Powering a windlass

[KREW2]

I am in the process of fitting a 1000 amp windlass. I have decided to run it from a separate battery in the forpeak, so as not to have to run 50mm2 cable. I have 2 x 110amp hour batteries on a 1, 2, both switch I know they are leisure batteries but I intend to use one for starting, and the other as a leisure battery. I'm going to buy a starting battery for the windlass, and charge it by connecting it to the designated starting battery.
My question is, as these 2 batteries will be in parallel I assume when I start my engine it will draw power from both, will I still be able to run a lighter cable to the windlass for charging purposes.

 

[havandra]

Batteries

You should not connect the windlass battery directly to the starting battery as this will result in one battery topping up the other until they are the same level. This could mean you having 2 flat batteries!
Connect the Windlass battery to your charging circuit using the necessary size cable, (This can be a much smaller size than the heavy battery cable, but it needs to be big enough for the charging ampage) and preferably through a switch so that you can isolate it if neccessary.

 

[Playtime]

I am in the process of fitting a 1000 amp windlass. I have decided to run it from a separate battery in the forpeak, so as not to have to run 50mm2 cable. I have 2 x 110amp hour batteries on a 1, 2, both switch I know they are leisure batteries but I intend to use one for starting, and the other as a leisure battery. I'm going to buy a starting battery for the windlass, and charge it by connecting it to the designated starting battery.
My question is, as these 2 batteries will be in parallel I assume when I start my engine it will draw power from both, will I still be able to run a lighter cable to the windlass for charging purposes.

No! If the windlass battery will be (permanently?) in parallel with the starter battery the cables must be sized in accordance with the starting current.

The normal arrangement with a separate windlass battery, to avoid running heavy cables forward, is to use a DC-DC converter from the service (leisure) battery to charge the windlass battery. This will only require cables able to carry the rated current for the DC-DC converter - say 10 amps.

BTW - I think you mean 1000W rated windlass not 1000A (=12 kW!)

 

[earlybird]

My choice is to run cables back to the starter battery. It's a lot simpler, avoids battery weight forward, where motion can be considerable and eliminates the risk of putting starter currents through the charging cables.
50sq. mm. seems big for 1kW. My 0.8kW windlass uses 4 or 6 awg and seems happy. Welding cable would be a low cost option.

 

[KREW2]

No! If the windlass battery will be (permanently?) in parallel with the starter battery the cables must be sized in accordance with the starting current.

The normal arrangement with a separate windlass battery, to avoid running heavy cables forward, is to use a DC-DC converter from the service (leisure) battery to charge the windlass battery. This will only require cables able to carry the rated current for the DC-DC converter - say 10 amps.

BTW - I think you mean 1000W rated windlass not 1000A (=12 kW!)

Thanks, I'm not sure what I mean, but yes it's 1000W.
Would the DC-DC converter also act as a saftey device, should the engine be started if the battery switch was left in the BOTH position.

 

[KREW2]

My choice is to run cables back to the starter battery. It's a lot simpler, avoids battery weight forward, where motion can be considerable and eliminates the risk of putting starter currents through the charging cables.
50sq. mm. seems big for 1kW. My 0.8kW windlass uses 4 or 6 awg and seems happy. Welding cable would be a low cost option.

That was my first choice, according to this site http://www.safety-marine.co.uk/Anch...Battery-Cable-(sold-per-meter).htm?P1354-S38-
I will need £450 worth of cable, as indeed my local chandler confirmed, but he will give me 10% off.

 

[daveyw]

That was my first choice, according to this site http://www.safety-marine.co.uk/Anch...Battery-Cable-(sold-per-meter).htm?P1354-S38-
I will need £450 worth of cable, as indeed my local chandler confirmed, but he will give me 10% off.

I notice from this site it is cheaper to buy smaller cable and twice as much to achieve the same result

 

[vyv_cox]

That was my first choice, according to this site http://www.safety-marine.co.uk/Anch...Battery-Cable-(sold-per-meter).htm?P1354-S38-
I will need £450 worth of cable, as indeed my local chandler confirmed, but he will give me 10% off.

£41 for 10 metres of 35 mm2 here That's what I have had for my 1000 W windlass for around 10 years now, absolutely no problems.

 

[Playtime]

Thanks, I'm not sure what I mean, but yes it's 1000W.
Would the DC-DC converter also act as a saftey device, should the engine be started if the battery switch was left in the BOTH position.

A DC-DC converter would charge the windlass battery (in the bow) from the leisure battery (presumably under a saloon or rear cabin berth). The wires connecting the DC-DC converter to the windlass battery need only be light, to handle say 10A, whatever is the maximum charge current that the DC-DC Converter can push out so you save (most of) your £400+ of heavy duty cable (you still need heavy cable from the windlass battery to the windlass switches and motor, of course but these can be short).

When the engine is running the leisure battery and the starter battery will be charged as normal (dependant on the 1 -2 - Both switch) and the windlass battery will be charged through the DC-DC Converter. No need for "additional safety devices".

