Battery: reading vs sleep vs shut down

[Tarana]

If it's a reader you use pretty much daily, use the Sleep Mode. If it's a device you use only occasionally (like a backup), you are best off turning it off (but turning it on and using it for a day every few months). Letting it drain the battery shortens the life of the battery. Even leaving it off for long periods without usage drains the battery.

For comparison, my brother and I bought Kindle Keyboards the same day. After a year, he shut his off and didn't use it for 2 years. He gave it to me. My Kindle was used nearly daily. When I received his kindle, it held a charge half as long as mine that had been in daily use.

[Mrs_Often]

The poll results are interesting: almost 75% have auto power off disabled... maybe Kobo should rethink the function (and perhaps build in much longer power off times). (I wonder whether Kobo developers and -employees use the auto power off function themselves?)

[JSWolf]

Originally Posted by Barbara1955

10 mins sleep/ Never shut down...

20 Min of no activity then sleep / Never shut down

[JSWolf]

Originally Posted by Mrs_Often

The poll results are interesting: almost 75% have auto power off disabled... maybe Kobo should rethink the function (and perhaps build in much longer power off times). (I wonder whether Kobo developers and -employees use the auto power off function themselves?)

I rather like the way Sony did it with the T series. if you don't use your Sony for two days, it shuts off. That way, it doesn't sit there sleeping if unused. But if you do use it daily or every other day, it won't shut off.

[jlemonde]

So now I have disabled the automatic shut down a week ago or so, and most of the time it is fine (I loose less than 1-2 % a night), but it happened to me twice that I would loose much more, as for example 40% in a night. My theory is that my Kobo had a pdf file open those nights.

Can you confirm my doubts that the suspend mode with a pdf file open makes much more consumption, as if the device did not really enter a suspend mode excepted from the back-lighting which would turn off?

[Mrs_Often]

Originally Posted by JSWolf

I rather like the way Sony did it with the T series. if you don't use your Sony for two days, it shuts off. That way, it doesn't sit there sleeping if unused. But if you do use it daily or every other day, it won't shut off.

Oooh yes that's exactly what I want!

[Mrs_Often]

Originally Posted by jlemonde

Can you confirm my doubts that the suspend mode with a pdf file open makes much more consumption, as if the device did not really enter a suspend mode excepted from the back-lighting which would turn off?

Hmmm that's an interesting theory. I never read PDFs, but coincidentally I was reading one last night _and_ I left it open while my Clara slept. I just checked the battery: 89%. I don't know what the percentage was last night before I put the device to sleep, but it can't have been 89+40%... However I did have the Clara plugged in for a while last night (to sideload some books including the PDF) so it would have been near fully charged. Maybe it depends on the size of the PDF, how much battery is drained?

In any case your theory would explain the battery issue Scott is having over in this thread: https://www.mobileread.com/forums/sh...d.php?t=310518

[Mrs_Often]

Delete

[rcentros]

Originally Posted by JSWolf

I rather like the way Sony did it with the T series. if you don't use your Sony for two days, it shuts off. That way, it doesn't sit there sleeping if unused. But if you do use it daily or every other day, it won't shut off.

I agree. Sony had that right. I think that's why the old (used) Sony Readers I've bought almost always have good batteries. Even 505s.

[JSWolf]

Originally Posted by Mrs_Often

Oooh yes that's exactly what I want!

The worst Reader made is the Kindle (for the battery). It doesn't have a shut off. So the battery wears down until it's flat. So if you have Kindles you don't use, you have to keep remembering to top it up with a charge.

[JSWolf]

Originally Posted by rcentros

I agree. Sony had that right. I think that's why the old (used) Sony Readers I've bought almost always have good batteries. Even 505s.

I would like Kobo to adopt such a feature or for someone to be able to patch the auto-shutdown for long enough to be useful.

[JSWolf]

delete post

[CRussel]

Originally Posted by JSWolf

The worst Reader made is the Kindle (for the battery). It doesn't have a shut off. So the battery wears down until it's flat. So if you have Kindles you don't use, you have to keep remembering to top it up with a charge.

