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Old 09-16-2012, 05:41 PM   #1
hkbeun
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Device: pocketbook 912
Battery life of pocketbook 912

I bought a pocketbook 912 in august 2012. I'm very happy with this eBook and it reads all the stuff I have. Nice big screen for 50+, only a little heavy.

I'm very curious about other user experiences with regard to battery life. With WiFi switched off, mine 912 last about 1000 to 1200 pages or about three books read in one or two weeks. Pocketbook is advertising with 7000 pages battery life. The battery has been charged and discharged a few times, but no improvement. Any similar experience with a 912, 902 or 903 pocketbook?

Note that my pocketbook was manufactured in November 2011, so it spent 6 months in storage but was still sealed and untouched. Software upgraded from 2.01 to software 2.03.
My brother had similar experiences with two Sony's. Much less battery life then promised.

Any thoughts or similar experiences?

Last edited by hkbeun; 09-16-2012 at 05:50 PM. Reason: spelling error
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Old 09-16-2012, 06:25 PM   #2
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Welcome to reality...

This is because of the test setup: Reader upright, no motion no touchscreen. Switch on and after booting remove power. Turn a page every two seconds until device turns off.
Just be happy about the awsome time between charging cycles and go to the next electronic market and buy a cheap USB wallcharger that delivers more than 1000mA so you don't need a computer to recharge.

BTW nearly everyone here made this experience to a more or lesser extent
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Old 09-16-2012, 06:34 PM   #3
hkbeun
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Device: pocketbook 912
In addition some thoughts and tries to reduce battery power consumption of the 912:

- Book format used is epub. Does RTF format take less (CPU) & power?
- Used an extra SD card of 8 gbytes. Does this increase power consumption? Haven't tried to operate without, there is an suggestion on the web that for Sony it makes a difference.
- Reduced total screen refresh settings from every page to once in ten. Much better reader experience (so I suggest you do the same) but didn't make a difference in battery life.
-In a separate trial, the MP3 player lasted at least a few hours. Does this indicate a healthy battery?

Last edited by hkbeun; 09-16-2012 at 06:40 PM.
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Old 09-16-2012, 08:52 PM   #4
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The best thing you can do for battery life is: not using the touchscreen (stylus in it's pocket, there's a switch) turn off G-sensor, avoid WiFi and audio player.
Book formats and page refresh do not influence battery life that much. If you want to know about the exact state of your battery the only way is to open the device, remove the battery and let it test by an expert.
Otherwise 1000 to 2000 pageturns is completely satisfying...
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Old 11-18-2012, 01:31 PM   #5
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Device: pocketbook 912
Battery life of pocketbook 912, power consumption measuring results

Well as an electrical engineer, I could not resist to measure it with the following results:

Han,
the Netherlands

912 e-reader power consumption measurement with two simple multi meters.

Results:
1) You can read 4 books maximum with one battery charge. Theoretical you could turn about 4500 pages but the continuous consumption of 30 mA will drain the battery more so practical is about 1200 pages maximum with one battery charge.

2) Playing MP3 music or browsing will drain your battery in 4 to 5 hours


Measurement details:

Equipment tested:
Pocketbook 912 e-book with software v2.13 with 8 gbyte SD flash,
battery capacity 1,530 Ah

Turning a page of an epub file on SD memory, current 0,3 amp for about 3,5 sec
Turning a page of an epub file on internal memory, current 0,3 amp for about 4,0 sec
Turning a page of a txt file on SD memory, current 0,3 amp for about 3 sec
So power consumption is typical 0,3 amp while green led is lit

Wifi on, browsing, in rest, no keyboard action, current 0,16 amp
Wifi on, Browsing active, current about 0,3 amp

MP3 player, current about 0,3 amp

No action, wifi off, continuous background power consumption current about 30 mA
E-reader locked, current about 3 mA
Powered down, current about 0,01 mA

Based on above, I estimate you can read without a recharge maximum about 4 books of 300 pages in a few days. About 2/3 of the power will be drained by the 30 mA continuous current, the other 1/3 by turning the pages and some due to the startup/power down.

So reading 1200 pages will drain battery:
1200 pages*0,3amp*(4/3600) equals 0,4 Ah

Based on a reading speed of 40 pages/hour including breaks, you need for 1200 pages about 30 hours, so continuous background power consumption will be:
30 hours* 0,03A equals 0,9 Ah

So total for 4 books 0,4 + 0,9 equals 1,3 Ah. The remaining of the battery capacity of 1,53 Ah will go coffee breaks, power/up/downs.

Browsing or playing MP3 will drain the battery in 4 or 5 hours. 5 hours * 0.3 amp equals 1,5 Ah

Keeping the 912 locked will drain the 912 battery in about 3 weeks 0,003*24*21 equals 1,512Ah

Measuring was done with two simple multi meters. The main meter was in 10,00 amp range, otherwise too much voltage drop across the meter would prohibit the 912 to work/boot. As soon there was a small power consumption, a second lower range current meter was switched in parallel and the main meter decoupled. Measured values could have an error due to the simple setup with DC multi meters and no correction for pulsating current. However results are matching with practical experiences

Last edited by hkbeun; 11-18-2012 at 01:39 PM. Reason: update
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Old 11-18-2012, 03:22 PM   #6
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Good work! Thanks for sharing that information.
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