Windlass connected to starter battery - Is this common?

[Ericson38]

Originally Posted by sailingabe41ds

I see you havea Jeanneau....I have a J 41DS same set up. Add to that that unless the engine is on my windlass wont work.
abe

I have always been curious about having a windlass (with very low internal winding resistance), able to pass 200 amps depending on load and lead in lead out cable resistance, in parallel with a running alternator, which ends up charging (although not charging in this case) close to a short circuit. At 12 volts, 200 amps = 0.6 ohms windlass circuit directly across the alternator.

[Searles]

Kish has nailed it ,a battery bank fwd for the anchor winch also the bow thruster the electric toiler electrascan ,on most yachts over 40ft this is not uncommon in Australia.⛵️⚓️

[GordMay]

A couple of excellent summaries:

Originally Posted by noelex 77

There are pros and cons.

The main advantages of using the start battery is that it avoids voltage spikes in marine electronics and if the alternator charging prioritises the start bank it ensures the alternator is always supplementing the draw.

The main drawback is the start battery is smaller, although it often has a chemistry more suited to high discharge loads.

Often the most important factor is minimising the cable distance between the battery and the windlass. This can favour the start or house bank depending on the layout.

Either using the house or start battery can work well if the system is well designed.

Originally Posted by kish

... The house bank, assuming it is of lead acid chemistry, has a construction optimized for deep cycle usage,

The starter battery has a plate construction to allow several hundred amps to be delivered in a few seconds to start the engine and a windlass will typically draw 50 to 100 Amps probably for several minutes.

Accordingly a starter battery is more appropriate as a windlass battery.
Also the starter battery is under rapid charge while the engine is running


To use a deep cycle house bank as a starter or windlass battery is detrimental to the long term health of the house bank and the voltage drop it encounters may cause electronic instruments to drop out as the house bank takes a voltage hit.
That is why a windlass should not be connected to the house bank.

Voltage drop is an issue.
A windlass is typically 10 metres [33 feet] from the starter and the cable length will be double that for a voltage drop calculation.
The cable to the windlass from the starter to the windlass terminals over that distance should be a minimum cross section area of 70 sq mm section [2/0 AWG]

If the battery voltage drops from 12.8 v to 10.8 volt in windlass operation, the windlass will only deliver 70% of its potential due to the lower voltage.

A separate battery up forward nearer to the windlass and connected in parallel with the starter battery, through a voltage sensitive battery combiner relay, will improve the windlass performance and allow a smaller cross sectional area cable to be used to link the windlass and starter batteries.
This arrangement works well with a bow thruster also.

Purists will argue about the extra weight of a battery forward, but when compared to the weight of anchor chain forward, a 15kg [33lb] battery is insignificant. but locker space needs to be organised to house the battery!

[Disailor]

I have an auto start battery housed in a box at the foot of the v berth (which also functions as a step up aid) for my windlass. Calculating the round trip length between this batt & the engine start batt (with 3% drop) require #6 stranded wire. There is a swith at the helm which fires a contin use relay to connect the two. Engine is always running when weighing anchor. Since I single hand I considered this an essential safety procedure.
I also have a remote wireless controlled relay (for an off road winch). All works great!

[DeValency]

Originally Posted by Tenedos

I figured that on our boat, the windlass is powered from the Starter Battery. I found it quite odd and wondering if this is common at all.

Oddly enough, we have three electrical winches that are connected to the house battery. Using those winches sometimes reboots the Chart Plotter, even when the batteries are fully charged. I suspect there was a similar thinking behind to connect the windlass to the starter battery instead, maybe to protect the sensitive instruments from surges in power draws (I read similar discussions but is this a thing?)

This setup causes some issues so I am planning to rewire the windlass to the house battery this weekend. My starter battery is 105 Ah and house battery is 6x105 Ahs.

Thoughts or suggestions welcome.

This is a logical setup as usually the windlass is used when the engine is on - same with the bow thruster - if you have one... However, most windlasses draw around 100-150A which is a bit too high for a 105A group 31 battery (guess AGM). I wouldn't recommend changing the wiring to the house bank.

As for the winches etc. - they should draw from the house bank as used when the engine is off and you don't want to draw anything from the starter battery. The problem is that flood deep cycle batteries have a low discharge current (vs. starter batteries and vs. LiFePo of course...), so in spite of the large bank you have and probably due to aging, they fail to maintain at least 10-11VDC when winches are used

[Jenst]

Hello, and sorry for adding to the confusion (and probably demonstrate my little knowledge). I am amazed about the many possibilities. Our starter battery has been depleted a number of times and will be replaced. At the same time my windlass is connected to the starter battery - so compounded problem is no ability to start and no ability to raise the anchor. I'm planning to place a dedicated battery (which type ?) in the bow for the windlass and a new starter battery in its original position. As there are already cables runnig from the starter battery to the windlass I hope to use these for charging the new bow battery. We always start the engine before raising the anchor. The new bow battery will be charged via a cristec battery separator. Maybe a VSR between the starter battery and the new bow battery would be better ?
will the cables now in place for powering the windlass from the engine battery be large enough connected to a new bow battery dedicated only to the windlass ?

