I have an iPad 2 and I have noticed how slow the charging is via usb through my early 2009 iMac. I have read where usb only outputs around 5-6 watts and the charger provides 10 watts. Would charging through usb from the computer be better for the battery, since it is charging slower? By the way this is my first iPad and it is pretty amazing. Definitely worth having even for the naysayers that have and iPhone 4 (as do I).
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iPad charging slow from 2009 iMac
- Thread starter shardey
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It has no effect on the battery either way you charge it, other then exactly what you said.. Taking longer.
Since USB outputs less watts it will take almost DOUBLE the time to charge. The wall plug is 10 watts so will charge faster.
Since USB outputs less watts it will take almost DOUBLE the time to charge. The wall plug is 10 watts so will charge faster.
I just always thought heat was the culprit of failures in electronics and assumed a warmer battery/being charged faster would result in a diminished charge capacity over time vs the slower charge.
I've NEVER had one of my Apple products get warm during charging. I have several devices. My Dell and toshiba laptop do get warm durning charging, but I haven't noticed that at all with my iPad and I always charge it in a case with the wall charger..
USB charging is pretty lame regardless of the OS. Use the wall charger.
In fact on windows it even says not charging when connected but actually does a very slow charge.
From my personal experience as long as I charge it using wall overnight I have never needed a charge till I got home.
In fact on windows it even says not charging when connected but actually does a very slow charge.
From my personal experience as long as I charge it using wall overnight I have never needed a charge till I got home.
Which iMac do you have? Also if you guys have an iPhone, letting it charge from at least 50% will fault in the rear case to get warm.
It's an iMac 24 inch early 2009. I'm charging it with the supplied cable on the first USB port closest to the audio port.
I've had iDevices and Macs for quite some time and I've never read or heard it be recommended that you charge via USB because it's slower and thereby easier on the battery.
I would almost argue the opposite. We already know that more charge cycles are bad for the battery. There's a decent chance that extended charging time is also detrimental to its longevity.
OP, I would just use the wall charger.
Here is the definitive answer from apple: http://support.apple.com/kb/HT4049
Looks like most newer Macs can charge at 5 volts, 1.1 amps which would charge the iPad similarly as from the wall adapter.
Looks like most newer Macs can charge at 5 volts, 1.1 amps which would charge the iPad similarly as from the wall adapter.
I wasn't saying slow charging is better. I was saying I've never heard that be recommended. In any event, I would guess it makes no difference at all. And if it does, it would be negligible in terms of battery life.
USB on a computer should provide 2.5 watt, which is just about enough to keep the iPad running. It doesn't hurt the iPad or the computer to charge the iPad through the computer, but it doesn't particularly help either. And if you charge from a MacBook running on battery, it will of course empty the MacBook battery a lot quicker. So I would only do this if you can't find a spare wall plug.
I know. Maybe I wasn't clear in what I said. I guess it should have started more like "I agree. In fact, I think the opposite is probably true..."
Good that they provided that capability. I don't like requirement #2 though: Your Apple computer or display must be powered on and must be awake. If your Apple computer or display is asleep, all ports will provide a maximum of 500 mA at 5 V. If your Apple computer or display is powered off, no power will be provided.
I'm not disappointed that it doesn't work when the computer is asleep, but I wish it still did it when the display is powered off. I use my iMac as a server sometimes, with the monitor powered off by Hot Corner. It'd be nice to just use it as a charger too instead of having to move around the power charger when I want to charge and use.
the reason slow charging as a general rule is better, is because manufacturers tend to slap a bunch of cells together and treat it as one big battery. when you do this, some cells may discharge at different rates, leaving them at different levels when recharging. the problem is that when you have a cell at 80% and a cell at 90%, but are charging them on the same circuit, a high flow of electricity makes the 90% cell heat up more. it's overcharging a cell that is detrimental.
apple has been implementing per cell charging throughout their products, helping to reduce this problem. this video shows some of what they've been doing: http://www.youtube.com/watch?v=w6lLdFxiZPc (i think around the 3:20 mark - can't watch it right now to make sure)
It still works while the iMac is asleep, although at the lower 500mA power. To get the high powered charging the iMac has to be awake.