One accessory which caught my eye at Nokia World was the DC-50 'Portable Wireless Charging Plate'. The idea is not only to have a portable emergency charger with internal battery, but to have it both charge a Qi-compatible phone wirelessly and be charged the same way. In theory then, no wires are involved at all, in any part of the process(!)

The DC-50 is described as:

Always be switched on

Our most flexible and effortless charger, the DC-50 has the ability to power up any Qi-enabled device – without plugging in.

Bring back to life

When it runs out of juice, lay the plate on another wireless charger. Or give it a power boost the old-fashioned way with the included microUSB charger.

What a great idea - to have the wireless charger itself charged in the same way! The benefits are a life free of wires, in theory, though if you're in any kind of hurry when back at base you're going to want to charge this using the legacy microUSB port instead, while your phone lies on top of your home/office-based charging pad.

One other possible caveat is that transfers of electricity are always less than perfectly efficient. Transferring charge via a traditional cable usually loses around 20% of the total charge available through heat and electronic inefficiencies. Transferring charge wirelessly in a typical Qi configuration is typically only about 70% efficient at best, so at least 10% less charge can be transferred, plus any transfers may be significantly slower than when using wires. In short, the internal 2400mAh will, at best, only be delivering a possible 1700mAh or so to a phone.

The standby consumption is higher, at 30mW, than would be the case for a traditional all-wired portable charger, because of the need for powered-up circuitry to detect the presence of a Qi-compatible device. However, at the rate quoted, you should still see a week or two of useful life 'on the shelf'. Plus, because of the convenience of the DC-50 being charged wirelessly too, you can probably just keep it resting on your main Qi charging plate whenever it's not being used, and thus it will always be topped up.

Finally, here are the full specifications:

• Connectivity
  • Charging connectors: Micro-USB 
• Power
  • Battery technology: Li-Ion 
  • Battery capacity: 2400 mAh
  • Battery voltage: 3.7 V
  • Removable battery: No 
  • Rechargeable battery: Yes 
  • Charger input current: 1200 mA
  • Charger input voltage: 5 V DC 
  • Charger standby consumption: Less than 30 mW 
  • Maximum charging time: 150 min
• Power Management
  • Wireless charging standard: Qi 
• Usage
  • Operating temperature: -15 - +55 C 
• User Interface
  • Operating keys: Power indicator key 
  • LED indicators: Battery level indicator, Charging indicator LED
• Dimensions
  • Width: 69 mm
  • Height: 134 mm
  • Thickness: 12 mm
  • Weight: 150 g