powering up a phone, no cords needed

It may not seem hard to plug a cord into the wall to charge your mobile phone or tablet. Nonetheless, a number of companies are trying to figure out how to save us from the effort.

While still in a nascent stage, wireless charging is becoming a reality, with recent announcements by Starbucks and Cadillac that they'll both be offering the technology. Set your smartphone down on a small mat at a table or in your car's dashboard, and your device will charge.

There are two main competing versions of wireless charging trying to gain market share. Both use a similar technology that allows users to place smartphones or tablets on a charging mat and power up in no more time than using a cable would take.

For the wireless connection to work, a receiver — which could be in the device but at this point is more likely to be in a special case that you have to buy — picks up an electrical charge from a transmitter coil in the charging mat.

The Wireless Power Consortium, a trade group, is promoting one technology, Qi (pronounced chee). The consortium's members include LG, Philips, Samsung, Sony and others, with more than 500 Qi-compatible products now available.

Its competitor, the Power Matters Alliance, has joined up with a third group, the Alliance for Wireless Power, or A4WP, which uses a slightly different technology, to create one interoperable version that will also allow the transmitter and receiver to be placed at greater distances from each other.

Powermat, the alliance's most prominent member, is supplying the technology that Starbucks will use when it embeds charging stations in all its company-owned stores in major United States markets by the end of 2015.

The Qi technology will introduce a variation that uses resonance technology, to allow charging to take place even when a device is 45 millimeters away from the charging point. That will allow the transmitter to be embedded inside a desk, for example.

If you're on the fence, which wireless-charging standard should you buy? Perhaps neither, said Ryan Sanderson, an associate director at IHS, a research firm.

"You might want to wait six months and hope that there will be a receiver that supports all three standards," he said. "There have already been demonstrations of chips that do that."