Paperwhite Battery life

[HarryT]

Originally Posted by DuckieTigger

Is there any danger in running the battery completely dead on Kindles (not just PW)? Do I lose where I am at? Does it try to sync just before it dies?

No, you won't lose anything. The battery isn't anything like dead when you get the recharge warning.

[Julius Caesar]

I posted my battery benchmark at Amazon forum but I will copy and paste it here for convenience. Please note that at all cases, wireless and page refresh are off. Battery life does not include the time when the device goes to sleep. Battery life is from the time the battery is fully charged to the time I got low battery warning.

I. Battery life: 13 hours 32 minutes
LED brightness: level 24 (Full blast)

Most people read less than 13 hours per day. So, as long as you plug your Kindle before you go to bed, your Kindle should meet your reading need for the whole day, even when the LED brightness is at full blast.

II. Battery life: 47 hours 39 minutes
LED brightness: level 10

Amazon advertised PW battery life with LED level 10, wireless off is 8 weeks, half an hour per day which amounts to 28 hours. So, 47 hours and 40 minutes exceeds all expectations.

III. Battery life: 49 hours 35 minutes
1. LED brightness: level 0 (lowest level)

Between LED level 10 and 0, battery life is only about 2 hours longer but keep in mind that at more than 49 hours, battery life is still significantly longer than that of Kindle Touch advertised at 2 months, half an hour per day which amounts to 30 hours.

IV. The time it takes to charge the battery: 3 hours and 20 minutes. The device is completely turned off when the battery is charged.

[geekmaster]

The battery power and charging is controlled by the firmware. A battery can go completely dead (which can damage it) if the kindle is bricked or left in diagnostics mode. It can take up to a full day to recharge a drained battery before the kindle can even boot all the way up. You can see this explained over and over in the dev corner, where a kindle APPEARS bricked when it really just has a COMPLETELY dead battery.

[sirmaru]

Originally Posted by Julius Caesar

I posted my battery benchmark at Amazon forum but I will copy and paste it here for convenience. Please note that at all cases, wireless and page refresh are off. Battery life does not include the time when the device goes to sleep. Battery life is from the time the battery is fully charged to the time I got low battery warning.

I. Battery life: 13 hours 32 minutes
LED brightness: level 24 (Full blast)

Most people read less than 13 hours per day. So, as long as you plug your Kindle before you go to bed, your Kindle should meet your reading need for the whole day, even when the LED brightness is at full blast.

How did you prevent the PW from going into Sleep Mode after 5 minutes? If you did not prevent that action, then your numbers are overstated.

I used an Excel Spreadsheet for one complete PW battery cycle to record start and stop times for 25 reading sessions carefully recorded. The total, when the recharge screen (battery icon + wire icon + power icon) was reached, was 10 hours and 29 minutes at PW light level of 22 out of a possible 24.

Power use records for the KF1G, KFHD and PW are overstated by most folks since precise measurement standards are NOT used. For the KF1G and KFHD the GSam Battery Monitor offers precise battery use measurements.

For the PW battery energy to be measured properly, it would have to be left on with automatic sleep mode disabled and then clocked to its recharge screen.

I leave WiFi on all the time for continuous syncing between my three Kindles and the GSam App shows WiFi uses very little energy compared to screen use.

[DuckieTigger]

Originally Posted by sirmaru

How did you prevent the PW from going into Sleep Mode after 5 minutes? If you did not prevent that action, then your numbers are overstated.

He clearly stated that the time the device was going to sleep are NOT included in his times. More than likely he just simply read through the 13 hours in one sitting or split it up to 6 1/2 hours over a period of 2 days.

[sirmaru]

Originally Posted by DuckieTigger

He clearly stated that the time the device was going to sleep are NOT included in his times. More than likely he just simply read through the 13 hours in one sitting or split it up to 6 1/2 hours over a period of 2 days.

True, that is the normal measurement standard used by most folks. However, it is unlikely that anyone can stay in reading mode wihout interruptions for even 2 hours, much less 6 or 13 hours.

To really have a valid way of measuring a PW, one MUST record each reading session in a spreadsheet using date, start time, end time, reading time. Then have the spreadsheet total the reading times. The vast majority of users would never devote the time or precision to make that measurement.

