After years of hope (and no little amount of hype), wireless power is finally getting into consumer hands. However, the technology that is showing up on trade show floors and store shelves is a far cry from the truly disruptive promise of wireless power.
As we cram more computing power into our mobile phones and use them to deliver the web, take photos and shoot video (as well as talk), a key limitation has become the battery. Anyone who has experienced a three-hour battery life after surfing on a Wi-Fi network knows first-hand that battery life can impede the enjoyment of a full-featured mobile device.
And that problem is the one that wireless power will one day solve. Not through the slew of charging mats that will be on offer over the holidays, but using the type of over-the-air power that Intel and WiTricity are trying to develop. Before we get all excited about the idea of a battery-less future, it’s worth talking about the different flavors of wireless power that exist.
- Inductive: There are two types of inductive wireless power on offer. One is promoted by the Wireless Power Consortium and relies on delivering power through magnetic contacts between the device that needs power and a charging mat. The other, promoted by Intel and WiTricity, relies on magnetic resonance and hopes to one day transfer without requiring device contact, although it still needs an electric connection from a wall outlet or a battery. Delivering power via contact is about 70 percent efficient, but delivering it over the air becomes less efficient the further apart the two magnets that are generating the power get.
- Conductive: This is the old-school type of wireless power that uses the contact between two metal plates to charge something. It’s fairly efficient, but its usefulness is limited by the plate-to-plate contact and the fact that it still needs an electric current.
- Solar Photovoltaics: Right now, solar panels aren’t a great source of wireless power for mobile devices because the surface area for a solar panel is small, solar panels aren’t very efficient at generated power, and people don’t typically keep their phones out in the sunlight.
- Kinetic Power: We’ve written about M2E Power’s charger that converts the motion generated by a person walking into usable power for a mobile phone. However, it takes about 6 hours of walking time to create enough power for 30 minutes of talk time. For some that will work, but for many that’s just not enough.
Current Market Players
Nikola Tesla identified the how to deliver wireless power using magnetic induction back in 1891, and the Consumer Electronics Show both this year and last was full of cord-free demos. But it wasn’t until earlier this month that Powermat, a joint venture between HoMedics (yeah, the company that makes all those massagers, water purifiers and personal spa gear) and Powermat Inc. of Israel, introduced a $99 charging mat available at Best Buy and Target. The mat clicks with your iPod touch, BlackBerry or iPhone using a special sleeve ($30-40 per device) charges them up, saving you a few outlets and avoiding the irritation of plugging in your micro USB cable.