Docking Station: The "Transformer" In Transformer Prime
Asus' docking station is one of the most important accessories to consider. After all, this is what makes the Transformer Prime, well, transform. And the option to use the tablet and dock together really sets Asus' offering apart from everything else. The docking station is sold separately for a hefty $149, which brings your total bill (assuming you buy the 32 GB model) up to $650. That's the same range as a number of very capable notebooks and high-end netbooks, necessitating a careful decision. Does a more portable experience justify what you'll spend?
In the video above, we used the Transformer Prime in much the same way we'd use a productivity-oriented laptop or netbook. The consensus is that paying extra for the dock is worthwhile if you want to use Asus' tablet as an alternative to one of those more traditional form factors. In utilizing Tegra 3, the Transformer Prime doesn't suffer some of the delays in response we encountered when we reviewed the original Transformer.
For example, when we'd enter a search phrase on the first Transformer's Web browser, the input stuttered during fast typing. And when we made a mistake, holding down the backspace key resulted in slow and delayed character deletion. That's no longer the case. Nvidia's quad-core Tegra 3 can handle the input more elegantly.
The docking station's USB port is truly functional. Rather than simply supporting removable media (something we've seen on other tablets), you can plug in an Xbox 360 wireless controller receiver, for instance. You don't need any additional drivers; it just works. PlayStation 3 owners can instead use Bluetooth connectivity, even without the docking station attached.
As if we haven't already driven home the idea of using Asus' Transformer Prime as a portable console, adding in controller support gets us even closer with a familiar interface.
Beyond its role in expanding I/O, the docking station also expands the Transformer Prime's battery capacity. The tablet's battery is marginally larger, holding 3380 mAh compared to the dock's 2940 mAh. Under certain workloads, the combined battery power should yield close to two times as much battery life compared to the tablet on its own.
There is variability in how long it takes to deplete the batteries, though, due to a rather uncommon charge/drain cycle built into the Transformer Prime's firmware. Instead of draining one battery and then the other, the transformed tablet first lets the main battery drop to 70%. Then, it recharges back up to 90% using the secondary power source before letting it drain again. This cycle continues until the docking station's battery can't provide any more juice. Presumably, both the tablet and docking station require power, necessitating this seemingly unconventional way of draining both batteries in a balanced manner.
Charging operates under the sample principle, which makes our battery life benchmark a bit more complicated. The results presented on the previous page are straightforward measurements we took of the docking station and Transformer Prime while they charged individually. When both components are connected, charging together as one unit, a complete recharge takes a bit longer due to jugging between tablet and dock.