Do not charge any sort of lipo battery (especially an unprotected hobby aircraft variety!!) using anything except a lipo battery charger. inputting 5v in to it via a usb connection is a bad idea and will destroy the battery at best or at worst, cause an explosive lithium fire which will be difficult to extinguish. Lithium battery fires are very good at burning houses down, and the gas flames that shoot out of those battery packs can be a foot long or even longer. If you insist on charging the battery in the most dangerous way, make sure you do it outside via a long extension cable where everything of value and everything flamable are at least one meter away from the battery, and keep an eye on it, ready to unplug it if it catches fire.
Hobby aircraft batteries are exceptionally good at catching fire, often doing so if they're shorted out or overcharged. People who work with the sorts of little airplanes that use those batteries usually charge them in a ceramic pot on a concrete surface away from anything prescious, or inside a special bag designed specifically for charging dangerous lithium polymer batteries.
Seriously, don't burn your house down trying to save the $2 a USB lipo battery charger costs you on ebay.
