By Victor Luckerson
March 12, 2015

The Apple Watch could be a big hit when it launches in April, but one key issue might keep the device from truly breaking into the mainstream.

Analysts are fretting over the relatively short battery life of the watch, according to the Wall Street Journal. Apple claims the device will last 18 hours on a full charge, but Forrester Research analyst James McQuivey believes the battery life will be more like 10 to 12 hours with heavy use.

All of these figures are less than the 24-hour battery life that some analysts had hoped for, and could prevent the watch from being a true lifestyle device.

“Every time someone takes off a smartwatch, you’re potentially losing that user,” Canalys analyst Daniel Matte told the Journal.

The 18-hour stated battery life is less than the Android Wear LG G Watch, which Ars Technica pegged at around 23 hours, and the Pebble smartwatch, which is supposed to last for five to seven days. To address battery life issues, the Apple Watch will come with a “Power Reserve” mode that will limit the device’s functionality in the name of preserving power.

Still, we won’t get a true understanding of the Apple Watch’s battery performance until reviewers conduct hands-on tests in the coming weeks. The Apple Watch goes on sale April 24, while a pre-sale and preview session begins April 10.

Contact us at editors@time.com.

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