standby power

[Ivan]

How can electricals be designed to have such awful standby power. Most appliances don't manage below 4W. Let's take an average 1500mAh 1.5v battery, actually, let's take 3 of them......that's 8100J x 3 = 6.75Wh of energy. So if they were powering an average appliance at 4W standby, they'd last for 100minutes.

My younger daughter has a few well-used toys that flash lights, play a tune etc. These are third hand, around 6years old and a couple have their original batteries. The three I'm referring to don't have on/off switches. One of them plays a tune after a while if you leave it unattended to let you know it's still there - so it is still 'live' even when you're not pressing any buttons.

So my question is, how is it that modern electricals won't go more than 100minutes on standby on 6.75Wh, and yet my daughter's toy can go 3years on standby and still have energy to spare?

[daftlad]

Rubbish power supplys
cheap components
AND A COULDN'T CARE LESS ATTITUDE PERPETUATED BY THE FACT THAT GOVERNMENT HASN'T GIVEN THIS STUFF ENERGY RATINGS.
You can take your fingers out of your ears now.
laters

[wookey]

I think the answer is that it's the difference between a microcontroller using a few picowatts and a mains power supply. There is no power conversion in the childs toy - microcontroller is connected directly to batteries. Most mains devices have a load of power-conversion stuff and this is often very inefficient. Linear-mode wall-warts were particularly terrible. Modern switch-mode stuff is generally a lot better under load, but unless it is very new, as you have observed, they still waste several watts when off load. Essentially because the efficiency drops with load, so they are very inefficient at low loads, which includes no load.

To date the design drivers have been (build) cost (and to some degree design time and reliability). Efficiency was a distant consideration. That should have been changed by recent EU legislation (anyone know if itis in force yet?). I don't know how much harder it is to design supplies with very low 'off' current which are also efficient when on, but I assume that a lot of work has been done on this recently.

Here is a useful article showing the limits required by the new EU and US regs, with a useful description of what is needed to meet them (supplies which vary the switching frequency with load, and turn off power-factor correction at low loads).

http://www.ecnmag.com/new-energy-efficiency-standards.aspx?terms=

Graph of no-load limits from above article:

[dimengineer]

Surely, the real problem is that so much stuff has "soft" on/off buttons. In the good old days (grumpy old man mode here), the mains switch was just that -it actually physically diconnected the power from the unit. Now what happens is that the mains switch is essentially "software" - it needs to be kept powered.

As an example, one of my PC set ups - PC, Screen, Louspeakers and Printer, pulls 24W even when all the "main" switches are off i.e its not even on standby. The only way is to actually switch it off at the wall socket. Which is a PITA, cos its not easy to get at.

I have cut it to 9W, which is what the PC box pulls, by using an Intelliplug, which cuts the power to the ancillaries when the main box is powered down.

Tim

[EccentricAnomaly]

I don't think soft on/off needs to cause significant power consumption.  I was involved in the design of the first generation of these loggers http://ewuk.co.uk/ (wrote the software).  They have a soft on/off and sit around for months running off a 9V PP3 battery drawing not a lot more power than the battery's self-discharge.

[Ivan]

Well, by my reckoning, if a kid's toy can do it, there must be a way of having an internal battery (say 1.5-4.5v) operated soft on/off which triggers a relay (solid state or otherwise) switching mains power onto the power supply. This in turn could incorporate a charger circuit for the internal NiMH battery used for standby.

I suppose the only downside is that when the battery is flat, the unit won't work (same as UPS systems) - but I'm sure we could all learn to live with that.

[EccentricAnomaly]

The trouble with internal standby batteries of any sort is that they tend to have a shorter life than the equipment.  Their loss may actually cause people to replace the equipment before there's a better reason, too.

Maybe supercapacitors have a role to play in some cases but surely it's possible to run a few tens of milliwatts of IR-listening power management circuit directly off the mains with a small transformer or capacitive coupling or something.  I guess the problem is that that makes the connection between the wall-wart and the main box more complicated.

[emacinty]

If often wondered if my house needs some kind of dedicated 5v/12v "ring", with an efficient switched mode PSU supplying it. It would need careful protection to limit the effects of accidental shorts. Might even be possible to power it off a solar-charged battery.

Ewan

[MR GUS]

Surely it's more to go wrong? ..especially if it's a design afterthought rather than integrated from the beginning?

I'm incredibly happy with my Bye Bye Standby's especially on the computer set up, far more efficient than an all in one powerdown, ..I have my dymo printer & canon laser copier on one button start up time is around 12 seconds which gives me time to lean over & pres the economy ink setting too! ..so rather than have it on for 8-16 hrs per day it's on for between 20 mins -1 hr overall, the remote sits by my lcd monitor & enables me to turn off the tv, sat, xbox & dvd player if i'm not in that room taking a break swearing about politico's & their latest snake-oil recipe for disaster.

