Paperwhite: how to turn of backlight completely? - Page 2

sparklemotion · 02-09-2013, 11:29 AM

Quote:

Originally Posted by Jackie7

But why is it not possible to turn it of? The other kindles don't have that light, and therefore much longer battery life. Why did Amazon sacrifice that?

This has actually not been true for me personally. If I use my PW at low light levels, the battery on my on my Paperwhite lasts longer than the battery on my touch, for instance. However, the battery on my kindle keyboard does last longer.

In the comparison with my kindle keyboard, I still don't see it as sacrificing because the Paperwhite performs a function that my other kindles don't. I think you have to take that into account.

What's more important to you, having a light, or having longer battery life? It's not a big deal to me at all to plug my PW in more than I would my kindle keyboard, especially since it means having the benefit of a built in light. So that's my take on it.

ProDigit · 02-09-2013, 10:45 PM

It's just one piece of bad manufacturing!
In many cases, people don't even see if the light is on or not.
In such cases you might as well save the battery!

I don't know how much the touch screen uses, but hope it uses very little, and turns off when not in use.

More than likely, the touch screen uses more power than the screen light, when setting it below 3.

Amazon knows they could have easily turned off the light. It would have made so many people worry less, in a society that has learned to preserve energy when they can.
Maybe in the US it's less of an issue, but generally in the rest of the world, you also turn off a light when you leave the room, or don't need it.
For many europeans (and asians, and perhaps other people in the rest of the world), leaving on a light, when leaving a room, is like leaving your car in a parkinglot, with the car keys on the door.
It just does not feel right.

Amazon does not seem to understand it, and despite the updates, hasn't yet addressed a 30 minutes programming error like this!

NullNix · 02-10-2013, 05:36 PM

Quote:

Originally Posted by ProDigit

It's just one piece of bad manufacturing!
In many cases, people don't even see if the light is on or not.
In such cases you might as well save the battery!

The difference in battery life is only a few percent at low levels (I've seen figures like half an hour for off versus level 5, let alone level 0). There's no point optimizing for that, not given that they doubled the size of the battery in the PW versus the Touch specifically because of the extra power draw of the lights. LEDs are pretty power-efficient contraptions.

Quote:

Originally Posted by ProDigit

I don't know how much the touch screen uses, but hope it uses very little, and turns off when not in use.

It's an e-ink screen, so, none, any more than a piece of paper uses power to display print. It uses energy to change state (i.e. to refresh content), not to display: you can rip the screen right out of the device and it will stay displaying what it displayed last. (The capacitative touch layer uses a little power, but we're talking milliwatts.)

kennyc · 02-10-2013, 05:55 PM

Quote:

Originally Posted by Jackie7

But why is it not possible to turn it of? The other kindles don't have that light, and therefore much longer battery life. Why did Amazon sacrifice that?

This is one reason I've avoided purchasing one I only use my e-ink reader when I'm outside or in 'normal' pbook reading light.

vxf · 02-10-2013, 08:14 PM

I am constantly amazed by how different people's opinions of the PW battery life are. I keep the wifi on and my battery lasts a blink. Well, ok, 12 hours. Lots of blinks. But still, not very long.
So people say 'it's the wifi/3g'. But the battery on my KT was endless.
Hence, it is the screen. But some users here seem to not have battery life issues.
I am starting to wonder if my unit is just defective. But I charge it every other day...

sparklemotion · 02-10-2013, 11:04 PM

Quote:

Originally Posted by vxf

I am constantly amazed by how different people's opinions of the PW battery life are. I keep the wifi on and my battery lasts a blink. Well, ok, 12 hours. Lots of blinks. But still, not very long.
So people say 'it's the wifi/3g'. But the battery on my KT was endless.
Hence, it is the screen. But some users here seem to not have battery life issues.
I am starting to wonder if my unit is just defective. But I charge it every other day...

I had that problem with my kindle touch. The battery barely seemed to last at all. Interesting that our experiences are the opposite. The best battery I've had on a kindle device is by far on my kindle keyboard. It seems to last forever. Then again, I realize it's a more basic reader without the frills.

