Is it a sin to leave your cell phone plugged in overnight? | Hacker News Reader

Is it a sin to leave your cell phone plugged in overnight?

slate.com

19 pointschwolfe32 comments

Correct me if I'm wrong, but the cell phone is going to be using about the same power when its plugged in and fully charged as it does when it is unplugged. The difference is only that the power is coming from the outlet, rather than the battery in the phone. Without some calculations on how much would be drawn from the battery, simply from having the phone on over night, its hard to say what kind of power savings are available. I would guess its next to nothing, even less than they make it out to be in the article.

It says that an idle, but plugged in charger pulls around 2.3 watts. I always thought that switching chargers (most modern celphones comes with those) were able to switch themselves off (something with keeping a capacitor charged to kick the circuit online once something starts drawing power).

They do switch the active charge circuit off but they still waste electricity. For that matter leaving the charger plugged in with an LED light on wastes electricity as well, but as the article pointed out the KW per year measurement is so infinitesimally small that you can do more for the environment by skipping a hot shower.

This is rather easy to tell. Leave your charger unplugged for an hour and feel how cold the plastic gets, then plug it in to let it idle. If you have a switching charger it should stay around roughly the same temperature as when it was unplugged, if it feels like it gets warmer then that means it's in idle and not switched off.

The flat-form transformers used in most cell chargers are rather inefficient, so the temperature difference tends to be more than expected. However when you're dealing with ~9W maximum, it's likely more energy efficient to produce a less efficient transformer than consume extra time on the production line.

Yeah -- and there also size (very small), weight (very light) and sound (coils hum at 50/60 hz, the switching ones "whine").

But I wouldn't think the lack of heat that I can feel means that it doesn't waste 2.3w?

If by "whine" you refer to a very high pitched noise (akin to a TV tube) then I'll take a non-switched one every day.

I have two such mosquito-infested powerbricks here, emitting a constant high-pitched noise each, and it's royally annoying. The charger for my DECT phone emits it when the handset is not sitting on it and one of my two BenQ screens (ironically both the exact same model!) emits it when turned off.

This may be an avoidable production bug but when it strikes it's plain out horrible. I had to ban that DECT-charger from the living room because the sound would drive us nuts...

(And yes I should have returned both items as defective but on the phone I was too lazy and on the screen the noise only started after it was about 2 yrs old)

It is, and I've had some of the bad chargers as well. Usually, however, I have to press my ear against the brick to hear it at all, and have really good hearing.

This guy tested this, and found that chargers measure 0.0 watts. By plugging a bunch in simultaneously, he was able to get a nonzero reading, but still less than 0.5 watts:

http://www.inference.phy.cam.ac.uk/sustainable/charger/

(He is now Chief Scientific Advisor to the Department of Energy and Climate Change in the UK.)

I think we need a new unit, the 'hamsterpower', for levels of energy use which are not worth thinking about. A hamster can generate about 0.15W, so rounding, I guess we could define 1 hamsterpower = 0.1W.

http://otherpower.com/hamster.html

http://en.allexperts.com/q/Science-Kids-3250/Hamster-Power.h...)

Would it better for me to charge my electronics during my morning commute, by plugging them into the car charger?

A commute long enough to charge your electronics is probably a bigger "sin" than a cell phone plugged in overnight.

But if you're doing the commute anyway (you sinner)...

Saving the environment is a task that's too difficult for one person to understand, so anything that seems slightly inconvenient is good enough to satisfy most people's "needs". Changing when you charge your cell phone is a lot easier than planning your life to be lower-impact.

(I love all the SUVs filled with one grocery bag at Whole Foods. Do you really think that buying some locally-grown organic carrots offsets the energy you spent driving your military vehicle 3 blocks?)

Indeed.

"Forget Shorter Showers" (http://www.orionmagazine.org/index.php/articles/article/4801...) points out that perhaps we've duped to think that energy shortages/waste are _our_ fault, when, in fact, it's industry, large-scale agriculture, and our military that are the biggest abusers. Of course, this isn't an excuse to not be lower impact ourselves (and perhaps not purchasing products that support certain industries), but we can't be fooled into thinking that changing our charging habit is going to save the environment.

For more from the wonderful Jensen on how abusive our culture is, read A Language Older Than Words (http://www.amazon.com/Language-Older-Than-Words/dp/189395603...). If you can look past the absurd stuff about talking to animals, there is a lot to be learnt from it.

if our changing habits were coupled with our buying, lobbying and voting behavior, then it would have a significant effect. furthermore, the culture and ethics we instill today will be in charge of corporations in a few decades.

There are other reasons than carbon offset to shop at Whole Foods...

Consider your energy sources too, here in ontario my power is coming from a mixture of Hydro and Nuclear. Plugging anything into my car to charge is most definitely worse, as you're then trading relatively clean energy sources for a car engine.

