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110 Volt Boat Built in Europe: How to Convert/Invert?

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We are buying a boat that is being built in Europe. We are going to use the boat in the US after sailing for a year or two in Europe. We are having the boat built to US 110 Volt standards as the boat will live most of its life in US and may even have to be shipped here after no use in Europe if the virus limits travel for much longer. I am sure these are common questions on Europe boats destined for the US>

1. We want most of the AC outlets at 110 volt with maybe one or two 220 volt outlets for use with small items we need to buy and use while in Europe.
2. Galley is mix of Propane and 110 volt electric.
3. DC system is mostly 24 volt with 12 volt starting bank.
4. There is a generator to be installed
5. We will have lithium batteries
6. We will have a small washer dryer..if US version its 110 volt 15 amp.
7 We will have a microwave/convection oven...110 volt 10-15 amps.

We have two main questions. I have very good understanding of 12 volt dc systems but inverting and converting not so much so please explain in some easy to understand ways.

1. We are finding that 110 volt appliances are near impossible to get in Europe and shipping importing them from US is very expensive. How can we invert/convert to use 220 volt Euro appliances with the thought that once in the US any replacements would then be 110 volt?
2. What is the best way to use 220 volt dock power for the time we are cruising in Europe but have the main boat systems eventually be 110 volt input from dock?

One option may be setup wiring/plumbing for washer/dryer and not install to later in the US. There is some risk of shipping an appliance to europe, having it damaged or not work and then have to do that all over. Too bad because the best of the combo waher dryers are made in Europe but they will not make the 110 volt versions available to dealers in Europe...US export only.

Thank you in advance.
Eden Rose

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You need to do a realistic load analysis of what you will be using away from the dock and on the dock over the long term.  This will dictate how you approach the dual voltage setup.  Voltage really isn't the issue as it's easy to step up or down with a transformer.  Hertz will be more of a challenge, most small 110v 60htz stuff will run on 50htz ok but not the opposite.  Small load applications are easy to supply via inverted power.  Of you will have large AC units a generator etc you will probably want to lean heavy on that voltage and htz in the design and layout then make a provision for the other via a inverter.  Shore power can be converted Voltage and Htz to accommodate the change from one country to another.  It's well worth the time go over all foreseeable electrical consumer needs and sit down with builder to come up with a simple solution.  This scenario is not new and there are lots of various solutions out there that have been implemented.  The biggest difference will be the availability of lower cost solid state components that will cover wider parameters and enable simpler design.

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Having been thru this a few times: Some stuff (mostly small electronics) is universal voltage. Larger items that you are listing are common household units. So two main approaches - install two independent inverters and plugs, or WIRE the boat for 120 VAC (larger gauge wiring) and run 230 VAC inverter until moving to US, at which point you swap out inverter and replace all 230 v appliances. 

Changing voltage is easy, but changing freq is expensive/heavy. Some stuff will function (usually downrated performance) with the wrong frequency, but you cannot know without testing each thing.

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8 hours ago, hbob said:

We are buying a boat that is being built in Europe. We are going to use the boat in the US after sailing for a year or two in Europe. We are having the boat built to US 110 Volt standards as the boat will live most of its life in US and may even have to be shipped here after no use in Europe if the virus limits travel for much longer. I am sure these are common questions on Europe boats destined for the US>

1. We want most of the AC outlets at 110 volt with maybe one or two 220 volt outlets for use with small items we need to buy and use while in Europe.
2. Galley is mix of Propane and 110 volt electric.
3. DC system is mostly 24 volt with 12 volt starting bank.
4. There is a generator to be installed
5. We will have lithium batteries
6. We will have a small washer dryer..if US version its 110 volt 15 amp.
7 We will have a microwave/convection oven...110 volt 10-15 amps.

We have two main questions. I have very good understanding of 12 volt dc systems but inverting and converting not so much so please explain in some easy to understand ways.

