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Customer Discussions > Kindle forum

Question for Bufo (again!) :)

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Showing 1-13 of 13 posts in this discussion
Initial post: Mar 17, 2009, 5:03:32 PM PDT
CarolinaCAW says:
I've read opinions on both sides of this issue, but I'd really like to know yours since I value it!

Do you normally leave your K2 on all the time, using the sleep mode...or do you turn it off, at night for instance, in order to preserve the life of the battery (not the life of a single charge, but the overall battery life)? I'm a little apprehensive about how long the thing will actually last before having to return it to amazon for a battery replacement. Will it help to turn it completely off at night, and/or if I won't be using it for several hours at a time?

Thanks again for you input! :)

Posted on Mar 17, 2009, 8:15:26 PM PDT
L. says:
To hear everybody talk about battery charging, maybe you could leave it plugged in all night to maintain full charge. Since reading all the posts of battery life, etc, I only turn on the whispernet when it is plugged in to charge, then I turn it off. Seems like the less you deep discharge the longer the battery life. (?) I'm interested in hearing the answer to this question, too.

In reply to an earlier post on Mar 17, 2009, 8:31:23 PM PDT
Mark says:
"Seems like the less you deep discharge the longer the battery life."

I've actually heard the opposite. More deep discharge the longer the battery life, i could be wrong though.

Posted on Mar 18, 2009, 3:17:33 AM PDT
CarolinaCAW says:
Very confusing, isn't it! That's why I want Bufo's input. Hmmmm...he must be working, he's usually quick to respond!

Posted on Mar 18, 2009, 3:25:07 AM PDT
As long as you leave wireless off most of the time, there's no need to "turn it off" at night; just let it go to sleep.

Posted on Mar 18, 2009, 4:47:17 AM PDT
SeaLevel274 says:
As Bruce stated, if you don't leave wireless on there's no need to turn it all the way off. Sleep mode doesn't put any extra strain on the battery, and it won't cause the battery lifespan to be less. You can probably expect the battery to last 2-3 years, depending on several factors. The Kindle 2 battery is lithium polymer, which is similar to the lithium-ion batteries that have been in use for a fairly long time. Battery experts will tell you that the life of lithium based batteries depends on more than just the charge and discharge rates. General guidelines include:

1) Avoid frequent full discharges, which means don't always let it drain all the way down before charging it up.
2) Do let it drain down every once in a while and then charge it fully just to keep the fuel guage working accurately - maybe every 30 charges or so.
3) Keep the battery cool - in orther words, don't keep your Kindle in a hot car.

Posted on Mar 18, 2009, 5:39:57 AM PDT
Last edited by the author on Mar 19, 2009, 5:52:04 AM PDT
Folks, the Amazon customer service thread here should be bookmarked, as it's really helpful. These are daily advisories made by Amazon's customer reps.

Here are a few items that help with our questions in this thread.
With Kindle 2's battery you don't need to fully drain the battery before recharging, or wait until the battery is fully charged to start using it again. The Lithium-ion battery is optimized in such a way that incomplete charging won't affect the battery life. For example, if you drain the battery halfway two days in a row while fully charging both times at night, this would only count as one charge cycle.
Leaving Kindle in extreme temperatures, like in your car, will have the most negative impact on the overall life of your battery.

Leaving wireless turned on or sustained use of the wireless functions will cause the battery to drain faster. If you would like to turn the wireless off, select menu from the home screen. Use the five-way controller to select "Wireless Off". Also, downloading a large number of books at once will cause the device to index new content. If you have recently transferred or downloaded a large number of books it is recommended that you leave the device turned on and connected to the charger overnight.

With Kindle 2's 25% longer battery life, you can read on a single charge for up to 4 days with wireless on. Turn wireless off and read for up to 2 weeks. If you use the wireless feature frequently, we do recommend keeping the battery at 25% at least. There is no specific need to let the battery drain out before recharging it; many owners do keep their devices plugged in each night, and this does not have any adverse effect on overall battery life.

You do not need to power down Kindle 2 between reading sessions, it is best to leave the device in sleep mode. Holding the switch at the top to power the device off is similar to pulling the power cord on your computer without shutting down the Operating System. If you turn the device off while in the middle of the book, the device cannot save that location. We save the location when the device goes into sleep mode or when you leave the book, so if you do need to power the device off then be sure to go to the Home screen first - this will save your last place in the book.
. . .
Kindle's wireless signal uses low power while in sleep mode so that your subscriptions can download overnight. If you are in a low coverage area, this could cause the device to use more battery power as it continually tries to maintain a signal. Unless you are subscribed to periodicals that you want to receive overnight, we recommend turning wireless off (Press the Menu button and select "Turn Wireless Off" of the menu options) before leaving the device in sleep mode. This will further conserve battery power.
=== END of some of the Customer Service thread topics at the top of this forum ===

Also, something that can confuse is that the Kindle comes to us with WIRELESS *ON* as a default.

