HTC Sensation: assault on battery

, posted: 2-Aug-2011 19:11

In my first blog post, I mentioned the battery as something I'd get back to, and here it is at last. (In case you're interested, the HTC Sensationsports a Li-Ion 1520 mAh battery with a stand-by time of up to 400 hours on 3G, and a talk time of up to 6 hours and 40 minutes. If not, don't read that bit).

Notice that it clearly says "up to" and the chances of achieving any of those figures outside of a lab with a perfect cell signal and no interference at all, are basically zero. However, the numbers are indicative of the potential and make for comparison fodder when looking at competing hardware.

But what does it mean in real life, I hear you asking. Let's have a look.

A negative charge levelled at your battery

Smartphoneshave become powerful computing devices as well as complex communicators, with functionality rivalling gadgets that were science fiction a short couple of decades ago, and that functionality doesn't happen without hefty power consumption. Relatively, at least.

So when we consider the number of energy-draining components in the HTC Sensation, that tiny 1520 mAh (milliamp-hour) power pack is apparently on a hiding to nothing. And frankly, folks aren't inclined to cut it a lot of slack.

Common complaints revolve around a battery's inability to last a day. That's generally expected to be from unplugging from the charger at 7am and plugging back in at 10pm. And fair enough too. I'd be somewhat grumpy if I couldn't get a day's use out of the HTC Sensation. So can I?

The short answer - "yes".

But will the battery last all day if I watch video for 6 hours, or surf the web for 8 hours, or record audio for 5 hours, or talk on the thing for 4 hours?

Um, nope.

The fact is that performing the above tasks puts considerable drain on the battery through intense use of graphics processor, radios, CPU, audio processor and the operating system activity that enables them. To paraphrase the old adage, in smartphones, there's no such thing as a free launch.

Let's have a look at some battery hogs

Testing requires screen on so baseline consumption assumes that plus CPU, GPU, Android system and kernel activity.

Baseline power consumption = 560mW

GPS: 871mW -560mW = 311mW

WiFi: 720mW -560mW = 160mW

Voice call: 716mW -560mW = 156mW

Download (HSDPA): 1020mW -560mW = 460mW

Bluetooth; 579mW -560mW = 19mW

Video: 898mw -560mW = 338mW

Audio:945mw -560mW = 385mW

Those numbers will not all be truly representative of real life usage; for example, during a voice call the screen will not be on which would deliver a lower baseline score and therefore a higher indicated power usage than shown, but the samples above demonstrate the general principle.

The big surprise, to me at least, was how little the Sensation's Bluetooth subsystem consumes, a mere 19mW. That's a very efficient service. I doubt you'd need to turn that off to save your battery. But as I hardly ever use Bluetooth (no BT headset, and wired hands-free setup), it's never on normally.

What you might expect from your battery

To work out how long you can expect your Sensation's battery to last doing some smartphone type activity, you'd take the total power draw in mW, divide that by your battery's average voltage (nominally 3.85 volts based on 4.05 volts charged and 3.7 volts when indicating flat), and then dividing that milliamp value into the battery's maximum capacity (in mAh).

Taking audio as an example from this test, that's as follows...

945 (mW) / 3.85 (volts) = 245.5 milliamps

1520 (mAh) / 245.5 (mA) = 6.2hours

Of course, if you only have the screen on long enough to start the music player, then the screen drain will not be a factor and you'll get more music out of your battery than my example, but you get the idea I'm sure.

And other factors apply, including in this case, the volume setting of the music player, the complexity of the track, and the bit-rate of the file itself, among other things.

Extending your battery's duration

It will hopefully be clear that if you have all your Sensation's capabilities in use all the time, your battery duration will be heinous. That same inconvenient truth applies to any smartphone you consider though, so a few simple rules will help you achieve the magic 'whole day' benchmark and do so with ease.

Rule #1

Basically leave all the hardware you're not actually using turned off.

Rule #2

I can tell you from experience that auto-syncing your Sensation will result in a lot of drain, especially where signal is marginal for either wifi or 3G, so disable auto-sync unless you carry a spare battery with you. Getting emails over the air can easily be done with a manual sync by just launching your email app every so often and quitting the app when the sync is complete.

Rule #3

Some apps, like Locations, don't always shut their processes down, and their activity can gobble power faster than a cop at a donut convention. Take the time to check out the processes running before, during and after you use an app, especially those that use data (or attempt to) via wifi and/or 3G.

Sometimes a poor signal or no signal just makes them consume more CPU cycles and system resources at major cost to your battery endurance.