1. We are finding that 110 volt appliances are near impossible to get in Europe and shipping importing them from US is very expensive. How can we invert/convert to use 220 volt Euro appliances with the thought that once in the US any replacements would then be 110 volt?

If you want a 120v boat you will be better off buying 120v appliances up front because even with advance planning the conversion costs will run to over $1000.  How many loads are we talking about?  You can get dual-voltage hair dryers and curling irons, most modern electronics are dual voltage, so it's really just the galley items that are a problem.

 

8 hours ago, hbob said:


2. What is the best way to use 220 volt dock power for the time we are cruising in Europe but have the main boat systems eventually be 110 volt input from dock?
 

Install a dual-voltage isolation transformer like the one from Victron.

 

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Those isolation transformers do NOT change frequency, only voltage. Several Victron battery chargers ARE universal input & can charge batts from any source. Then invert off of batt bank to what your boat runs on.

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Do you have loads that require shore power to run? E.g. big air conditioners? If not I would suggest the following. :

  • make your whole boat 110v 60hz as you plan
  • spend the extra money to ship/install 110v appliances where ever possible
  • install a 110v to 220v transformer and wire a few 220v outlets in the galley for locally bought small appliances (these will be running at 60hz not the 50hz they were designed for. Usually not a problem, but can be)
  • have your shore power connect only to a large 110-240v multi voltage battery charger, not to your internal AC panel - this way you can plug into any dock in the world without worrying about voltage and frequency
  • run your AC panel/circuits from a large inverter and the generator if needed. If your loads are small enough, you could run all AC off the inverter and just use the generator to charge the batteries and keep the system simpler

You don't say the size of your boat or the AC loads so this may not scale up to your boat.

Basic idea is if you can to run everything AC inside the boat off the inverter/batteries so you are immune from the voltage and frequency choices of the country you are in. All inputs - shore, generator, solar, alternators etc go through the batteries so the loads don't care. This doesn't work if you have appliances that need to run directly off shore power. Slightly more complicated is you have the AC panel sourced from both the inverter and the generator, but not shore.

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1 hour ago, longy said:

Those isolation transformers do NOT change frequency, only voltage. Several Victron battery chargers ARE universal input & can charge batts from any source. Then invert off of batt bank to what your boat runs on.

The only common load on sailboats that is frequency sensitive is washing machines.

The most straightforward answer to the conundrum of having a 60 hz washing machine at a 50 hz dock is to use the coin laundry at the marina instead.

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Not really true: microwaves do not deliver as much power, for instance. Now that microchips are so cheap, many get used in applications that do not use all their functions - but most now have a clock built in, which keeps time by tracking the input voltage frequency. When the clock runs faster (or slower) strange things can happen. And you cannot tell from the specs until you do a full test on it.

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In reading your op again, it sounds like you are already committed to US standards.  I would just ship whatever you need over ocean freight.  It's possible the builder can get you a exclusion on duties if the boat is not going to be imported into the country it's built in, there are all sorts of wierd laws but worth looking into. As Longy said a good dual input voltage Battery charger will take care of any time in Europe and it's a small amount of work to change over the connection to 110vac 60htz when State side.  You may end up having to run a generator some for high AC loads but that's a small compromise.

It's highly unlikely the builder is going to let anything questionable go into the boat engineering or safety wise, it doesn't hurt to throw ideas at them, even bad ideas can sometimes generate a discussion that provides a superior solution.  In any project changes are the most expensive thing,  delayed items are a close second.  The initial dialog to get to what your long term needs are is the most important thing.  Everything goes together in layers so holding off on a component with a high initial cost can end up being a wash or even in the hole to try and do later as a retrofit.

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So: boat built in Europe to US standards, used for a while in Europe, then exported to USA.

That must be fairly common scenario.  Builders should have well-established solutions

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5 hours ago, 2airishuman said:

The only common load on sailboats that is frequency sensitive is washing machines.

