Battery Life

[patrickt]

I hope someone more technical than I can advise me. Are there any negative consequences for putting a Kindle in a drawer and leaving it for six months? Should you take it out every two months and charge the battery? Does it matter?

[Dr. Drib]

Moved to the Kindle forum, because this is a question that concerns.......a Kindle.



Don
(Moderator)

[patrickt]

I thought it concerned the nature of LiIon batteries. Foolish me.

[HarryT]

Ideally if you want to store a lithium battery long term, you should charge it to a level of roughly 40-50%, and top it back up to that level every month or two. Don't store it fully charged, or fully discharged.

[patrickt]

Thanks, Harry. I'm giving my PW1 to a friend of my sister but my sister wants to wait until January. I'm hoping to convince her to let me give it to her friend now.

Thanks.

[barryem]

Waiting 6 month is pretty risky. All rechargeable batteries self discharge, although lithium ion does so less than most. In 2 to 4 months a full one can discharge to the point where it won't turn on till the battery is charged. This isn't good for the battery but in and of itself it's not usually fatal. The real problem starts after that.

The device refuses to turn on when the battery is very low. It doesn't wait till the battery is completely dead. So if it's not charged soon it continues to self discharge until it does become completely dead. This is fatal.

If you try to recharge a fully dead lithium ion battery it can catch fire, so the electronics in our devices make sure that can't happen. If the battery is totally depleted it won't let any charging current get to it. It can't be recovered. The device is designed to guarantee that.

This is true of all electronic devices that use lithium ion batteries. There's a lot of information on the web about it. A good place to look is batteryuniversity.com.

Anyway, if you leave it for 6 months it's very likely it'll be ruined. You might get lucky. You probably won't.

Barry

[Dr. Drib]

Originally Posted by patrickt

I thought it concerned the nature of LiIon batteries. Foolish me.

It' OK to feel foolish.

However, since your battery question is directed specifically for the Kindle when stored, then this is where your thread belongs - the Kindle Forum - where Kindle experts can assist you in your questions regarding......a Kindle, and all things Kindle, including a Kindle battery, in addition to what happens when you store a battery or a Kindle.


Don
(Moderator)

[patrickt]

Originally Posted by Dr. Drib

It' OK to feel foolish.

However, since your battery question is directed specifically for the Kindle when stored, then this is where your thread belongs - the Kindle Forum - where Kindle experts can assist you in your questions regarding......a Kindle, and all things Kindle, including a Kindle battery, in addition to what happens when you store a battery or a Kindle.


Don
(Moderator)

You are absolutely correct. It's fine to be able to feel foolish. Try it sometime.

[HarryT]

Originally Posted by barryem

Waiting 6 month is pretty risky. All rechargeable batteries self discharge, although lithium ion does so less than most. In 2 to 4 months a full one can discharge to the point where it won't turn on till the battery is charged. This isn't good for the battery but in and of itself it's not usually fatal. The real problem starts after that.

Yes, that's why I advised Patrick to top it up every month or two. A Kindle battery only self-discharges by 10% or so in a month, in my practical experience.

[drofgnal]

I recently pulled a kindle 4 NT out of a drawer. I hadn't used it since last summer at the beach (wrapped in a quart freezer bag for water proofing). It was totally dead, charged fine and works fine with no apparent drop in battery capacity. Li ion batteries are pretty robust. I have alot of them in the garage with power tools. Edger, weed wacker, blower. They don't get used all winter. They are ready to go after charging in the spring.

But I'd excercise caution and try to keep some charge in them. with Li batteries copper can shunt from inside the cell and short the battery when fully discharged.

[Dr. Drib]

Originally Posted by patrickt

You are absolutely correct. It's fine to be able to feel foolish. Try it sometime.

Most of us, if we can be honest, almost always feel foolish.


Don
(Moderator)

[cybmole]

Originally Posted by HarryT

Yes, that's why I advised Patrick to top it up every month or two. A Kindle battery only self-discharges by 10% or so in a month, in my practical experience.

in which case , assuming that meand lose 10& of current charge - it will only fall to ~ half charged over 6 monhts - which is well within recommended levels

I can't do **12 exponentials in my head but taking off 10% of a remainder twelve times will gave a value after one year of ... boot up excel.... fail to remember how to do powers... never mind . replicate a cell 12 times....
~28% charged.

I once had a backup sony PRS T1 stored for well over a year ( & that has a similar li-on battery) and it was fine when taken out of storage & switched on

[patrickt]

Thanks all.

[barryem]

Originally Posted by drofgnal

I recently pulled a kindle 4 NT out of a drawer. I hadn't used it since last summer at the beach (wrapped in a quart freezer bag for water proofing). It was totally dead, charged fine and works fine with no apparent drop in battery capacity. Li ion batteries are pretty robust. I have alot of them in the garage with power tools. Edger, weed wacker, blower. They don't get used all winter. They are ready to go after charging in the spring.

But I'd excercise caution and try to keep some charge in them. with Li batteries copper can shunt from inside the cell and short the battery when fully discharged.

First, you probably just got lucky. That's not something you want to depend on. Last year I found several MP3 players I'd forgotten I had, stuck in the bottom of a drawer. They'd been there at least a year, possibly 2 or 3 years. I just don't know when I charged them last. I tried charging them. One did recover just fine. The other 4 wouldn't charge. No real loss since I have no need for them anymore, but I hate to see good devices go to waste.

The other thing in your post, that they were totally dead, means they didn't have enough life to turn on. But the battery wasn't dead yet or they wouldn't have been allowed to charge.

Batteries are variable things. One might last a lot longer than another even though they're used the same way. I have a number of older devices, speakers, etc. that use AA batteries and I use NiMH rechargeable batteries in them which I charge in a good quality charger. I used to write the date on the batteries when I got them so i have some idea how long they lasted. Typical is 2 to 3 years. Some are gone in a few months. A few last twice or three times the norm. You just never know. They all rotate through the same 6 or 7 devices, which themselves are pretty similar, so I'm pretty sure it's just variations in the individual batteries that account for this.

Presumably lithium ion batteries are as variable as NiMH batteries.

Barry

[Readirect]

Originally Posted by barryem

Waiting 6 month is pretty risky. All rechargeable batteries self discharge, although lithium ion does so less than most. In 2 to 4 months a full one can discharge to the point where it won't turn on till the battery is charged. This isn't good for the battery but in and of itself it's not usually fatal. The real problem starts after that.

The device refuses to turn on when the battery is very low. It doesn't wait till the battery is completely dead. So if it's not charged soon it continues to self discharge until it does become completely dead. This is fatal.

If you try to recharge a fully dead lithium ion battery it can catch fire, so the electronics in our devices make sure that can't happen. If the battery is totally depleted it won't let any charging current get to it. It can't be recovered. The device is designed to guarantee that.

This is true of all electronic devices that use lithium ion batteries. There's a lot of information on the web about it. A good place to look is batteryuniversity.com.

Anyway, if you leave it for 6 months it's very likely it'll be ruined. You might get lucky. You probably won't.

Barry

That's ridiculous. I've left multiple ereaders untouched for 6 months or more; found them completely drained and recharged them without problem. They're all still going strong. Even the NookST that must be 4 years old by now. Used it constantly for a year, moved on and left it alone for probably a year, no problem charging or using it. Over the years since, I've left it alone for months & months. Continues to work, just fine. Latest Nook Glow, Kindle DX, the same.

There are plenty of things to worry about. This issue isn't one of them.