I have spent my entire weekend trying to locate a place where I can buy a 5 Volts - 2100mAh Electric Motor/Generator. My goal is to spin this motor up to a certain RPM to generate the 5 volts and 2100mAh required to charge an iPad. It's an experiment I've been trying to accomplish for some time now.

Can you kindly point me in the right direction? Is there such a motor in the first place? If I need to somehow modify an exiting one, where can I read about doing so to these specifications?

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    \$\begingroup\$ The capacity of the battery (mAh) and the required charging current (A) are two different things. \$\endgroup\$ – W5VO Apr 21 '14 at 15:35
  • \$\begingroup\$ Do you know of a DC motor that would achieve the required charging current of this capacity? Hopefully I've asked this question correctly. \$\endgroup\$ – suchislife Apr 21 '14 at 15:47

A battery that has an "energy" capacity expressed as 2100mAh is able to supply 2.1mA for 1000 hours or 21mA for 100 hours or 210mA for 10 hours. Or any mA-hour ratio you want providing the hours and the milliamps, when multiplied together equal 2100.

This is not the charging current for said battery because current is measured in milli amps and not milliampere hours.

Now that hopefully you know what you are looking for you might be able to find it and you must ask yourself the question - what current should I be using to charge an iPad - I don't know the answer but you certainly need to find this out. It wouldn't surprise me if it needs a regulated constant current feed. Hey, it might be OK with a plain ordinary 5V feed.

  • \$\begingroup\$ After some more research I found that the charger is rated at 10W. The output is 5VDC @2A. Could this help you suggest a specific DC Motor that can perform at these specs? When attached to a computer via a standard USB port (most PCs or older Mac computers) iPad will charge very slowly. My goal is to get a DC motor to provide the same charge a wall charger provides in order to achieve maximum charging speed. \$\endgroup\$ – suchislife Apr 21 '14 at 16:18
  • \$\begingroup\$ Alright. What do you think about this motor? goo.gl/9Vfb4G I'm guessing if this works, all I need is a Voltage regulator down to 5vDC. \$\endgroup\$ – suchislife Apr 21 '14 at 16:49
  • \$\begingroup\$ @IdleMind Ideally, you need to find out how much current the charger puts into the iPAD. You shouldn't just go into this eyes closed - it might need constant voltage or it might need constant current. If it needs constant current and you apply constant voltage there might be smoke from the iPAD. You need to find out what these devices need CV or CI (or maybe something else. Charging batteries aint like it used to be in the NiCd days of yore. Regards the motor, that comes next but the important smke-avoiding stuff comes first dude. \$\endgroup\$ – Andy aka Apr 21 '14 at 17:10
  • \$\begingroup\$ First of all, thanks a lot for replying to me so promptly. Here is a link to the iPad 4 charger specs. It's just a picture really. goo.gl/SRxdqN \$\endgroup\$ – suchislife Apr 21 '14 at 17:21
  • \$\begingroup\$ @IdleMind Everyone here helps for free and you should do some research into the charger spec - have you looked at it? Is there a particular page that gives likely answers? \$\endgroup\$ – Andy aka Apr 21 '14 at 17:36

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