On 7/9/2015 2:47 AM, 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

Probably the latter...
But
since you provided zero information about the inverter,
zero information about the lamps,
zero information about the meter,
It's hard to tell.

That the lamps didn't explode suggests you may not have
330V...maybe...depends...