[chbot] Power monitoring

[Mark Beckett]

The discussion started with this.
/I bought an old fridge off Trade Me and it seems to be on //most of the 
time, so I'd like to graph it's usage to see what's going on. 
Just a single socket for a start. Might add more sockets later, but 
would probably look into monitoring the whole house at that point./
/
/Volker Kuhlmann wrote:
> In contrast, all those arduino projects don't give you any promises, and
> neither should they, because that'd be lieing^H^H^Hmisleading the user.
> The absence of any accuracy discussion in any such project is a sure
> guarantee that it doesn't have any.
>   
>  What's the point of making a
> measurement instrument then? 
You use a clamp meter which feeds it's data into the Arduino.
You use a voltage that is derived from the mains and then measured.
Most sensible people would verify the figures being supplied to work out 
the accuracy and adjust it accordingly, so where is the problem?.
> I can make a random number generator
> cheaper than that. Unless a guestimator is all that's required - like
> the USB power gimmick I showed recently, which is very useful in
> verifying ("sanity check") USB power supply promises for example. Took
> me 20 seconds for a 1 star feedback on a car charger yesterday.
>
> Volker
>
>   
Mark