Apple's 4.7-inch "iPhone 6" is expected to come with a 2,100mAh battery, according to a report analyst Sun Chang Xu in a report on Chinese social media site Sin Weibo.
If the post is true, it would represent a huge 45.8 percent increase compared to the current battery found in the iPhone 5C.
Apple could possibly accomplish the increase by decreasing the size of other internal components, and also by featuring more internal space, along with a larger display, according to AppleInsider.com.
Apple's flagship iPhone 5S comes with a 4-inch display in a 16:9 ratio. The next iPhone device, which hasn't been officially named yet, is rumored to come in two sizes: 4.7-inches and 5.5-inches.
An 1,810mAh battery supposedly for Apple's next phone was unveiled in photos that leaked online last month. While the smaller battery was legit, it was only used for testing purposed during development of the actual battery, according to a recent post by Sun.
The final 4.7-inch device will come with an even larger battery, which would be an increase of 660mAh from the iPhone 5S.
Apple is expected to hold a big media event on September 9, where it will most likely unveil at least one of the two new iPhones.
Other rumored specs include: 1704 x 960 pixel resolution, a faster A8 processor, a thinner profile, bezel-free design, camera upgrades, and a more durable, sapphire screen.
A number of market watchers think the updated processor could help the next device become Apple's biggest product launch ever.
A new iOS 8 operating system that the next iPhone will utilize debuted at Apple's 2014 Worldwide Developers Conference earlier this month.