The Apple iPad Review (2012)
by Vivek Gowri & Anand Lal Shimpi on March 28, 2012 3:14 PM ESTBattery Life
For a company that has been so laser focused on reducing weight and device thickness, the new iPad actually growing in both of these dimensions was unexpected. From a technical standpoint, the tradeoff makes sense. The new Retina Display consumes significantly more power than its predecessor, as do the A5X and MDM9600 baseband. Both of those ASICs are still built on a 4x-nm LP process and will surely increase power consumption over the iPad 2.
With more transistors switching on the same process node and a display (and backlight) driving more pixels at the same brightness, the battery either had to be larger or battery life would suffer. Apple understandably chose the former and the new iPad ships with a 42.5Wh battery—the largest we've ever seen used in an ARM tablet. The new iPad's battery is so large it's even bigger than what Apple uses in the 11-inch MacBook Air, and it's within striking distance of the 50Wh unit you'll find in the 13-inch model. I do believe this move says a lot about how Apple sees the iPad moving up in the world, but I'll get to a discussion about that later.
With a 70% larger battery than the iPad 2 but with more power hungry components inside, how does the new iPad fare in real world usage? Subjectively: it doesn't last as long as its predecessor. Objectively, our numbers seem to agree.
Our web browsing battery life test browses through dozens of web pages, pausing on each to simulate reading time, until the battery is depleted. All of our tests are run at the same brightness settings (200 nits) to ensure we are comparing apples to apples.
On WiFi we measured an 8% decrease in battery life compared to the iPad 2—nothing huge but not insignificant either. Fall off of WiFi and depend on LTE and you'll see around a 9% decrease in battery life, again—noticeable but not unusable.
I also threw in numbers from the Motorola Xyboard 10.1, an LTE enabled Android tablet running 3.2. Equipped with a much smaller battery (~26Wh), the Xyboard 10.1 delivered 7.31 hours in our LTE web browsing test. The new iPad managed to last 16% longer on a single charge—a smaller advantage than you'd expect given the 70% increase in battery capacity, showing just how much power the new Retina Display and its backlight consume.
The iPad is more than usable on long flights or throughout the day without being tethered to a wall outlet, but in practice you can expect a decrease in battery life compared to last year's model.
Keep in mind that these values are all at 200 nits (roughly 70% brightness on the iPad). If you use the iPad at max brightness (~400 nits) you'll see considerably lower numbers:
In our web browsing test, at max brightness, we saw 5 hours and 34 minutes of continuous use before the battery died. The iPad 2 incurs a similar penalty, lasting under 7 hours in the same test. Do keep this in mind if you need to get a lot of untethered use out of the new iPad. In order to come close to Apple's battery life estimates you'll have to be below 70% brightness.
Charging
Despite the significant increase in battery capacity, Apple continues to ship the new iPad with the same 10W USB power adapter as the previous two models. You can charge the iPad via a Mac/PC USB port that implements the USB charging spec, however doing so will take a minor eternity to fully charge the tablet. Just as before, the new iPad will not charge off of a USB port if the tablet is awake; it will only charge when locked/asleep. The convenience of having a USB based charger is evident, but you'll want to stick with the 10W adapter to actually charge the iPad.
Charging the larger battery does take longer. If we measure from a completely dead state to when the iPad indicates that it's fully charged the increase in time is approximately 50%, from 4 hours with the iPad 2 to 6 hours with the new iPad. ASUS' Transformer Prime, by comparison, requires only 2.5 hours as it ships with an 18W charger. And no, you can't use ASUS' charger to speed up charge times on the new iPad—when connected, the TF Prime charger will only supply 9W to the iPad.
The story doesn't end there however. While the iPad 2 will draw 0W after its 4 hour charge cycle is complete, the new iPad will continue to draw around 3W after it claims to be fully charged. This will continue for roughly another hour at which point the power adapter will draw anywhere from 0.1—0.6W.
Note that when running at full brightness and with a heavy GPU load (e.g. Infinity Blade 2), the power adapter can't supply enough to keep the iPad charged and drive the display/internal components.
There's no good solution here other than for Apple to start shipping the iPad with a higher wattage power adapter. I do believe faster charge times are going to be necessary if Apple is keen on sticking with this larger battery, not to mention the usage issues of not being able to maintain charge equilibrium under load.
Thermals
The increase in power consumption of the new iPad also manifests in the form of increased heat production. A 163mm^2 SoC built on a 45nm LP process is a serious chip. Although it doesn't run hot enough to require active cooling, the SoC alone is responsible for a couple of watts of the iPad's TDP under heavy load. Combine that with a 45nm LTE modem and the heat put off by the more powerful backlight and you've got a recipe for a noticeably warmer device.
Does the new iPad get warmer than the previous one? Absolutely. I would even go as far as to say that it can get uncomfortably warm, but it never gets too hot to hold. If you've used any of the modern Mac notebooks, I don't believe it's anywhere near as bad.