Rule #4

If your battery behaves poorly (no, I don't mean painting graffiti on the neighbour's fence, or pulling some young lady's pigtails) and seems always to have done, you may need a calibration. This juju is much derided by clever people on tech sites far and wide, so I will ignore that and tell you about it anyway.

Step onerequires you to charge the battery to its maximum capacity, and is best done with the Sensation turned off. When the little LED is a nice shade of green, unplug the phone and remove the battery for a couple of minutes. (No, I don't know why. Stop asking difficult questions). Then replace the battery and without turning the phone on, plug it back in to the wall charger.

Step tworequires that when the green light comes on again, unplug the Sensation and fire it up. Leave the phone on and run it flat. Not just until the warnings appear. Run it down until it shuts down by itself.

Step threeis a repeat of step one, so follow that. Your battery is now conditioned, or so say some including me. There are many who think that it's just superstitious mumbo-jumbo, and while they may be absolutely correct, it seems to work for me. Which probably says a lot about my mental health.

So what can I tell you... doesn't hurt to try and if it works for you, send me a six-pack of something cold and fizzy.

Step fourdoesn't exist.

Rule #5

Buy a spare battery. It'll cost you very little and will make your iPhone-owning friends seethe with envy and force them to claim that their phones never fail to last a day, something I can positively refute by detailing my better-half's iPhone battery tales of woe. But that's a future blog post perhaps.

There are after-market batteries of the same claimed capacity as the HTC Sensation's, the genuine OEM replacement (if you can find it), and the step brother of the Sensation, the EVO 3D, apparently has a longer duration (1730mAh) battery as standard and rumour suggests that it's an exact fit for the Sensation. But you didn't hear that from me.

Is it true that the HTC Sensation's battery life is poor?

No. Quite the opposite. While the HTC Sensation is an undeniably powerful smartphone with superb media and application capabilities, it's capable of quite stunning battery performance. If you're used to having to regularly put your current smartphone on charge during the day to keep it going until bedtime, you're going to be delighted by the Sensation.

Because we early adopters (take a bow lokhor and Linuxluver) are filled with admiration for the technorati who read this blog, we are happy to test the living daylights out of the Sensation so you won't have to. And so your experience will be as great as ours has turned out to be. Okay, that sounded a bit like an ad (not surprising considering my background), but honestly, we have done a bucket-load of testing to get down to a few simple truths.

And the most apparent one is that even with the standard firmware we're saddled with as this is written, the Sensation has stellar battery endurance. No fancy ROMs here folks. This is how the beast performs with the stock standard firmware and software out of the box.

What you see above is not some economy run special "nobody ever uses it like this" one-off fake benchmark rubbish. During a break in the intensive testing we testers have been doing on the highly demanding hardware and software capabilities of the Sensation, I used the phone in the way I normally would - albeit over a weekend. In fairness, the number of incoming calls, emails and txts reflect that weekend situation, but neither was the Sensation spared.

I have real doubts that any other smartphone with an equivalent specification will match the HTC Sensation in battery performance on a standard firmware. Moreover, when the 2.3.4 ROMs arrive for it, it's my honest expectation that its battery endurance will be even better. Much better.

The inescapable conclusion?

The battery endurance of the HTC Sensation is another impressive feature of this beautiful and powerful smartphone, and it possesses arguably the best combination of performance and endurance of any smartphone available anywhere. Good job HTC and Telecom New Zealand.

About that video post, erm...

About the author:

Andy (ArtooDetoo) may be a relative noob in comparison to his fellow HTC Sensation testers, being merely an "Ultimate Geek" in Geekzone, but it hasn't prevented him from commenting at length on numerous topics and forums, with a prolific presence in the Geekzone 'Android' area.

An advertising creative in his day job, he also possesses a passion for tech stuff - software and hardware - and besides having a number of gadgets to keep him interested, he also has a background in software development.

These attributes should at least give him the kind of analytical slant to temper opinion with reason. He and his fellow Telecom Ambassadors have already been hard at work testing and benchmarking so you'll get all the info without the effort. At least, that's the theory. Judge for yourselves.

Other related posts:
HTC Watch on HTC Sensation in New Zealand
HTC Sensation: The Story So Far
Testing mobile data speeds with HTC Sensation

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Telecom Tech is a different type of blog. We're sponsored by Telecom New Zealand, but most of the posts here are from every day users like you.

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Catch up on previous Telecom Tech reviews - read about the Nokia Lumia 1020Nokia Lumia 920, Samsung Galaxy Note II, Nokia Lumia 800, Nokia Lumia 710 and HTC Sensation.

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