DC-AC Inverters

Are the (relatively) cheap inverters I see on E-Bay adequate and safe
to use with my Dell 5100? The specs say that the laptop uses 70W.
If so, what's the right power rating - they see to come in all sizes?

"Jim T." <> wrote in message
news:...
> Are the (relatively) cheap inverters I see on E-Bay adequate and safe
> to use with my Dell 5100? The specs say that the laptop uses 70W.
> If so, what's the right power rating - they see to come in all sizes?

I use a 150W (continuous) inverter with my IBM T22 and have had no problems.

As to power output, I'd say that you need a minimum of 120 to 150 watts,
but I'd recommend that you buy a 300 to 500 watt model. Sams club has a
500 watt inverter right now for $29.95. [your 70 watt spec is the
OUTPUT of the laptop power pack. But it's efficiency is less than 100%.
The inverter's output needs to match the INPUT requirement of the
power pack. If the power pack is 60% efficient, you would need a 120
watt inverter to power the 60% efficient 70 watt laptop power pack. 60%
is probably low, but since, again, the actual number isn't known, it's a
good conservative number to use for estimating the requirement.]

As to quality, really, it's just about impossible to say. There are a
number of issues, but the two major areas are the output waveform, and
the internal construction quality. The problem is, you don't have any
information about either of them! Which makes it very difficult to make
anything but the most superficial judgements.


Jim T. wrote:

> Are the (relatively) cheap inverters I see on E-Bay adequate and safe
> to use with my Dell 5100? The specs say that the laptop uses 70W.
> If so, what's the right power rating - they see to come in all sizes?

I agree that 70 watts would probably be inadequate. I'm not sure which
cheap inverters on eBay you are refering to but some are better than others.
I have an old "Power-To-Go" 300 watt unit that still works fine. I have
another 300 watt unit made by Wagan that works quite well except I had to
replace the cooling fan. I also have another Wagan rated for 700 watts that
will actually run an electric coffee maker (900 watts) or an 1100 watt
microwave (actually uses closer to 1200 watts). I am using it to write this
on my Dell 2400 2.4 ghz desktop with 15" LCD monitor. A Compaq Armada 7770
is also running from it now.

I would say yes to a Wagan (Harbor Freight Tools and other sources).

I had a 2000 watt inverter made by Galaxy. It was a piece of crap.

I had a 300 watt unit that said Coleman on it. It had nowhere near the
power output of my other 2 300 watt units.

Many of the cheap inverters are the same unit but with a different name on
it. That, I'm afraid, you'll have to sort out for yourself.

Aside from everything else I've had no problems running laptops (maybe 5
different ones) from MSN (modified sine wave) inverters. They cause wavy
lines in the display on CRT monitors.