The iPad 2,4 Review: 32nm Brings Better Battery Life
by Anand Lal Shimpi on May 4, 2012 12:50 AM ESTSignificant Battery Life Improvements
We'll start with the latest iteration of our WiFi web browsing test. With some additional logic to defeat overly aggressive browser caching, this test cycles through dozens of web pages, pausing on each one to simulate reading time before moving onto the next one. Display brightness is kept constant at 200 nits while the test runs. Results are reported in hours of battery life before the tablet dies.
Most web browsing tests end up being significantly display limited, as in the display dominates most of the power draw. That being the case, the fact that we see a 15.8% increase in battery life from the new 32nm HK+MG SoC alone is very significant. Apple is very conservative internally about revising battery life ratings so it's no surprise that we don't see a change in the specs on the iPad 2, especially considering that so many units out there on the market are still older iPad 2,1 models.
The increase in battery life here is almost certainly due to lower leakage at idle and better active power as well. This is a real improvement.
Things get even better when we stress the real power hog on the SoC: Imagination Technologies' PowerVR SGX 543MP2 GPU. Taking up more area on the die than the dual Cortex A9 cores, the 543MP2 is really stressed during 3D gaming. What better way to measure the impact of the new 32nm SoC on battery life than with one of the most stressful 3D games out for iOS today: Infinity Blade 2.
Here we're looping through the same scene until the battery dies, once again at normalized brightness.
The 3rd generation iPad obviously doesn't do as well as the iPad 2 here, as it not only has a more power hungry GPU but it's also rendering the scene at a higher resolution (and driving a higher resolution panel). What's most impressive however is just how much better the iPad 2,4 does here: a 29% increase in battery life over the original iPad 2,1.
Riptide GP, a less stressful title, shows us similar results:
Finally we have our brand new video playback test. Here we've got a copy of the last Harry Potter movie with the credits stripped out (1:58:00 running time), transcoded to a 720p High Profile H.264 video with a 4Mbps average bit rate, playing back in a loop until the battery dies.
The iPad 2 holds a 19% advantage over the 3rd generation iPad (once again for obvious reasons), however the iPad 2,4 absolutely dominates with an 18% increase in battery life. At 15.7 hours this is an insane amount of battery life from a single charge. Granted end users will see lower numbers if you watch at higher brightness settings (200 nits on our test panel was around 40% brightness), but the advantage from the new iPad should still remain just as significant.
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Anand Lal Shimpi - Saturday, May 5, 2012 - link
An update - I didn't feel settled with my response to you so I ran a sanity check against a brand new (never before discharged) 45nm iPad 2 and measured a 2.2% difference between the results (fairly normal for run to run variation) and our iPad 2,1 numbers here.Take care,
Anand
Oxford Guy - Friday, May 4, 2012 - link
"There's no known way to tell whether you're getting an iPad 2,4 vs. the older iPad 2,1 without opening the box. The 2,4 unit I ended up with was made in China, ruling out manufacturing region as a way of telling. The external box looks identical, as does the device itself.To deal with that fact, Apple is continuing to ship the original 45nm iPad 2,1 alongside the new 32nm iPad 2,4. Any hiccups in Samsung's production of the A5 and there are still more than enough iPad 2,1s to go around. The risk of moving to 32nm is effectively mitigated, while the learnings Apple gains from building the 32nm A5 will pay off later this year as Apple ramps up production of a 32nm SoC for use in the next iPhone. It's a very smart strategy, one you would expect from an experienced chip company - not a device vendor."
Sorry, but I call this bad business. It's simply bad business for one customer to get something better than another, due to luck. It's business for people to not know what it is they're getting for their money.
Oxford Guy - Friday, May 4, 2012 - link
Correction: "It's bad business for people to not know what it is they're getting for their money."pixelstuff - Friday, May 4, 2012 - link
It's only bad business if people get something worse than what they think they are getting.Deelron - Friday, May 4, 2012 - link
They're either getting exactly what they paid for or more, I don't see any problem with that.ThreeDee912 - Saturday, May 5, 2012 - link
It's the same thing Microsoft and Sony have been doing with consoles. There are literally dozens of different revisions of the 360 and PS3 with more efficient components in them, with little or no difference in the packaging. It's why Anand referenced gaming consoles in his article.Mrmixor - Sunday, May 13, 2012 - link
Incorrect. Read latest posts! Buy iPad 2,4 at will! Crushes the iPad retina in key areas!Xerazal - Friday, May 4, 2012 - link
Serial number was DMQH98DRDFHW, not sure if that helps.had it exchanged without knowing it was the 32nm model, and now i have the normal ipad 2.. whats weird is that i checked the serial to see when they were both manufactured, and the 32nm ipad 2 was manufactured in March 2012 while the 45nm ipad 2 was manufactured in APRIL 2012. they still make the 45nm one i guess.. either that or this is a 32nm version, but geek bench is showing it as ipad 2 now with A5 processor?
Xerazal - Friday, May 4, 2012 - link
Part numbers are different. at least for black it is. Part number for old ipad is MC769LL/A while new is MC954LL/A. too bad i already exchanged my 32nm ipad out and got the 45nm model as a replacement because of light bleeding on the screen.. T~Tpixelstuff - Friday, May 4, 2012 - link
Is there a weight difference between a 2,1 and a 2,4 tablet? If so then maybe there is a weight difference in the full package.I suppose it is possible there are enough discrepancies in the batteries of an identical iPad model that it could make a weight reading impossible.