I've only done that for ONE cycle and will probably never do it again. It is simply too much of a bother.

A better way would be to disable the normal sleep mode trigger and then just leave the unit on permanently until the battery ran down to the recharge screen. One would also have to observe it the entire time to be sure one got the ending time correct.

Even then the measurement would be for just one unit at one time in it's life. Battery cycle life may vary by unit and over it's own total life.

A better way to observe the battery is just to record how many days it goes until recharge is necessary on a spreadsheet with one's own reading habits. My PW has lasted 7 or 8 days until a recharge is necessary using the battery meter to judge when to recharge. However, my latest PW cycle has already lasted 14 days. However, this time I am not using the battery meter but instead I'm awaiting the appearance of the Recharge screen (battery icon + wire icon + power icon).

[Julius Caesar]

Originally Posted by sirmaru

To really have a valid way of measuring a PW, one MUST record each reading session in a spreadsheet using date, start time, end time, reading time. Then have the spreadsheet total the reading times. The vast majority of users would never devote the time or precision to make that measurement.

That's exactly how I measure the battery life and I don't mind doing it. If you find that your battery life is less than satisfactory, your device may still indexing books while you are reading. Indexing will drain your battery pretty quickly.

[sirmaru]

Originally Posted by Julius Caesar

That's exactly how I measure the battery life and I don't mind doing it. If you find that your battery life is less than satisfactory, your device may still indexing books while you are reading. Indexing will drain your battery pretty quickly.

If you did that, then your numbers are reliable. I only ran that test once when I first purchased the PW.

I have noticed now that, waiting for the Recharge screen, I have already gotten 14 days on my current charge versus 7 or 8 when relying on the meter looking low.

I may do one more measurement after the Recharge screen is reached until the following Recharge screen notice. It well could be a longer cycle than I recorded initially.

Its too bad we don't have an Active Content Battery Meter for the PW with similar measurement capabilities to the GSam Battery Monitor for the Kindle Fire HD.

[SchrodingersCat]

Originally Posted by sirmaru

To really have a valid way of measuring a PW, one MUST record each reading session in a spreadsheet using date, start time, end time, reading time. Then have the spreadsheet total the reading times. The vast majority of users would never devote the time or precision to make that measurement.

To be even more pedantic, you would also have to record the number of page turns per reading session. As previously mentioned, a major consumer of power for any e-ink device is changing the display. You would also need to note whether you're doing a full refresh each time, as that also changes the amount of power consumed per page turn.

Any way of measuring the battery life that works for an individual is "valid." Few people are especially concerned with the total hours of reading time, so much as how many days they can go without charging their device based on their own personal usage. So someone saying "I read about 2 hours a day and it lasts two weeks" is an extremely valid, albeit completely subjective, way to measure battery life.

What's more interesting to me is the difference between level 0, 10, and full. It's nice to know that turning the light right off isn't "worth it" from a battery consumption POV if it affects my reading comfort, but that cranking it will reduce my time between charges by almost 75%. With all your spreadsheet advocacy, you didn't mention what level you were reading at and whether you changed it depending on lighting conditions.

[guitarizt]

I like hours instead of days/weeks. Some weeks I'll read 20+ hours and others much less. On the amazon threads it seemed that people were getting 28 hours from real life usage. This wasn't very scientifically done, but since so many people were getting that number and it's in line with Amazon's 2 months at 30 min a day it's good enough for me.

Like schrodingerscat said, to do it right I'd like to see reading time, firmware version, page turns, font type and size, the same file being used, refresh times, age and serial number of the kindles, estimated number of recharges and at what level, and temperature.

[sirmaru]

I leave my PW light level always at level 22 of 24. It works for me best that way in all ambient light levels during daylight. As evening approaches I use my KFHD7-32 with white on black settings. For totally dark settings like, if I wake up in the night to make a note on my KFHD7-32, I leave that unit's light level at a very low level to accommodate my eyes.

For total battery analysis I use GSam Battery Monitor on the KFHD7-32. There is no equivalent app for the PW so far as I know.

My PW lasts 11 to 13 days before the battery recharge indicator shows. My KFHD7-32 last 5 to 9 days.