Amazon claims that the Amazon Kindle Fire HD 7 is good for 11 hours of use in between charges, and everything we've experienced in our hands-on time suggests that they're about right.
With the screen cranked up to full brightness and in heavy usage (video watching, gaming and web browsing) we came in a little short of double figures on the Amazon Kindle Fire HD 7, but it's still very respectable and in line with its big rival, the iPad mini.
After playing our standard self-installed test movie, which is 720p and one hour and thirty minutes long, with the screen brightness cranked up to full and Wi-Fi and notifications on, we were left with more than 80 per cent battery life in the tank. Not bad at all.
The Amazon Kindle Fire HD 8.9 is good for around an hour less than its little brother - its larger 6,000mAh battery offset by the demands of a larger, sharper screen and a faster processor. Suffice to say this is competitive with other nine to ten-inch tablets.
Arguably of more interest when it comes to battery life is Amazon's decision to omit a mains charger from both packages. You get a USB lead, which will charge the tablet through your computer or a generic USB mains adapter, but it's an odd omission nonetheless.
Instead, Amazon is pushing its PowerFast adapter, which at least has had something of a price drop to £12.99 (though this has crept back up from £8.99 back when we covered the 7-inch model late last year), showing that consumers may have been more than a little angry that they have to charge such a high drain object through a computer... and neither the Nexus 7 nor the Nexus 10 charges for the privilege of being able to plug into the wall.
That's a bit steep, but it does promise to fully charge your Amazon Kindle Fire HD in less than four hours for the 7-inch model - although this is no quicker than the iPad mini, despite both having a capacity of 4,400 mAh. The 8.9-inch model will charge in less than five hours.
Both Amazon Kindle Fire HD devices are Wi-Fi-only, so you won't be able to carry them around and take advantage of 3G connectivity. Still, with tablets that's far less of an issue for most users.
Besides which, Amazon claims that the Amazon Kindle Fire HD range's Wi-Fi is superior to its rivals, utilising a dual-antenna system and MIMO (Multiple In, Multiple Out) technology to boost Wi-Fi speeds.
This approach effectively increases the amount of bandwidth in the link between your tablet and your Wi-Fi hotspot, as well as improving stability.
Both are good things to have in a device that's so reliant on internet connectivity, and we can confirm that our connection didn't drop in the slightest, regardless of where we were in the house.
In practice, though, that supposed extra Wi-Fi speed really isn't noticeable.
We tried downloading a number of large email files on both Amazon Kindle Fire HDs and then did the same on our third-generation iPad, but couldn't see any difference.
In fact, the iPad seemed to process the files (if not download them) faster overall.
Amazon can pack its tablets with super-fast Wi-Fi if it wishes, but it's no substitute for a slick OS working well with its processor.
Outside of this, both Amazon Kindle Fire HD tablets come with a microUSB and a microHDMI port for outputting your video content directly to your HDTV.
They also comes with Bluetooth for use with speakers, keyboard and other wireless peripherals. There's no microSD card slot in either.