using a power inverter

How do you calculate the wattage draw from a device that will be plugged into a power inverter so you dont overload it? For example plugging a vcr and laptop into a 300 watt inverter. Can it be done or will it be to much. I have know idea of what the formula would be.

Look on the vcr and the laptop power supply, and they should give you a power consumption.  300 watts may be cutting it close, but as long as you are not trying to charge the laptop battery at the same time you are using the vcr you should be OK.

I took a look and nether the vcr or laptop have a "wattage" rating. The vcr only tells me that it's 120v and 60hz. Is there a way to calculate the watt consumption with only those figures? Oh and thanks for your response.

300 watt inverter isn't all that big. I have installed 1500 watt units into the progressive insurance claim vehicles. They use a lap top and printer hooked up to it. I would try to invest in a 500 - 1000 watt inverter. And run dedicated power wires direct to battery. 6 awg - 4 awg wire. That is how I put the ones in for Progressive.

I had bought the 300 a while ago just to charge the laptop during long trips. It's been sitting for a little while so I was trying to see what else it could do for me. I got it at a truck stop for like 30 bucks so I didn't have high hopes for it being very versatile. I was also wondering how to calculate wattage draw for later installs of inverters but I cant seem to find info on it.
Thanks for your responses.

I have a 75 watt cigarette ligther inverter that ran my laptop for 1 year plus.

Recheck the label, there should be an amperage rating on the label.  Multiply the amperage by the voltage to determine the wattage (P = V(I))

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Kevin Pierson

Thanks for the help. I skimed through my mecp study guide and didn't see that but I most likely overlooked it.