The main unit has an in-built battery, that on a full charge will last from five hours to several weeks, depending on the poll interval. Ours struggled to last more than a few minutes, so we can only assume it has been somewhat abused by journalists prior to myself. Charging is done via the supplied mains transformer – but it can also be powered by a mini-USB cable – although this won’t charge the device.
The main unit has a bit of an IKEA feel about it and I quite like the style. There is no technical reason why it is as big as it is, other than to be more aesthetically pleasing and to make a point to your visitors that you’re energy conscious. As well as displaying your current power consumption in Watts, there are multi-coloured LEDs on the back that glow varying shades depending on how much power you are using. If you tilt the device, the display switches from displaying how much power you are using, to your yearly projected bill. The display is reminiscent of a 1980’s alarm clock, so you’ll be thankful to know that you can select “night mode” which turns the display off. Unfortunately, this “night mode” is not automatic.
Plugging the Wattson into your computer via the supplied mini-USB cable and using the accompanying “Holmes” software is where the Wattson’s features start to show. The software is only available for Windows and Mac, which considering the device is only technically a USB to serial adapter (i.e nothing complex), we don’t know why DIY Kyoto couldn’t have coded something cross platform to allow Linux users in on the game. Obviously people trying to save money in their household wouldn’t be turning to free, open source software.
After dusting off a copy of Vista running on VirtualBox, I was able to take a look at the more advanced features of the device. Unbeknownst to you, the Wattson secretly stores your power usage every time it updates. When you plug it into your computer, you can download this data for analysis – automatically, if you so choose. Armed with said data, you can monitor your average and total electricity usage, in both terms of cost, power and carbon footprint.
Some of you might be wondering how it gives you an estimated yearly cost at all. Out of the box, this is set at a default 13p per KWh, but via the software you can update this to whatever you are currently paying. Via the advanced settings, you can also specify a different night time cost if you happen to be on such a tariff. It won’t support more complex tariffs, such as the one I was on previously where I was charged a different rate for the first X units per month, than those after it. It is only supposed to be a guide after all.