When holding the new iPad in portrait mode, with the home button at the bottom, the lower left corner of the device ends up being the warmest. Along the left edge of the iPad is where the logic board resides, and the lower half is home to the A5X SoC. Under load, particularly a heavy GPU load (e.g. playing a 3D game), this area is going to heat up quickly.
I took several measurements using a contactless IR thermometer in the same ambient conditions on a new iPad vs. the iPad 2. The results are below:
Thermal Comparison (Max Temperature) | |||||
iPad 2 | iPad (3rd generation) | ||||
Web Browsing (2 hours) | 32.7˚C | 37.6˚C | |||
Infinity Blade 2 (1 hour) | 34.2˚C | 41.9˚C |
Again, I don't believe this is a deal breaker but it's the obvious result of remaining on Samsung's 45nm LP process combined with a more power hungry display/backlight. I suspect there will be improvements in efficiency on the display side over time, but I can't see the Retina Display being any lower power than the iPad 2's 1024 x 768 screen. The real avenue for improvement will be when Apple shifts to 28/32nm silicon for the SoC and LTE modem. If you want a cooler running iPad, you'll have to wait until next year for that.
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doobydoo - Saturday, March 31, 2012 - link
Lucian Armasu, you talk the most complete nonsense of anyone I've ever seen on here.The performance is not worse, by any stretch of the imagination, and lets remember that the iPad 2 runs rings around the Android competition graphically anyway. If you want to run the same game at the same resolution, which wont look worse, at all (it would look exactly the same) it will run at 2x the FPS or more (up-scaled). Alternatively, for games for which it is beneficial, you can quadruple the quality and still run the game at perfectly acceptable FPS, since the game will be specifically designed to run on that device. Attempting anything like that quality on any other tablet is not only impossible by virtue of their inferior screens, they don't have the necessary GPU either.
In other words, you EITHER have a massive improvement in quality, or a massive improvement in performance, over a device (iPad 2) which was still the fastest performing GPU tablet even a year after it came out. The game developers get to make this decision - so they just got 2 great new options on a clearly much more powerful device. To describe that as not worth an upgrade is quite frankly ludicrous, you have zero credibility from here on in.
thejoelhansen - Wednesday, March 28, 2012 - link
Hey Anand,First of all - thank you so much for the quality reviews and benchmarks. You've helped me build a number of servers and gaming rigs. :)
Secondly, I'm not sure I know what you mean when you state that "Prioritizing GPU performance over a CPU upgrade is nothing new for Apple..." (Page 11).
The only time I can remember Apple doing so is when keeping the 13" Macbook/ MBPs on C2Ds w/ Nvidia until eventually relying on Intel's (still) anemic "HD" graphics... Is that what you're referring to?
I seem to remember Apple constantly ignoring the GPU in favor of CPU upgrades, other than that one scenario... Could be mistaken. ;)
And again - thanks for the great reviews! :)
AnnonymousCoward - Wednesday, March 28, 2012 - link
"Retina Display" is a stupid name. Retinas sense light, which the display doesn't do.xype - Thursday, March 29, 2012 - link
GeForce is a stupid name, as the video cards don’t have anything to do with influencing the gravitational acceleration of an object or anything close to that.Retina Display sounds fancy and is lightyears ahead of "QXGA IPS TFT Panel" when talking about it. :P
Sabresiberian - Thursday, March 29, 2012 - link
While I agree that "Retina Display" is a cool enough sounding name, and that's pretty much all you need for a product, unless it's totally misleading, it's not an original use of the phrase. The term has been used in various science fiction stories and tends to mean a display device that projects an image directly onto the retina.I always thought of "GeForce" as being an artist's licensed reference to the cards being a Force in Graphics, so the name had a certain logic behind it.
;)
seapeople - Tuesday, April 3, 2012 - link
Wait, so "Retina Display" gets you in a tizzy but "GeForce" makes perfect sense to you? You must have interesting interactions in everyday life.ThreeDee912 - Thursday, March 29, 2012 - link
It's basically the same concept with Gorilla Glass or UltraSharp displays. It obviously doesn't mean that Corning makes glass out of gorillas, or that Dell will cut your eyes out and put them on display. It's just a marketing name.SR81 - Saturday, March 31, 2012 - link
Funny I always believed the "Ge" was short for geometry. Whatever the case you can blame the name on the fans who came up with it.tipoo - Thursday, March 29, 2012 - link
iPad is a stupid name. Pads collect blood from...Well, never mind. But since when are names always literal?doobydoo - Saturday, March 31, 2012 - link
What would you call a display which had been optimised for use by retinas?Retina display.
They aren't saying the display IS a retina, they are saying it is designed with retinas in mind.
The scientific point is very clear and as such I don't think the name is misleading at all. The point is the device has sufficient PPI at typical viewing distance that a person with typical eyesight wont be able to discern the individual pixels.
As it happens, strictly speaking, the retina itself is capable of discerning more pixels at typical viewing distance than the PPI of the new iPad, but the other elements of the human eye introduce loss in the quality of the image which is then ultimately sent on to the brain. While scientifically this is a distinction, to end consumers it is a distinction without a difference, so the name makes sense in my opinion.