I need to buy a few more to hammer a few more standby's down individually.

Whilst it's admirable to tackle these things form point of concept, companies are so slow to change & incorporate energy features versus any other fashionable buzzword selling features, we can address the issue ourselves & swap the control units  around as required, big manufacturers will not standardize a switch off to allow you the paying consumer to allow it to fitt in with your lifestyle, they'll merely want to brand it so you purchase their systems & their all encompassing remotes as they've always done.

From my own industry experience if it's not " insert brand name here" & therefore not going into MY pockets (sic) ..then they care not one jot!

call me cynical.

[Ivan]

Any idea what the power consumption of a bye bye device is?

[MR GUS]

Any idea what the power consumption of a bye bye device is?

 it's overestimated (apparantly due to variances in production tolerances down the line for incorporated components) at .4 of a watt, which if like me you have 2-4+ items hooked to them (i use the up to 1000w type not the industrial 3000w variant)
small watch type battery in remote.
..that's the word from domia.

[wookey]

Ewan - me too, but the problem with low-voltage supplies is that any voltage drop becomes signifcant and currents can be high (raising voltage drops). If you work it out the losses can still be tiresomely high. And in practice you often end up with 5V, 6V, 9V and 12V (at least) devices. I might give it a go though for all my routers/home server/cable box/NAS tye boxes. most of it is physically quite close.

[excited]

Wookey, Not sure how to overcome the Current loss. But the Voltage drop could you just allow for the drop at the furthest point and then up the voltage from your PSU to overcome the loss.

My understanding is that all devices have their own built in voltage regulation anyway. So if you if you have something which requires 9V and you provided it with 11V, then it would regulate it down to 9Volts inside the unit.


Just my 2p worth, please pull it apart.

excited

[KenB]

List,

The manufacturers of appliances need to get together to define a new standard, allowing their machines to draw sufficient milliwatts from the mains to keep the microcontroller alive and power up the main power switch. Perhaps someone will come up with a smart power switch IC, which will be incorporated into all new consumer equipment.

If they all follow the same standard for a smart switching appliance, then standby power could be reduced by several orders of magnitude - the only problem is getting the manufacturers to follow a common standard.

It is no longer acceptable that a washing machine uses 4W to keep its controller powered and an LED on.

The cost of a smart power switch, consisting of a leakage power supply, a microcontroller and a mains relay, should be considerably under £1 - so there is no excuse to fit this to every £200 washing machine.

The worst culprits are TV and satellite set-top boxes.  Manufacturers have conspired together such that these need to be permanently on, and draw more than 10W - just so that they can receive some over-air, or modem download. 

I was horrified to find that my stack of TV, video, DVD and DVR were drawing a monster 26W at 0.65 power factor, when doing nothing.  If these devices are idle for 16 hours a day - that's  0.4kWh of wasted energy.

Here are my culprits: The first figure is leaving the device in standby (SB) mode so that it can be turned on properly using the remote control.  The 2nd figure is the idle power for the DVR and VCR when sitting idle waiting for you to press play or record or whatever.

TV (SB)     6W
DVD (SB)   8W
DVR  (SB)  3W     (idle) 16W
VCR  (SB)  5W     (idle) 11W

The DVR is often left in its idle mode by my wife - so it consumes nearly 0.4kWh per day before its even used.

Microwave ovens are also guilty of a few watts standby power, and that's just keeping their clock on.  I turn mine off whenever I've finished using it.

A bit of common sense and smarter design  could reduce the combined mean idle power requirements of these devices to well below 1W.  I worked on a smart thermostat design that powered its microcontroller from mains leakage current and about 3mW of power.

Even small devices such as mobile phone chargers, mains adaptors, broadband/wireless routers could all benefit from smarter design.  Why should a mobile phone charger draw anything from the mains if the phone is not plugged in for charging or already fully charged.  Why should a broadband router continue to draw 15W if clearly there is no real net traffic - a lower data rate, idle mode would be beneficial, with the router resorting to full power, full datarate when significant data traffic is demanded.

So many of our plug in devices are converting one kind of power (230V ac) to low voltage dc, and are doing this with pitiful low conversion efficiency.   Design engineers should strive for new standards in conversion efficiency, and also come up with smart circuits that can retain their "always ready on demand" functionality but without drawing excessive power from the mains. 




Ken

[Flamethrower_]

Ken, List,

I've just had an update from my cable supplier (Virgin) saying that we are going to be upgraded from 2MB to 10MB service, for that we are going to require a new cable modem.

Now my question is will the new modem consume more power in my home than the existing one,this sort of information never seems to be given to the consumer I know it may be miniscule in the grand plan but
.
(I suppose that the service provider possibly sees it as a  negative or not important to the consumer! as long as we get all the benefits of super speed and the bells and whistles)

My system which is left  left on 24/7 (young adults in the house! energy guzzlers ) if it was me it would go off when I went to bed.

Thoughts?