While the iPhone 13 is not expected to look much different from the iPhone 12, except for a smaller notch and a new color for the iPhone 13, there are rumored to be many other upgrades inside Apple's new iPhone.

These include a new A15 Bionic processor that could (again) wipe out Android phones, a faster 5G modem, and cool camera software upgrades like portrait video mode and a night mode that can actually shoot stars.

The iPhone 13 Pro and iPhone 13 Pro Max should be the stars of the show with their 120Hz refresh rate displays, the possibility of always-on display mode, and improved ultra-wide cameras. But none of the above would matter without the important upgrade of extended battery life.

The good news is that previous rumors point to a larger battery size for all 13 iPhone models. The bad news is that Apple has not disclosed the battery capacity of the iPhones and will likely not confirm this at the Apple event today (September 14). We will probably have to wait until the iPhone 13 teardown takes place shortly after launch.

The iPhone 13 mini is said to have a larger 2,406 mAh battery; the iPhone 12 mini's 3,227 mAh was very poor in our web surfing battery test at 7 hours 28 minutes. We believe 10+ hours is very good.

Another leak last week predicted an hour longer battery life for the iPhone 13 mini, which is definitely a step in the right direction.

Next would be the 6.1-inch iPhone 13 and iPhone 13 Pro Max. Both of these models are said to offer batteries ranging from 2,815 mAh to 3,095 mAh. The caveat here is that the iPhone 13 Pro's battery life could take a hit due to the rumored 120 Hz panel. iPhone 13 Pro and Pro Max will reportedly scale down to 60 Hz in low power mode.

The iPhone 13 Pro Max will also see an increase in battery size, from 3,687 mAh to 4,352 mAh if rumors are accurate. iPhone 12 Pro Max was the only phone to approach 11 hours in battery tests last year, so this 6.7-inch phone is once again a champion of endurance and should earn a spot on our best phones battery life list.

Of course, there are many other factors in a cell phone's battery life besides battery size. For example, Apple may be able to achieve some efficiencies with its new A15 Bionic chip and machine learning. The 5G modem may also be able to reduce power consumption, depending on how it is integrated with the rest of the design.

It is also possible that the new iOS 15 software, which Apple plans to release at the same time as the model, could provide some power savings. So far, the only iOS 15 battery feature Apple has detailed is a power reserve feature that will allow users to use virtual keys stored in the revamped Wallet app for up to five hours after the iPhone's battery runs out.

Anecdotally, I have found the battery life of the iPhone 12 Pro Max to be quite good, but now that it has been on the market for a year, I find its durability to be a bit less than when it was new. I typically find that by the time 7pm rolls around, the battery capacity is down to 20% (sometimes even less).

So if Apple can make meaningful progress on the iPhone 13's battery life, it would be welcome. We will be running battery tests on all four models in our lab, so stay tuned for the full results.

In the meantime, check out our iPhone 13 hub for all the latest news and updates and follow Apple's event live blog for all the updates Apple announced today.