Battery Life?

[millydog]

I thought that battery life in e-readers was supposed to be great, but I am not getting great battery life out of my iRex iLiad v2 at all. I am having to charge it daily. The battery drains even when the iLiad is just displaying a page, with no page turns. Before you wonder if I have posted this in the wrong thread, I am wondering if anyone could please tell me if they get better battery life from a Bookeen Cybook Gen3? I love my iLiad, especially due to programs such as FBReader and Calibre, but battery life is just worse than I expected from an e-reader device. I can live with the daily charging, but I am just curious.

Thanks,
Jodi

[Ortep]

Yes a Cybook has an execelent battery life. I don't even carry a charger on trips that last under a week. Of course it depends on how often and how long you read. We have one member that never switches his reader off and he says it lasts only 100 hours. But that is more than 4 days. If you swich it off during the night you will get 33% more time if you switch it as soon as you wake up. That will give you almost 6 days. But you'll get the idea. Even if you leave it on 12 hours per day, it will last 8 days.

[Jellby]

I think someone said that the power consumed during boot up is equivalent to ~15 minutes of idle time, though I guess that would depend on the number of books in the library (since apparently the Cybook processes/reads the whole library when booting up).

[emellaich]

I believe its hit or miss. I got 'adequate' but not great battery life out of my early generation Gen 3. Well adequate considering the promises made for e-ink, but much better than a standard LCD PDA. There are some things to consider in regard to the battery life:

1) You've heard they only use juice when the page turns? Well that is true for the e-ink screen, but not necessarily for the device itself. The processor uses juice as long as it is awake. I believe your Irex has 802.11b? This is sure to burn up a battery if its left on. You might see about turning it off when its not needed. Also, I expect the touchscreen to use some battery capacity.

2) The manufacturer states 8000 page turns. My interpretation of that is more like half that number. When e-ink devices turn the page they first 'blank' the screen with a black flash. My guess is that the flash counts as a page turn, and then the actual page being written is another page turn for the purpose of battery life. You are displaying two pages (a black page briefly, followed by the true page).

3) The idea of page turns also gets funny for me, because I reread books a fair amount. When re-reading I will quickly skip through some pages. However, hitting next page ten or twenty times in a minute takes just as much screen juice as reading those pages and turning them at a slower rate. Therefore, the battery will run out sooner if you are skimming through a book - same number of page turns, but it takes a much shorter time to go through the pages.

3) I do believe that not all batteries are created equal. For example, my daughter had a problem with her cell phone battery and she was told that there were a number of phones of that model that had battery issues, while others were just fine. The bottom line is that any given unit could have a weaker battery in it due to manufacturing variation.

[millydog]

Thank you all for your responses.

Ortep, even 4 days sounds great to me. I usually turn my iLiad off when I am not using it, unless I will use it again within half an hour, since it takes some time to boot up and I am sure that is a big part of the battery drain.

Jellby, that is interesting what you say about the Cybook reading in the entire library when booting up, the iLiad has a boot time and a shut down time....so I wonder if it is also reading the entire library.

Emellaich, the wifi is off on my iLiad by default, so it only turns on when I press the button to do so...and that is not often. Having said that, I plan on playing around with the wifi to see if I can connect it to my computer for file transfer.
I had not considered the 2 page refreshes per page turn, so thanks for that info. I am sure that is the case. lol I sometimes skim through books as you say, but more often I probably burn up the battery life by switching documents and turning the iLiad on and off.

Thanks again everyone.
I am going to the Melbourne MobileRead meeting tomorrow and one of the forum members is bring a Cybook, so I will get to see one then. I also hope to check out other e-readers as well.

Jodi

[tompe]

The Bebook has much better battery time than the Cybook. They seem to have implemented proper power management.

[Snuffi]

Originally Posted by emellaich

1) You've heard they only use juice when the page turns? Well that is true for the e-ink screen, but not necessarily for the device itself. The processor uses juice as long as it is awake. I believe your Irex has 802.11b? This is sure to burn up a battery if its left on. You might see about turning it off when its not needed. Also, I expect the touchscreen to use some battery capacity.

