The biggest hurdle for the Apple iWatch and all smartwatches in general is battery life. No one wants to charge another gadget every day. We do that too much as it is.

Case in point, one of the major cons we mentioned in our Samsung Galaxy Gear review revolves around its pitiful one-day-per-charge battery cycle. It has a 300mAh battery.

The LG G Watch, which also runs Android Wear, is hardly better at a day-and-a-half average capacity running off of a still-tiny 400mAh battery. Moto 360 is in the middle with a 320mAh battery.

Apple iWatch
Curved battery design by Apple (credit: USPTO)

Apple has previously patented a curved battery design that could give it the extra space that it needs to boost the rumored iWatch beyond a day or two.

The smartwatch components need to be small, but the battery life does not, according to energy-drained consumers.

At the same time, they require more than the monochrome display of the Pebble Steel and the original Pebble watches, which eked out a respectable 3-4 and 5-7 day battery life.

This impossible task may be why Tim Cook and company reportedly faced battery woes early on with the iWatch and still hasn't overcome them completely.

Wireless battery charger

At least when the iWatch battery dies, there may be a cool way to recharge the device thanks to wireless charging technology.

Apple has reportedly called upon a wireless charging coil supplier in China to send samples of its technology so that it can implement it into the iWatch.

Apple iWatch
Certain iWatch apps could drain the battery quickly

The iWatch could therefore wirelessly charge through magnetic induction, a method similar to the Qi-compatible Moto 360 smartwatch.

The Moto 360 wireless charging cradle is rather slick, perfect for a nightstand. It could even come with the iWatch, sort of like the first iPhone included a dock in the box initially.

Qi is quickly becoming the more popular wireless charging standard ahead of its rivals. That being said, Apple does like going with its own proprietary technology more often than not.

Waterproof

A lightning connector could also be an alternate way to charge the iWatch, but that may be a more difficult task if Apple is to make it waterproof or at least water resistant.

Smartwatches that can stand up to the elements are being demanded by consumers who want their "24/7 wearables" to be true to that term down to the second.

If the iWatch is like currently Android Wear watches, expect it to be splash proof up to IP67, which is rated for a depth of 1 meter (3.3 feet) for 30 minutes.

That's good for the shower and accidental submersions, but not exactly fit for dunking the iWatch in the swimming pool or taking it in the ocean. Not this first generation at least.

Compatibility

iWatch is likely to loosely follow the iOS 8 compatibility chart by working with new iPhones and iPads that contain newer Bluetooth antennas.

The battery-saving Bluetooth 4.0 Low Energy made its debut in the iPhone 4S, iPad 3 and iPad mini and can be found in all newer models.

It's the exact same lineup that can wirelessly sync with the Fitbit Force, Jawbone Up24 and NikeFuelBand SE.

The iPad 2, which can be upgraded to iOS 8, is the one exception to the chart. It may be left off of the iWatch compatibility list.

It may mean it's time to turn in that old iPhone 4 for an iPhone 6 or a price-reduced iPhone 5S when the new phones launch later this year.

Just don't expect any Android phone, new or old, to work with the iWatch. Android Wear can't connect to Apple's devices, and we expect Apple to return the favor.