Apple Inc. (NASDAQ:AAPL) announced its Apple Watch alongside the iPhone 6 and 6 Plus last month, and many consumers and analysts were excited. It’s been pointed out time and again that the company won’t talk about the device’s battery life.

Experts believe that, based on current available technology, the Apple Watch might not even last a full day.

Apple Smartwatch May Greatly Disappoint Buyers

A challenge for Apple Watch

Quartz spoke to a number of experts who said the small size of the Apple Watch will make it extremely difficult to give it a decent battery life. They said it will probably be easier to solve the space issues in cars and even smartphones because they are larger.

SiNode Systems CEO Samir Mayekar told Quartz, “The ratio of active material to dead weight in a wearable is much lower than in a smartphone or a car.”

What Apple may do

The website reports that experts believe Apple will use the same materials that are used in most laptop batteries, smartphones and other lithium batteries. That material is cobalt oxide, which was developed in 1991. The benefit of that material is that it is able to pack a lot of power into a small, dense space.

However, the small size of the Apple Watch will prevent the company from using very much. As a result, the smartwatch’s battery will probably die much earlier than the battery in the iPhone, which lasts most users for a full day before it must be charged.

An alternative for the Apple Watch

Apple may be able to increase the battery life of its watch using newer lithium-ion cobalt oxide batteries. The experts interviewed by Quartz said those batteries offer higher voltages so that they can deliver more energy.

Lawrence Berkeley National Lab scientist Venkat Srinivasan expects Apple to use some type of cobalt oxide that operates at 4.35 volts and provides approximately 165 milliampere hours per gram. That would be 22% better than the best lithium-ion cobalt oxide batteries that have been used in the last few years.

Nonetheless, it doesn’t seem like the technology exists for the Apple Watch to have a battery that will last all day. Of course it’s always possible that Apple could surprise us.