Windless operation and critical voltage drop

[alexincornwall]

On our last trip of the past season I noticed an issue with our previously perfect Lewmar windless, which felt as though it was losing torque and struggling to retrieve chain/anchor when the load increased i.e. the last 10-20 meters. When I returned from the deck to the cockpit my plotter was displaying a low can bus voltage warning. I was singlehanded at the time so unable to drive the boat towards the anchor, but always run the engine in neutral at around 1400rpm when using the windless in such instances.

I had an electrician investigate whilst we were ashore over the winter but we weren't able to replicate the problem. The following were inspected:

Windless motor bushes - all good
Power to windless - fine, no notable voltage drop across the cable run
Domestic supply (3 x 130ah decent quality AGM, approx. 18 months old) - all holding a healthy charge and no alarming voltage drop whilst the windless was in operation (we couldn't run it under any real load)

All of the connectors were cleaned up and checked and we left it there pending a sea trial. Unfortunately, our problem remains. The windless eats up the first 50-75% of chain without issue and then struggles with the remaining. On my last test the voltage drop was so significant that my plotter and instruments all shut down and rebooted themselves.

The electrician is returning next week and we intend to put to sea to try and replicate the issue. He suspects the batteries but they've always been looked after meticulously with a good year round solar charge and never allowed to drop below 70% SOC.

Does anyone have any suggestions to consider please?

 

[Bobc]

You've covered everything I would have suggested looking at.

Best of luck. Let us know what it was when you find it.

 

[jwilson]

Are you sure the windlass is connected to the domestic batteries: very often it is wired to the starter battery.

By chance I had a similar experience last week, windlass got slow after some use. On test the next day by a local specialist battery supplier the starter battery nominally 650 CCA was only showing about 200-ish CCA although the voltage was fine. It had been starting the Yanmar 3YM engine with no problem, but that is normally and still was near-instant.

I have a new battery in the car awaiting a chance to go to the boat to fit it.

 

[gregcope]

Could any of the wiring have got wet? I had an issue with a cable that had corrosion inside (non-tinned automotive 25mm2) and it would react oddly when warm/used.

As @jwilson suggests, try measuring the battery voltage when this happens.

Does anything get warm? Ie sign of high resistance? Connections, cable, windlass or the breaker?

 

[gregcope]

If you can get a spare battery and cable to try just that, that would isolate the windlass as not being the issue.

 

[alexincornwall]

Are you sure the windlass is connected to the domestic batteries: very often it is wired to the starter battery.

By chance I had a similar experience last week, windlass got slow after some use. On test the next day by a local specialist battery supplier the starter battery nominally 650 CCA was only showing about 200-ish CCA although the voltage was fine. It had been starting the Yanmar 3YM engine with no problem, but that is normally and still was near-instant.

I have a new battery in the car awaiting a chance to go to the boat to fit it.

I doubt the electrician would have ruled out the possibility but I have since considered that. We're definitely seeing a nominal voltage drop from the domestic supply when the windless was operated with the boat on the hard and the plotter/instruments are definitely connected to the domestic supply. Their rebooting symptoms only present themselves when the windless is in use.

We didn't test the starter battery though so I think that would be a logical step, thanks.

 

[[2574]]

Don’t forget about potential issues with the mechanics of the windlass increasing the power required to operate. Bearings seizing? Roller seized?

I had a similar issue with an 8hp thruster motor wired to the domestic bank, every time the thruster was used the electronics booted. Very poor wiring design. So I added a dedicated thruster & windlass bank up forward. Improved performance noticeably.

 

[alexincornwall]

Could any of the wiring have got wet? I had an issue with a cable that had corrosion inside (non-tinned automotive 25mm2) and it would react oddly when warm/used.

As @jwilson suggests, try measuring the battery voltage when this happens.

Does anything get warm? Ie sign of high resistance? Connections, cable, windlass or the breaker?

Yes, my initial thought was damp in cabling and connectors. Our bow locker doesn't leak, but it's the dampest part of the boat for obvious reasons. No notable corrosion was spotted and nothing was getting warm. The problem with a yard trial is that it's difficult to replicate real-life use and the problem only exists when the load increases.

 

[alexincornwall]

Don’t forget about potential issues with the mechanics of the windlass increasing the power required to operate. Bearings seizing? Roller seized?

I had a similar issue with an 8hp thruster motor wired to the domestic bank, every time the thruster was used the electronics booted. Very poor wiring design. So I added a dedicated thruster & windlass bank up forward. Improved performance noticeably.

Good points, will investigate that.

 

[Sandy]

My windless is connected to an 80 Ah battery at the bow. Big chunky cable from that battery to the windlass and a thinner charging cable running from the main batteries.

 

[Tranona]

Same with mine - just finished taking the charge wires from the B2B up to the bow. Bow thruster uses the same battery. All serious heavy duty cables from battery to windlass and BT


However, not much use to the OP whose windlass runs off the domestic bank at the rear of the boat.