take the load of a windlass motor.

That is a valid point, but there is no reason why a bow battery should fail without notice. Just like an engine start it has an easy life in the sort of use the OP (and myself) will give it. Short periods of intensive use followed by quick recharging means it does few cycles and spends most of its life sitting fully charged. The biggest negatives of bow batteries is the weight up front and space difficulty of fitting them. My Bavaria 37 had no room up front because of a water tank so was wired back to the house bank, but the 33 was designed to have a bow thruster and a dedicated battery for both the windlass and thruster.

As ever there are compromises and one chooses the better solution for the specific circumstances.

 

[ash2020]

I know I can lose touch with reality but why is wiring + big circuit breaker the windlass from the house batteries so expensive.

If you add a dedicated battery you will need to charge the battery which will need wiring and have a some means to control the charging.. The battery is single use, windlass, which seems inefficient as most of the time it will sit idle.

Jonathan

Even on eBay the cable is around £20-25 per metre - per colour.

 

[IanCC]

Even on eBay the cable is around £20-25 per metre - per colour.

Tinned Copper Battery/Starter Cable

 

[ash2020]

I have the same view. Batteries fail. What do you do when the battery won't work the windlass? Connecting to the house bank must surely be a better engineering solution. The house bank will likely be a larger bank and happier to take the load of a windlass motor.

As I said, I cannot afford the cable. Looking for a cheaper solution otherwise I can't do it and I'll stick with my jump start 17Ah battery pack.

 

[ash2020]

Tinned Copper Battery/Starter Cable

Nice. Thanks Ian.

 

[IanCC]

Nice. Thanks Ian.

I have a bow thruster running off start battery. 250amp fuse just after battery. 70mm sq cables. 30 footer.

 

[Tranona]

As I said, I cannot afford the cable. Looking for a cheaper solution otherwise I can't do it and I'll stick with my jump start 17Ah battery pack.

A Sterling B2B is around £200 and 10mm cabling is less than 20% of the price of 70mm so a little cheaper than running off your existing battery, but you have to buy and install an additional battery. As usual there is no such thing as a free lunch and which method you choose depends on what is most appropriate for your specific installation. As i suggested earlier check what the power demands are for your windlass as from memory the power requirements, particularly starting draw in the South Pacific are much more modest than for example Lofrans which would require 70mm. However a Lewmar Pro Series like I had on my last boat would only require 25mm for up to 15m (7.5 there and back).

 

[geem]

A Sterling B2B is around £200 and 10mm cabling is less than 20% of the price of 70mm so a little cheaper than running off your existing battery, but you have to buy and install an additional battery. As usual there is no such thing as a free lunch and which method you choose depends on what is most appropriate for your specific installation. As i suggested earlier check what the power demands are for your windlass as from memory the power requirements, particularly starting draw in the South Pacific are much more modest than for example Lofrans which would require 70mm. However a Lewmar Pro Series like I had on my last boat would only require 25mm for up to 15m (7.5 there and back).

We are fortunate enough to have a 24v boat. Cables only need to be 1/4 of the cross-section of 12v for the same load. Our 1700w windlass runs of ludicrously small cables even though it's a long run to the windlass

 

[Tranona]

We are fortunate enough to have a 24v boat. Cables only need to be 1/4 of the cross-section of 12v for the same load. Our 1700w windlass runs of ludicrously small cables even though it's a long run to the windlass

Not everybody is in that situation and it is always a good idea to look at the poster's situation and base your response on that. The OP has a 27' old style small sailing cruiser so his problems with powering his windlass are rather different from yours so require different solutions.

 

[Neeves]

Tinned Copper Battery/Starter Cable

You would need a large yacht with the batteries on the transom to cost Stg500, not forgetting the alternative cost of wiring and controlling a battery located in the bow. Increasing the house bank seems a good option as the house bank is never big enough, adding a battery to the existing house bank uses the same charge controller. If the house bank is big enough and the OP uses his engine when he retrieves, and deploys using gravity, he has no need for an extra battery at all. Just 2 cables to the windlass a circuit breaker and switch for the windlass. It would my beleiief running 2 heavy duty cables will be easier and much cheaper than setting up wiring to have a battery (which in fact may be, the battery) optional) in the bow..

Unless the OP is a sparky I'd suggest he starts a thread on how he is going to charge his independent windlass battery - and how much it might cost.

I take Tranona's point in favour of a battery located 'aft' as one in the bow detracts from sailing performance. I suspect most people would not tell the difference, nor care, about sailing performance - but I can think of better location for a battery than a bow locker (specially on an old yacht where a bow located battery was never considered. I suspect that a battery in the bow will demand a plinth on which to sit said battery - more money.

KISS - 2 cables, circuit breaker, switch - run engine. Nothing can go wrong. You could wire it up yourself in 2 hours.

Each to their own.

