Marine vs. Airstream Electrical System

[JimmyJames]

Can anyone explain the main difference between an Airstreams electrical system and a typical mid - sized (or similar sized) boats electrical system. We have shore power coming into a CONverter, they have a battery charger then an INverter.

They have a separate battery charger and the inverter along with their battery bank. They have 110 when docked while the batteries are being charged, which allows them to run 110 stuff. They can also charge the battery bank by running the motor. They can also run 12 volt stuff as well. They then have batteries available to run 12 volt and with the inverter, any 110 volt stuff while on the water.

It just seems like both systems are capable of doing the same thing and do, less the 110 power from the inverter when self contained in an Airstream. If an inverter were installed in an Airstream would it have to be a separate and isolated battery bank or be switched off the converter system when it was used ?

There is a really cool boat supply locally who's staff are very helpful. I was invited to come to the garage and look at a typical install. I looked at pictorials of the basic system and I have plans to research this and look into it but a brief overview from one of our smart and generous members would satisfy my curiosity in the mean time. What is the basic difference. Is this like one of those really simple math problems that is impossible to solve cause I am thinking too much, overlooking the obvious ?

Thanks !

[overlander63]

You can put an inverter in your coach, so you can run some limited 110v stuff while running on batteries, but it won't last long before you drain the batteries. You will also want to make a disconnect for the inverter when not in use, as it does have a parasitic draw that will run your batteries down over a time.
If you install, say, a solar panel, you can use the inverter to run a couple of items briefly, say a television and DVD player. Most people prefer about a 1000 watt inverter for this.

[dwightdi]

They accomplish the same thing. But why would you run the inverter if you are plugged into 110 volt ac shore power? The marine systems usually cost more because they think boat owners are even richer than they think Airstream owners are. If you are looking for an ecomonic solution do not admit to owing a boat or an Airstream. Shop Walmart, Farm and Fleet, or other places catering to the ecomomically disadvantaged.

[overlander63]

Originally Posted by dwightdi

They accomplish the same thing. But why would you run the inverter if you are plugged into 110 volt ac shore power? The marine systems usually cost more because they think boat owners are even richer than they think Airstream owners are. If you are looking for an ecomonic solution do not admit to owing a boat or an Airstream. Shop Walmart, Farm and Fleet, or other places catering to the ecomomically disadvantaged.

And if they ask you, tell them it is so you can watch your 5" black and white TV using the battery from your Yugo...

[markdoane]

A big difference is that boats have lots of metal hangy-down parts that are immersed in water. Therefore the need for isolation transformers between shore power and boat. The worse cases of corrosion in boats occurs in the marina where you are tied up next to someone who did not do a good job of isolation, or has sacrificial anodes that are all gone.

[JimmyJames]

Thanks, good advice. Yeah, don't you just peeve the "economic profiling". Why do they do that. I bought an inline strainer for my water supply at C_ _ _ _ _ _ _ W_ _ _ _ a few weeks ago then found the same unit for 50 percent less at a boating supply place (of all places). The boat guy said in discust "why do they have to take advantage of people like that ? " and again....that is sentiment coming from boating supply. Go figure.

When hooked up to shore power everything is even with both systems. I just wondered why they ( the boaters) were more concerned with converting stored DC into AC (a very inefficient affair). They have huge battery banks to essentially take the DC and turn it into AC instead of buying AC/DC TVs and other appliances. The explaination about the separation due to proximity to water helps.

Thanks guys

[markdoane]

Another reason for inverters is that most boats have large DC loads. Might as well use the batteries for AC since they are there anyway.

Large DC loads are bow thrusters and anchor winches. They might take 500amps or more, so there are usually some rather large battery banks.

Also the weight of batteries doesn't usually cause axle problems on a boat. All that weight helps with ballast.

[JimmyJames]

Ok, that's the answer that made it make sence. I appreciate the input. Boats don't need axles.... imagine that !

[ralley]

There is another issue, at least for some boats (and Airstreams). Boats (at least for some of us) are intended to be self sufficient in any weather, for long periods of time--weeks or months on end. Large battery banks, recharged by solar or wind power, are an absolute necessity, as you absolutely must replace your daily voltage draw (plus a small percentage, perhaps, to allow for days with no wind or no sun) EVERY DAY. Failure to do so will eventually result in chronically undercharged batteries and battery failure, usually somewhere where spares are not available. Because of the long charging curve to fully charge deep cycle batteries, running your engine to fully charge is not an option on a sailboat. Neither is a generator.

I was agast at the small battery banks I found when I bought my first MH (a Winnebago) and eventually figured out that what folks did was go from battery charger to battery charger to keep things charged up. Sailors have a word for this--going from marina to marina--but this is a family forum.

A good solar panel or three (or wind generator) and the best charge controller you can buy will go a long way towards avoiding battery problems, once you get things working properly. Most deep cycle batteries fail from being chronically over or under charged, regardless of what kind of vehicle they are in.

Rob