Newbie - What runs off battery vs shore power?

boater2065

boater2065

Active Member
Jul 30, 2018
222
Everett, WA
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Searay
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merc
Hi all, looking to purchase a 260 or 280 sundancer and since this will be my first time owning a cruiser i'm curious about some simple things. (Excuse my naivety here, but i am a newbie to these boats so any info surely helps.) Generally speaking i know these boats are equipped with a microwave, refrigerator, water heater, lights etc. But what i'm not sure about is how the electrical system in the boats work and what will actually run off of battery power vs shore power. For this example let's presume i have a sundancer without a generator. Say I want to stay over night on the boat tied up to a bouy (with no shore power). Will I will be able to use the microwave? Or Refrigerator? Or are these appliances only able to be run when shore power is on? What about the water heater? I assume some things such as lights and radio etc will run off battery power? Thanks again for the time and appreciate any insight you all can offer.

Cheers
 
Welcome!!

The fridge will run on 12V but just about every other "major" appliance will not. Heat/AC, Microwave, water heater, none of those will run when you're unplugged. Your water heater likely has a heat exchanger that will produce hot water when your engines are running but the water heater itself will not run on 12V.

All of the simple stuff like lights, toilet, fresh water pump, radio - those generally all run on 12V and you can easily last a weekend on good batteries.

If you want to run the bigger items while away from the dock you should add a generator to your shopping wish list. Generators also have a tendency to make the boats easier to sell when you're ready to move up. In a 260/280 you're starting to get into the size range where generators are starting to become "must haves" for a lot of buyers.
 
I will add Stee's comments that the refrigerator is most likely AC/DC. Meaning it runs on shore power while plugged in then switch's to battery power when the boat is unplugged. Letting the refrigerator run on battery all night may drain the battery to the point that it can't start the engine.

Also, the lights may be a mixture of both 12 volt DC or 120 volt AC.

Everything at the helm will be DC and so will the windlass (if you have one).
 
@Stee6043 @LTD.330 Thank you for the input, much appreciated. That definitely helps as i go through the search for a boat. I have read that adding generators after the fact can be very expensive. Do you have any experience with that? I've also read about inverters vs generators being a better cost efficient decision. Thoughts on that?
 
LTD.330 said:
I will add Stee's comments that the refrigerator is most likely AC/DC. Meaning it runs on shore power while plugged in then switch's to battery power when the boat is unplugged. Letting the refrigerator run on battery all night may drain the battery to the point that it can't start the engine.

Also, the lights may be a mixture of both 12 volt DC or 120 volt AC.

Everything at the helm will be DC and so will the windlass (if you have one).
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Excellent additional detail. Agreed on the fridge, they surely should be dual voltage. It's funny you mention both 110v and 12v lights. I have some 110v lights but I'm not sure I've ever used them :)

On batteries - if you can't run a boat fridge (or two) for a couple days without killing the batteries - you need new batteries. And just for clarity - if the boat is wired correctly you can't kill the starting batteries on both sides by running the fridge. If you kill the one side you should always be able to start the other side and use the "emergency start" solenoid to start he other side.
 
Jeff Fabiani said:
@Stee6043 @LTD.330 Thank you for the input, much appreciated. That definitely helps as i go through the search for a boat. I have read that adding generators after the fact can be very expensive. Do you have any experience with that? I've also read about inverters vs generators being a better cost efficient decision. Thoughts on that?
Click to expand...

Bookoooo big dollars to add one after. You'll be miles (and thousands of dollars) ahead by getting the boat you want with the generator already installed. If you're on the fence...add it to the list of must haves.

There are a lot of members here running inverters for things like coffee makers and TV's and the like. The inverter conundrum is the amount of battery capacity it takes to make them useful. Also big money...but surely cheaper than a shiny new Onan gen set :)
 
The power panel on the boat will give you a starting point for understanding what is AC vs what is DC. When you are looking at a boat, go ahead and read through the labels. It's not 100% reliable because sometimes there are empty switches with labels, but as a newbie trying to learn your way around, it is a good place to start. The owner or broker showing the boat should also be able to guide you as to what is what, but if you are uncomfortable asking them, start with the panel.

Edit: For clarification, the power panel is typically divided into an AC section for devices powered from shore power (or generator) and a DC section for things powered from the batteries. In general, the switches tell you what each switch controls. Turn off the cabin lights switch, the cabin lights should all go off. You may find some devices, such as the refrigerator (as mentioned above) that can be powered off of either, and you should find an AC switch and a DC switch for that. Again, as a newbie trying to learn your way around, this will give you a quick orientation to how the boat is set up. After looking at a few panels, things will start to become familiar.