Without reading the manual, we would not even know that it should be turned off in the Menus when we are not needing it. Otherwise it is a drain on the battery.

I think that during the first week that the Kindle 2 was released, we saw many people with very quickly reduced battery power as a result of not knowing Wireless was 'On' and that we should turn it off to keep battery-power higher when we are not needing wireless on. And at that point most of us did not even know where the Wireless 'off' feature was.

The older, nickel cadmium, batteries needed full draining - but the lithium ion based battery (enhanced with polymer) is the opposite. A forced draining below 25% can actually weaken it and cause problems if you need battery power while downloading material or when the Kindle is busily trying to index your Kindle contents after downloads. (It's easier on Amazon these days when we former Kindle-1 users no longer keep moving things to SD cards, causing Amazon to re-index everything as a result.)

Remember that Cust Svc recommends keeping it above 25% "at least"...

- Andrys

In reply to an earlier post on Mar 18, 2009, 6:41:31 AM PDT
Amazon Customer Service says: "Leaving Kindle in extreme temperatures, like in your car, will have the most negative impact on the overall life of your battery."

To add to that, charging the battery fully and then leaving it unused (storing) for a long time will also have a large negative impact on the battery. If you are going to not use your Kindle for an extended period of time it is best to leave it at about 60% charged (and at around 70 degrees). This of course would mostly apply to K1 owners who switch to a K2 and keep the K1. Charge/discharge the K1s battery to about 60% before storing it and then check on it every few months to keep it around 60%. The K1s battery should stay OK for a few years if you do that.

Posted on Mar 18, 2009, 6:51:27 AM PDT
Bufo Calvin says:
I'm glad everbody else answered this! I especially appreciated Arts reproducing the Customer Service response, and Tom's last answer.

Yes, Carolina, I've been working. :) When I'm in a large group meeting, I can learn and respond on the forums at the same time. ;) When I'm training, I'm really focused on my students, and that was happening yesterday (and will happen today).

You asked for the way I use it and my opinion. I do leave my on almost all the time, just putting it into sleep mode. I did that with my K1 as well. I actually tend to leave the wireless on as well. My feeling is that the battery thing is going to happen or not happen at some point. I'm hoping the battery will last a very long time before needing replacement. If I could be very mindful all the time and extend the life by a few months, or be able to not think about it as much and need to do it a bit sooner, I'm probably opting for the latter. :)

The weather thing does seem important, though, and if I was in an area with extreme weather, I'd try and keep it in a middle temperature range (like I would for a lot of things).

You probably won't hear much from me today, but I will try and go back and catch up later on. :) Oh, and at some point, I'll get some writing done outside these forums. ;)

I'm very flattered that people address questions to me specfically, but these forums collectively have a lot of great (and witty and supportive) people on them. I'm always happy (literally) to help, and I love to see other people answering questions (including mine) as well. :)

Bufo Calvin
Author, Free Books for Your Kindle

In reply to an earlier post on Mar 18, 2009, 7:06:34 AM PDT
Thanks for that, Tom. My K1 battery is currently at about 75% so I'll leave it that way but transfer some books to it that I've gotten mainly for the K2 and see if it is closer to 60%.

Living in San Francisco area, that temp will pretty much hold :-)

Posted on Mar 18, 2009, 7:37:49 PM PDT
CarolinaCAW says:
WOW!!! I just got home after a lonngggg day, and my question is not only answered, but answered by a BUNCH of incredible Kindlers (including you, Bufo, so happy you could add your bit of wisdom too!) THANKS to each of you for the great info, and I will definitely leave my K2 in sleep mode rather than turning it off! Thanks for the CS links, too. And Andrys, you have a very interesting website...can't wait to check out your blog! :)

OK, I'm ready to put ME into sleep mode now... :)

In reply to an earlier post on Mar 19, 2009, 5:55:37 AM PDT
Glad we all could help while Bufo was busy with students!

As for the blog, I added (since I'm so wordy) a new Kindle blog which
I will try to make a sort of how-to with photographs as well as the odd tips we all pickup.
It's and has only a photo comparison as of now, between the K1 and k2 displays. But I have ideas. Maybe others will have suggestions.

- Andrys

Posted on Mar 19, 2009, 4:00:00 PM PDT
CarolinaCAW says:
Great Kindle blog, Andrys! I love the photo comparisons, especially since I've never seen a K1 up close and personal! :) Thanks again!
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Discussion in:  Kindle forum
Participants:  8
Total posts:  13
Initial post:  Mar 17, 2009
Latest post:  Mar 19, 2009

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