iPad Air Delivers 24 Hours of Battery Life as LTE Hotspot
by Anand Lal Shimpi on November 2, 2013 1:15 AM EST
A year ago during my review of the LTE iPad 3 I decided to find out how long the iPad would last as a personal hotspot. With the display off and a single notebook tethered wirelessly to the iPad downloading at a constant 50KB/s, the LTE iPad 3 lasted 25.28 hours on a single charge.
The new iPad Air moves to a much smaller battery (32.4Wh vs. 42.5Wh), but at the same time it enjoys much lower platform power. The A7 SoC is built on Samsung's 28nm LP process, while the A5X used in the iPad 3 was a 45nm part. Qualcomm's MDM9600 in the iPad 3 was also built on a 45nm process, compared to the 28nm process used on the MDM9615M (the same modem used in the iPhone 5s). An improvement of two process nodes on both the SoC and modem should account for something.
I also crudely measured idle platform power as being substantially lower on the iPad Air compared to the iPad 4. All indications seem to point to the iPad Air being just as capable of an LTE hotspot with insane battery life as previous generation models. To find out I crafted a slightly updated version of the old test.
I set the iPad Air up as a personal hotspot, wirelessly tethering it to a 13-inch MacBook Pro with Retina Display. I started a constant 100KB/s transfer on the MacBook Pro (2x the transfer rate of my iPad 3 test) and with the iPad Air's display off I measured battery life. Last time I chose 50KB/s as it was the average transfer rate across our old WiFi web browsing battery life test, I doubled the workload to be more reflective of more strenuous demands. In reality I'd expect to see a burstier usage profile, but that's something for me to test down the road.
A total of 24.08 hours and over 8GB of transfers later, the iPad Air finally died. Just like last time, you'll likely burn through your monthly data allotment before you run out of power.
I've always been a fan of tablets with cellular connectivity as it is really improves the usability of the device. Tethering to a smartphone is always an option, but there's something to be said about the convenience of having a single device that is immediately connected. The ability to turn a tablet into an LTE hotspot with incredible battery life is just an added bonus.
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djscrew - Saturday, November 2, 2013 - link
thanks for giving me one more reason to hate the big 3 carriersHrel - Monday, November 4, 2013 - link
Who do you consider the big 3? ATT Verizon and Sprint or ATT verizon and Tmobile?Amkitsaw - Saturday, November 2, 2013 - link
That is pretty marvelous. I'd love to know how well the Nexus 7 (2013) and the latest iPad Mini do in this test; I already have a rMBP 13 so the iPad Air would be too similar in footprint for me to get.teiglin - Saturday, November 2, 2013 - link
Agreed, it'd be nice to have at least a few points of comparison--even if only one per SoC. I assume baseband power dominates a test like this and 95% of devices you'd be looking at us MDM9x15, but if it degrades into a linear test of battery capacity, that'd be good to know too.As for better tests, why not just run one or two of your desktop battery tests while tethered? As I understand, they all hit the internet in a pseudo-realistic fashion. It would also be nice to see how the battery life varies with number of devices tethered, though I realize I'm now asking for multiple days' worth of testing. Still, one can hope!
ananduser - Saturday, November 2, 2013 - link
Don't forget to add the Nokia 2520 LTE tablet, currently the only Windows(RT) tablet with LTE capability.bountygiver - Saturday, November 2, 2013 - link
Yup, I'd be happy to see how different phone and tablets perform compare to dedicated dongle, some stress test also can be done by sending large files between 2 devices connected to same hotspot.Malih - Saturday, November 2, 2013 - link
I'm actually interested how some phones are with LTE Hotspot battery life, probably should be a standard test with future smartphones and tablets review?djscrew - Saturday, November 2, 2013 - link
I agree, LTE hotspot battery life test for smartphones would be nice. Get on it Anandtech!Impulses - Sunday, November 3, 2013 - link
Umm, haven't they tested phone battery life as hotspots for years? Might've left it off a few reviews due to time constraints but it's been a staple of AT. Pretty sure they've tested with LTE when available too...jeffkibuule - Sunday, November 3, 2013 - link
Yeah, the problem with doing any kind of battery life testing is you can't effectively use the phone during that time. It kinda sucks.