Monday, Jan 10, 2005 at 16:32
Eric,
It really depends on your intended application. Just before Christmas I bought a $79 150w unit from Jaycar to run my son's laptop whilst travelling. It's purpose was so the kids could watch DVD's while we did the long run from
Melbourne to
Sydney and back.
I estimated that the Laptop would draw about 70 - 80 watt max. (Charging and with the DVD playing) Imagine my surprise and annoyance when after 45 minutes, the inverter started beeping and was too hot to touch.
I double checked every thing and tried again, and the experince was repeated.
Having an electrical bent, I did some tests to find out how much current the unit was drawing and whether the Laptop was "pulling" more than 150w.
With the Laptop, it was 5.2 amps at 12 volt hence 62.4 watt.
I tried a 40 watt light and it was drawing (at 12 Volt) approx 60 watt. No problems, cool to touch, no alarms, not even after 2+ hours.
I took the unit back to Jaycar, after all, it states in the catalogue, that the unit I bought was suitable for Laptops.
I explained the problem, and gentleman behind the counter agreed, and he stated that any devices which use a switch mode power supply, will cause the modified square wave invertors to overheat
well below the stated power output. He even suggested that the modified square wave invertor could potentially damage the power supply for the Laptop.
It was suggested that a pure sine wave convertor is the only way to go when using devices with switch mode power supplies. The big disadvantage is the price. The equivalent 150w invertor in pure sinewave was approx $230. Much more than what I wanted to pay.
But to keep the kids happy .........
Hope this helps.
Cheers, Mal58
PS : Jaycar gave me cedit for the invertor I originally bought and reduced the price correspondingly for the new one.
AnswerID:
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