Power & Energy Monitor by Brennenstuhl

Good for measuring power drawn during normal usage, not for low standby power usage - Pros+ Measure power drawn during normal usage+ Batteries to store readings so that you can plug out from mains before taking readings+ Show voltage, current, watt, duration, KWh, cost based on KWh and clockCons- Inaccurate, seems to give larger values than actual power drawn. Give 17W reading for a 13W lamp- Doesn t show low values. For some devices, e.g. clock, it gives a reading of 0W. The lowest reading that I have is 7W, hence it doesn t show anything between 0-7W and is not suitable to measure low standby power drawn accurately.- Too wide to insert into some power extension plugs, will eat into space for next plugBottomlineIf I have read Howard Wright review first, I would have buy the other meter instead of this. Although the other meter does not have batteries, you can work around it by using extension cable/plug. However you can t work around the inaccuracy of this meter.

fascinating! - Thanks to the purchase of this little gadget we are a bit more frugal with boiling the kettle - never knew how much it was costing!I m going to monitor the tumble dryer next!Recommended.

Out of three they all give slightly different readings - I bought three of these and they each give slightly different readings (this includes simple readings such as current and voltage). For example, one shows a steady 236 and the other closer to 246 as the voltage for the same socket. I suppose it doesn t really matter too much. The other one (prodigit 2000MU) I have I think is more accurate and also works at lower wattage where this one doesn t work at all.I m not sure how accurate these things are but there are a few other design faults. One is that the timer stops itself when the device stops or draws less than about 10 watts of power (so you need to time things yourself for things like fridges). Another is that it for some reason stores the maximum wattage and it can t be easily erased from memory like other stuff (although it s not really worth knowing anyway). You probably have to remove the battery as even the reset button doesn t clear it.

Positives: battery, negatives: everything else! - Having batteries to store the measurements is a good idea, making them readable after you ve unplugged the meter and appliance (no problems if the plug socket is awkward to get to). Unfortunately, this useful feature doesn t compensate for the other weak points of this power meter.The Brennenstuhl meter isn t well suited to measuring power consumption accurately for household appliances, for various reasons. It has a low current threshold, so doesn t give any readings for appliances that draw a low current. This can be a problem not only for measuring standby power usage, but also for measuring some low-consumption appliances when they re switched on (e.g. portable radio). When the current is above the threshold, the power measurements aren t always accurate. I ve compared the Brennenstuhl against another meter (Plug-In Power and Energy Monitor Meter), and the Brennenstuhl usually overestimates the power (it s readings look more like apparent power than actual power). For example on a low-energy light bulb, rated at 11W, the Brennenstuhl measured the power at 15W, the other meter measured correctly at 11W.(Measuring actual power for AC devices is not straight forward: the shape of the AC current and the phase difference between voltage and current need to be measured. The apparent power is easier to calculate as it makes simplifying assumptions about the current signal and phase, but isn t a useful figure: power companies don t charge you for apparent consumption! The power factor is the ratio of apparent and actual power. Not all power meters can measure the power factor and actual power consumed by a device).I mistakenly thought the Brennenstuhl meter could measure actual power, as one of the available measurements is the power factor (cos phi). But this value always shows 1.0 for the measurements I ve made (TV, video, PCs, hi-fi, fridge, freezer etc). I thought my meter wasn t working properly and contacted the manufacturer, who explained that the meter only works for sinusoidal currents, for non-sinusoidal currents the power factor will always read 1, and the power measurement won t be an accurate measure of actual power consumed. The manufacturer also confirmed that many household appliances (e.g. amplifiers, TV, video) don t have sinusoidal currents, so this meter won t give accurate readings for them. It s also awkward to switch between the different measurements: you have to keep pressing the same button to move between current time, voltage, current, power, usage time, energy used (kWh), unit price, energy cost etc. If you want to check the power, then current, then usage time you have to press the same button 7 or 8 times to make each change! The other meter I tried displayed most of the same measurements, but each could be reached within 1 or 2 button presses - much more user friendly. Not all meters give you the option of setting the electricity unit price, and I suppose this is useful: the Brennenstuhl can display the actual cost of the energy use it has measured. But if the power measurements are not accurate (true for many appliances), this is a useless figure. It s also not that hard to work out the cost yourself if you ve got the kWh values!As for the main plus point of this meter, the fact that it has batteries: this is useful as you can plug it in anywhere, without having to worry about crawling under desks or into awkward corners to get close enough to read the meter while it s plugged in. Just unplug it and view the stored readings afterwards. But... not all of the readings are stored (e.g. current isn t stored). What s worse: average power isn t stored, only maximum power. As many appliances will have varying power usage the most useful measure is average power, the maximum power reading is pretty much useless. Of course you can work out the average power yourself by getting the total energy reading (in kWh, which is stored) and dividing by the time the appliance was plugged in, but it seems crazy for the meter not to do the work for you. Also, as other reviews noted, the meter only measures use time when the appliance s current is above the threshold. For devices that switch on and off as they work (fridges, freezers, washing machines), that means you have to do your own measurements of usage time as well in order to measure average power. This seems a bit much - why doesn t the meter measure the time a device is plugged in, as well as the time it s actually drawing current?So overall: poor design and the inaccurate measurements mean it s no good to do a serious energy audit for home appliances, but if you just need something to measure very rough consumption figures, and you don t need to measure low/standby power, it might be OK.

It has one good point - it has a battery! - The Brennenstuhl meter is ugly as sin, a hideous lump of grey plastic with an undersized lcd screen that looks like a soviet era leftover. But you re not buying it to put on the mantlepiece, so the question is how does it perform?There are plenty of sleeker products that do the same job, but the Brennenstuhl has one virtue to commend it, and it is an important virtue - it has a battery!! This means - as the first reviewer has said - that it can be unplugged from the appliance to read the recorded data in comfort. Much better than having to ram your head into the space between the sink and the washing machine to read it in situ!Performance-wise it does what it claims. There is one, really irritating shortcoming - the timer stops working if the appliance being monitored uses too little current. How stupid is that? It means that if you monitor the fridge or something that cuts in and out on a thermostat the timer doesn t record the monitoring period correctly - you have to make a note of the time it started and ended.This product fulfills a need but IMO looks outdated and but for the battery it wouldn t get a look in!

• Clear LED display includes actual time and day of the week
• Voltage and frequency display in Volts and Hz
• Displays present current consumption and true power in amps and cos phi
• Power consumption in Watts
• Displays metered period in hours and minutes & Cost