Battery problems are holding back Apple's big plans for the Apple Watch

Don't expect to be able to use your next Apple Watch independently of your iPhone.

Apple is running into serious difficulties in its attempts to add cellular support to its next-generation wearable, according to a new report from Bloomberg's Mark Gurman, a reporter with an extremely good track record on upcoming Apple product news.

The problem? Battery life.

Apple reportedly wants to add a cellular chip, like the one found in phones, to the Apple Watch. Existing Apple Watches have to be tethered to a smartphone constantly in order to access most of their functions, limiting its usefulness.

Incorporating a cellular chip would prevent this, giving Apple Watch customers much more freedom in how they use it. A user could wear it on a run and make use of its full functionality without having to carry their iPhone, for example.

But, Gurman reports, the cellular chip is too demanding on battery life, already a pain point for the Apple Watch. Executives have reportedly expressed concerns that an Apple Watch that incorporates cellular tech in a satisfactory way won't be ready in time for a planned Autumn launch; December is the earliest possible timeframe for shipments.

Apple is rumoured to be making other sacrifices for battery life in the next Apple Watch. Reliable KGI Securities analyst Ming-Chi Kuo says that the next generation model will be just as chunky as the current device, with Apple deciding to improve the battery rather than slim down its bulbous design.

Battery life has been a major bugbear for users of the Apple Watch, with apps restricted to save battery and charging required every night.

The original Apple Watch launched more than a year ago, back in April 2015. It's pretty comprehensively dominating the wearable market, but it isn't exactly setting the world on fire. Smartwatches remain a niche market, and Apple doesn't break out sales figures - a sign they're not spectacular. One analyst believes they dropped 40% from Apple's Q1 to Q2 this year.

Mark Gurman and Ming-Chi Kuo both report that the next Apple Watch will be getting a GPS sensor for the first time, to improve its location services.

Don't expect Apple to confirm any of this, however: Apple never comments on unannounced products.