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"Wireless" or Inductive Charging for mobile devices

Unread postPosted: Wed 30 Aug 2017, 08:26:30
by KaiserJeep
The world is still full of people who understand Physics, but never use it for anything, it would seem.

The problem with inductive charging is that the chargers are "dumb", they do not know whether a device is charging or not, and therefore consume just as much power creating an unused magnetic field 24X7 whether there is a device in that field absorbing power or not. It would be possible to create an inductive charger with a "start" button which would shut itself down and cease generating the magnetic field when the device was charged, but none of you would buy it, as some of the convenience results from not having such a button.

The older "linear" wall wart chargers with transformers were also "dumb", in the sense that they also consumed power when not charging a device, as long as they were still sitting in a receptacle, as the transformer primary winding was connected to the AC. They began to be replaced with smaller and lighter transformerless smart chargers about 2012. Such chargers monitor the level of charge in the device and shut off the charger when it is topped off, or the device disconnected. Although they still require a wired device connection, such chargers are energy consumption champions, very efficient compared to inductive charging or linear chargers.

For those of you with "convenient" multiple inductive chargers per device, congratulations, you have the highest energy consumption of any mobile device users. Likewise those oh-so-convenient combination AC/USB receptacle-type power sources are linear transformer type chargers that are on all the time, whether wired devices are charging or not.

The champions of low energy consumption are the transformerless wall warts that shut themselves down when the device is topped off. Period. Lest you think that this does not matter, measurements of the grid consumption by type of device disclose that the grid consumption today is about 18% mobile devices and other battery charging applications such as electric vehicles. The mix is telling as more than 99% of the charger power consumption is in handheld devices (smartphones and tablets and e-readers), the remaining fraction of 1% includes laptops, portable power tools, appliances, and battery EVs. Which means that in a USA which consumes approximately 10 terawatt hours of power per day (2016 EIA figure), mobile devices consume 1.8 terawatt hours, from a power grid that in 2016 was still 65% fossil power, 18% nuclear, 14% renewables, and 3% "other carbon producing energy sources". (EIA and IEEE sources.) In terms of carbon emissions, mobile devices (the vast majority being smartphones) are responsible for spewing 328 million metric tonnes of carbon into the atmosphere per day (EIA figures again). (For the whole world, multiply the US figure by four.)

If you care about carbon emissions, choose wired charging from a smart charger. Also, never leave an inductive charger plugged in unless you are using it.

Re: "Wireless" or Inductive Charging for mobile devices

Unread postPosted: Wed 30 Aug 2017, 09:34:05
by GHung
Likewise those oh-so-convenient combination AC/USB receptacle-type power sources are linear transformer type chargers that are on all the time, whether wired devices are charging or not.


Being off grid, I'm paying attention to such things. The combination unit I installed on our kitchen bar (2 USB ports and 3 ac outlets) is drawing zero watts when not in use, according to my tests with my Kill-o-Watt meter. It is also too light weight to have any transformers in it (which was one of my criteria for purchasing this one).

I don't grok the inductive chargers at all. My phone has a simple charging stand that was, I'm betting, cheap compared to those trendy inductive chargers. Seems people put "cool" above practical these days.

Re: "Wireless" or Inductive Charging for mobile devices

Unread postPosted: Wed 30 Aug 2017, 11:07:08
by KaiserJeep
Congrats, you figured it out, most people buy USB receptacles based on price, and get energy hogs.

As for conservation, my parents drilled it into me as a kid, I compulsively turn off lights in empty rooms, I cannot stop even though it annoys the wife. In case you have any "security lighting", be aware that a 10-25 watt IP camera and some motion detecting software can replace a 500w security light.

Re: "Wireless" or Inductive Charging for mobile devices

Unread postPosted: Wed 30 Aug 2017, 11:26:21
by Tanada
KaiserJeep wrote:As for conservation, my parents drilled it into me as a kid, I compulsively turn off lights in empty rooms, I cannot stop even though it annoys the wife. In case you have any "security lighting", be aware that a 10-25 watt IP camera and some motion detecting software can replace a 500w security light.


You might replace the light and get nice pictures of the thief who thinks they are concealed in the darkness, but my 150w security light does a fair job of keeping thieves at a distance because they feel like they are easily seen. You can never ignore the psychology aspect of crime prevention.

Re: "Wireless" or Inductive Charging for mobile devices

Unread postPosted: Wed 30 Aug 2017, 12:17:29
by KrellEnergySource
Read the first review of this charger, where a person measured its power usage with a KillAWatt meter.

https://www.amazon.com/Energizer-Qi-Ena ... B0041RRORA

Summary:

Kill-a-watt shows:
0 Watts - Not Charging
6-7 Watts - Charging
3-4 Watts - N4 (phone) at 100%, stays here for about 5 mins then goes to Not Charging Mode.