A suitable DC-DC Converter is available here - £99 plus VAT. There are other similar items available elsewhere.

 

[KREW2]

£41 for 10 metres of 35 mm2 here That's what I have had for my 1000 W windlass for around 10 years now, absolutely no problems.

This method certainly seems to bring the cost down, I suppose it only comes in red, but I cannot see that being a problem.

 

[KREW2]

A DC-DC converter would charge the windlass battery (in the bow) from the leisure battery (presumably under a saloon or rear cabin berth). The wires connecting the DC-DC converter to the windlass battery need only be light, to handle say 10A, whatever is the maximum charge current that the DC-DC Converter can push out so you save (most of) your £400+ of heavy duty cable (you still need heavy cable from the windlass battery to the windlass switches and motor, of course but these can be short).

When the engine is running the leisure battery and the starter battery will be charged as normal (dependant on the 1 -2 - Both switch) and the windlass battery will be charged through the DC-DC Converter. No need for "additional safety devices".

A suitable DC-DC Converter is available here - £99 plus VAT. There are other similar items available elsewhere.

I'm beginning to understand, I think, should I start the engine on the donor battery the DC-DC converter would restrict the current flow protecting the lighter charging cables.

 

[Playtime]

I'm beginning to understand, I think, should I start the engine on the donor battery the DC-DC converter would restrict the current flow protecting the lighter charging cables.

Correct. The solution I proposed (using a separate windlass battery in the forepeak and a DC-DC Converter to charge it) is the 'preferred' solution on big boats where the cost of heavy duty cable running the length of the boat would be significant.

However, if you are happy to use welding cable as suggested by Vyv (but note there are mixed feelings about the use of such cable on boats - see this thread here ), then it will provide a cheaper but adequate solution.

 

[maxi77]

I am doing the same, and I am planning on using a liesure battery for'd for the windlass and charging it through a voltage sensitive relay which will only connect when the system voltage reaches about 13.5

 

[KREW2]

Correct. The solution I proposed (using a separate windlass battery in the forepeak and a DC-DC Converter to charge it) is the 'preferred' solution on big boats where the cost of heavy duty cable running the length of the boat would be significant.

However, if you are happy to use welding cable as suggested by Vyv (but note there are mixed feelings about the use of such cable on boats - see this thread here ), then it will provide a cheaper but adequate solution.

Yes, been looking at that thread. Thanks for keeping it simple, problem is now that I understand, is I have to make a decision.

 

[Rivers & creeks]

Is it feasible to put a small - say 5W - solar panel in the bow and trickle charge from that? Assuming a few days between anchoring each time?

 

[Playtime]

I am doing the same, and I am planning on using a liesure battery for'd for the windlass and charging it through a voltage sensitive relay which will only connect when the system voltage reaches about 13.5

If you are using a VSR you need to ensure that the charging current to the windlass battery does not exceed the safe capacity of the charging cable. This can happen if the windlass battery is heavily discharged and the other batteries are well charged.

 

[VicS]

f you are using a VSR you need to ensure that the charging current to the windlass battery does not exceed the safe capacity of the charging cable. This can happen if the windlass battery is heavily discharged and the other batteries are well charged.

I reckon the VSR is the way to do it although the downside is that the windlass battery will only charge when the main battery charging system (engine, shorepower, genny) is operating and the battery from which it is daisy chained has at least partly recharged.

The cables to the windlass battery will have to be sized to keep volts drop to a reasonable level and in practice that will mean they will be appreciably heavier than required to provide a safe current carrying capacity.

 

[mitiempo]

Another solution is to use an Xantrex Echocharge to charge the forward windlass battery. When a charging source is present it will pass upto 15 amps to the battery. This allows for light cables. The cable from the Echocharge or whatever device is used should be fused near the windlass battery for safety as well. If an Echocharge is chosen this need not be a large fuse as long as it is bigger than the 15 amps charging current and less than the wire ampacity. What this protects is the wires from the battery amperage. If a VSR is used the cables as has been said have to be much larger and so does the fuse.

 

[Playtime]

I reckon the VSR is the way to do it although the downside is that the windlass battery will only charge when the main battery charging system (engine, shorepower, genny) is operating and the battery from which it is daisy chained has at least partly recharged.

The cables to the windlass battery will have to be sized to keep volts drop to a reasonable level and in practice that will mean they will be appreciably heavier than required to provide a safe current carrying capacity.

Umm - how do you decide the required current carrying capacity to size the cable? As I implied earlier, with a heavily discharged windlass battery and fully charged 'daisy chained' battery the charging current could be very high when the VSR closes.

 

[mitiempo]

Since a VSR will allow the full current from one battery to pass to the other it is a bad idea and if used would require heavy cables. The Echocharge will limit the current to the windlass battery to 15 amps so will only require 10 awg cables to be run and is a better solution.