280ec battery wiring question

NickWight

When we last visited our boat (2008 280ec with Volvo Penta D4/260) a few days ago, we experienced some odd problems, the cause of which I think I have tracked down to a failing/failed battery. I say "think" because one thing that is happening does not fit the pattern.
I have always assumed that the anchor windlass is powered from the house/domestic battery and that seems to be confirmed by a wiring diagram that I have, although one or two people have told me that it would be supplied from the starting/engine battery. Can anyone confirm which it is?
Trying to cut a long story short, what happens is everything runs OK while the battery charger is running, but with the charger off if you try to operate the anchor windlass such things as cabin lights, water pump, etc will stop operating. So far so good -- failing house/battery is probably the cause.
However, if you try the windlass switch a couple of times the engine will stop? Now of course we have the Volvo Penta EVC system and as I understand it the two electronic modules receive a stabilised voltage supply from the engine and that should be unaffected by any problems with the house/domestic battery????
The volts to the helm and all instrumentation are lost when the fault happens, but I cannot see why that would cause the engine to shut down, although we do have the optional EVC System Display at the helm??
I should add that here in the UK we are still not allowed to stay over on our boats and so I had very little time to investigate this after we discovered the problem, before we had to travel back home. We will be there again on the 3rd July when we will be allowed to stay onboard and so of anyone has any thoughts or ideas before then, I would love to hear them.

reneechris14

I think you're on the right track. Going to have to load test the batteries and see if you can check the amp draw on the windless. Maybe the windless is going and drawing to many amps as well. Glad to hear you will be able to use the boat.

LaRea

According to this schematic, the windlass is on the house circuit.  Well, it was when Rinker built the boat in 2008.  

When the engine is running, the alternator is sending current to the battery isolator, which feeds it to the batteries.  If the house battery has failed, any current needs will be supplied directly from the alternator, with essentially no help from the battery.  Maybe the alternator doesn't have enough capacity to drive the windlass startup surge.  

NickWight

Thanks for your replies. Yes LaRea, that's the schematic that I've got and that's why I've always assumed the windlass is supplied from the house battery.

I like your idea that the Volvo Penta EVC might somehow be detecting the heavy demand on the alternator output and interprets that as a fault and shuts the engine down. You might be onto something there -- could that be so??

LaRea

Could be.  I'm not familiar with VP systems.  Do you know the age of the house battery?  If it's older than 3-4 years, I'd replace it and see if the problems go away.  

Cableguy Greg

I have had some battery issues with my 2008 280EC over the past few years and here is what I have found. First, my battery breakers in the battery panel were bad and the connections on the back were loose. I replaced the breakers and made sure that the connections were tight. I recently found out that my battery charger was not properly charging the batteries, causing them to discharge at a rapid rate. I changed the charger and so far this summer, I have not had any issues, knock on wood. 

The windlass and the helm are on the house battery. So when your lights are on in the cabin and you use the windlass, the entire house side of the boat could and probably would shut down. I am not sure if it would cause the engine to stall. Like LaRea, I am not familiar with the VP system. I have a Merc and it never stalled. I would check the age of the battery along with the connections behind the battery panel. You might also consider changing the house and engine breakers. I would also suggest changing your house lights to LED bulbs so there is less draw on the system. I changed all of mine a few years ago and I am happy that I did so. It also helps keep the cabin cooler. 

NickWight

Thank you Greg, very useful information. All batteries and the charger were replaced almost exactly 2 years ago. It is likely that the house battery would have been heavily discharged recently, when due to lockdown we were unable to visit the boat for 3 months and credit on our mains power supply meter would have run out long before that, so the charger was not running. May have trashed the battery?

How do I get at the rear of the battery panel? No easy access from inside the engine compartment, so does it just unscrew from the cockpit side?

Cableguy Greg

If your fridge, or fridges were running, that would discharge the battery in a few days. I am not sure if VP has a mercathode style device on the drive, but that would also discharge the battery over time. Both could have done the battery in. 

The panel unscrews from the front. There should not be any nuts behind the panel. If the sealant is still in tact, just slowly pull the panel out. The sealant will come loose. I didn't reseal mine with 3M4000. I just screwed it back in place. 

NickWight

No, as far as I am aware, the VP does not have an equivalent of the Mercathode system, but there are a number of other maintained circuits that would have run the battery flat over a couple of months. Thanks to all of you for your ideas and information.
Regards, Nick.