This might be better suited for the mobile section of this forum.
They make portable battery chargers with interchangeable tips. Mine does micro, mini, USB, samsung, and iphone. It has a ~5000mAh battery which after losses is good for about 2 full phone charges. It recharges through the same USB cable, which you can then plug into a wall or car charger. Just charge it up every night. Mine has two ports for simultaneous charging, but only comes with one cable.
USB 2.0 is not bad for devices, but is much slower, I believe. Should not affect your device.
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