The most straightforward answer to the conundrum of having a 60 hz washing machine at a 50 hz dock is to use the coin laundry at the marina instead.

refrigeration and A/C are both very cycle sensitive and 60hz compressors dont like 50hz  at all

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16 hours ago, longy said:

Having been thru this a few times: Some stuff (mostly small electronics) is universal voltage. Larger items that you are listing are common household units. So two main approaches - install two independent inverters and plugs, or WIRE the boat for 120 VAC (larger gauge wiring) and run 230 VAC inverter until moving to US, at which point you swap out inverter and replace all 230 v appliances. 

Changing voltage is easy, but changing freq is expensive/heavy. Some stuff will function (usually downrated performance) with the wrong frequency, but you cannot know without testing each thing.

That sounds complicated and expensive, but I can't think of a simpler option!

I hadn't realised that the USA hadn't transitioned to 220/240V. So how do you power machinery, is 110V good enough for instance for a wood planer or do people owning small workshops with for instance woodworking machines subscribe to a 3 phases connection ? Those 3 phases power ends up being 190V ?

I know that in Colombia they have a mix of 110V and 220V, it isn't always clear what you get, so you need to ask before using a 110V appliance and you can also get cheap transformers. I am not too sure about the frequency though.

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2 hours ago, 167149 said:

refrigeration and A/C are both very cycle sensitive and 60hz compressors dont like 50hz  at all

On sailboats the fridge and freezer will be DC

Most marine A/C is dual frequency

 

44 minutes ago, Panoramix said:

That sounds complicated and expensive, but I can't think of a simpler option!

I hadn't realised that the USA hadn't transitioned to 220/240V. So how do you power machinery, is 110V good enough for instance for a wood planer or do people owning small workshops with for instance woodworking machines subscribe to a 3 phases connection ? Those 3 phases power ends up being 190V ?

I know that in Colombia they have a mix of 110V and 220V, it isn't always clear what you get, so you need to ask before using a 110V appliance and you can also get cheap transformers. I am not too sure about the frequency though.

The USA residential standard is single phase 120/240V.  There's a neutral on the center tap of the transformer, which is bonded to ground, 120v from the neutral to either hot, and 240v between hots.  240v (single phase) is used for larger loads.  In a home woodworking shop it depends on scale, some people keep the equipment small and run everything off 120v.  You can get 12" surface planers for example that are 120v.  Otherwise people run 240v circuits.

Light industrial runs three phase usually at 208/120 or 480/277 with a few mostly older buildings wired for 240v midpoint-grounded delta.  It is nearly impossible to get this in a home shop from the power company but some people build phase converters (I have).  Used woodworking and metalworking equipment is usually much cheaper if it is wired for 3 phase because most of the home shop guys can't use it.

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1 hour ago, 2airishuman said:

On sailboats the fridge and freezer will be DC

Most marine A/C is dual frequency

 

The USA residential standard is single phase 120/240V.  There's a neutral on the center tap of the transformer, which is bonded to ground, 120v from the neutral to either hot, and 240v between hots.  240v (single phase) is used for larger loads.  In a home woodworking shop it depends on scale, some people keep the equipment small and run everything off 120v.  You can get 12" surface planers for example that are 120v.  Otherwise people run 240v circuits.

Light industrial runs three phase usually at 208/120 or 480/277 with a few mostly older buildings wired for 240v midpoint-grounded delta.  It is nearly impossible to get this in a home shop from the power company but some people build phase converters (I have).  Used woodworking and metalworking equipment is usually much cheaper if it is wired for 3 phase because most of the home shop guys can't use it.

Thanks, so effectively you get 2 phases. In France power is dispatched over 3 phases but most residential units subscribe to a single phase grid connection (cheaper). So single works out at 220V (unlike in the UK where it is 240V) and 3 phases works out at 380V. 3 phases used to be common in farms but it is now disappearing outside the industry. And 3 phases machinery can also be had for peanuts!

