Non-US Shore Power

[coyotejack]

From a practical standpoint, is it worthwhile to prepare ahead of time in order to hook up to shore power after I leave the US/Mexico area? I understand that in Australia and NZ I will need a step down transformer and new connectors to plug into shore power, but is it worth worrying about ahead of time or should I just go and adapt as I go? I intend to cruise the South Pacific, Aus, NZ, Indonesia, Singapore, Thailand, South Africa and South America.

[hellosailor]

You'd need to check into your destinations, to see which ones are 120/220/240 and also, 50 cycle versus 60 cycle. A transformer won't correct the cycle difference and some equipment will not work without that.

How heavy your power loads are will determine how expensive the right converters become, but you may find that a shore power charger, which can charge your batteries from any combination (110/120/220/240, 50/60 cycle) of what you find, is good enough. Then just stick to running on your batteries and using an inverter for any smaller AC loads onboard.

If you plan to use large amounts of AC for long periods...then spending money on converters becomes a more tempting option.

Apparently part of the electrical crisis in Japan right now, is because half the country uses 50 cycle power, the other half uses 60 cycle power, so there's no way they can just "patch around" their damaged equipment. Who'd have thought?

[Zanshin]

Much of the world is 220V/50Hz instead of the 110V/60Hz in the US.

Voltage (ignoring Hertz)
Often in the U.S. a 220V supply consists of 2 parallel 110V supplies where you could separate one leg and get 110V and thus feed your AC system. In Europe the 220V is delivered with 3 wires (ground,neutral,phase) so it is not possible to simply get 110V. If you want to run 110V from shore power you will need to use a step-down transformer - which will not change the Hz frequency, just the voltage.
Hertz (ignoring voltage)
Many, if not most, AC devices aren't sensitive to the frequency. A device with AC motors that is designed for 50Hz will run 20% faster with 60Hz; which can cause heat problems. My 220V boat A/C system specifically allows running at 60Hz (using the doubled 100V supply mentioned above, which keeps the 60Hz frequency) and most devices that convert the source power to DC nowadays support input voltages of 110-220 and 50-60Hz.
Thus, if you know your devices and none of them are critical, you could easily run your boat's AC using just a step-down AC transformer. If you need to convert the Hertz from 50Hz to 60Hz then you will need a much more substantial (end expensive) converter.

One option is to use an inverter for AC loads, even when hooked up to shore power. Many battery chargers can accept both 110/200v and 50/60Hz; so shore power input goes into your battery bank as 12V DC, then an inverter converts that into the correct voltage and frequency; losses are around 10% but as you are on shore power that isn't critical anymore. This works for almost all AC loads (excepting A/C, water heater and washing machine)

[coyotejack]

Thanks for the input folks. So if I want to use the batteries and inverter to power my AC equipment, how do I size the transformer (or converter if I decide the equipment is 60 cycle sensitive) without knowing whether the shore power connection would be 16, 32 or 63 amps? I suppose the safest way (and most expensive) is to set it up for the largest size service of 63 amps.

Would I need to get a large enough step down transformer to handle from 250 volt 63 amp power, which as I understand it is the largest normal shore power connection that I would likely run into, to 120 volt 30 amp power so that I could just set up the line coming off of the transformer to simply plug into my normal 30 amp shore power receptacle so that I do not need to disconnect my battery charger from the main distribution panel every time I want to power it up?

I understand that for continuous use, such as I would need for a battery charger, I need to have the wattage to be 4 times the stated requirement....so would I size the transformer for the 30 amps x 120 volts x 4 (3600 watts x 4)?

Thanks for your input.

[Zanshin]

You would need to size 2 things - the shore connection would use only the amps that the battery charger could consume; in my case I have a big Victron inverter/charger which we could use as an example, the 12v 5000.
It can charge 200amps at 12V (if the battery bank allows that high a charge rate) which would draw 11amps at 220V or 22amps at 110V.
The inverter can produce 5000Va (or 4000Watts at 100deg. F) at 110V/50Hz, this is a bit more than it can charge the batteries with. This means that you can draw continuous 4000W at temps above 100degF where your batteries are just used as throughput, if you draw less than that your batteries will be charged and if you draw more the unit uses stored power from the batteries to make up the difference.
A 12,000BTU air conditioner (from Climma), will use about 9.3 amps at 110V so theoretically you could cool 24,000BTU using the charger/inverter system on shore power, that should be roughly sufficient for a 43 foot boat in the tropics. The Victron has a cold startup capacity of up to 10000W so that should be enough for the AC to start up.
These are very rough numbers and don't take several factors into account (hot temps reduce rated inverter capacity, wiring eats up amps/volts, etc.) but should give you a feel for what the approximate numbers are.
If you don't need air conditioning then everything can be significantly downsized.
In order for the charger-inverter system to work well you would need to stock up on the amount of batteries in the house bank.

[Zanshin]

Oops, part of what I'd written went AWOL.

Work your power demands backwards, figure out what your absolute maximum AC draw will be if everything is turned on, then you can use that amperage number coupled with expecte temperature and find out what your minimum transformer or converter size would need to be. The shore power maximum values don't factor into the equation (unless they are lower, in which case you'd blow the shoreside breaker).

[coyotejack]

Thanks Zanshin. That helps.