A while back there was a discussion about why wall wart transformers that
were not under load would draw no current. Anyone recall that thread? As I
recall there were some references to the induced currents created by
collapsing magnetic fields etc.
Anyway, I'm trying to either prove or disprove the statement that unplugging
wall warts when not actually using them to power or re-charge your device
will save electricity. My recollection is that it doesn't matter. Right or
Iron losses are constant for all loads including none.
Copper losses are proportional to the load.
You will save the energy used by the iron losses. Whether
this is enough to make more than a few cents difference
in a year is the question.
Assume 1/4 watt loss and $.20/kw.
(1/4 / 1000) * 24 * 365 * .20) = $0.438 per year.
Does it get warm whel left plugged in with no load? If so, it IS
wasting electricity. It may not be a whole lot, possibly you can feel
loss of less than a watt. And, it can't be a whole lot, as those
little plastic cases can't dissipate more than a couple watts without
getting VERY warm.
A very high quality transformer can be very efficient. But, the stuff
they put in a wall wart is NOT going to be high quality. So, if it gets
warm, that is absolute proof energy is being wasted.
On Sat, 08 Apr 2006 20:35:17 GMT, the renowned "Siggy"
It does matter. Just put your hand on an energized wall-wart which
isn't plugged into anything and you'll feel warmth- losses which are
typically in the 1-4W range. The Asian wall-wart sweatshops use about
the cheapest of materials, particularly the laminations, and push them
to the limits of saturation (meaning they don't use any more material
than absolutely necessary), so there is substantial loss. Using better
magnetic alloys would push the cost up perhaps 10-20%, so it's not
California is supposed to be enacting a regulation mid-this year wot
prohibits sale of new gadgets with losses of more than 500mW, which
will knock out most linear AC adapters (also the active mode losses
are limited). It's already voluntary in China, Canada and the EU, and
mandatory in Oz. Manufacturers will probably more go to switchers
rather than improving the linear adapters**, which has advantages in
shipping weight and size, and allowing 'universal' input voltage which
can be used anywhere in the world, from 100VAC in Japan to 240VAC in
Europe etc. Also less losses in regulation.
Anyway, if the losses are 2.5W and you're running it 24/7, you're
wasting 22kWh/year, which is probably worth more than the adapter cost
to make, but it's still only a couple dollars, so not really a big
deal for one. But if you made all of them in the US twice as efficient
you could save energy equivalent to the output of a nuclear power
plant or two, IIRC.
** Or maybe just hire lobbyists..
"it's the network..." "The Journey is the reward"
firstname.lastname@example.org Info for manufacturers: http://www.trexon.com
I just used my "Kill-A-Watt" power meter to take a look at several wall
warts. All the samll ones were slightly warm to the touch, at no load
used less than 1 watt (limit of resolution) on the power meter, and had
a power factor down in the .15 range. I tried a bigger one used for
charging my big cordless drill, it ran 4 watts and .47 power factor.
As a side note, I got a "Kill-A-Watt" power meter
run about $30 to $35, used it to track down about 3/4 of my total
household power useage. The wall warts were NOT an issue, the freezer,
the refrigerator, and my wife's reading lamp were heavy hitters. The
reading lamp got a 40 watt florescent, saves about $6 a MONTH on that
I took a reading for several days on each item, loaded the KWH reading
and hour reading into a speadsheet, and calculated the monthly power
consumption and cost. Real eye opener!
I knew Malcolm Coleman at Motorola - well - I did custom designs for him
at his request - and they were approved by the divisional Engineering in Ill.
I flew all over the U.S. with members of Malcolm's Dallas team and the Sch. Ill.
Sadly, some friends were on a plane in the fateful day in Chicago - another
plane and lived. The system was a computerized Utility Load Controller -
power substations .... and shedding loads (hot water, well pumps, air
I lost track of him when the small company I was working for got smaller. I went
work for SLB and a long string of home moves.
Fond memories of the local Motorola office and memories of our trips.
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH & Endowment Member
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member
Robert Swinney wrote:
One household won't notice much difference, but if everyone unplugged their
wallwarts and turned off (instead of let sit on stand-by) their computers I
bet there would be quite the loss in consumption.