You can also download the owners manual for the models you are considering. The owners manuals are a little more generic, but also will give you a starting point to learn. You wont necessarily be able to trust that what a manual says is the way your boat is configured.
 
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The standard # of batteries and how they are wired is going to depend on the boat configuration. A 26 is a single engine and likely will have 2 equal sized deep cycle batteries split into 2 switched banks. No dedicated starting battery.

A 28 is likely to have 2 engines, and perhaps a starting bank and a house bank of multiple batteries.

The 28 will be easier to isolate and use the battery capacity then the 26. One option is to add additional battery capacity to what ever boat you select. Use the fridge, etc for the weekend on the house bank and save the starter battery. When you get back to the dock (assuming you have one) let shore power recharge the batteries.
 
Oh, and just to be clear, using a portable non-marine generator is not an option anyone around here endorses. It’s quite dangerous for a number of reasons.
 
@b_arrington Thank you for the information. I just did a tour of the 260 we are interesting in and it has 2 batteries attached to the switch and a 3rd smaller battery that is dedicated to the engine itself. I looked at the electric panel as @yobub advised and saw the AC vs DC switches and what is used on what power. I saw the fridge has a switch on both panels.

For winter boating on nice days, i'm curious what people use as a heat source? This particular boat doesn't have a heater and i'm wondering if an inverter could provide power for a small heater while running the boat away from the dock?
 
I don’t boat in the winter enough so don’t have direct experience. However an inverter might be possible?

There are also heat exchanger kits on the market. They are driven off engine coolant similar to the water heater. The hot coolant goes to a box where a fan delivers warm air via duct work. There are retrofit kits.
 
Hi all. So we have reached an agreement for the 260DA and are just waiting on an engine inspection. With that said i do have one more power question (remember i'm a newb here). Does using shore power charge the two deep cell batteries(i'm assuming not)? Or does only running the engine do this via the alternator? Reason i ask is, i'm curious whether i really need to pay for shore power at the marina? This particular marina is not pretty and i doubt we will be going to boat just to sit, hang out, have dinner etc. If that is the case, is there any reason to pay for shore power? Aside from this question, we are really stoked and hoping the engine inspection pans out. Very ready to join the cruiser world and make some fun memories.

Cheers
 
On your AC panel, you should have a switch marked Converter. That is your battery charger, assuming a previous owner didn't remove it. You would be able to charge batteries anytime you're hooked up to shore power.

Not sure what your shore power cost is, but I would hate to be without it. Besides charging batteries, I can use my stove, microwave, plug in a wet vac, run fans, etc. I don't overnight away from the dock normally, but on some days if the weather is bad, AC can make a day at the dock more tolerable
 
Heating... I'm asking this because you may not know... IF the boat has air conditioning, then it also has heating as these units are of the heat pump style and can work in reverse. BUT, that would only work on 120V power. For short times, I've used the stove to warm things up and take the chill off. It warms things up pretty quickly. This would work when away from the dock if you have the alcohol or the butane stove.

If the battery charger is wired correctly, it should be wired to all three batteries. Check by following the charger leads or comparing voltage at each battery with the charger on and off. FYI... your battery switch should be able to be left in the off position and the charger will still do it's thing. But, double check - you never know what a previous owner may have done.
 
UPDATE: We pulled the trigger on the boat and will be making all transactions today and picking up the boat tomorrow. Super excited. Appreciate all the advice given on this thread and others. It's nice to have a place to come to ask questions to folks to have been there done that with these types of boats. I'll be sure to return with more questions soon:)

@Dave - M Yes, the marina we will be at for the summer is pretty cheap for utility costs so we will definitely be using shore power. In the fall we will move to a marina closer to our house when covered slips become available. This marina is more expensive with more expensive utilities, but since we place to leave it in year round, we'll need the shore power for the bilge heater and other things.

@Lazy Daze Thanks. This boat does not have a heater/AC unit. For the cold days on the water away from the dock we place to use a low oxygen portable heater. They are safe for indoor use and are great for campers, boats etc. For cold nights on shore power we plan to use a small space heater running off of AC.
 
If the boat doesn't have one, add a carbon monoxide sensor by the bed. Although you don't have a generator, you never know when someone might go lay down while you are running the engines. Cheap safety device against a silent killer.
 
One thing not mentioned (unless I missed it) regarding shore power; You want shore power connected especially when you are away from the boat. Not only does keeping your batteries charged extend their life, but you want to make sure there is always juice available for the bilge pumps.

In the grand scheme of all things boating, the cost of electricity won't even move the needle. (see what I did there?)
 
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