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New Apple 12W USB Power Adaptor charges iPhone 5 in 3/4 the time
- Thread starter bushman4
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From a quick scan of the thread, this seems to be the only test performed.
Although, it'd be great if someone could use the same phone and run it down to empty - charge with both different chargers - time the process to 100% and post the results on here.
The results of two charging runs with each would be even better.
I don't have an iPad charger otherwise I'd do it myself.
Actually it's not all "we" care about because it isn't valid. The measurement from the 110(or 220)V lines you get with Kill-A-Watt isn't the same as the measurement drawn from the adapter through USB during charging. They are 2 different measurements and can be quite different. This has been discussed & confirmed many times over the years when this same discussion for any type of USB device, (not just an iPhone) has come up.
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That has been done but it is inaccurate as you can't tell what "empty" actually is. The battery is never fully discharged despite the phone shutting itself down and the "empty" (shut down) state of the battery can vary quite a bit making the charging time inaccurate (and variable).
It'd be a better test than any other performed so far on this thread and we don't need absolute perfection.
If the OP is accurate, the difference should be obvious and it would prove a useful tip.
Well, surely it can be useful to use the Kill-A-Watt, right? For example, just plugged my iPhone 5 into the iPhone 5 charger and the Kill-A-Watt says that it's using 4.7W. Whether all of that wattage is being transferred to the iPhone, we don't know, I suppose, - BUT there's a max of 4.7W draw.
If we then plug an iPad charger into the iPhone 5 and see the same 4.7W draw, then we know that the iPhone is not pulling MORE than 4.7W, right?
Let's test that theory...
Just plugged my iPad 10W charger into the Kill-A-Watt. It's still reading 4.7W power draw when I plug my iPhone 5 in.
By my logic, this puts this whole debate to rest, no? We know that the iPhone 5 pulls up to ~4.7W. Certainly not MORE than ~4.7W.
I'm not a power expert, but the above makes sense to me in my head.
You make a faulty assumption that the AC/USB adapter is always pulling the same amount of wattage. It has already been pointed out in this thread that that isn't true.
The phone's built-in battery charger is a lithium cell smart charger and, in order to maximize the life of the lithium cells, it will sometimes draw much more power (for example when the battery is 30% charged state) and sometimes a lot less (for example when the battery is at 95% charged state). In most cases for lithium the charger will charge at a rapid rate up to about 80%, then switch to a slower rate until 100%, then either switch again to trickle charge or toggle on/off periodically.
To make matters worse, we're talking about the actual state of charge, which is different than the displayed state of charge, which is all lies. For example, when the display says 0% and the phone turns off, there's probably 10-20% left. Lithium batteries die if they are completely discharged and cannot be recharged, so undervoltage protection circuits cut off the battery. Likewise when the display reaches 100%, the battery hasn't actually reached 100% and will still continue to slowly charge until it does reach 100%.
This is why the only surefire way to know if it is faster or not is to drain the cells, start a timer, and do a full charge. And while there might be slight differences in the state of charge when drained, it won't be enough to mask a claimed 3/4 speed difference.
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It may be possible but this subject has been beat to death already over multiple years. The phone decides how much current it will draw, not the charger. The only way this would change is if the chargers themselves had a logic board telling whichever devices to draw so and so amount of amperage.
I am not sure why the industry standard is 1-2 amp chargers. Most likely it has to do with the standard 15a circuits in USA house holds. Not sure what the rest of the worlds standards are. The other factor is the higher the amperage the higher percentage that death is possible if something goes wrong and a user is shocked somehow while the device is charging. All it takes to kill someone technically is 0.1 amps. Sure that rarely happens, but that is all it actually takes. The farther you get away from that number the higher the risk of course.
But ya, I would like to see a device draw 4-5a and charger 5x as fast. This would be great but people would have to be aware of where they are plugging in there devices so they don't overload a circuit and be popping breakers all the time. Even better, make it user select-able from within the phone settings...
I am not sure why the industry standard is 1-2 amp chargers. Most likely it has to do with the standard 15a circuits in USA house holds. Not sure what the rest of the worlds standards are. The other factor is the higher the amperage the higher percentage that death is possible if something goes wrong and a user is shocked somehow while the device is charging. All it takes to kill someone technically is 0.1 amps. Sure that rarely happens, but that is all it actually takes. The farther you get away from that number the higher the risk of course.
But ya, I would like to see a device draw 4-5a and charger 5x as fast. This would be great but people would have to be aware of where they are plugging in there devices so they don't overload a circuit and be popping breakers all the time. Even better, make it user select-able from within the phone settings...
The chargers do. There's no standard for it (official standard), but there's an accepted one that describes what the charger can output without having to have any intelligence:
http://blog.curioussystem.com/2010/08/the-dirty-truth-about-usb-device-charging/
The reason the iPhone doesn't charge with more than 1 amp at a time is because it can't without burning out the battery. The reason the iPad can is because the iPad has more (battery) cells.
Hypothetically if you have 4 cells and can charge at 1 amp, then an 8 cell battery can charge at 2 amps. I don't know how many cells the iPhone and iPad batteries are, but that's how it works.
The iPhone knows it's connected to a 2 amp Apple charger or Mac computer but only pulls the 1 amp because, it simply can't charge any faster without killing the battery.
Hypothetically if you have 4 cells and can charge at 1 amp, then an 8 cell battery can charge at 2 amps. I don't know how many cells the iPhone and iPad batteries are, but that's how it works.
The iPhone knows it's connected to a 2 amp Apple charger or Mac computer but only pulls the 1 amp because, it simply can't charge any faster without killing the battery.
Nope. Straight from Anandtech's Brian Klug: https://twitter.com/rjonesy/status/332653750487482368
"Sorry bro." The phone dictates the amperage and current draw. Just becuase that charger works "with" the iPhone doesn't mean it send 12W.
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How does it feel to use huge red font and be wrong?
"Sorry bro." The phone dictates the amperage and current draw. Just becuase that charger works "with" the iPhone doesn't mean it send 12W.
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How does it feel to use huge red font and be wrong?