Asus has equipped the Asus Padfone 2 with a sizable 2,140mAh battery, which means it's good for an estimated 16 hours talk time and 352 hours standby time.
In real world usage, with Wi-Fi and GPS on and the display brightness set to auto and a fair amount of web browsing, emailing, Dropbox uploading and game-playing (strictly for testing purposes, you understand), we found that we were easily getting a full day's usage out of the phone with a decent amount to spare.
It certainly put our HTC One X to shame.
As well as having that larger-than-average battery, we put this added stamina down to the famously efficient Qualcomm Snapdragon S4 processor.
In our standard battery test of playing a 90 minute video with the screen on full brightness with all notifications switched on, the fully charged battery dropped to an average of just 79 per cent, which is pretty strong.
As is the norm for modern Android smartphones, Asus has implemented its own Power Saver mode, which can be accessed at any time from the notifications bar.
This reins in various power-leaching functions such as screen brightness and email update frequency.
The battery is removable, but Asus clearly isn't encouraging you to take the rear cover off too much, as we outlined in the Introduction page of this review.
With such a strong battery capacity allied to the backup of the tablet dock - not to mention the top-loading SIM tray and the lack of a microSD slot - we don't anticipate you having to do so all that often.
There's a prominent battery power widget on one of the home screens, which seems a little pointless until you slot the phone into the tablet dock.
The tablet portion of the Asus Padfone 2 has its own relatively meaty 5000mAh battery. That's smaller than roughly equivalent rivals such as the Sony Tablet S or the Samsung Galaxy Tab 2 10.1, but of course you also have the 2,140mAh battery of the phone portion to add to that.
This results in a tablet experience that lasts as long as pretty much any other. You'll likely be able to get several days of moderate usage out of a single full charge.
There's also a neat feature whereby a fully charged Asus Padfone 2 tablet can recharge the phone portion three times over. It means that even if the core tablet experience isn't the best around, the Padfone 2 tablet dock is an excellent travel companion - if only to juice your phone up on long journeys.
When you slot the Asus Padfone 2 phone into the tablet dock, a second custom battery widget appears alongside the usual phone one, showing you the power levels of both devices.
Asus has included all of the connectivity options you'd expect from a modern smartphone.
You have Wi-Fi (both 2.4GHz and 5GHz), 3G (including DC-HSPA+), A-GPS and DLNA.
There's Bluetooth 4.0, but with the inclusion of Wi-Fi Direct technology, you can hook up to eight devices together and share files without the need of a Wi-Fi network to act as an intermediary.
Only one device needs Wi-Fi Direct for this to work, too.
You can also use the Asus Padfone 2 as a Wi-Fi hotspot, which is handy when working away from an internet connection.
It also has support for Near Field Communication (NFC), which means it's ready for any contactless mobile payment systems that get adopted (as they inevitably will) in the near future.
It also enables simple peripheral pairing and the exchange of information with other NFC-equipped smartphones through a simple tap.