I think you'd find the same thing on an inductive cooktop. Turned on with no pot of water to boil vs. placing a pot of water on the cooktop.

I remember in high school trying to power a 60 watt bulb with a hand crank generator. With the bulb out of the socket....zero effort. With the bulb in the socket, nearly impossible.

Brian

Re: "Wireless" or Inductive Charging for mobile devices

Unread postPosted: Wed 30 Aug 2017, 12:18:58
by jedrider
Tanada wrote:
KaiserJeep wrote:As for conservation, my parents drilled it into me as a kid, I compulsively turn off lights in empty rooms, I cannot stop even though it annoys the wife. In case you have any "security lighting", be aware that a 10-25 watt IP camera and some motion detecting software can replace a 500w security light.


You might replace the light and get nice pictures of the thief who thinks they are concealed in the darkness, but my 150w security light does a fair job of keeping thieves at a distance because they feel like they are easily seen. You can never ignore the psychology aspect of crime prevention.


The LED replacement lights probably consume 10-20 watts if even that and the ones that are tied to a motion detector makes the draw negligible.

Re: "Wireless" or Inductive Charging for mobile devices

Unread postPosted: Mon 04 Feb 2019, 05:26:16
by lpetrich
I've found some wireless/inductive chargers that have on/off switches.

Re: "Wireless" or Inductive Charging for mobile devices

Unread postPosted: Mon 04 Feb 2019, 19:26:48
by Outcast_Searcher
KaiserJeep wrote:The world is still full of people who understand Physics, but never use it for anything, it would seem.

The problem with inductive charging is that the chargers are "dumb", they do not know whether a device is charging or not, and therefore consume just as much power creating an unused magnetic field 24X7 whether there is a device in that field absorbing power or not. It would be possible to create an inductive charger with a "start" button which would shut itself down and cease generating the magnetic field when the device was charged, but none of you would buy it, as some of the convenience results from not having such a button.

Funny how you convince yourself you know everything about everyone's decisions.

How about for street charging or charging in any area outside a garage where for safety, weather, etc. reasons lack of a cord to get wet, tripped on, etc. would be desirable? I for one, don't want to get sued because someone trips on a power cord in my car port, even if I have cones, etc.

And like some of the posts above showing how the current can indeed vary by the usage, it's not hard at all to imagine an inductive charger that wakes up every X seconds, and does a test to see if something "wants" a charge, or is done charging so it can cease providing power, and thus doesn't need an "on" button at all.

"Understand physics" isn't a binary condition, by the way. It's a big complex field, with various branches and a hell of a lot of math, even at the undergraduate level.

Re: "Wireless" or Inductive Charging for mobile devices

Unread postPosted: Mon 04 Feb 2019, 19:50:09
by KaiserJeep
Yet I still unplug dumb wall wart chargers with no smarts about a load, because those are the cheapest made in China, and therefore wind up in lots of devices. Like for example every ethernet hub/switch, wifi hotspot, and most cheap printers. I try to plug the dumb chargers into power strips with switches.

The one redeeming feature of the mobile devices with 5v USB cables is that you can most often substitute a smart charger for a dumb one.

The wife's hopeless, happily leaves on every light in the house, in case she wants to enter another room.

Re: "Wireless" or Inductive Charging for mobile devices

Unread postPosted: Fri 08 Feb 2019, 04:02:47
by Outcast_Searcher
KaiserJeep wrote:Yet I still unplug dumb wall wart chargers with no smarts about a load, because those are the cheapest made in China, and therefore wind up in lots of devices. Like for example every ethernet hub/switch, wifi hotspot, and most cheap printers. I try to plug the dumb chargers into power strips with switches.

The one redeeming feature of the mobile devices with 5v USB cables is that you can most often substitute a smart charger for a dumb one.

Clearly, trying to use smart devices to save power makes sense. Dumb transformers, for example, tend to vibrate and/or stay warm, even when nothing is plugged into them. Obviously that wastes power, though from what I've read, for small ones, the cost is in the range of a few pennies a week or so -- but it's the principle of the thing.

I just love the trick of using power strips, and switching the thing off when not using the stuff on it. Protects the stuff too (I started using surge strips for all electronics when a bad lightning storm ruined multiple devices like TV's in one go. It literally looked to me like my apartment building was being attacked by lightning. Dunno if it was ever hitting, but it looked damn close multiple times. I was afraid to go in until that storm calmed down.)