An Update on Transformer Prime Battery Life & WiFi Issues
by Anand Lal Shimpi on December 2, 2011 11:14 AM ESTIn our review of ASUS' Eee Pad Transformer Prime I mentioned that I couldn't sustain speeds greater than 2Mbps over WiFi on my review unit. In practice, most web pages loaded at a meager 0.5Mbps. ASUS insisted the problem was limited to my unit however CNet referred to a similar issue in their testing:
Unfortunately, during the review process, we experienced some very suspect performance issues (detailed below), which led us to believe we were possibly in possession of a faulty unit. So, we are going to hold off on giving final ratings for the Prime, but check out our initial impressions.
At the same time, I had test data from both ASUS and NVIDIA that show the Prime is capable of reasonable WiFi speeds. Yesterday morning I received a replacement Prime which was tested prior to being sent my way. The good news is the 2Mbps cap and poor range are both gone, the new sample is much faster on WiFi. Clearly there was something wrong with my original unit and it's being sent back to ASUS today for an autopsy. The bad news is I was still getting numbers around half of the original Transformer.
Using Ookla's Speedtest.net web app I get a consistent 34 - 37Mbps on the original Eee Pad Transformer (our actual WiFi performance tests involve downloading a file from a local server, but Speedtest was a quick and easy way to verify the problem). My original Prime review sample averaged around 0.5Mbps, while the replacement Prime got around 10Mbps - all in the same test location. Fiddling around with location I could get the replacement Prime up to 16Mbps. My test area is riddled with challenging interference so I setup a separate test area in another room. Even after buying the same Netgear WNDR4500 wireless AP that ASUS verified 31Mbps+ operation on, I wasn't able to break 16Mbps.
I have four other APs covering my house, I turned all of the radios off as a last ditch effort. Boom - 36Mbps on the Prime.
The culprit appeared to be either my 3rd gen Time Capsule or 5th gen Airport Extreme, with those radios off and using the WNDR4500 I was able to get performance competitive to the original Transformer. Here's where things get interesting. The original Transformer was made out of plastic, through which RF travels quite nicely. The Prime's metal construction makes things a bit more finicky. Indeed this is exactly what I saw, where depending on tablet and AP orientation I'd see anywhere between 10Mbps and 36Mbps downstream (average speed tended to be in the 15 - 20Mbps range). Apple gets around this issue in the iPad by putting the WiFi antenna behind the plastic Apple logo, however it's not entirely clear to me where the WiFi antenna is on the Prime (I have this policy about not taking things apart until I'm done testing them).
As to why performance was lower with the Apple APs active, I'm not entirely sure. Chasing down RF interference issues can be a severe undertaking. One thing is for sure, the Prime is going to be far more finicky than its predecessor when it comes to reaching peak speeds over WiFi.
WiFi performance isn't the only thing that improved with the new unit - I'm getting much better battery life as well. Our video playback battery life test doesn't have anything running in the background, but we are actively connected to a WiFi network throughout the duration of the test. As I surmized in our review, it's possible that whatever was causing the WiFi issues also had a negative impact on battery life. Curious to find out if battery life had changed as well as how the TF Prime did in its Balanced power mode, that's the first test I ran upon receiving the new review unit. Things are starting to look a lot better:
I'm running the new unit through the test in Normal mode as well, I'll have updated results there by the end of the weekend. Given the rush to get the initial review out, you can expect a followup (along with a video review) sometime next week. I'll be working on it as well as some HDD/SSD caching stuff all weekend.
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Anand Lal Shimpi - Friday, December 2, 2011 - link
I'm very tempted to build a small Faraday cage, if I can manage a break before CES this is what I will be doing.Take care,
Anand
eddman - Friday, December 2, 2011 - link
Wouldn't a Faraday cage defeat the purpose? After all there is interference in real life all around us and devices should perform well in such conditions; or maybe you're thinking about conducting tests both inside and out of it.ATOmega - Friday, December 2, 2011 - link
Maybe it's a good way to create a baseline for other measurements?Lugaidster - Friday, December 2, 2011 - link
As much as I like reading news on new gadgets like the prime. Probably what excited me the most in this short article was this:"I'll be working on [...] some HDD/SSD caching stuff all weekend"
I hope to be reading about that soon :)
Cheers
quiksilvr - Friday, December 2, 2011 - link
I'm now even more curious as to what improvements ICS will or will not have on performance and battery life. My guess would be better quad corre optimization because even at 11 hours, this is still pretty low compared to a year old tablet.3DoubleD - Friday, December 2, 2011 - link
Why is there an expectation for significantly improved battery life when the Prime has1) Faster Quad-core vs Dual core manufactured on the same processing node (yes there is an LP companion core, but at best I'd expect that it would keep power draw equal between the two eg. better performance for the same power draw)
2) Brighter screen
3) Same lithium ion battery tech
And finally, when did 10+ hours of battery life become mediocre? In the world of laptops and cell phones, 10 h of constant use is incredible! And If you really want more battery life, buy the keyboard dock!
And sorry for venting on your post, but I've seen this comment all over the place and it's mind boggling. If you are comparing it to the iPads, then go with iOS if you want iOS. Like Anand has been saying, few people cross shop between iOS and Android. If you can deal with iTunes and Apple, then enjoy your 10% more battery life. If you can't, enjoy the "pathetic" 11 hours of HD video playback that you get with the Prime (without the dock).
Shazboticon - Friday, December 2, 2011 - link
I would love to see at least one reviewer perform a battery life test under the same conditions as Asus to see if the Asus claimed times can be duplicated. Specifically, the Asus site has the following footnote:"Battery life tested under power saving mode, playing 720p video
playback, Brightness:60nits, default volume with headphones."
I have yet to see any reviews do a battery test under these conditions. I understand reviewers are probably trying to do a more realistic battery test but I'd still like to see if the Asus claims can be met. Based on the 11 hour time reported in this review I'd guess yes.
Chillin1248 - Friday, December 2, 2011 - link
Anand, there is no need for you to wait to open the tablet, here are the pictures of the internals:http://www.wirelessgoodness.com/2011/11/02/asus-tr...
Anand Lal Shimpi - Friday, December 2, 2011 - link
I'm aware of the FCC photos unfortunately I can't really tell where the antenna is routed based on those photos :-/Chillin1248 - Friday, December 2, 2011 - link
I would say that the WiFi antenna is in the upper left corner in those images. Sensible location as well.