On Fri, 10 Jul 2015 09:14:47 +1000, John G wrote:

wrote :
On Thu, 9 Jul 2015 02:47:20 -0700 (PDT), robobass
wrote:

I know this is a metalworking site, but there is quite a bit of expertise on
subjects like this here.

I just bought a 200/300Watt 230v inverter. I attached it to a car battery on
the bench (nothing else attached) and plugged in a few lamps. The output
measured 330v with loads of 50 and 150 watts. The lights did seem brighter,
but not excessively so. The voltmeter is a cheapie, but seems generally
accurate. I know that these devices produce a modified sinewave, and I
should expect a different reading, but I thought the reading should be lower
if anything. Is this inverter a dud, or do I just not know how to measure?

Thanks
You should read about 0.7 x the rated voltage on a modified square
wave inverter.

I am amazed no one has suggested using a good old Simpson 260 or
similar ANALOGUE meter and get the real answer.
All this waffle about transformers and peaks and average is typical of
the impractical answers so common in some of the electronics groups.
KISS Keep It Simple Stupid. :-?

(Grin)...kinda makes us old farts wonder how the yout' can find their
asses with either hand.

Gunner, with (5) Simpsons 260s and (2) 280s