Wiki: Wallwart energy use

One very useful number is that every continuous watt is a pound a year, based on 10,000 hours in a year and 10p/KWh.

So a 300 pound appliance that saves 100W average pays for itself in 3 years.

Another useful number is that a liter of oil is about 10 units of electricity, when comparing prices oil v electric.

An expensive device would have to be repaired professionally or thrown out if the power supply failed.

and conversely:

• If the wart fails, you still have the expensive bit.

A potential disadvantage is the risk of blowing up said expensive bit by using the wrong voltage/polarity/(un)stablised/ACvsDC wart by the non-technician who doesn't appreciate the differences, or the tired technician with several different ones stacked together in a dark place.

Chris

Original message didn't show up here ...

You probably covered the reasons why wallwarts (do you have to call them that?) are used in the first place ...

• Ease of certification (CE, UL etc) of the product by moving the PSU to be external
• Producing a single product and then just supplying various PSUs for different markets (various voltage/frequency/plug standards) though now the wallwarts tend to accept anything from 90-260v,50/60Hz anyway.
• Separately outsourcing to cheap far-east PSU manufacturers, even if the appliance manufacture isn't outsourced.

More points incorporated, thanks everynoe

NT

I would include a "proper" name in the tile as well for folks who want to search for power supply or PSU etc.

You need to differentiate between older style linear supplies and switched mode ones. The switchers have a negligible current draw when plugged in but not connected to their equipment - so the "waste" is almost non existent.

I don't mind approximations when they are reasonably close but 10,000 hrs in a year is pushing it bit too far IMHO. 365 * 24 =3D 8760...

Make the units cost 12p/unit, which isn't that far from the average these days(*), and it's better. 8760/1000 =3D 8.76kWHr @ =A30.12 =3D =A3=

(*) I pay 9. but that is about the cheapest I can get.

heck this is just basic back of envelope nearest power of ten type stuff.

Anyway £1 per watt per year is not a bad scribble factor.

So you want to look at anything much over 50W continuous..and forget maybe anything less than 5W continuous.

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Tabby saying something like:

I'll bet the saving's much higher in the real typical household, where the damn things are never unplugged/switched off.

Isn't he assuming 20 to 23 hours of standby usage per day as it is, so 1 to 4 hours of actual use, savings can't get that much higher ...

Re. cheap ones, is it worth a note to warn of the unbranded /very/ cheap 'n' nasty ones that catch fire/explode/give shocks/fall apart?

a) How would you determine which ones will do that? b) For electrocutions, wallwarts aren't a significant cause of electrical fatalities. (For fires we dont have the data.)

NT

Yup, though its not an assumption fwiw.

NT

I'll include those points later. But to be accurate, the electronic ones vary in efficiency widely, I've got a couple that have always run fairly hot, even on no load they're very warm. And a couple of thoers that run stone cold even on max output.

NT

I don't think there's any point in including the extra anal option (i.e., turning all things off when not needed). It's too unlikely to happen. I think your comparison figures should be:

In practice, (1) is what happens in most houses. The question is, is (2) worth going for? That's going to depend on individuals' situations. E.g. TNP with IIRC 550W of background (WTF!!??) what could he achieve? There's other folks here with large amounts of kit that might be unrepresentative, but what about those with a more "normal" set of devices? I'd say that for this Wiki entry to be really useful, there'd need to be various categories of user defined in the article with their figures represented. I think that would be really helpful.

I wonder if you might have misunderstood what the 57p/hour figure means. Its the money value of the labour involved in switching warts off. It (roughly) applies regardless how many warts one has.

NT

Agreed, difficult, so a generalised sentence re. market stalls, =

I bought wallwarts once for 40p retail, the quality was flawless. There are various reasons why things go cheaply, lack of safety isnt the only or even the prime one. The junk is sold both cheaply & expensively.

As for weight, again it has little to do with quality in electronic appliances. Adding weights made of steel/clay/lead etc to create an end user impression is common practice. I dont think we have any useful safety assessment data to pass on to readers.

NT

So are you going to expand your proposed page in the way I suggest or not. I think what you have is a potentially useful page, if expanded.

It's probably worth mentioning as a rule-of-thumb that if a wall wart doesn't get warm, it's power consumption isn't worth worrying about.