Saving electricity with an OWL

penrhyn

I'm very surprised that your Owl can 'see' whether a phone charger is there or not.
The KWh display only shows two decimal places i.e 3.55 kWh, in other words the smallest increment it can see is + or - 10watts.
In fact if you look at the specifications Current accuracy for less than 1 amp is unspecified, 1A to 3A is 10% and 3A to 71 A is 5%.
So for all practical purposes any power consumption reading of less that 230 watts ( which will be displayed as (00.23) will not be very accurate.

The Owl was formally marketed as Electrisave, its also known as Cent@meter.

1carminestocky

penrhyn wrote: »

I'm very surprised that your Owl can 'see' whether a phone charger is there or not.
The KWh display only shows two decimal places i.e 3.55 kWh, in other words the smallest increment it can see is + or - 10watts.
In fact if you look at the specifications Current accuracy for less than 1 amp is unspecified, 1A to 3A is 10% and 3A to 71 A is 5%.
So for all practical purposes any power consumption reading of less that 230 watts ( which will be displayed as (00.23) will not be very accurate.

The Owl was formally marketed as Electrisave, its also known as [EMAIL="Cent@meter."]Cent@meter.[/EMAIL]

I personally don't believe the Owl is the last word in accuracy (I also don't believe my plug-in usage monitor is either), but the massive advantage the Owl has over other forms of cost monitoring is the constant visual readout of the cost of the equipment you are currently using (I'm not bothered if it's completely accurate to the nth degree or not, personally). A constant reminder is IMO the best way to concentrate one's mind on the task in hand. It's changing our family's habits with regard to the using of electricity, and hence saving us money. For that reason alone, it's VERY useful to me and in no way a fad gadget.

espresso

kittie wrote: »

I too have noticed how some posters have been shouted down by a couple of `know it alls`.

Nobody has been shouted down, inaccurate posted information has sometimes been corrected but it's obvious that some posters have absolutely no electrical qualifications or basic electrical knowledge whatsoever and incorrect information can mislead other readers of the thread.

If you think that posters who question or challenge information given by other posters are 'know it alls', then your knowledge is presumably also very limited, or you would know yourself when someone is talking absolute rubbish, rather than simply accepting everything that you see posted must be correct! There is a big difference between someone's misguided thoughts or opinions and the fundamental laws of physics.

markbloke

espresso wrote: »

There is a big difference between someone's misguided thoughts or opinions and the fundamental laws of physics.

Has somebody been challenging the laws of physics on here? That's going too far. In this house, we obey the laws of thermodynamics.

AdrianHi

For what it's worth, I bought the OWL expecting it to be less than perfectly accurate but view it as a guide to what I might have forgotten to turn off at night before going to bed and to get a rough estimate of what it actually costs me to run the tumble dryer for example. I feel it's doing that job well.
If it's resolution is 10 watts the phone charger works out at 40-43 watts so it is detectable even if not perfectly accurate. Just because the display resolution is 10 watts does not mean the sensor has the same resolution - it may well be greater with rounding to the nearest 10 watts for display.
I have qualifications in electronics so I know my ohms law and the nature of tolerance in electronic components. Since the probe is in the electricity meter box outside I'm also wondering what effect different temperatures (e.g. winter) will have on it's measurements.
In the end the OWL will still be a relative guide, if I want more accuracy I'll get my multimeter out.

espresso

markbloke wrote: »

Has somebody been challenging the laws of physics on here? That's going too far. In this house, we obey the laws of thermodynamics.

I am questioning the validity of these posts, nothing to do with the definition of a smart meter:

AdrianHi wrote: »

Correct it is a ACP-12X.
I did the sums on 240v, the OWL is working on 230v as per instructions.
The charger is saying Input: 100-240v 50-60hz 180ma. The OWL and my sums based on this agree.
Have not measured it on charged to see if different, but I'm interested in the waste here.

AdrianHi wrote: »

It's not shown, but because I know Power in watts = volts x amps (VA) I can multiply 180mA or 0.18A x 240V = 43.2W or 43.2VA
or if you want to use 230V as the OWL instructions say and is set to it's 41.4W

I do not believe that a Nokia ACP-12X consumes over 43W offload as displayed by the OWL. I have measured two different Samsung chargers, two different Ericsson chargers, a Motorola and a Nokia and none come anywhere near to this figure, also mentioned by other posters. I do not have a Nokia ACP-12X to check.

markbloke

43W is a bit warm. Warm as a 40w light-bulb if it was in a black plastic box in fact. Then again I've seen some rotten designs out there.

The efergy meter I've got has helped me to push down the house's sleep-state from around 240W to around 100W. The few devices running 24/7 are constant loads and the sum of their rated consumptions agrees well with that figure. In theory I could have done it without the efergy but then I can always sell the device on once I'm finished auditing the house.
One thing is the "blip" you get when unplugging a device. Displayed power consumption actually goes up for a second! I'm assuming this is down to reverse EMF as the field collapses around the clip but it's disconcerting to think you're saving energy only to see it skyrocket!

