We've all been there: you're sitting at a coffee shop trying to crank out a presentation at the eleventh hour when all of a sudden, your laptop blares out a warning that you have less than 5%remaining battery life.
In an age when manufacturers trade the functionality of removable batteries for the convenience of lighter, slimmer form factors, mobile computing users struggle with balancing portability and power.
Mobile battery packs, also known as juice packs, are fairly common for smartphones, allowing you to get a few recharges. With these devices, you're out of luck if you need to recharge a more power-hungry Windows-based tablet or a laptop. However, several manufacturers make dedicated laptop battery packs, and I recently bought two different models to test: the IntoCircuit Power Castle PC26000 ($99, £65, AU$136) comes with a 26,000mAh battery and the RAVPower Xtreme 23000 ($99, £65, AU$136) that comes with a 23,000mAh internal battery.
Both units are about the size of a small 7- or 8-inch tablet. Both units share the same 7.3 x 0.8 x 4.9-inch (18.5 x 2.0 x 12.4cm) measurements, and traveling with either battery pack will add 1.5 pounds (0.68kg) to your gear bag. The upside is that with more than 20,000mAh of battery power, you likely won't need to carry your laptop's charger.
How much is 20,000mAh? For comparison, the Dell Latitude 12 7000 Series (E7250) battery is about 7,000mAh, while the Surface Pro 4's battery is just over 5,000mAh. Microsoft's 12-hour Surface Book battery comes in at a total of 9,187mAh, with the base containing a 6,800mAh battery and the tablet portion housing a 2,387mAh battery.
The IntoCircuit's 26,000mAh battery, if it's completely efficient, is theoretically capable of giving the Latitude three times more battery capacity than its internal battery and five times the charge of the Surface Pro 4.
I haven't done a full battery run-down by continuously using my Surface Pro 2, which comes with a 4,200 mAh battery, or my Surface Pro 4 and the IntoCircuit yet, but I had no problems lasting two full workdays without recharging either my tablet or the battery pack. The battery provided more than enough power to run my Surface Pro 4 for 18 hours of web browsing, emailing, word processing, and light video and music playback.
The IntoCircuit is housed in a silver brushed aluminum frame, whereas the RAVPower unit has black metal surfaces, save for the black plastic on the base. I prefered the IntoCircuit because I am rough on my gadgets, and the all-metal construction feels more reassuring than the RAVPower, which creaked when I pressed on the plastic.