Just thinking outside the box after reading your post I think that may be the OP could be clever and run a 2 phase system so that he gets 120V and 240V wherever he is. I am not an electrical engineer so I am not too sure if there is a practical way to do a phase converter on a boat.


24 V 
battery bank --Inverter--
  or                     |        |-----------------| ------ Phase 1 ---  120V
120V main ------------ 120 V -----| Phase converter | ----- Neutral  -----  0
  or                     |        |-----------------| ------ Phase 2 ---  120V (@180º)
230V main ---Transformer-|

  That would solve the issue in a rather elegant manner, in Europe he would buy 230V appliances that he would plug between phase 1 and phase 2 and if he needs to replace them in the US he would just plug them between neutral and one of the 2 phases (paying attention to load as equally as possible the 2 phases).

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15 minutes ago, Panoramix said:

Thanks, so effectively you get 2 phases. In France power is dispatched over 3 phases but most residential units subscribe to a single phase grid connection (cheaper). So single works out at 220V (unlike in the UK where it is 240V) and 3 phases works out at 380V. 3 phases used to be common in farms but it is now disappearing outside the industry. And 3 phases machinery can also be had for peanuts!

Just thinking outside the box after reading your post I think that may be the OP could be clever and run a 2 phase system so that he gets 120V and 240V wherever he is. I am not an electrical engineer so I am not too sure if there is a practical way to do a phase converter on a boat.


24 V 
battery bank --Inverter--
  or                     |        |-----------------| ------ Phase 1 ---  120V
120V main ------------ 120 V -----| Phase converter | ----- Neutral  -----  0
  or                     |        |-----------------| ------ Phase 2 ---  120V (@180º)
230V main ---Transformer-|

  That would solve the issue in a rather elegant manner, in Europe he would buy 230V appliances that he would plug between phase 1 and phase 2 and if he needs to replace them in the US he would just plug them between neutral and one of the 2 phases (paying attention to load as equally as possible the 2 phases).

The UK is effectively the same as France, I believe: we downrated from a nominal 250V to 240V a long time ago and then adopted a loose EU standard which includes UK  and French nominal voltages within its tolerances.

 The issue is more to do with frequency than voltage: as detailed upthread, some appliances are quite sensitive to the difference between a European 50Hz and US 60Hz feed.

 For many services this can easily be fixed by using low voltage DC appliances (also detailed upthread) which often have the advantage of being designed for efficiency in order to maximise battery life.  This is impractical for high power draws, though... hence the concern over air conditioning and the washer-dryer...

 Mark Morwoods approach appeals to me but may not cover the AirCon requirement.. Can you get efficient AirCon that runs off low voltage DC? If so, that seems sound...

Otherwise, I think I'd look for a US unit that's intended to be able to cope with an international input, on the grounds that it's more likely to require maintenance later in life when the boat's in the US than when in Europe and maintaining US stuff is likely to be much easier at that point than EU kit...

Cheers,

              W.

 

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1 hour ago, WGWarburton said:

The UK is effectively the same as France, I believe: we downrated from a nominal 250V to 240V a long time ago and then adopted a loose EU standard which includes UK  and French nominal voltages within its tolerances.

 The issue is more to do with frequency than voltage: as detailed upthread, some appliances are quite sensitive to the difference between a European 50Hz and US 60Hz feed.

 For many services this can easily be fixed by using low voltage DC appliances (also detailed upthread) which often have the advantage of being designed for efficiency in order to maximise battery life.  This is impractical for high power draws, though... hence the concern over air conditioning and the washer-dryer...

 Mark Morwoods approach appeals to me but may not cover the AirCon requirement.. Can you get efficient AirCon that runs off low voltage DC? If so, that seems sound...

