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my iPad mini came with this charger and cable. If i leave it charging overnight, what prevents it from overcharging my iPad(is it the charger or the iPad itself)?

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I ask because I also own a Dynex cable (only the USB-iPod cable, not including the charger shown in the picture below). And the Dynex cable has a note attached that says "charging will automatically stop after 8 hrs to protect your devices, unplug and replug the charger to recharge if needed". Why is this 8 hr charge limit needed?

I'm guessing that it is the Dynex charger that sets the 8 hr charge limit. If I plug my Dynex cable into the iPod charger is that going to be ok?

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up vote 4 down vote accepted

All Apple products have a charging demand circuit that senses the battery charge level and only engages charging current when the battery needs a charge.

When you plug in power to the iPad, it only initially channels enough current to run the system (or boot it up if it's off) and establish some sensing of the battery. At that point, it will start charging (and drawing more current) if needed.

If you think of electricity like water plumbing, there are two pipes - one to run the CPU/screen and another valve that only gets open when you want to send some of the water pressure into a water tower for use later. Just like a town wouldn't pump water into the tower when it's full (or when they decide they need to send all the output into town) - the iOS device isn't a simple unregulated system where the batter gets a charge whether it wants it or not.

The dynex charger simply has a time limit so it would work normally until the 8 hour shut off finished (most iOS batteries - even old failing ones) are done charging by 4-5 hours) and at that point, rather than have your iOS device stay running on wall current, the battery would have to kick in and start self-powering the device. For that reason, I would say skip the Dynex for Apple product and save it for less sophisticated / simple electronics that don't self-govern charging current.

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thank you for your answer!! however, does that mean that it is the Dynex charger that controls the 8 hr charge limit? and I can plug the Dynex cable into the Apple charger and it would be safe and it would not induce the 8 hr charge limit? thanks –  user133466 Jan 26 '13 at 19:19
    
If you look at the picture, the dynex plugs into the wall. It has USB charging out of the bottom. I don't think you could piggy back either the Apple charger into the Dynex or the other way around hence my suggestion to not even use the Dynex for iOS charging. –  bmike Jan 26 '13 at 20:28
    
i understand using Dynex charger may not be a good idea, but I can certainly insert the Dynex USB-iPod cable into the Apple charger's USB port. The Dynex cable itself will not induce the 8 hr charge limit correct? –  user133466 Jan 26 '13 at 22:37
    
my bad - I didn't see the "cable" qualifier. I agree the cable should work - thinking it was some sort of switching cable defies all logic. –  bmike Jan 26 '13 at 23:06
    
so it not be possible to overcharge an ipad battery if i were to continue to charge it for say 19 hours? –  user133466 Mar 5 '13 at 5:50
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