Windlass battery - house or engine

[Storyline]

I have a Lewmar 1000W windlass and need to decide whether to connect it (via 35mm cable) to either the engine start battery (100ah 700 CCA - flooded truck starter type) or to the house batteries (3 x 105ah - dual purpose Delco Freedom type).

Any thoughts would be appreciated. I should add that we intend to have the engine running when using the windlass.

 

[oldsaltoz]

Engine running and connect to house bank sounds fine. More capacity, safer for start battery.

 

[ccscott49]

House bank, dont want to flatten engine battery even if the engine is running, maybe a time when engine isnt running or wont start and need to lift anchor. Safer all round.

 

[jerryat]

Hi,
I've got a similar service system to you (we have 4 x 105amp Delco's) and run the windlass from that bank, definitely not, as others have said, from the engine start battery.

Keep the engine running and you be fine! /forums/images/graemlins/smile.gif

 

[pmyatt]

Have you considered a separate windlass battery. We started with ours connected to the house bank (4 X 105 Ah Delco Freedom) and subsequently upgraded to a dedicated Red Flash 1200 which is charged off the house bank through a Xantrex Echocharge unit. The charging current is a maximum of 15 Amps so you don't need a long length of battery grade cable. A windlass is basically a starter motor so, large current draw for short space of time - a starter type battery is probably more suited. We felt that, by separating the systems out, we could use more specific battery types and, additionally, in-extremis, if both house and starter batteries are knackered, the windlass battery can be used to replace the engine start battery.

 

[Storyline]

Thanks all.

I had sort of arrived at that decision - good to have it confirmed

FF38 - I did think of that, however having just put 70m of 3/8th Chain on and a 20kg rocna on the bow the stern is now 2 inches higher out of the water so weight is an issue!

 

[pmyatt]

The Red Flash battery is AGM and is only about twice the size of a motorcycle battery so would not be over the top. I know where you are coming from re: weight in the bow. Last year we put on 75m of 10mm and a 27.5 kg Manson - we are now countering it with a generator and watermaker in the stern - with all our spares, tools and liveaboard gear I think we are about 4" down on the previous waterline.

 

[Sans Bateau]

I'm sorry, but I do not agree with the house battery solution. Mine is connected to the starter battery, up until recently this was a completely underrated 54AH 'car' type starter battery, not really suitable at all. This has now been replaced by a 110AH 1000CCA sealed battery.

We spend a lot of time at anchor rather than marina visits. Our domestic bank of 2 x 105ah batteries became heavily discharged over Easter when we spent the holiday in Newtown creek, the lights, Eber, CD player and water/shower pump all took their toll. I suspect that had I had to lift the anchor with those batteries it would have failed.

The characteristics of an anchor windlass motor is far more like that of a starter motor, a relative short period of drawing a large number of amps, not the trickle drawn from a deep cycle battery.

I can understand the theory of keeping all the current untouched for the starter, but one would always start the engine before lifting the anchor. I would imagine that a heavily discharged domestic bank, being recharged whilst having more current taken from it could cause problems in premature failure of the alternator, wiring or batteries, or even overheating and damage to the windlass motor. Not enough current being supplied to an electric motor when asking it to work will overheat it.

However, if the windlass is attached to the starter battery, even in the unlikely event that the engine wont start (you WILL have serviced it, wont you?) you will have a fresh battery perfectly matched to the job, that will lift the anchor and let you sail away.

 

[rosssavage]

Agree with galadriel.. My battery system is thus: Domestic = non essential equipment, Engine = essential equipment. Hence my engine batteries (2x 90Ah) run engine starters, anchor windlass, lower helm VHF and horn. Then, when I inevitably flatten my domestics by accidentally leaving the inverter on / fridge door open / etc etc overnight, essential services are maintained.

If you're concerned, start the engine before using windlass.