We have introduced lots of portable chargers with large-capacity batteries, but if you need an ultra compact option, the Fuel backup battery may be more suitable for you.
The Fuel is the world’s smallest cell phone charger that measures 1.3 x 0.9 x 0.6 inches. As we can see from the images, the ultra portable charger is shaped as a tiny gas can so you can conveniently attach it to your keychain or just put it in your pocket. Of course, there is no fuel in the keyring sized gas can die-cast aluminum, but the built-in 220mAh rechargeable battery can offer you around 20-30 minutes extra talk time, or a few hours on standby, and the integrated LED indicator shows you the status of the backup battery, while the switch allows you to turn the backup battery on/off. Apart from that, the emergency charger is charged via USB port.
At present the team of the Fuel is raising fund at Kickstarter. Pledging $20 will let you own the ultra portable backup battery. If you’re interested, jump to Kickstarter official site for more details.