As part of my recent review of the Sonnet Echo 20 Thunderbolt 4 Dock, I reached out to readers for tips on a more practical energy cost meter. After the suggestions were manageable, after some research I decided on the Voltcraft SEM6000, the at Amazon for just under 40 euros is listed as a “#1 bestseller”.Compact
Type of energy cost meterAn energy cost meter is not only useful for testers like me who deal with constantly changing components. I have been using an Energy Master Basic for my purposes for years Energy cost meter from ELV. This is simply plugged in between the socket and the consumer and shows various values with a high level of accuracy on a small LC display. The only disadvantage: the display is firmly connected to the device, which is often connected behind desks or cupboards where it is difficult to read. If I want to determine many different values in different operating states, that means I have to go to the diving station all the time.Voltcraft SEM6000
A measuring device that could transmit its values to an iPhone or iPad (or even the Mac) via Bluetooth would therefore be welcome. It doesn’t have to be a “smart device”. The Voltcraft SEM6000 fits well into the concept. In addition, the pleasantly compact adapter (also important if no other sockets are to be covered or other obstacles are in the way) should have a high measurement accuracy, which is shown in the display of the associated app with a full three digits after the decimal point. A measurement accuracy of 0.1 W would be enough for me. But more on that later.
Other features of the Voltcraft SEM6000 are:
Green, yellow, red colored rings roughly indicate the current power consumption Colored rings can be deactivated with a “night mode” The box can be switched on/off via a button on the housing or the app The box can be switched on by a timer or schedule using the app Display of additional values such as mains frequency, voltage , Apparent power and moreStatistics of energy consumption/costs over timeOverload protectionProgrammable overcurrent displayPassword protection, firmware upgrades
App screenshots: Maybe the makers should correct the spelling mistake in the name here. The app says “Volcraft” (without the “t”) throughout.
The Voltcraft SEM6000 in practice
Within a few days after receiving the device (at Amazon bought) I measured various components with the SEM6000. Including my television and various hi-fi devices. The following test series is therefore only one of several and is “representative” within my measurement attempts. The behavior of the Voltcraft compared to the (significantly more expensive) ELV also tended to be similar for the other measured components.
The test setup here consisted of the HiFi Rose RS520 streaming integrated amplifier (test report), which I measured in three different operating states with both the ELV and the Voltkraft under the same conditions. Only one network cable (apart from power) was connected to the device in order to obtain a realistic value when measuring the corresponding network standby.
Streaming amplifier Rose RS520 in the measurement setup for operation, network standby and low-power standby
Device in operation, idle (without music, no particular background activity in the system) Device in network standby (accessible via app, but otherwise “switched off”) Device in low-power standby (means “shut down” for the Rose)
Top row of ELVs from left to right: Standby > Network Standby > Powered On (idle). Below that, in the same order, are the measurements with the Voltcraft and its display in the app.
Two anomalies emerged. First: the Voltcraft always shows slightly less watts than the ELV. Even if the deviation is only in the range of around or below 1 W, this is of course unpleasant. I can’t determine which of the two displays is more correct without additional measuring devices.
Second: The display of the Voltcraft with a power requirement of less than 1 W, as is usual for devices in standby according to EU specifications, is unreliable. In the case of the RS520, for example, the Voltcraft displayed values of around 0.5-0.6 W in standby for a few seconds (the ELV determined around 0.8 W here), but then switched to 0.000 W. Only a few seconds later did it briefly switch back 0.5 W displayed and then zero again, etc. The same phenomenon occurred with another streamer with a 5V power supply.
The display of the Voltcraft changed between 0.0 and 0.55 W every few seconds.
On my Samsung television, which according to the ELV requires around 0.4 W in standby, the Voltcraft constantly displayed 0.0 W. So it looks like the Voltcraft’s sensitivity is not high enough to reliably and consistently display low consumption values below 1 W. This also makes it clear that the three digits behind the decimal point are only for display purposes, but do not represent exact measurements. Unfortunately, the Voltcraft is actually unusable for me because I have to determine exact consumption values even in standby.
In addition to the disappointing measurement accuracy and reliability of what is displayed, it is also a pity that the area in which the colored rings indicate “low, medium, high” consumption is neither defined nor adjustable in the app.
Incidentally, the self-consumption of the SEM6000 (measured with the ELV) is 0.5 W with the colored rings deactivated (night mode) and 0.7 W with the colored rings activated. It is not clear from the documents whether the self-consumption is deducted from the measurements, but I assume it in dubio pro reo.
Own consumption of the SEM6000, measured with the ELV.
I cannot give a clear recommendation for the Voltcraft SEM6000 due to the unsatisfactory measured values, especially below 1 W. As a remote-controlled switch socket with a “rough” measuring function and additional features such as a timer and time control, the product is fine, but there are also offers from for the money (or less). smart socketswhich can also measure energy costs, can also be used via WLAN/Home control and come in packs of three or four.
For this reason, I unfortunately have to pull the ripcord and send the Voltcraft back. Until an adequate replacement for the ELV with data transmission to a smartphone or Mac is found, I’ll rather crawl under tables to read it.