this post was submitted on 20 Sep 2026
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The losses in a 25' cable are negligible, the losses on this specific wireless pad is 10% according to the linked article. At 11kW that's like running a space heater outside while charging. Seems quite wasteful.
Unless you install it in the garage and call it a heater I guess
I wondered about this. I have "qi charger" in my car, on my desk, and on my bedside table, and all of them put out a fair amount of heat, so I knew there was loss, but didn't know it was in the 10% range. That's a lot!
10% is so low, that I doubt it's factual. For comparison, QI charging loses 20-30% in addition to what wired chargers lose. Here is an article with cited studies: https://www.engadget.com/2200186/wireless-charging-wastes-electricity-why/
Moral of the story: plugging the phone in is worth it in the long run.
Add that to the fact that the "qi charger" in my car is very finicky about position. So, if I want to grab the phone to change music, take a picture, etc, etc while driving, then when I put it back in place I always have to fiddle with it to get it to start charging again. Whereas if it's plugged in to a wired connection, there is no fiddling about while I'm attempting to drive safely.
The qi charger in the car, and on the desk at the office don't get a whole lot of use. The one by my bed, a disc with one functional side, always!?! is wrong side up when I try to connect it, sleepily, in the dark. Plug in is just easier to use. I appear to have convinced myself to swap it out with a wired connection.
For phones, though, the absolute amount of energy is so low that a high percentage loss doesn't actually mean that much. A typical smartphone battery is about 15 Wh, so charging it literally every day for a year consumes 5.4 kWh. Doubling that won't make a noticeable difference to your energy consumption, the heat released in your home, your electric bill, etc.
That's why small device chargers are engineered without much regard for efficiency. For that specific application, having long flexible light cables is better than making sure it squeezes every bit of efficiency out of it.
For cars, though, even a 10% loss can make a difference.
I would disagree. The difference might not mean much for a single household but looking at all mobile phones paints a significantly different picture.
If everyone in the world population of 8.3 billion wasted that much energy per year (5.4 kWh), that would represent a global increase of 44.8 terawatt hours.
Global energy use was about 177,000 terawatt hours in 2025 so that represents about 0.025% of total energy use.
Consumer electronics, especially mobile devices, just don't use any significant amount of energy worth talking about, and has basically no effect on overall demand. Making them half as efficient wouldn't be noticeable on any scale.
For comparison, a liter of gasoline contains 8.9 kWh of stored energy. There's probably a lot more to gain by just getting people to drive something like 5 km less per year, rather than trying to squeeze just a little bit more efficiency out of their phone chargers.
The gain may not be much but the cost is even less. Reaching for a cable costs a second more and would save around 10000 tons of coal per year (based on your calculation) if the equivalent of coal power plants were reduced by the same amount. It's not like using wired charging is any sort of effort that would outweigh the benefit.
You can't have it both ways. If you're counting the energy consumption of 8.3 billion people consuming 15 Wh, 365 times, then you're also talking about "a second" for each, or 3 trillion seconds, or 95,000 years of time saved in exchange for that coal.
The difference is, that one second is personal cost. The CO2 is socialized cost. If you have a different perspective on this, I understand. When I looked up wireless charging because it looked cool and saw the numbers, I decided to stick with cables and not buy any wireless charging hardware.
And I'm saying that this particular issue is completely inconsequential. Based on worst case scenario assumptions (fully discharging a 15 Wh battery down to 0% every day, waste heat equal to 100% of the charge, all electricity from coal), you're only using a 5.4 kWh per year, or about 2.5 kg of coal, about 4.6 kg of CO2 emissions.
That's about 170g/6 oz of beef (27 kg CO2/kg beef). Commit to eating (or wasting) one less burger per year and you've made up for the worst case scenario, calculated using unrealistically large assumptions.
Or that's 1.9 L/0.5 gallon of gasoline. Drive 25 km/15 miles less per year.
More realistically, we're probably talking 80% charge per night, 80% efficiency, and an electricity mix that generates the US average CO2 emissions of 0.384 kg/kWh. That cuts it down to 3 Wh/day, 1.1 kWh/year, and about 0.42 kg of CO2.
That's 16g of beef, or 0.17 L of gasoline.
The real impact comes from changes around the bigger uses of energy. Focus on the things using many orders of magnitude more energy, within your control: transportation, climate control, food choices. Consumer electronics are less than a rounding error.
That's not in the cable, that's the "end to end" charging system, and yes, that is comparable to wired charging. Efficiency in the wireless transmission is 96-99%, depending on distance and alignment. This has been studied extensively. Like I said, this is not new technology. Have a web search.
Here's a couple articles to get you started:
https://electreon.com/blog/debunking-wireless-ev-charging-myths/https://www.energysage.com/ev-charging/wireless-ev-charging/
https://www.witricity.com/blogs/comparing-efficiency.php
https://www.osti.gov/servlets/purl/1876291
https://www.ornl.gov/news/ornl-demonstrates-120-kilowatt-wireless-charging-vehicles#%3A%7E%3Atext=97+percent+efficiency%2C+which+is+comparable+to+conventional%2C+wired+high-power+fast+chargers
https://www.mckinsey.com/industries/automotive-and-assembly/our-insights/perspectives-on-wireless-and-automated-charging-for-electric-vehicles#%3A%7E%3Atext=A+wireless+inductive+charging+system+is+at+least+one+or+two+percentage+points+more+efficient+than+a+DC+%5Bdirect+current%5D+fast+charger+at+the+same+power+level.
So that whole wall of text had one source that showed 4% losses in a lab with coils really close together, which is still a lot more loss than a copper conducter.
The marketing hype basically says if you factor in all of the losses from the power generation and transmission all the way to the wall then our additional 10% loss is no big deal so you can ignore that 1kW of lost heat you have to pay for on top of the grid's losses that are already a part of your costs.
If you don't like my sources, feel free to find your own, they all say the same thing. There is no additional 10% loss. You even ackkowledged that in your reply, then came back and reported it again. What's that about?
This is why misinformation is so hard to deal with, i put in effort to read and assess what you provided and found that you came to the wrong conclusion even with the sources YOU provided and now you want me to find even more evidence that you will just ignore? Nah, your mind is already made up, you ate the marketing hype and no amount of data will sway you.
That fist article actually has some interesting concepts that dont really apply to a pad on your driveway but like if the infrastructure was kinda everywhere then you could have smaller batteries, keep the charge in the sweet spot further reducing capital costs and keep your fleet trucking and not idling at a charger reducing opcosts. Neat. Maybe we'll get there some day.
Good on ya for not feeding the trolls.
Ah yes, "the trolls", those assholes that always show up with facts and half a dozen sources and then invite you to educate yourself more!
Sick maymay bro
This is why misinformation is so hard to deal with. I put in effort to find a half a dozen sources and highlight the relevant sections and you dismiss them outright because you don't like them, but you can't be bothered to do so much as a web search to inform yourself.
You don't want to learn, that's not something I can do for you.