2) The manufacturer states 8000 page turns. My interpretation of that is more like half that number. When e-ink devices turn the page they first 'blank' the screen with a black flash. My guess is that the flash counts as a page turn, and then the actual page being written is another page turn for the purpose of battery life. You are displaying two pages (a black page briefly, followed by the true page).

3) The idea of page turns also gets funny for me, because I reread books a fair amount. When re-reading I will quickly skip through some pages. However, hitting next page ten or twenty times in a minute takes just as much screen juice as reading those pages and turning them at a slower rate. Therefore, the battery will run out sooner if you are skimming through a book - same number of page turns, but it takes a much shorter time to go through the pages.

4) I do believe that not all batteries are created equal. For example, my daughter had a problem with her cell phone battery and she was told that there were a number of phones of that model that had battery issues, while others were just fine. The bottom line is that any given unit could have a weaker battery in it due to manufacturing variation.

ad 1) WiFi is a battery killer, hands down. Blue tooth alone cuts battery time in half for most people I know if they have it on all the time, WiFi is supposed to be even worse according to a friend of mine who has WiFi on his mobile. Touchscreens necessarily use energy, how much depends on the technology but as far as I know it's quite a bit. That depends on what you compare it to, though, the Cybook has a rather small battery (you can see that when comparing the time it can play MP3s to any current MP3 player) but it uses so little that it still lasts you several days even if you have it on all the time.

ad 2) Manufacturers always try to give you the highest number they can get in tests. If you insert a brand new, fully charged battery and press page forward as fast as you can (via a program would be best), I am sure you can get very high page counts because the energy used by the processor, card controller and/or RAM makes only a very small portion of the total consumption. When actually reading page presses are rather far in between and therefore the device the energy uses reduces the number of page turns you have left considerably.
In my opinion, though, Bookeen calculated the maximum number rather than try it out: They probably just took the energy consumed by one page turn (most probably the number they got from EInk) and divided the battery max by that number, leaving out the rest of the device entirely.
I activated automatic shutdown after one hour (seems to me a fair compromise, if I cannot get back to my book within that time frame I usually have to finish whatever interrupted me first). With that I can easily get through the week reading on the tube to work and in the evening, whenever I have the time.

[Kaero]

Yes, manufacturer gives the best number, but I think someone in netronix once measured only the display itself, obtained the 8000 number, and every producer using any similar device just copy that number. I haven't seen any other number.

When I measured count page (search for my old thread), i got about 4500 page turns (without the consumption of the processor in sleeping mode). Of course with black flash, without this feature the screen is not good for long reading.

Anyway, most of the time i am recharging every two weeks, reading at least 2 hours a day, possibly more. Comparing to any lcd device, i am quite happy

[K-Thom]

Same for me, I counted about actual 4000 page turns last time. And this means just two large novels. An amount I do easily read while on vacation. So I indeed need to recharge my Cybook if I want to enjoy it throughout my vacation.

Not what I had in mind when I bought it ...

[Ortep]

Everything has to be seen in perspective.

When I'm on a trip I also carry a phone and an MP3 player. Both of them effectively have a worse battery life than the Cybook. The MP3 player last for only 16 hours, the phone lasts about a 100 hours. The same as the Cybook but I keep it on all the time. I switch off the Cybook when I'm sleeping. So the phone lasts only four days but I have to charge it every two, because if I wait for 3.5 days, I can only use for a couple of minutes.

For me this means that with normal use I have to charge the phone at least every two days, the MP 3 player every 3-4 days and my Cybook once a week

The Cybook is easy to charge. I have a universal charger with several plugs. So I need only one charger. Simply connect one device per day and all of of them stay charged to the max. It even works for about one charge without a wall outlet

http://www.consumer.philips.com/cons...05_GB_CONSUMER