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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pk de cville - Sunday, November 3, 2013 - link
The $130 looks good when you consider...1 - T-mobile provides 200MB FREE data each month.
2 - The iPad Air supports any USA telecom sim on an easy swap switch. Can't find Tmobile? Just swap in your ATT, VERIZON, or SPRINT Sim, whatever works at the moment.
ivan256 - Monday, November 4, 2013 - link
It doesn't look good when you consider they're adding $30 in hardware to the device and charging you $130 for it.eek2121 - Sunday, November 3, 2013 - link
Heh...we android users don't need no stinkin extra 'monthly bill'. Just install this fabulous 'cyanogenmod' and save yourself $40/mo for the rest of your life. Loved the fact i was seeing 40 megs down, 10 megs up on a verizon LTE network in Ogunquit ME on my laptop last summer. Wish my cable internet were that fast.kmmatney - Monday, November 11, 2013 - link
We iPhone users (well, those of us who had Jailbroken devices) have been using the fabulous MyWi. But it does drain battery fairly quickly.dokujaryu - Saturday, November 2, 2013 - link
Can you run this again with bluetooth turned off?Hymnotix - Monday, November 4, 2013 - link
Hey Anand, thanks for doing this test. As a hotspot, does the iPad also have the capability to act as a router? Specifically I want to be able to send low-latency MIDI messages between the hotspot device and other iPads connected to it. This is a music making function that works great on my home wifi but I would love to know if I could go completely mobile by making a cellular iPad serve as my router.darkcrayon - Monday, November 4, 2013 - link
I haven't tried your particular scenario but I can confirm the "hotspot" iPad can communicate directly with the devices tethered to it (naturally, I mean why wouldn't it)? I've used it with one of those "remote camera" apps to connect an iPhone to an LTE iPad without needing an external wifi network.Hymnotix - Monday, November 4, 2013 - link
thanks, that is good to know. But does the data go thru the cell tower? That would use up data limits; and more importantly take longer than is acceptable for my music production apps.mkozakewich - Tuesday, November 5, 2013 - link
No, your iPad (or whichever tethering device) acts as a wi-fi router, so every device sends messages through it like they would a normal wi-fi router. Just like your home router, the wi-fi is combined with a modem so that outside calls can be made to the internet.Hrel - Monday, November 4, 2013 - link
Nice little test. But why don't you guys ever complain about data caps... you mention it in this article yet you say nothing of the moral negligence of implementing it or the corruption it's indicative in the ISP industry.I think the constant harping on about shitty screen, from this site, is at least partially to thank for the recent increase in screen quality. You should try and do the same thing with the evil the ISP's are getting away with. Not to mention network specific phones. We all know we SHOULD be able to buy a phone and take it to any network, but no one ever even talks about it.