Otherwise, I think I'd look for a US unit that's intended to be able to cope with an international input, on the grounds that it's more likely to require maintenance later in life when the boat's in the US than when in Europe and maintaining US stuff is likely to be much easier at that point than EU kit...

Cheers,

              W.

 

I am pretty sure that EU appliances are rated for 50 to 60Hz so the issue would only happen if the boat was to sail back from the US to Europe with US stuff on board. They are also rated for 220V to 240V so can work as well in the UK as in France but the actual voltage differ.

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2 hours ago, Panoramix said:

I am pretty sure that EU appliances are rated for 50 to 60Hz so the issue would only happen if the boat was to sail back from the US to Europe with US stuff on board. They are also rated for 220V to 240V so can work as well in the UK as in France but the actual voltage differ.

I has a look at the manufacturer plate of some electric goods here and found out that some are rated for 50 to 60 Hz but not all of them. So the OP would have to shop carefully.

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I would expect as more and more appliances are switching to DC motors and electronic controllers, the voltage and frequency requirements will become more flexible because there's an intermediate AC-DC converter, like with most electronics. 

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On 6/21/2020 at 7:04 AM, Panoramix said:

That sounds complicated and expensive, but I can't think of a simpler option!

I hadn't realised that the USA hadn't transitioned to 220/240V. So how do you power machinery, is 110V good enough for instance for a wood planer or do people owning small workshops with for instance woodworking machines subscribe to a 3 phases connection ? Those 3 phases power ends up being 190V ?

I know that in Colombia they have a mix of 110V and 220V, it isn't always clear what you get, so you need to ask before using a 110V appliance and you can also get cheap transformers. I am not too sure about the frequency though.

We have always had that. My house has mainly 120 volt outlets, but there is a 240 volt outlet in the kitchen and the laundry room for a stove and a dryer, respectively. My air conditioner and water heater run on 240 volts. I don't have any 240 volt tools out in the shed, most small/medium stuff is available in 120 volts. If I did need 240 volts for bigger tools I would run a new line out to the shed.

3 phase power is a very different animal. 480/277 volt and 208/120 volt 3 phase power is very common in industrial buildings. Getting it at your home might be very difficult or impossible. Where I live on the island the houses are fed from 1 phase, the point where the high voltage line splits off from 3 phases is probably a mile or two away. There is no way I could get the other two phases run all the way here.

Also note standard marina outlets in the USA usually are two 30 amp 120 volt outlets on opposite legs of the transformer so you can Y plug into both and get 240 volts 30 amps and bigger slips usually have a 240 volt 50 amp outlet. I think we have one slip at our marina with 3 phase, not totally sure.

What we have at homes and marinas:

 

240.jpg

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@kent_island_sailor it makes more sense now. Or 3 phase system is 380V/220V,.

I am not an electrical engineer but I suspect that a good one could recreate what you've just drawn solving all the OP issues apart from the frequency. The Frequency issue could be solved by being picky about the appliances brought onboard.

The OP seems to have disappeared so this discussion is a bit pointless!

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It's been gone over fairly well above, but to put a fine point on it... Voltage is not a issue and easily addressed.  Htz is the issue.  In particular large load items.  Phase converters do in a small compact unit what most modern boats do in there existing configuration.  AC power is converted to DC power then back to AC power.  The conversion of AC of a given voltage and htz is easy to DC and can cover both sets of standards.  As the OP has already headed down the US standard road it would make sense to continue that way.  If large AC loads are going to be incorporated it makes sense to have them be of the voltage and htz that will be used the most.  Playing with the wrong rated power to even small items has fire hazard written all over it, it's not great advice.  I work on a 50htz ship that is based out of the US.  Yes we do use mostly off the shelf power tools, small consumers etc running on 120 50htz.  I certainly would not recommend someone else to do this, especially on a new build.

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I own a EU built boat that was imported by the previous owner. He had a second AC loop installed, complete with separate shore power, US outlets in a couple spots and powers the airco.

