# OK to unplug before K3 is fully charged?



## Sandpiper (Oct 28, 2008)

My K3 was dead / near dead when I wanted to read this morning.  That kind of surprised me.  Last time I had it on it was half charged.  In any case it's been plugged for an hour plus and is still charging, but I want to take it with me now.  OK to unplug before it's fully charged?


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## SailorMerry (Dec 18, 2010)

It's fine- go ahead.


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## David Derrico (Nov 18, 2009)

Yes, it's fine. In fact, they say keeping the Kindle's battery between 25% and 75% charged is ideal.


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## mooshie78 (Jul 15, 2010)

Yeah, there's not much memory issue anymore with rechargeable batteries so you don't have to worry about things like that much these days.


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## Elk (Oct 4, 2010)

There are two minute issues:

1) lithium ion batteries can be cycled only so many times (between 1,000 and 3,000).  Each charging depletes a cycle.  This is of little concern as even 1,000 charges on a Kindle's  long battery life is essentially forever.

2) lithium batteries need to be fully discharged once every 30 cycles or so to enable accurate reporting of remaining battery life.


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## Morf (Nov 18, 2010)

Elk said:


> There are two minute issues:
> 
> 1) lithium ion batteries can be cycled only so many times (between 1,000 and 3,000). Each charging depletes a cycle. This is of little concern as even 1,000 charges on a Kindle's long battery life is essentially forever.


...but the total cycle count depends on how much the battery is discharged before recharging. If you flatten it completely you may only get 500 cycles. If you only discharge it a small amount you may get 4-5000 cycles. (http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries)

I prefer to think of it that there is a certain amount of electricity that a li-ion battery can give out in it's whole life. You'll get more or less the same out of it in total if you keep running it all the way down and charging it back up, or if you only run it down a small amount. You'll get a different number of cycles, but roughly the same total usage out of it.



Elk said:


> 2) lithium batteries need to be fully discharged once every 30 cycles or so to enable accurate reporting of remaining battery life.


I'd personally be careful of recommending this. The thing that kills a li-ion battery quickest is over-discharging it. If you fully discharge it you *must* charge it immediately, if you leave it for even a short while the Kindle will be drawing power from it and that may push it into the "dead zone". Personally I'd only recommend a full discharge cycle if the battery indicator starts to be wrong, not as a routine.

At the end of the day, though, there are as many different opinions about how to treat batteries as there are batteries on the planet, so let's not start a 'battery war' here.

Bottom line: for all practical purposes, it doesn't matter what you do to the battery in a Kindle you won't significantly damage it (by normal use, of course!)


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## Elk (Oct 4, 2010)

Morf said:


> I prefer to think of it that there is a certain amount of electricity that a li-ion battery can give out in it's whole life.


Very good way to think of it.



> Personally I'd only recommend a full discharge cycle if the battery indicator starts to be wrong, not as a routine.


It's rarely something one needs to actively do. (Good warning about not driving a rechargeble into shutting down.)



> Bottom line: for all practical purposes, it doesn't matter what you do to the battery in a Kindle you won't significantly damage it (by normal use, of course!)


Fully agreed! You are not going to run into problems - which is why I indicated these are minute issues and that the Kindle battery will last essentially forever.


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## Tuttle (Jun 10, 2010)

Elk said:


> 1) lithium ion batteries can be cycled only so many times (between 1,000 and 3,000). Each charging depletes a cycle. This is of little concern as even 1,000 charges on a Kindle's long battery life is essentially forever.


Except that that is effectively not true. Lithium ion batteries lose their lifespan almost entirely based off of time spent at particular charges. Cycling has minimal affect on them. Primarily they just degrade over time, with the speed of degrading being dependent on how close to the extremes it is being stored at. A battery being stored at completely full or completely empty will degrade much faster than one stored at ~40%. This is why batteries tend to be stored and shipped at 40% rather than full.

