The Efest K2 Charger buries this horror in the past. It has been built with portability in mind, and can quickly refresh your batteries in the shortest amount of time.
Fitted with a number of safety features, including polarity protection, the unit is built from a durable, but lightweight material and can easily fit snug in any backpack or travel case.
As is the case with all battery chargers, please ensure that your batteries are of a rechargeable build to suit the K2 or of a PCB build. Never leave the charger unattended or charging overnight.