The factory side has one of the aforementioned voltage converters to step up from 110 to 220 for the battery charger. The inverter is to EU spec and only produces 220/50hz.

It's mostly not a problem, as others mentioned. Battery charger is totally happy on 110.

We have never used the inverter, but are prepared to do so for laptops. Most higher spec AC->DC converters can handle 220/50 hz : laptop chargers, etc. However, US spec tools do not and getting 220 small appliances is a pain. I had previously been working in Europe, was there 1x/month and wish I had bought a couple things. Most notably, a small shop vac. Getting those for 220 in the US is a giant hassle and expensive. Annoyingly, none of the major cordless power tool manufacturers charges support 220.

Right now, one of my fridges died - looks like a refrigerant leak. I'm guessing I need to vacuum the lines after I fix the leak. Living on a mooring, using the inverter to run the vacuum pump for the recommended 24 hours would be relatively easy. However, the cheap refrig kits all have 110/60 pumps. If I fry one, it's only a $60-80 pump, so I'll probably just do it, but annoying nonetheless.

It's more hassle than I expected and pretty much means I live on 12/24v DC.

If I were you, I would wire to US spec as you suggested, keep the appliances to a minimum and switch it all back when you get to the US. Being able to buy a quick appliance for not much and plug in w/o thinking is pretty well worth it.

 

 

 

 

 

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Penumbra, for something that small a eductor will provide enough vacuum.  They are pretty cheep, if you have a wash down  pump it should provide enough flow.  Just make sure you put a clear hose loop with a check on the suction so you don't fill the unit....A 110 60htz vacuum pump will run on 110 50htz but better safe than sorry.

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8 hours ago, kent_island_sailor said:

 Where I live on the island the houses are fed from 1 phase, the point where the high voltage line splits off from 3 phases is probably a mile or two away. There is no way I could get the other two phases run all the way here.

For clarification, the power company only needs to run one extra wire to deliver three phase power, and that is exactly what they do if they are asked to run three phase power out someplace for one or a handful of motor loads.  They'll run two transformers instead of three in order to save a dollar or two, sometimes even if the third phase is right there.

Usually they will run three phase power anywhere they are asked to, but the construction charges they bill for doing so tend to be high.  Think in terms of $10 a foot.  Sometimes they'll cut you a deal if they want to replace the lines for some other reason anyway.

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2 hours ago, penumbra said:

 Annoyingly, none of the major cordless power tool manufacturers charges support 220.
 

 

https://www.amazon.com/Milwaukee-C18C-220-240v-Cordless-Battery/dp/B00355CEG0

https://www.amazon.com/dp/B003556L32?tag=duckduckgo-ffab-20&linkCode=osi&th=1&psc=1

 

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On 6/21/2020 at 2:50 PM, Mark Morwood said:

Do you have loads that require shore power to run? E.g. big air conditioners? If not I would suggest the following. :

  • make your whole boat 110v 60hz as you plan
  • spend the extra money to ship/install 110v appliances where ever possible
  • install a 110v to 220v transformer and wire a few 220v outlets in the galley for locally bought small appliances (these will be running at 60hz not the 50hz they were designed for. Usually not a problem, but can be)
  • have your shore power connect only to a large 110-240v multi voltage battery charger, not to your internal AC panel - this way you can plug into any dock in the world without worrying about voltage and frequency
  • run your AC panel/circuits from a large inverter and the generator if needed. If your loads are small enough, you could run all AC off the inverter and just use the generator to charge the batteries and keep the system simpler

You don't say the size of your boat or the AC loads so this may not scale up to your boat.

Basic idea is if you can to run everything AC inside the boat off the inverter/batteries so you are immune from the voltage and frequency choices of the country you are in. All inputs - shore, generator, solar, alternators etc go through the batteries so the loads don't care. This doesn't work if you have appliances that need to run directly off shore power. Slightly more complicated is you have the AC panel sourced from both the inverter and the generator, but not shore.