If your power comes from a coal/oil plant, it's a rather harder decision, which depends on your vehicles efficiency. However, it's most certainly going to use more fuel (and thus cost you more) than it would take to receive the equivalent electricity.

I recently got the Kill-a-Watt to test electricity usage by different devices. My laptop uses a mere $13 worth of electricity per year (And that is assuming that I leave it on constantly rather than closing the lid and letting it hibernate). Modern computing devices have become so efficient that they make little impact. If you want to save energy it is better to look at your refrigerator, stove, AC, and the other major electricity burners.

I have a home music production studio with 15 devices (mixers, synths, processors, amp, laptop, ancient PC). I used a measuring device and even though the PC is supposed to use 250 watts or so, the entire studio is only 468 watts! This is a cost of around 4.68 pence an hour (I think a kilowatt here is 10 pence), which isn't bad when a commercial studio costs at least 10 pounds.

I'm not a US citizen but this helps you calculate (each value is the cost of a kilowatt):

http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_b.html

I leave my phone plugged in overnight, and when I get to work, I have it plugged into the USB drive on my computer. On the occasion where I'm driving, I've got an Alpine stereo with an iPhone adapter, and a mount for my phone, so I leave it plugged in there.

I haven't done any hard numbers, but my battery capacity doesn't seem like it's worn down from when I got the phone over two years ago.

Nonetheless, there are definitely more important things to worry about whether you're looking to cut back on your electric bill, or are trying to be more 'green.'

1) conservation of energy - if the phone is switched on, it is drawing current. If the latter is from the battery, you will pay for it (plus the charger's and DC-DC converter's inefficiencies) later.

2) battery wear - how much energy does it take to manufacture a new Li-ion pack?

It seems like the phone 'knows' when it is fully charged, so why don't phone manufacturers simply disable charging once it is full?

They do.

But the switching power supply that regulates the mains voltage to 5v (or whatever is required) is always on, and although they are extremely efficient the loses do add up.

Arguably it should be possible for the phone to switch off the supply before the switching power supply, but this will add complexity and cost to the product. And because the power supply is normally seperate from the phone some kind of signalling from phone to power supply would need to be implemented. Again adding complexity and cost.

As mentioned in the article, http://www.withouthotair.com/ is well worth the read, and will help you understand what is actually worth doing to lower energy use and carbon footprint. (The book is considerably better than the appearance of the website would suggest!)

I will second the recommendation of the "Sustainable Energy – without the hot air" book, and mention that it is free to download from the above site. It looks at the debate from a technical perspective, with extensive appendixes containing the author's calculations.

One thought from the book that struck me is that all the batteries in the (eventual) nationwide fleet of electric vehicles, could serve to smooth out the fluctuations from renewable energy sources. The author envisions battery-exchange stations as commonly-found as petrol stations are today.

My iPhone stops charging when it's full. (I'm going to buy a killawatt and prove it soon)

This has nothing to do with the cell phone, nut with the charger. Even if the phone stops drawing current, old-style transformer based chargers still draw power from the grid. Newer switching power supplies do not - at all, as the link above [1] showed.

[1] http://www.inference.phy.cam.ac.uk/sustainable/charger/

I expect the MSM to try and keep their audience entertained with this inane charging your electronic crap is killing the earth meme. But I would think HN is the one place this meme would not be able to infect. Am I wrong?

I don't know whether to point out the article is arguing against that it's killing the earth or question if you even opened the link before responding. I thought hn was the one place the latter was avoided (and hey, why comment if you disapprove of the thread's popularity?).

I did read the article, but already knew the meme is stupid and wrong and thought the same of the HN readership, thus I'm surprised to see it in any form, pro or against.

And I comment when I disapprove of a thread because the flag and shut up mantra has never sat right with me. I prefer to explain why I dislike something.

If all you did was explain why you disapproved of things you'd be giving undo (reasonably) attention towards something you felt was stupid. Why waste the time when you're not obliged? That's all I'm curious about - you could find another topic more important and make that topic popular.

It's a (perhaps undo) attempt to purge non-HN type stories from HN. It's a kind of not very useful or productive hobby.

It's disheartening that the Slate analysis does not calculate the approximate cost in dollars of alternate leaving-things-plugged-in strategies.

Even when prices are distorted by non-competitive markets, subsidies, regulation, and so forth, they remain vaguely related to the actual opportunity costs of a path of action.

According to this chart, the average retail price of a kilowatt-hour in the US varies from about 8¢ (West Virginia) to 22¢ (Hawaii).

http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_a.html

So given Slate's estimate that leaving a phone plugged in an unnecessary 8 hours every day for a year would use 6.5 kWh, we're talking about a cost over the whole year of 54¢ to $1.43.

Is a full year of fussing with the charger to minimize hours-plugged-in worth a savings of $1.43 in time or energy? If once, over many years of following this strategy, it means your phone dies at an inopportune moment, was it worth the years of savings?

We spend energy all the time for convenience, and $2/year for not having to micromanage a device that's supposed to make life easier is a bargain.

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