Inverters

They will all be 220 - 240 volts (nominal 230).

" I understand that if voltage is lower than it should be amperage goes up to compensate."

It depends - only those devices that have electronic controls in them designed to do this operate this way.

Those devices that will automatically operate on 110 or 240 volt do this.

Some units that are designed for the UK or say HK will be 220V not 240V. You are right, some devices may not work properly and in fact the current draw will be less than normal. This is on top of the fact that some devices will not work on modified sine wave inverter anyway ( notably some laptop power supplies).

Unless you have a sophoisticated application my advice is buy one from Dick Smith. They let you take it back for a full refund, no questions asked if you are not happy. Alterantively buy it somewhere esel with a full refund policy.

You hear stories that identical inverters and identical laptops work, or do not work so unless you buy a true sinewave inverter it is a bit hit and miss IMHO.

I have never had a problem with anything rated at 220v , it is my understanding that our rated electricity fluctuates by 10% and hence 220-240v ratings.

I lived in London for a while and did have problems with some equipment designed for 240V, inc a Hifi and a TV that would not work. That's how I found out about the issue.
Most stuff is ok, Most of the time.

Mains voltage is specified as +/- 10%.

As it happens 220V -10% is 198V or in other words 240V - 17.5%

If you havent had problems good luck to you and most stuff should be ok, but to give advice to someone that it will definitely work is ill informed in my opinion. I know from personal experience that it is not true. I was told that things with certain switching power supplies are the things that generally are not suscetable. Others are ok with 110 to 240V such as laptop power supplies, BUT you need to watch the modified sine wave.

I bought a 300W one from Ebay that was 220V.

I had a 240v fluro ( 40W) and a laptop ( about 100W). The fluro worked fine by its self but cut out when the laptop was plugged in even though the total was way less than 300W ( but the laptop charged ok). When I unplugged the laptop the fluro turned on again. My mate measured the voltage with a multmeter with both plugged in and it was just over 205v or something. I tried his Inverter and it worked ok. I have replaced it with a 300w one from Jaycar and no problems since. Mind you I replaced the fluro about a year ago with a couple of 12 ones.

I would buy another Jaycar one anyday and steer clear of the overseas doodaas.