All my stuff like that is hooked up through a "power strip" and
turned off with one switch. One for the computer and its stuff
and another for the TV and its stuff.
My antenna pole has been stuck by lightning at least 3 times (that I
was here to witness) and since I'm about as high as anything around
here, during that season the antenna is disconnected too and only
connected when it's being used. It was disconnected the first time
it was stuck and so only burned up the house wiring and out-building
That first bolt was a whopper and some of the electricity "spilled
over on me". I woke up laying on my back with my arms and legs
in the air like a dead cockroach. All my muscles were frozen and
as tight as they could posibly be, even my diaphram. I couldn't
move and I couldn't breathe. "shear terror"
It was cool! :)
No, I don't want to be struck again, thank you, once was enough.
I'm a retired railroad signal ape and can say, that bolt that got me
wasn't anywhere near the strongest, but was a good solid stike
anyway, the next two were more typical. There's been several times
I opened a signal case full of relays and lightning arrestors, to
"hunt down the signal trouble" and "couldn't see anything in the he
case" because it was -all- one flat-black color. It looks creepy as
Anyway, I figure I only -got- about 1%.
It -felt- like the whole friggin thing tho! :)
Believe it? ;)
Alvin in AZ
This computer, the on I'm running right now (750Mhz AMD K7 T-Bird),
net ID lazarus, was struck by lightning about three years ago (2003).
Well, it actually hit outside on the driveway, but a lot of my electronics
got fried - including this computer!
Power had just gone off, but the cpu was on battery - shutting down - when
When the lights came back on (reset all the breakers) the VCRs and TVs (2)
were all gonzo, but the computer tried to start up - and then
Stinky Black power supply smoke!
Along with a bright yellow glow from the back of the box!
I remember being dumbstruck thinking "It normally doesn't do that...",
before swatting the switch off.
Which did cause the "glow" to go out immediately, but it just rolled smoke!
A few days later, figuring "what the heck" I swapped out the power supply,
and the machine came up an ran, sort of. Cad was no problem, but it would
hang up on things it used to do just fine... couldn't dial!
I did a careful visual exam of the motherboard and found every one of the small
electrolytic capacitors had the tops blown off. Little round tops hinged over
to one side and the stuffing's oozing out - like tiny spinach cans in a Popeye
So I made a list, found all the right caps (which all looked a lot better quality
than the originals, btw) and very carefully replaced them one at a time.
And finally replaced the modem to get back on line.
And it rocks on...
But under a new name: lazaruz
For what it's worth?
That was out in the country - local shore power not exactly always stable.
I had a battery backup on the cpu/monitor (with surge suppressers)
Surge suppresser on the master power switch box.
Surge suppresser on the printer power outlet strips (2).
Surge suppresser on the laptop circuit (Laptop not connected at the time)
All in one room.
And the phone line physically disconnected.
Yet it still somehow fried the modem...
Now somebody explain that one!
<snipped cool story about fixin a computer 99.9% of people would
have scrapped :) I do the same silly thing with old pocket knives>
"could come up with a thousand senarios and none of them would be
exactly right" ...is my typical answer, just before I procede to
speculate my ass off. ;)
Easy. ;) The dangged lightning can jump miles outside and jumps from
one thing to another (at-will;) inside. BTSeenT when looking at the
evidence of it and it sometimes makes no sense at all why it chose
that particular path (other than lightning has no sense and makes no
The bolt that got me had -at the very least- jumped 1+1/4" between
metal objects, then through me to ground. It was the first bolt
from two clouds that came together at about a 90 degree angle...
I was watching them hoping it'd rain. It was late June in the
desert and the first rain is a big deal for us born here.
Alvin in AZ
True. Any transformer has slight losses, even when idling. Just FEEL a
'wall-wart' ... they get warm, even when NOT under significnt load. That
heat comes from resistive losses in the wire and magnetic losses in the
core. Even when NOT under external load, there are short-term internal
current flows in the coils (or there would be NO magnetic field).
Current in a wire is always a resistive LOSS, no matter which way it
flows. For a well designed transformer, those losses are slight, but
never zero. It's doubtful that you'd ever SEE a difference in your
electric bill from letting ONE idle, however.
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