An ordinary battery charger at a reasonable price. The Zero-Watt function is a very useful feature, the device is really completely disconnected from the mains. Small minus: For me personally, could the movable contacts, which press the batteries, be smoother. When inserting tilt and slide like this hook a little. However, this is absolutely no reason not to buy the device. What I lack is a way to measure the capacity of existing battery in a charge-discharge-charge cycle. This can, however, along with the Zero-Watt feature of course not so easy to implement because the device would have to stay here turned to the cycle for reading. The devices that can cost also doubled up three times (and have no Zero-Watt).