There isn't problems with unplugging the kindle before the battery is fully charged, in fact there are advantages to it, just like there are advantages to not fully emptying the battery.


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## Elk (Oct 4, 2010)

Of course, if you never use the battery it is best to store it only partially charged.  The problem is we want to use the silly things  

Bottom line, as I originally pointed out, in normal use the battery will last longer than the user will typically keep a Kindle.

So what motor oil is best?


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## Tuttle (Jun 10, 2010)

But still,  thinking in terms of cycling is just wrong for all lithium ion batteries - because time (and temperature) is what matters. Basically all the storage information would mean is "if you're a crazy person who has a kindle and won't use it for over a month, don't leave it plugged in, put it at about 40-80% and turn it off".

But yes, I can say for sure that I've had my kindle since May 2009, and have not had any issues with battery with it, except when a book was indexing and I didn't realize it, so didn't bring my charger.


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## Victorine (Apr 23, 2010)

This is great information on batteries, I had no idea.  I was still thinking that you needed to let it run out and then fully charge.  Good to know things have changed.

Vicki


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## Elk (Oct 4, 2010)

Tuttle said:


> But still, thinking in terms of cycling is just wrong for all lithium ion batteries - because time (and temperature) is what matters.


Yes, I know, but most people simply want to know how long the battery will last. Translating this into a real-world approximate number of recharges is easy to understand and to apply - and is surprisingly accurate.



> I can say for sure that I've had my kindle since May 2009, and have not had any issues with battery . . .


Precisely my point; battery life is not going to be an issue. 

Summary: I'm not losing any sleep tonight worrying about my Kindle's battery.


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## mrscottishman (May 18, 2010)

I don't know how many years I have had my ipod photo and I know I am over two years on my cell phone. Just about a year on my Kindle.  Christmas was two years on my netbook. So far none have shown enough shortening of battery life to be really noticeable or a problem. The Ipod used to run about a day and a half max on full time, now it runs about a day or a little over when constantly on. I used to go through a cell phone a year over the battery. With the reduced prices on the phones it was as cheap to get a phone as a battery. Then after research I do the following:

1. I try to obey the 80%-40% rule. I don't charge too full and I don't let it go too low.

2. I avoid cheap car chargers and only partially charge with a car charger when really necessary. I think they can heat up the battery by charging too fast and overcharge the battery. Some of the cheapo's I am convinced don't cut off. I had a car charger I am convinced ruined a cell phone battery. 

3. I don't just leave the charger on the battery. I have fried two batteries back in the day thinking they would quit charging when the battery was topped off. Evidently they didn't.

4. I avoid temperature extremes as much as possible. I don't leave my laptop, ipod, kindle, cell phone etc in the car overnight when it is cold outside. I put my ipod and Kindle in the glove box when I stop somewhere and the van will heat up so they are out of the sun. I take them with me if I know the van will be in oven mode.

5. I try not to jar or vibrate the batteries. I carried a company phone in my pants pocket and the batteries just didn't hold up. I was always banging the phone against something as I worked. I read somewhere that vibration was bad for batteries, it made sense so I put the phone in a shirt pocket and the last battery lasted longer than the company I was working for. I don't know, but I am just saying . . .

I am part skin flint and cheap, and I am part environmentalist. I got to where I hated to get a new phone when the battery went out. I take comfort that if my Kindle 2 outlasts its battery you can get them on the internet and they don't look too bad to change if you can just get the cover apart!

p.s. Since you asked, I use Castrol Synthetic oil in our service vans and haven't had a lubrication related failure. We use a premium filter and changed at 6-9 thousand miles depending on when we could spare the vans on the route. I have spent all day Saturday just driving vans to the lube center.(Wish I had a Kindle back then!) I got over 700,000 miles out of our 95 windstar (16? brake jobs- I lost count, replaced two water pumps, three alternators, 4 or 5 car batteries,1 a/c compressor,three heater-ac blowers, three sets of transaxles, three transmissions and one transmission repair,I gave up when the fourth one went out and sold it for junk, but the motor still ran and the ac worked!) before it was over the electric windows wouldn't work, the back hatch was cracking at the hinges, the floor board was getting weak on the driver's side and the third windshield was cracked. I wanted to get a million miles out of it, but I was just getting tired of it.