NullNix · 02-11-2013, 08:07 AM

Quote:

Originally Posted by vxf

I am constantly amazed by how different people's opinions of the PW battery life are. I keep the wifi on and my battery lasts a blink.

The wifi uses a *lot* of power, and isn't entirely off even when the machine is otherwise suspended (IIRC). When I turn it on, associated and with a strong signal, my battery drains about twice as fast as it otherwise would. If the signal is weak, the drain is even faster. That suggests it's using more power than the screen.

Amazon's suggestion that people leave the wifi on so they can receive OS updates is nuts in my opinion. I don't know anyone who does it, though perhaps people who are used to plugging everything they own in to recharge every night are happy to leave the wifi on 24/7.

HarryT · 02-11-2013, 09:21 AM

Quote:

Originally Posted by vxf

I am constantly amazed by how different people's opinions of the PW battery life are. I keep the wifi on and my battery lasts a blink. Well, ok, 12 hours. Lots of blinks. But still, not very long.
So people say 'it's the wifi/3g'. But the battery on my KT was endless.
Hence, it is the screen.

It's easy to determine whether it's the screen or the WiFi. Time the battery life first with WiFi on, and then with WiFi off.

What brightness do you have your screeen set to? The lighting uses many times more power at maximum brightness than at mid brightness-levels.

vxf · 02-11-2013, 09:43 AM

Quote:

Originally Posted by NullNix

The wifi uses a *lot* of power, and isn't entirely off even when the machine is otherwise suspended (IIRC). When I turn it on, associated and with a strong signal, my battery drains about twice as fast as it otherwise would. If the signal is weak, the drain is even faster. That suggests it's using more power than the screen.

Amazon's suggestion that people leave the wifi on so they can receive OS updates is nuts in my opinion. I don't know anyone who does it, though perhaps people who are used to plugging everything they own in to recharge every night are happy to leave the wifi on 24/7.

I get the Wall Street Journal and the Financial Times delivered via WIFI.
Plus, I like my books and notes to sync.
So I don't ever turn it off.

vxf · 02-11-2013, 09:46 AM

Quote:

Originally Posted by HarryT

It's easy to determine whether it's the screen or the WiFi. Time the battery life first with WiFi on, and then with WiFi off.

What brightness do you have your screeen set to? The lighting uses many times more power at maximum brightness than at mid brightness-levels.

Brightness 12-14 usually.
I have tried somehow casually, but I get very inconsistent results.
I think it has a lot to do with what/how I read. I noticed that on days I just sit down and read a book linearly, battery consumption is not high.
But, on days I flip back-and-forth on the WSJ, the battery drains much faster during the same reading time.

But one thing I know is that my reading habits were the same on my KT - and I used to get the same subscriptions. So I think that means that it is, after all, the screen that makes the difference.

hunnymonster · 02-11-2013, 12:51 PM

Quote:

Originally Posted by NullNix

(The capacitative touch layer uses a little power, but we're talking milliwatts.)

I'd hope it was micro watts actually.

NullNix · 02-13-2013, 08:58 AM

Quote:

Originally Posted by vxf

I get the Wall Street Journal and the Financial Times delivered via WIFI.
Plus, I like my books and notes to sync.

So do I (well, the Economist, NS, and a bunch of SF magazines). That's why I flip it on and sync every morning. So the wifi is on for half a minute rather than a whole day. That saves rather a lot of power.

(Of course, if I had other devices and wanted the last-read-position syncing rather than just using it as a backup mechanism, I might value leaving wifi on...)

ProDigit · 02-13-2013, 03:20 PM

Quote:

Originally Posted by hunnymonster

I'd hope it was micro watts actually.

usually a cap touchscreen uses like 100mW. However I do believe on these small devices, that there's much less power draw than on my 14" laptop.
10mW would be a guesstimate...

