[rrd-users] Modifying results for GPRINT output

Piers Kittel mailing at biased.org
Sun Sep 2 14:41:43 CEST 2007


On 2 Sep 2007, at 13:12, Alex van den Bogaerdt wrote:

> The way you set it up means that the database stores ticks per second,
> not kWh or similar.


> Suppose you see 60 of such ticks in a minute, that's 1 tick per
> second, thus 1.25W/s. This is what RRDtool should display. This
> means you should multiply by 1.25, not by 1250.
> If you only see one such tick per minute, that's 1/60 tick per second,
> thus 1/60 * 1.25 = 1.25/60 = 0.0208333... = 20.8333... mW/s.
> Seeing "m" for milli isn't bad, it's expected.  That's because you
> look per second, not per hour.  Try multiplying by 3600.

Ah... hmm.... OK have tried multiplying by 3600, and here's what I'm  


Looks a bit high to me now?  Though the tumble drying figure (first  
spike) looks more correct at nearly 3kWh.  But now I'm seeing "k"  
which I doubt is 3,000kWh.  Should I be using Wh instead of kWh?  I  
need to make 100% sure, as it's basically saying I'm using 500 watts  
continuously on average.  Which is a lot!  :(

> Sidenote: Watt is already something per second (Joule per second).
> What you are probably measuring is kWh, not kW.  See wikipedia.

Yup you're right, it's kWh not kW.  My bad.

> I am also monitoring this usage. Unfortunately I have to do so by
> hand, as of yet I have not found a way to interface this :-(

Yeah, me too, until the law required my electricity company to  
replace my old meter which had a disc - the new one has no disc, but  
has a flashing light instead for some reason.  So my friend was able  
to make a sensor to allow my server to record the flashes.

Thanks very much for your time!

Regards - Piers

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