Just for clarity, Jon, you CAN turn off any Kindle. Just press the power button and hold it until the message pops up. Say "Yes" and it shuts down. As for battery life, the Oasis is hard to beat. OK, I agree, the battery in the cover is a really crap idea. But the result is an eReader I can easily get a solid week of reading out of. And I read a LOT.

[Derf]

So... I've been really bad lately... I haven't read from my Clara in 3 weeks!

I wish I could provide some more data points, so I'll say that exactly 3 weeks ago I charged my Kobo to 100% on a Thursday night, and took it with me for a weekend trip planning to read. I have the sleep setting set at 10 minutes and never shut down enabled.
I checked the battery % exactly once per week by taking the device out of sleep mode by opening the clara's cover, which causes a page refresh of the book cover art screensaver to the home screen, clicking on the battery % and noting what it was, and then turning it back to sleep and causing a page refresh to the cover art screensaver. I recall at the end of the first week it was at 92%. At the end of the second week it at 86%. And now at the end of the third week it is at 77%.

My device is really only 6 weeks old too, so the battery is very fresh.
But it seems that while in sleep mode, you lose roughly 1% battery per day. At this rate the battery could last for at optimal 100 days, or roughly 3 months.

Side note : Auto power off should retain the battery level much better. Perhaps weeks could go by and the battery % would barely budge.

Kobo stated battery life is "weeks*" where they stipulate "dependent on individual usage", but which is also what Amazon states for their paperwhite.
Nook states that their glowlight 3 can last for 50 days on a single charged, and qualifies their claim by stating 'based on half an hour of reading per day'.

Based on 30 minutes of testing per day and 1 page refresh per minute with Glowlight at 10% brightness and wireless off. Battery life tests conducted using specific units tested for 25 days with an average drop in power of 2% per day. Actual results may vary based on device settings, usage, and many other factors.

I'd tend to think that all 6" eReaders with an eInk Carta HD screen, similar if not identical cpu and memory, all of roughly the same dimensions, would be matched to roughly the same battery requirements. Therefore, I'd extrapolate these quotes to apply to any of the devices interchangeably.

If Kobo says weeks, we could be generous and apply these rules to any of the readers.

HYPOTHESIZED:
I estimate that every 30 page refreshes drains something less than 1% battery.
I estimate that 30 minutes of glowlight at 10% brightness drains less than 1% battery, but combined with 30 page refreshes equals about 1% battery drain.
Factoring in the battery life lost per day sleeping, you could get a perfect ideal 50 consecutive reading days before the device requires charging on a new battery.

I would also recommend that if you know you will not be reading for consecutive days to turn the device off and power shutdown, to save battery. Otherwise you will not get 50 reading sessions out of a single charge, or in other words, almost a month and a half of reading. Of course, if you're spending more than 30 minutes reading per day, you'll get less. At one hour per day you'd get 25 days, or just over 3 weeks. If you read 2 hours per day, you might only get 12 days, just shy of 2 weeks. This is all just extrapolation though.

It's also fun to think that if you read at one page per minute, you would be able to read
(1 page/minute)*(30 minutes/day)*(50 days/charge) = 1,500 pages.

And if the average book is 500 pages long, then you could read roughly 3 books per charge.






TL;DR
So, in response to this OP,
MEASURED::
my Clara loses 1% battery per day while in sleep mode (tested over 21 days).
GUESSED::
You lose barely any battery when the device is powered off. I'd guess that Clara is similar to the Nook Glowlight 3 and would last 50 days when reading 30 minutes a day with dim front lighting.

[jlemonde]

I estimate that every 30 page refreshes drains something less than 1% battery.

Well, that is not easily believable since I don't loose 10% of battery every time I turn 300 pages in a pdf, searching for something (it happened to me a few times that I had to search through so many pages).

But nonetheless I agree mainly with your calculations for the rest.

I my case, 1 hour reading at 15 % backlighting, then switching wifi on, syncing, switching wifi off again and reading additional 30 minutes, then and 22h30 hours of sleep conduct to 3 or 4 percent battery loss. And 24 hours of sleep represent 1 % battery loss.

I begin to think that battery loss within the sleep mode is more drastic when the page your Kobo is sleeping on contains a huge image or is part of a pdf (which are sometimes composed by heavy images). I had once over 15% loss in a night, and this is the only explanation I can think about.