Standby power

Recently DONG Energy have started a campaign to reduce the part of power consumption spent on standby LEDs[In Danish]. As they explain it, “Standby is the small red or green lights or numbers on a display showing that the device is ready for use.”

First of all, I’m quite sure that isn’t actually the meaning of standby. I think the LEDs are only a byproduct of the actual meaning idea of standby – quicker startup times and, for modern devices, the ability to turn them on using a remote control.

Now, I do agree that standby power consumption should be as low as possible – DONG Energy has numbers showing that as much as 10% of the power consumption in Danish homes is spent running standby devices, and this is obviously doesn’t match the very minor convenience of not having to touch a switch to power on a device. In particular, they bring up mobile phone chargers, where studies have shown that the small devils use as much power when not charging a phone as they do when actually charging up a battery. This does sound very wasteful indeed!

However, why is the solution turning off devices, retaining their terrible standby power consumption if, for instance, you need your DVD-recorder on to record something? Why not instead work on a better solution for standby power that doesn’t kill the fruitbat, or whatever the problem is they’re trying to solve. Of course, realizing this I promptly thought up a better system, that’s probably doomed to fail due to being too complicated. I’ll try to present it none the less, hoping it’ll spawn a vigirous, if somewhat isolated, discussion.

Centralized power

First of all, let’s get rid of the silly idea that 110v or 230v is really the power we are interested in for these modern devices. Sure, it’s nice for lots of things – running washing machines and hairdryers, and to some extent lamps and stereos. But for most of our consumer electronics, we would be much better off with 12v DC in our wall sockets. I know it’s probably not feasable using this for all our devices, all the time, as some devices require a high load capacity (lamps, amplifiers, computers) and some devices want really nice and smooth power delivery (computers in particular). But why not use it for all our standby power needs?

Most of our devices would want either 12v or 5v, or something close to that, for running on standby. They would run a bit of electronics for the remote control, a LED (more about this later), and some electronics for controlling the power supply. Not a whole lot of power, I would imagine, if supplied directly. But using a power supply that’s meant to supply the entire device, the standby unit is far outside the optimal running conditions, wasting lots and lots of power in transforming from wall socket voltage to internal unit voltage.

Alternative? Provide 12v DC externally, putting in a voltage regulator if you need less, like 5v, and draw only the current really needed for the standby unit. If the same kind of power supply is used, nothing is really changed – you get the same waste, possibly more. But what if we add that all devices have both 12v in AND 12v out, and a suitable standard for cabling between devices. Let’s chain the devices, supplying them all from the same source. Or, add multiple out-sockets to a single master device, such as an amplifier or a TV, making it only a single touch of a button (or switch) to turn off all the standby devices.

Now, this requires that devices either all come with a seperate standby power supply – what a waste – or that behaviour is defined for what devices should do when they don’t get any external power. A requirement for this could be that the devices all sense whether there is a cable in their “in” socket: If there is a cable, the device will never use the internal power supply for standby power. If there isn’t, the device will use the internal power supply, and provide this power through the “out” socket. This way the need for external standby power supplies is eliminated, and device designers have a much easier time designing built-in standby power supplies for devices such as TVs and amplifiers, as they can expect the current draw to be somewhat higher, making it easier to achieve a reasonable efficiency.

I won’t claim to be an expert on the electronics involved in this, not in how the cabling should be done, but it does seem to be a lot neater than going around, turning all the devices off, and a lot easier to get people to use. And if some devices could even be constructed to use little enough power to only require this 12v supply – DVB-T receivers come to mind – it would even reduce the cabling mess. Otherwise, perhaps standby power could be included in future digital video and audio cabling, working towards only using one kind of cable between all your devices.

Standby LEDs

Just because I hate them, I have to say a little about standby LEDs. Why is it that suppliers of consumer electronics insist that there must be an LED to show you that your device is in standby – I know it is, I put it there. If the power is out, I’m not going to figure out from the fact that my DVD player doesn’t have it’s LED on. Please, give me an option to get rid of the sea of green, amber and blue light from the forest of LEDs surrounding my TV – it’s a complete waste of power, and if this other idea of mine catches on, isn’t even necesarry to remind you to turn off the device.

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