for what it is worth,
Scott


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## Book_Worm (Feb 25, 2011)

So, assuming a 10 day battery life, and 500 charges (worst case scenario on both), I calculate a 13.69 year battery life.  If your Kindle survives 13.69 years, you owe it to yourself to buy a new one!


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## Elk (Oct 4, 2010)

mrscottishman said:


> p.s. Since you asked, I use Castrol Synthetic oil . . .


Uh oh.

Can open. Worms everywhere. 

(I included the reference in my post as some of the biggest - and most useless - internet arguments are over what oil to use in a car or motorcycle.)


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## Elk (Oct 4, 2010)

Book_Worm said:


> So, assuming a 10 day battery life, and 500 charges (worst case scenario on both), I calculate a 13.69 year battery life. If your Kindle survives 13.69 years, you owe it to yourself to buy a new one!


Exactly!

It is a non-issue.

Some batteries will prematurely fail, like any other electronic item. In this case, replace the Kindle under warranty or, if out of warranty, buy a new battery.

Read on!


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## mrscottishman (May 18, 2010)

Not everyone uses it like that (10 day charge life). Assume a vision impaired user listens to it everyday and charges everyday. I see posts elsewhere that the Kindle is very popular with the vision impaired.

Once a day charging, 500 charge cycles= about one and a third year. Certainly worth trying to extend battery life for these users. I myself would like to see my electronic devices last two or three years. Five would be worth celebrating!

I used to make ink pens and markers. They did fine for most people, but there were these people that kept them on their hot car dashes, flew in airplanes (low air pressure at altitude can make some leak) and some that marked on things in the ice and snow. When we came out with a new product we had to realize there would be some people using these in ways we weren't thinking of.

The ongoing joke with the quality control department was, "What if you bake it in a pie?"

I asked them, "Apple or Cherry?"

YMMV,
Scott


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## Elk (Oct 4, 2010)

mrscottishman said:


> Not everyone uses it like that (10 day charge life). Assume a vision impaired user listens to it everyday and charges everyday.


Fortunately, the average 500 cycles applies only if the battery is fully discharged each time. The number of cycles goes up dramatically if they battery is partially discharged. For example, if discharged to 50%, the battery can be recharged 1,500+ times. This is why it is perfectly fine to recharge a cell phone each night.

Modern lithium ion batteries are amazing.



> I used to make ink pens and markers.


Very cool!

I adore fountain pens. They are all I have used to write with for many years.


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## Book_Worm (Feb 25, 2011)

mrscottishman said:


> Not everyone uses it like that (10 day charge life). Assume a vision impaired user listens to it everyday and charges everyday. I see posts elsewhere that the Kindle is very popular with the vision impaired.
> 
> Once a day charging, 500 charge cycles= about one and a third year. Certainly worth trying to extend battery life for these users. I myself would like to see my electronic devices last two or three years. Five would be worth celebrating!
> 
> ...


Wow, I hadn't even thought of that, good catch! I'd still think, that even with that type of usage, that you could expect to get at least 3 years out of it. I say this, because I drain my cell phone nearly every day (its Android based, love the OS, hate the battery life!), and I'm approaching 2 years on a single battery with no noticeable degradation of the battery. Even with audio, I'd assume the drainage is less on a K3 than on a cell phone.


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## didjaever (Mar 2, 2011)

A very valuable thread...thanks everyone!!


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## Alan Ryker (Feb 18, 2011)

It's time to go to Battery University!


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## Elk (Oct 4, 2010)

Alan Ryker said:


> It's time to go to Battery University!


Morf nicely linked the relevant portion early in this thread.


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