A smartwatch runs for a year on a standard button cell

Las Vegas: "Smart" watches that talk to cellphones have been around for some time, but they've been hampered by their high battery drain - usually needing recharging every few days. At this week's International CES electronics trade show in Las Vegas, a startup launched a smart watch, the Cookoo, that runs for a year on a standard button cell.

What it is: The Cookoo is a somewhat beefy watch, most suited for the male wrist. It has analog hands to show the time, but the watch face can also display several digital indicators, prompted by Bluetooth signals from your smartphone. Aided by beeps and a vibration motor, it can tell you that someone is calling or that you missed a call. It can also alert you about new email or an appointment. The watch can also talk back to the phone, so you can use it as a remote release for the camera.

How it works: A free app on your iPhone prompts it to send signals via the Bluetooth wireless technology to the watch. The reason the Cookoo can run for a year on a button cell is that it uses a new, low-energy flavor of Bluetooth, known as 4.0.

The caveats: Only a few devices have the chips necessary for low-energy Bluetooth connections. The app is for Apple devices only, so the watch is limited to talking to the iPhone 4S, the iPhone 5, the full-size iPad models released last year, the iPad Mini and the latest iPod Touch. Early reviewers on iTunes complain of the watch dropping the connection to the phone and running down the phone battery - problems that might be fixed with a software update.

Price and availability: ConnecteDevice, which makes the Cookoo, sells it on its website for $130. AT&T's flagship store, in Chicago, is also carrying it for the same price.

The competition: CES also saw the launch of the Pebble, a programmable smart watch with a fully digital display. Users can send different "watch faces" to it and make it perform a wider range of tricks than the Cookoo can, but it needs to be recharged every week. Like the Cookoo, the Pebble raised the money to start production by selling units on group-fundraising site Kickstarter.