Cardew

kittie wrote: »

I too have noticed how some posters have been shouted down by a couple of `know it alls`. The op has given a very clear breakdown of usage and how to use an invaluable money-saving device.

I use a simple plug-in meter and have input my local cost at 12.72p/kwh. It has made a very big difference ref my use of various appliances. I was pretty good previously but I have been able to fine tune lots of things. By the way these meters are accurate. I am well able to work out costings myself but the meter takes varying wattages into account while eg cooking a meal

I don't know quite what point you are making here. Are you talking about a "simple plug in meter" or the owl?

As you say the OP has given a very clear breakdown of usage and although obviously well intentioned - it is completely wrong in some respects.

As others have pointed out a phone charger typically will use 1 or 2 watts not the 41 watts that the OP states.

The fact that something has a power supply capable of supplying 40 watts is absolutely meaningless. For instance most PCs nowadays have a a 500 watt to 750 watt power supply, but in use they will rarely exceed 160 watts consumption.

The extract on the tumble dryer is another example and demonstrates why the Owl/electrisave is quite useless at determining costs for almost all plug in appliances:

Tumble dryer?
31.4p per hour :eek:
or 47.1p for a full load taking 1.5 hours.

Now I will concede that at times a tumble dryer will be drawing 3 kW, but the typical tumble dryer certainly doesn't draw 3 kW for 1.5 hours - even in the unlikely event of a full cycle taking that long.

My washing machine draws 3kW at times(say 30p) and a cycle takes around 1.5hours. However it doesn't use 4.5kWh but typically 0.6kWh or 0.9kWh.

Virtually all appliances that draw large amounts of electricty have thermostats(they cycle on and off) or variable power; and the Owl as said above just cannot give any meaningful data about these items. The only way to find out what they cost is to use the simple plug in meter.

Our great advocate of the Owl make great play on the fact that the simple plug in meter cannot measure costs of an oven/immersion heater etc; which is true of course -but neither can the owl.

However in another thread, using data from his owl wonder device, he estimated that an immersion heater left on 24/7 would cost £1,314 a year!!!

As far as I have seen nobody has denied the Owl has some uses, essentially it saves you having to watch the dial on your electricity meter spin and presents that information to the layman in monetary terms. However it is only the consumption at that instant and as so often demonstrated in these threads is completely misleading unless you understand something about electricity - and if you did you probably wouldn't need an owl.

What I am also unclear about is your reference to 'know it alls'. If someone makes a mistake(like the OP) and misleads people reading this thread; surely they should be corrected - as several people have done.

I, and several others on this Forum, understand electricity in both theory and practice. It is painfully obvious there are some who post regularly, dispensing(bad) advice, that lack even a basic understanding of electricity.

markbloke

Virtually all appliances that draw large amounts of electricty have thermostats(they cycle on and off) or variable power; and the Owl as said above just cannot give any meaningful data about these items. The only way to find out what they cost is to use the simple plug in meter.

Energy monitors like the owl also provide total kWH used since a given point in time. This actually makes them great for monitoring the effect of using washing machines and other large but variable loads. You can look at the total kWh used that day before switching it on, and then again after the wash has finished. You've already got a rough idea of the background energy use in your home, and it's simple subtraction to find out if cleaning your clothes is cheaper than buying new ones made by slave-labour. If you're really worried about switching on an electric fire by mistake and ruining the figures, go out while your wash is on, or go to sleep.

AdrianHi

Mmm, OK an update after some more experimentation.

Lets start with the tumble dryer.
The figure I originally quoted was based on looking at the OWL just after starting a load where it's fair to say it's probably at peak power heating up. So I will concede the point that it won't use that for the whole cycle and so will not cost as much as I originally quoted.

Yesterday when I looked at what was happening with the phone charger I switched it on and off at least 5 times observing the effect and did it again later in the day. same process for the other phone charger.
I've repeated that process in the last hour or so in response to the OP saying they don't see anything like 41w+ use on other chargers. This time I've done it with the OWL showing kw/H and again with pence per hour.
This time I have not seen any change at all in the OWL reading
This makes 1 or 2 watts look likely and not 41w+.
I'm confused as to why I saw such a repeatable and obvious change yesterday, seems a bit coincidental that something else was creating a load in time with me switching the phone charger on and off.
Given the heat that can come off a phone charger 41w did not seem out of the question, knowing that it's comparable with a "40w" light bulb.
To be honest I was surprised to see 41w out of a 180mA device, I would not have expected it to be drawing near the maximum 180mA all the time, but that is how it looked yesterday when I was experimenting.
I have observed the varying electricity use as the washing machine goes through it's cycle too.