Jonathan

 

[William_H]

We have an old South Pacific windlass which I have always used by taking a Halfords jump start battery pack and clipping it on each time we go away. Not very convenient but I can't afford the £300 it will cost to wire back to the main batteries. I think it may be a good deal cheaper to mount a small 60 or 80 Ah battery up the pointy end and wire in a charging cable. Any ideas on the sort of circuit to prevent the accidental draw of big current down the charge wire. Would it be something like a massive zener diode or relay?
Thanks.

Yes as said use heavy wires rather than bow battery. However re last line. zener diode would not be useful at all in your situation probably not a relay either. In fact if you use light wire the resistance of the wire will limit the current to the battery/winch when winch is drawing current. Problem is that wire in limiting current will get hot. Possibly a fire danger and precluding use of correct value fuse. A fuse value correct for the wire size would blow with winch current (in supporting the battery) but a big enough fuse might allow wire to burn in a fault situation. ol'will

 

[Boathook]

I've got a dedicated battery for my bow thruster and windlass and this is kept charged by a Adverc B2B charger with fuses protecting its wiring from the main battery bank. The battery is a basic lead acid type and seems to last well. The B2B wasn't cheap many years ago, but has proved good value in that I don't worry about it. If I went for a different type of battery I suspect the the B2B would have to be replaced as it was only meant for a basic battery.

 

[Tranona]

You would need a large yacht with the batteries on the transom to cost Stg500, not forgetting the alternative cost of wiring and controlling a battery located in the bow. Increasing the house bank seems a good option as the house bank is never big enough, adding a battery to the existing house bank uses the same charge controller. If the house bank is big enough and the OP uses his engine when he retrieves, and deploys using gravity, he has no need for an extra battery at all. Just 2 cables to the windlass a circuit breaker and switch for the windlass. It would my beleiief running 2 heavy duty cables will be easier and much cheaper than setting up wiring to have a battery (which in fact may be, the battery) optional) in the bow..

Unless the OP is a sparky I'd suggest he starts a thread on how he is going to charge his independent windlass battery - and how much it might cost.

I take Tranona's point in favour of a battery located 'aft' as one in the bow detracts from sailing performance. I suspect most people would not tell the difference, nor care, about sailing performance - but I can think of better location for a battery than a bow locker (specially on an old yacht where a bow located battery was never considered. I suspect that a battery in the bow will demand a plinth on which to sit said battery - more money.

KISS - 2 cables, circuit breaker, switch - run engine. Nothing can go wrong. You could wire it up yourself in 2 hours.

Each to their own.

Jonathan

I think I have already covered all this. There is no right or wrong way - it really does depend like so many things on a boat - on the specifics of the installation. Cost is similar for each method, particularly for smaller boats. However the longer the boat (and therefore the longer the cable runs) the greater the cabling costs if you are using rear mounted batteries. If retrofitting running 70mm cables through the accommodation can be a challenge. The extra weight in the bows really is not a big issue - my 95Ah AGMs weigh 24kg and can often be mounted well back and low down. As I said my two Bavarias were wired differently reflecting a design decision. Both worked.

In my latest project I could have used either method as there is an easy run through the bilges for any size cable, but the bow battery was already installed and charged by solar/wind. Easy decision for me (as I don't need the solar or wind) to go the B2B route for charging the battery - helped by buying the charger off a forumite at a good price. If I had been starting from scratch and only powering a windlass I would probably have used the house bank and heavy wire approach. As it is I am happy with the bow battery as it will make life easy if I wish to fit a bow thruster in the future.

 

[geem]

Not everybody is in that situation and it is always a good idea to look at the poster's situation and base your response on that. The OP has a 27' old style small sailing cruiser so his problems with powering his windlass are rather different from yours so require different solutions.

I never suggested his set up was the same as mine! I fully understand the OPs set up. I still believe wiring from the domestic bank is a far better engineering solution especially in a small boat where space and weight of an additional battery in the bow is a big issue. The cost of the wire may be significant but like most things in life you get what you pay for. I was pointing out the benefits of 24v for anybody following this post.

 

[PaulRainbow]

35mm battery cables from the engine or domestic batteries. Do not fit a fuse, it should be fitted with a suitably rated thermal circuit breaker. Unlike most circuits, the windlass circuit protection is not just for the cable it's for the windlass motor too. If you fuse for the cable you can overload the motor and damage it, if you fuse for the windlass you can suffer with blown fuses if you heavily load the windlass.

Some windlass installations are connected to the engine battery, others to the domestics. With small domestic banks the windlass can cause a voltage drop and the electronics will shut down/restart, which is not good for them. If wired to the engine battery, make sure the engine is running when using the windlass.

The alternative of a battery at the bow is also a valid one, though not really appropriate in this case. Charging can be really simple, a lighter rated cable from the engine or domestic batteries, fused at one end and a thermal breaker at the other works perfectly OK. Contrary to rumour, the windlass doesn't normally draw high currents through the cable and cause any issues, but the thermal breaker covers such an eventuality should it occur. Have the fuse at a higher rating then the breaker, so if there is an issue, the breaker trips (which can be reset), rather than blowing fuses.