External battery explanation please

Dave Waterman

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Dec 11, 2013
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Hi, I was wondering to buy the Kingston mobilelite wireless cardreader and battery. I noticed that it can 'hold' 1800mAh. My phone is a Galaxy Note 2 which has 3100 mAh. Now the simple theory if i am correct: for exapmle: the phone has 2000 mAh and the charger 1000mAh, could i charge under perfect conditions 50% of the phone? Or are there a lot of factors which cause it to charge like 25%???
I would appreciate some explanation, happy Christmas/hannukah/kwanza or whatever you like :)
 

jnkweaver

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Nov 11, 2011
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Milliamp Hour (mAh)

Milliamps Hour (mAh) is important because it's the easiest way to distinguish the strength or capacity of a battery. The higher the mAh, the longer the battery will last. Batteries with different mAh ratings are interchangeable. If your battery is rechargeable then the mAh rating is how long the battery will last per charge.

Milliamps Hour is 1/1000th of a Amp Hour, so a 1000mAh = 1.0Ah

Think of a cars gas tank. Voltage is how much gas is being used, and mAh is the size of the gas tank. The bigger the gas tank (mAh) rating the longer the device will run. If your battery is rechargeable, then think of the gas tank as refillable (rechargeable).


So no, It would in theory take 2 hrs for you to charge a 2000mAh battery with a 1000mAh charger.
 

Dave Waterman

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Dec 11, 2013
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Its not about the time it would take to charge. But rather how much % it would charge my phone. In theory it would give my phone a 50% battery boost under ideal cirumstances? or would it be rather 20% in reality?
 

jnkweaver

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Think about a battery charger for your car. It puts out 6 amps and your car battery can crank out 450-750 cranking amps depending on the battery. You fully charge the battery by having a higher voltage than it needs. For a 12V car battery they usually use 14V to charge. Amp ratings is just an indication of how much the battery wii hold.
 

ipwn3r456

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Mar 21, 2012
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Asides from above, you do have to realize that external batteries are only about 70-80% efficient (heat, voltage conversation, etc. while charging your device), like a typical PSU on a computer. I have an external battery charger, and I notice that. So if you have a 4000mAh external battery, it would be around 3000mAh (just an estimate).