I was at a trade show recently, and one of the booths was giving away cell phone backup battery packs with the company name on them. These are a useful gadget for use with a microcontroller!
They have one or more 18650 batteries in a case; you charge them up via USB and then they put out a steady 5V via a USB cable. The free one I got is about the size of two packs of gum, and uses the same cable for both charging and powering a device, you just flip it around after charging.
These are currently a popular gadget on ebay. They would make a good power source for a robot or other project that needs a battery. Just need to work out a cable.
They have one or more 18650 batteries in a case; you charge them up via USB and then they put out a steady 5V via a USB cable. The free one I got is about the size of two packs of gum, and uses the same cable for both charging and powering a device, you just flip it around after charging.
These are currently a popular gadget on ebay. They would make a good power source for a robot or other project that needs a battery. Just need to work out a cable.