A pretty good approach.

Our boat was built in Europe and at it's core is a 220V/50Hz boat with a 220V/50Hz generator.

So I had the opposite problem, when I it in the U.S. the only 110V power was a kluged up hack the PO did with a Marinco fitting, a square D household junction box, and your grandfathers old white electric cord with the brown bakelite ends. I removed all this...

The one 110V thing it did have was a 110V to 220V step-up transformer permanently installed through the shore power system, so I could plug it into a 30A 110V shore power connection and at least charge the batteries or run one AC unit. I have a two three way switches on my AC sources - 110V-Off-220V to tell which source is in use, and Generator-Inverter-Shore Power to switch between the sources.

 

We tried getting 220V appliances at first...marginal, though they did work off the inverter/charger we had. They were expensive and hard to find, and didn't last long. And the plugs didn't match our two prong euro plugs. We tried 110V appliances with a small transformer. The potential for screwing that up was too high, and we baked a couple of blenders and coffee makers.

Finally, I installed a 1500W 110V sine wave inverter and ran some permanent 110AC plugs - one to the galley and one behind the nav station. Eventually, I bought a second small 400W sine wave inverter and installed it up near the nav station, where I run the various computers, media centers, etc. off it. I could run them off 220V for the most part if I needed, but at them time I had a couple of 110V only sources for things. When we're at anchor, we don't have 220V or 110V all the time, only when inverters are on, so I liked the 400W inverter because it's low overhead.

For me, dealing with 110V with inverters and 110V sockets solved the smoking appliance problem. We could use the 110V stuff we bought in the states, and when we left the U.S. and had to replace some things we could buy local 220V appliances.

I suspect you could very easily do the same sort of setup, except with a 220V to 110V step down, and a 220V inverter. If you are building from scratch, why not a couple of 220V sockets sprinkled around as well, running off that inverter? It will make life easier for you in Europe, and if you ever take the boat to 220V land again.

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Ages ago when I worked on Marine Air stuff, they said EU 50hz air conditioners going to the USA was a non-factor, a little more voltage and spinning the compressor a little faster was all good. The other way was bad, a little less voltage and a little less RPM was very hard on the compressors and would shorten their life, possibly by a lot. YMMV, that is old info.

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20 hours ago, 2airishuman said:

Let me rephrase: none of the major manuf support this by default. $135 for a charger isn't crazy expensive, but it's definitely annoying when even cheap Chromebooks AC-DC converters handle 220. 

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20 hours ago, kent_island_sailor said:

Ages ago when I worked on Marine Air stuff, they said EU 50hz air conditioners going to the USA was a non-factor, a little more voltage and spinning the compressor a little faster was all good. The other way was bad, a little less voltage and a little less RPM was very hard on the compressors and would shorten their life, possibly by a lot. YMMV, that is old info.

That's interesting and counter-intuitive as I would have thought that a compressor working less hard wouldn't be stressed.

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1 hour ago, Panoramix said:

That's interesting and counter-intuitive as I would have thought that a compressor working less hard wouldn't be stressed.

Forget all the anecdotal stuff. 

Ohms law for AC circuits. Take a given whatever, it's designed to operate safely at A volts and B htz drawing C amps.  Replace the values with another standard and see what happens. Since you are rarely dealing with purely inductive loads the math gets long, but you can see fairly quick how things are effected. Some things are designed to cover the full span of impedance and resistance so it's not a issue.  Most new large three phase motors are like this, the insulation class is such they only adjust the HP and amperage rating from one voltage and phase to another.

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2 hours ago, Panoramix said:

That's interesting and counter-intuitive as I would have thought that a compressor working less hard wouldn't be stressed.

Air conditioners don't like spinning too slow. I think the basic idea is it takes X torque to turn the compressor. When voltage drops, current increases to get that torque and heat increases. Similar with the speed, the same HP at a lower RPM is more torque which equals more current.

