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Whatever you call it, the humble AC adapter, external power supply, plug pack, plug-in adapter, domestic mains adapter, line power adapter, wall wart, or power brick is due for significant changes next month.
The U.S. Level VI energy-efficiency regulation, aimed at energy savings in external power supplies, goes into force on February 10, 2016, and will impact all OEMs selling into the U.S. market. The European Union (EU) also is expected to harmonize with the new efficiency standard.
This article includes a quote (& pun) from one power supply vendor,
"It's a two-pronged approach," said Johnson. "The regulation addresses active mode when the adapter is powered up and supplying power to the end product. Under the regulation, efficiency is increased by roughly five percent."
But the big change is at no load when the adapter is plugged into the wall – like a cell phone charger – and nothing is connected to it, Johnson added. "Power consumption at Level IV was .5 watt and at Level VI it's decreasing to .1 watt, which when you talk about the millions of adapters in the market it's significant in power savings."
Another article can be found at http://www.metlabs.com/blog/energy-star-2/external-power-supplies-must-meet-level-vi-energy-efficiency-requirements-for-u-s-doe-by-february-2016/
US Department of Energy has an information page with several linked documents
https://www1.eere.energy.gov/buildings/appliance_standards/rulemaking.aspx/ruleid/28
"Rulemaking for Battery Chargers and External Power Supplies Energy Conservation Standard"
(Score: 0) by Anonymous Coward on Saturday January 02 2016, @02:41PM
There's two types of wall-warts.
The first one uses a big 60Hz transformer to reduce voltage, then whatever rectifier and possibly voltage regulator seem appropriate to the application. These have rather high power consumption when unloaded, and relatively poor efficiency when loaded, too. Of course, they're practically unheard of the past decade or more.
The second type is a switch-mode power supply, which are not only smaller, cheaper, and more efficient at the same design load, but also can easily have very low power consumption when unloaded. Even designs where unloaded power consumption isn't a design criteria are typically still much better than any transformer-type wall-wart.
Your belief of zero no-load consumption can be a practically correct approximation, but it is an approximation, and its usefulness depends not only on actual no-load power consumption, but also on duty cycle. Consider a SMPS with no-load consumption equal to 5% of rated load. For a device that functions 8 hours a day, and is left plugged in the other 16 hours, neglecting the unloaded consumption only gives about a 10% error, but for a device used 30 minutes a week, the unloaded consumption is an order of magnitude higher than the in-use consumption. (Even if we go to 1%, as for a 10W power supply complying with the new 0.1W standard, no-load for 167.5 hours is over 3x in-use for 0.5 hours.)
(Score: 2) by gnuman on Saturday January 02 2016, @05:07PM
The first one uses a big 60Hz transformer to reduce voltage, then whatever rectifier and possibly voltage regulator seem appropriate to the application. These have rather high power consumption when unloaded, and relatively poor efficiency when loaded, too. Of course, they're practically unheard of the past decade or more.
https://en.wikipedia.org/wiki/Switched-mode_power_supply [wikipedia.org]
It seems that transformers remain. A SMPS does not remove the need for a transformer. On the contrary, transformer is a requirement to have an isolated circuit.
(Score: 0) by Anonymous Coward on Saturday January 02 2016, @07:40PM
Of course. That's why I said the non-switch-mode type has "a big 60Hz transformer", as opposed to the little >kHz transformer in a SMPS.