Powering an Inspiron 6000 with a modified sine wave inverter
Feb 2006
| Summary: I have had no problems powering a Dell Inspiron 6000 laptop using a low-cost (US$25) modified-sine wave power inverter that produces 120VAC when connected to an auto 12VDC power socket. The laptop's standard AC adapter plugs into the three-prong socket of the power inverter. |
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| Power inverter |
Power inverters are available that convert 12VDC (eg., from an auto 'cigarette lighter' power socket) to 120VAC. The best quality and most expensive ones (~$75) produce a 'pure sine wave' output, while less expensive inverters (~$25) typically produce a 'modified sine wave' (like a square wave).
Does a Dell Inspiron 6000 laptop require an expensive 'pure sine wave' inverter, or will it work just as well with an inexpensive 'modified sine wave' inverter?
Dell is vague about it, and I wasn't able to find advice on the internet (although I found lots of people also wondering).
So I consulted a friend who is an engineer at Intel. His opinion was that modern power adapters, such as used by Dell, would have no problems with a modified sine wave. Out of curiousity, we checked the waveform output by my inexpensive 'modified sine wave' inverter (pictured to the right). With no load, it generates a three-level waveform (+V, zero, -V), but under resistive load (a light bulb), it becomes essentially a square wave (+V, -V), with only a brief pause at zero during transitions.
With that reassurance, I plugged in the inverter into my car's power socket, and plugged in the Dell AC adapter (that came with the laptop) into the inverter, and it worked fine, just as if powered by house current. I've used it on several road trips with no problems. The laptop operates just as at home, whether charging or running on power while connected to the power inverter.
The power inverter I use has a capacity of 175W continuous, 350W peak. It was purchased in the USA for approximately U$25.
[A power inverter, as pictured here, converts 12VDC from an auto to 120VAC. It has an ordinary household power socket, into which you can plug the Inspiron's normal three-prong AC adaptor, just as if at home. Power inverters can be purchased at stores that sell auto supplies and hardware stores. Household voltage is a sine wave, but it's easier and cheaper to generate 'modified sine waves', eg., square waves, which works just as well for many, but not all, things -- hence the concern addressed here.]
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| Kill-a-Watt meter |
Separately, I measured the power consumption of the Inspiron 6000, using a 'Kill-a-watt' meter (pictured here with a 60W lamp plugged in).
| Activity | Power consumption |
|---|---|
| Charging battery (laptop off) | 50W (charging LED lit continuously). During the final phase when the charging LED flashes approx once per 5 seconds, the power consumption ramps down to zero, then the charging LED goes off. |
| Booting (active disk) | ~34W (25 to 41) |
| Idle (in Windows) | ~23W |
| Wireless enabled | Adds 2 to 3W |
Jim Elder
Ottawa, Canada
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