Penforhire · 02-13-2013, 04:29 PM

Hmm, You might be spot-on at 10 mW. I haven't found typical values for current draw by touch screen type. I see an example capacitive panel for sale at http://olink.en.alibaba.com/product/...uch_Panel.html claiming --
Deep sleep state current draw: 0.2 μA typical
Low power state current draw 0.8 mA typical
Active state current draw (continuous finger tracking): 8 mA typical

I imagine IR touchscreens use more energy (enough to create and detect many criss-cross IR beams).

ProDigit · 02-14-2013, 02:43 AM

mA is something different from mW.

But then again, a touch screen uses less energy than an SD card drive.
It is best to use the touch screen sparingly, by tapping. When you slide a lot to swipe pages, you're using more CPU, and touch screen power.
It registers every point your finger goes on the screen.
The less points, the less computation.

02-09-2013, 10:45 PM	#17
ProDigit Karmaniac Posts: 2,158 Karma: 9023682 Join Date: Oct 2008 Location: Miami FL Device: PRS-505, Jetbook, Jetbook Mini, Jetbook Color, Astak Ez Reader Pro	It's just one piece of bad manufacturing! In many cases, people don't even see if the light is on or not. In such cases you might as well save the battery! I don't know how much the touch screen uses, but hope it uses very little, and turns off when not in use. More than likely, the touch screen uses more power than the screen light, when setting it below 3. Amazon knows they could have easily turned off the light. It would have made so many people worry less, in a society that has learned to preserve energy when they can. Maybe in the US it's less of an issue, but generally in the rest of the world, you also turn off a light when you leave the room, or don't need it. For many europeans (and asians, and perhaps other people in the rest of the world), leaving on a light, when leaving a room, is like leaving your car in a parkinglot, with the car keys on the door. It just does not feel right. Amazon does not seem to understand it, and despite the updates, hasn't yet addressed a 30 minutes programming error like this! __________________ --------------------------------- BOOO! ks. I read Internet instead of books.

02-10-2013, 08:14 PM	#20
vxf Guru Posts: 876 Karma: 1397724 Join Date: Jun 2010 Location: Norman, OK Device: Sony PRS 350, 900, 950; iPad3, iPad Mini; Kindle Touch, Paperwhite	I am constantly amazed by how different people's opinions of the PW battery life are. I keep the wifi on and my battery lasts a blink. Well, ok, 12 hours. Lots of blinks. But still, not very long. So people say 'it's the wifi/3g'. But the battery on my KT was endless. Hence, it is the screen. But some users here seem to not have battery life issues. I am starting to wonder if my unit is just defective. But I charge it every other day... __________________ I received in inheritance neither god, nor a given spot on earth from where I can draw the attention of a god: no one either legated me the well disguised fury of the skeptic, the Sioux guiles of the rationalist or the burning innocence of the atheist. So I dare not throw the stone neither at the one who believes in things which inspire me only doubt, nor at the one who cultivates his doubt as if it was not, just as well, surrounded with darkness. STIG DAGERMAN

02-14-2013, 02:43 AM	#30
ProDigit Karmaniac Posts: 2,158 Karma: 9023682 Join Date: Oct 2008 Location: Miami FL Device: PRS-505, Jetbook, Jetbook Mini, Jetbook Color, Astak Ez Reader Pro	mA is something different from mW. But then again, a touch screen uses less energy than an SD card drive. It is best to use the touch screen sparingly, by tapping. When you slide a lot to swipe pages, you're using more CPU, and touch screen power. It registers every point your finger goes on the screen. The less points, the less computation. __________________ --------------------------------- BOOO! ks. I read Internet instead of books.

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02-13-2013, 04:29 PM	#29
Penforhire Wizard Posts: 1,845 Karma: 5514220 Join Date: Nov 2007 Location: Southern California Device: Kindle PW, PRS-650, iPhone 4, iPad 4	Hmm, You might be spot-on at 10 mW. I haven't found typical values for current draw by touch screen type. I see an example capacitive panel for sale at http://olink.en.alibaba.com/product/...uch_Panel.html claiming -- Deep sleep state current draw: 0.2 μA typical Low power state current draw 0.8 mA typical Active state current draw (continuous finger tracking): 8 mA typical I imagine IR touchscreens use more energy (enough to create and detect many criss-cross IR beams).


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