[DeValency]

You may need a marine electrician to do the work for you as I think there is a lack of basic knowledge here.
1. You don’t want to connect anything to your starter battery. It must be 100% dedicated to the starter.
2. It is a good idea to place a dedicated battery to the windlass, in the bow charged from the same sources of the House batteries (basically in parallel to the house batteries). Guess the conductors you have to the bow are thick enough for charging, as these were originally used to power the windlass.
3. Make sure all the batteries used for the house and windlass are of the same age and type. (Deep cycle)
4. The new battery for the starter should be a starting battery type (high short term power), not deep cycle type.
5. Make sure to have a good battery isolator between all batteries. Victron ArgoFET is the best.

Good luck.

[noelex 77]

Originally Posted by DeValency

You may need a marine electrician to do the work for you as I think there is a lack of basic knowledge here.
1. You don’t want to connect anything to your starter battery. It must be 100% dedicated to the starter.

Keep in mind this an old thread. Hopefully Tenedos has solved his problem by now.

Some boats have an electrical system designed to use the start battery to power the windlass so this is not an absolute rule. There are pros and cons, but it is a system that can work well and make sense, although my slight preference is to have the start battery just for starting the engine.

[SailingHarmonie]

Originally Posted by Tenedos

Oddly enough, we have three electrical winches that are connected to the house battery. Using those winches sometimes reboots the Chart Plotter, even when the batteries are fully charged. I suspect there was a similar thinking behind to connect the windlass to the starter battery instead, maybe to protect the sensitive instruments from surges in power draws (I read similar discussions but is this a thing?)

Thoughts or suggestions welcome.

All the fussing about the windlass, and this comment about the sheet winches rebooting your instruments has been ignored (mostly!)

This should NOT happen. Period. Ever.

There are a couple possible causes. Maybe the winches are drawing more power than they should, but if it happens withall three winches that would be unlikely.

It is possible that your instruments are being more sensitive to voltage than they should be, but this is also not very likely.

I am going as the likeliest fault is with your batteries or their installation. A battery bank of that size should not have any issue maintaining a reasonable voltage with that draw for the short period of time a sheet winch is actually under load. Your batteries might just be worn out, or the connections between them are either badly configured, or too small, or otherwise compromised.

This has a section on how parallel batteries should be connected for best life AND performance in high amperage service.

https://fetchinketch.net/boat_thoughts/battery-connections/

This situation should be intolerable.

[carstenb]

One of the issues with Jeanneau (and many others) is that the alternator on the engine si a Hitachi 80A run with a single v-belt. A single v-belt will not turn the alternator without squealing if it is trying to put out 80AH. Running the anchor winch will force the alternator to try to put out maximum effort.

You end up with two problems.
1- The alternator will quickly drop to putting out 40AH since this is what is can handle without overheating - now you are depleting your battery big time
2- The v-belt will slip and you'll have rubber dust all over your engine room (don't ask me how I know this)

We've changed out 80AH alternator out with an 160AH alternator and the v-belt with a serpentine belt.

problems solved

[waterman46]

Your plan is good. Use a starting type of battery forward and avoid using any VSR that uses a mechanical relay. Contact resistance increases slowly over time and can go un-noticed.

[Simi 60]

Originally Posted by DeValency

You may need a marine electrician to do the work for you as I think there is a lack of basic knowledge here.
1. You don’t want to connect anything to your starter battery. It must be 100% dedicated to the starter.
.

Depends on the boat

Our windlass is connected to start batts and was done that way by a marine electrician
Back in a previous life she was a commercial trawler and had the windlass connected to starts then as well

[kavw]

Windlass should be used in spurts, to pick up the cantenary. Money is best spent in large cables going to the house bank, the house bank not sized small. Preference for having engine on, charging house bank and a voltage sense relay to charge engine battery. I see little logic in a forward battery bank unless the yacht has a separate generator and a battery charger for those batteries, and still you need a way to charge them if generator craps out, which usually means cables to a alternator charge splitter which has voltage drop….nope, best with big cables to the house bank otherwise, and house bank placed at center of yacht for weight distribution. I’d prefer for vhf and chart plotter to be in their own battery to avoid voltage fluctuations.

[donradcliffe]

Originally Posted by aqfishing

Why on earth would you pick up anchor without your engine running? For starters, surely you ease the load by driving up as you retrieve your anchor?

Why on earth would you require the engine to running to pick up your anchor? You may need to pick it up NOW and your engine won't start....

[Scubaseas]

Separate battery in the bow fan here. Keep the big cables if already run and add an emergency bypass switch to the starter battery. If not there's a spare starting battery in the bow for you. Use an AGM starting, not deep cycle battery. Resists vibration and motion, does not have to be vented and can be run on it's side (with some loss of ampacity). Starting batteries are designed to give a large volume of amps in short bursts. Running a starter type motor which both windlass and thruster use draw a lot (100 to 300amps) but for a short time. If you run your windlass off the starter or the house bank use cables big enough for the job. On a 40' boat these might be 60' of wire round trip which means use 3/0 cables.