[RE-wrenches] Reactive Power

[Alex MeVay]

Hi Drake,

25W should be the draw from the batteries after accounting for
inverter efficiency.  Note that the low power factor will reduce the
effective inverter efficiency, since the inverter still has 49VA of
reactive power causing losses.  For a small switching power supply
like the laptop's, the poor power factor is most likely caused by high
current peaks as the internal capacitors charge for just a small
fraction of the total sinewave cycle, rather than a large phase
difference like you might see with a motor or other inductive load.

Alex MeVay

Blue Sky Energy * http://www.blueskyenergyinc.com
Genasun * http://www.genasun.com

On Tue, Dec 17, 2019 at 10:17 AM <drake.chamberlin at redwoodalliance.org> wrote:
>
> Hello Wrenches,
>
> I checked my laptop with a Kill A Watt meter. It drew 25 W,but 49 VA. Which number represents the true draw on the batteries?
>
> Thanks,
>
> Drake
>
>
> _______________________________________________
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> www.members.re-wrenches.org
>