[XCSSA] Sine of the times?

[X-otic Computer Systems of San Antonio]

I wasn't expecting anything near 300W, especially since the car has little
stickers on the cigarette lighter stating "MAX 120W".

So I guess that the only way I'm going to be able to run the monitor off of
the inverter is to replace the inverter with a "true sine" inverter or get
that little LCD display?


FIRESTORM_v1

On 4/4/08, X-otic Computer Systems of San Antonio <xcssa at xcssa.org> wrote:
>
> On Friday 04 April 2008 15:20, X-otic Computer Systems of San Antonio
> wrote:
> > I've got one of the $29 inverters in my car to power my phone charger
> > and HP tablet.  Despite being rated at 300 Watts, it cannot run my
> > Dell laptop with an 80W power brick.  I can plug in the brick and the
> > laptop will charge, but as soon as I turn on the laptop the inverter
> > squeals and powers down.
>
> It should be obvious that even 300Watts is unrealistic, as most cigarette
> lighter fuses are 12V 20A fuses.. which will only get you 240watts max
> (12*20).  My guess is that they're measuring "peak power" (at the top of
> the
> sine wave), which would be = (RMS*(1/0.707)... or in other words..
>
> Real Power = RMS power = Peak Power * 0.707
>
> In the case of the listed 300Watts, that would be 212 Watts.
>
> But even still.. one would think that it should at least power your
> laptop's
> 80 watts.  There may also be a real vs reactive power rating component to
> think about too.  Especially when dealing with switching power
> supplies.  The
> thinking there goes that the output of a power inverter does not like
> feeding
> a purely inductive load (like in a laptop power supply) IIRC.
>
> Charles?
>
> Tweeks
>
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