Electrical Load Distribution

[friz]

I am working up an electrical load spreadsheet for my procrastinated project. Which loads are commonly on the starting battery? Starter, engine (gasser), engine monitor gauges and? I have read discussion on this somewhere in the past but can't seem to find it.



If anyone has a load spreadsheet they would pass along, that would be appreciated.


Thanks, Friz

 

[DavidM]

Well, builders often connect lots of things to the starting battery, but that doesn't mean they are the best practice particularly if the boat's DC system is well thought out and set up.


In general, the only thing that SHOULD be connected to the starting battery is the starter, the starting circuit- key switch and relay and the engine instruments which are typically powered from the key switch or equivalent.


All others are house loads including the much debated bow thruster and anchor windlass IMO.


As a corollary, the propulsion engine's alternator should be connected to the house battery. The starting battery is charged either through a combiner switch or an ACR.


I suspect that very few boats are delivered this way.



David

 

[sunchaser]

Friz
Suggest you get Nigel Calder's marine electrical book. 99% of what you need is in there.

 

[john61ct]

I agree with the "should".

I like a "nav/essentials" circuit that can be switched from one to the other bank as needed.

Rest of House loads on LVDs to ensure it's not drawn down too far by fridge, entertainment etc.

 

[friz]

2nd Edition okay?

Friz
Suggest you get Nigel Calder's marine electrical book. 99% of what you need is in there.

Thanks for the suggestion. Although Nigel may well prefer me to buy his 3rd edition for $36 I can buy his 2nd edition , in good condition, for $0.99. Looking forward to reading it.

Thanks, Friz

 

[friz]

Friz
Suggest you get Nigel Calder's marine electrical book. 99% of what you need is in there.

You are referring to Nigel Calder's Boatowner's Mechanical and Electrical Manual?

 

[friz]

Thanks for the suggestion. Although Nigel may well prefer me to buy his 3rd edition for $36 I can buy his 2nd edition , in good condition, for $0.99. Looking forward to reading it.

Thanks, Friz

Found the 4th edition, new on ebay (hardcover) for $23. I'll spend the extra money.

 

[JDCAVE]

Other than the starter, the only other load I have connected to the starter battery is the windlass. I’m aware of that and take it into account. In nearly every instance I can think of, the windlass is only engaged when the engine is running. Also, I have a mosfet Matervolt battery isolator that transmits immediate amperage on demand to the starter circuit.

Before the installation of the Mastervolt battery mate, and before I understood the function of the Blueseas ACR, I operated the boat for several days, including windlass and starting the engine without any charge going to the starter battery. It was down 50% SOC, and could still start the engine and raise the anchor. That problem (and my lack of understanding!) is now fully corrected.