Some quick google-fu shows there may be units available now that don't mind using either frequency. I'll check more when I have time. The voltage aspect is a bit less of a deal than frequency, USA voltages can run from 220 to 250, but usually are around 240-something and the new EU wider tolerance runs from 220 to 240 (I think). The lowest I have seen at my house in the summer is 230 volts.

 

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@SASSAFRASS @kent_island_sailor Yes I realise that impedance changes with frequency and that current is the enemy for Joules losses. It is just that within such a narrow difference of frequency and Voltage I would have guesstimated that the efficiency was similar thus that heat losses would be roughly proportional to the power output of the motor. Ah well, best way to learn is to confront ideas with reality!!!

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Easy thought experiment - imagine bolting the motor output shaft to a tree. It can't spin the tree, but it tries, sitting there humming until it burns up. At best, unless we are talking about variable speed inverter-driven compressors, a frequency tolerant conventional AC compressor will do 17% less cooling at 50Hz than 60Hz. I am not sure if it works the other way, a 50Hz unit on 60 might not be 17% better, there may be some other limiting factor in there.

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The compressor issue was probably more a function of the compressor not the motor.  Internal cooling, via refrigerant flow, or if larger oil flow. Also a fan cooled condenser running slower will have a significant effect on duty cycle and load. We have probably 100 plus inverter driven applications on the current ship I'm on, all three phase.  As low of a range a 3-5htz and as high as 120htz on different applications.  If the motor is designed for it it's fine. On a previous vessel we even had a manufacturer tell us they had no idea how high we could go but to please get back to them when we found out.  

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1 hour ago, kent_island_sailor said:

Easy thought experiment - imagine bolting the motor output shaft to a tree. It can't spin the tree, but it tries, sitting there humming until it burns up. At best, unless we are talking about variable speed inverter-driven compressors, a frequency tolerant conventional AC compressor will do 17% less cooling at 50Hz than 60Hz. I am not sure if it works the other way, a 50Hz unit on 60 might not be 17% better, there may be some other limiting factor in there.

Yes but when motor is still, the inductive impedance is probably much lower (I would think as there is no rotating magnetic field!), so current goes up and fries everything.

I have a few single phase motors in my workshop that were scavenged, I just check temperature, less taxing on the brain!

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58 minutes ago, Panoramix said:

Yes but when motor is still, the inductive impedance is probably much lower (I would think as there is no rotating magnetic field!), so current goes up and fries everything.

I have a few single phase motors in my workshop that were scavenged, I just check temperature, less taxing on the brain!

Very true and it probably applies to 50 vs 60 hz as well.

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2 minutes ago, kent_island_sailor said:

Very true and it probably applies to 50 vs 60 hz as well.

I think that it is when it gets complicated and varies depending on the torque and the slip angle, it surely isn't a linear thing, for a start an unloaded engine won't mind much the frequency change I think. Many years ago I had the opportunity to play with big synchronous and asynchronous motors in a lab, sadly I've forgotten most of it as I never got the opportunity to play professionally with electric motors. May be I need to own an electric powered sailboat to hate electric motors as much as I hate diesel engines!

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5 hours ago, kent_island_sailor said:

conventional AC compressor will do 17% less cooling at 50Hz than 60Hz. I am not sure if it works the other way, a 50Hz unit on 60 might not be 17% better, there may be some other limiting factor in there.

The values aren't quite linear.  In a static speed compressor where capacity is not regulated by compressor speed the compressor will have a set capacity.  This will be matched to the heat absorbing capacity of the evaporator and the heat rejection capacity of the condenser.  For a given unit that is using a fan or water pump for condensing.  Operating at a lower htz and speed on all will always reduce capacity and increase duty cycle.  However operating at a higher htz than design won't nessesarilly increase capacity as the evaporator and condenser may not be able to handle any more heat load.

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