One of the unsung uses of the iPad is as a personal LTE hotspot. It's rather easy to set up the device as a hotspot for a MacBook if you need to work away from WiFi, although you'll need to keep an eye on your data usage. Last year, Anand Lal Shimpi at Anandtech discovered that an LTE iPad 3 could work as a wireless hotspot for 25.28 hours, downloading data at 50 KB/s. Shimpi repeated his test with the new iPad Air and discovered that even despite having a much smaller battery, the iPad Air can run for 24.08 hours as a hotspot at twice the throughput rate (100 KB/s).
The iPad Air battery is quite a bit smaller due to the slim profile of the device -- it's a 32.4 Wh battery compared with the 42.5 Wh battery built into the third-generation iPad. As Shimpi points out, both the A7 system-on-a-chip and the Qualcomm MDM9615M modem in the iPad Air use a 28nm LP process that sips power.
Shimpi's test was to set the iPad Air up as a personal hotspot, using WiFi tethering to connect it to a 13-inch MacBook Pro with Retina display. He started the 100 KB/s transfer -- twice the data rate of the earlier test -- and turned the iPad Air's display off. After a day and 8 GB of data transfers, the iPad Air ran out of juice. As Shimpi notes, "you'll likely burn through your monthly data allotment before you run out of power."