Does the battery wear off even if unused?

I'm just wondering if the battery will lose its effectiveness over time, even if it's unused? I read somewhere there's a chemical reaction going on because of the Lithium etc. used in the battery, causing it to wear off over time. But I don't know if that reaction is also happening when you don't use the battery and thus keeping it cool all the time.

If someone can answer, that'd be great. The reason I'm asking is because I'm about to buy a Dell Inspiron 6400 and in my country you can't choose a 9-cell baterry, you have to buy it separately (for extra 118,80€!). So if the battery wears off anyway, it's not a problem for me to delay the purchase of the better battery for a year or so.

 

yes, the quality of the battery will degrade over time
best you can do is keep it cool (and dry) (don't put it in the freezer)
and charge/discharge it once a month ... then store it away again, 40% charged

(thx to Chaz (I think) for his guide )

 

Thanks for the quick answer. So with 40% you mean, I need to fully charge it, then let it discharge to 40%. Why is that good?

Oh, and can you post a link to Chaz's guide?

 

guess it wasn't Chaz

http://forum.notebookreview.com/showthread.php?t=91846

and I think you better discharge it completely, and then charge it again to 40% ... but maybe the answer is somewhere in that guide

 

The main problem is moisture loss. Even when not used, moisture in the electrolyte would be lost through the seals as well as broken down to hydrogen and oxygen. Laptop batteries are hermetically sealed so once the moisture is lost, there's no way to add it back. (In contrast, large UPS batteries have service caps that can be used to add water.)
It would still degrade but not as fast as if it were actually used.

 

So how long would you say an average battery would hold to still be usable, when necessary?

 

I kept my battery plugged in the last 2,5 years
and it's DEAD
I started noting diminished capacity after 1,5 years or so

dunno how it would evolve when it's never used, but stored
but i guess it'd be equal or better?

 

Is it bad for the battery to keep it plugged in most of the time? Should I remove the battery when plugged in?

 

It is perfectly fine when the battery plugged in most of the time. For 3 years, I used the same battery, and I got a secondary battery as well, which I rarely used.

JC

 

no you shouldn't
but you shouldn't keep on charging it
in Vista you can set charge to and discharge from %
in xp, i think you just have to unplug the power lead

 

When a notebook is 100% charged, is there still a charge being applied to the battery? or is there some automatic switch that stops charging the battery?

 

No, it is not bad to keep the battery in. I have never taken the battery out in either of my laptops. The Hp is almost 4 years old and has a 4 cell battery and I still get about 45 or so minutes on it.

 

Actually it isn't really good to leave the battery if you're on AC power.
Of course it's nothing terrible but you'll get better battery life if you take it out and store it in a cool place.

Read the Notebook Battery Guide (someone else also linked it) for answers to pretty much all your questions when it comes to battery care.


As far as I know, leaving it plugged in means that it's pretty much always being charged. For example, turn off your notebook. Unplug it (when the battery is full). Wait a little and then plug it in. You'll notice that the battery is no longer at 100% and will be charged up for a short time. So the battery is always being charged back up to 100% when it's plugged in.
So leaving the battery in the notebook when it runs off the AC power means you use up some cycles and your battery will also be heated up (causing accelerated aging).
Here's a quote from the guide:

Again, read the battery guide for all the information and how to store your battery when you're not using it.
With that being said, it's really not that big of a deal. I always leave my battery in my notebook (mainly because it's also one of the legs of my notebook) and I usually run off the AC power. I almost never use my battery since I leave my notebook on my desk. It's just a battery and I'm not too concerned about its life.

 

So if I understand this correctly, the battery starts deteriorating the second it's built by the manufacturer and even if it goes directly to the store and then directly to the consumer, who doesn't use it and keeps it safely stored somewhere (thus, never even coming in contact with any electrical device), it will still be significantly worse off a few years after it was manufactured (when I'd first use it)?

edit: And what is better then for the battery - not charging it at all in those years of non-usage or charging it and then discarching it to 40% and only then storing it?

 

Thanks to Kwakkel and Thibault for links to the battery guide - very useful info

 

Yes:

Now let's not go crazy. If you bought a second battery and store it in a cool and dry place, it will still be good after a few years (even if you just leave it out next to your computer it will still be good).

If you want to store your battery you should discharge it to 40% and then store it:

 

if you leave it plugged in, when its fully charged it stops charging and no more charge is being sent into the battery. its not bad to leave it plugged in.

 

you might want to read about every post above yours
it IS bad for your battery

 

it really isnt.

 

all lithium ion batteries have a smart chip that stops the charge once it reaches 100%.

all lithium batteries will degrade overtime. if you're that worried buy a second battery

 

I feel like I am going crazy, but this same question is asked every day! The battery has as smart chip that turns the charging off. There is no significant change by leaving the battery plugged in all the time. The smart chip can keep it charged properly, without being bad for it. Li-Ion (laptop batteries for the msot part) have no memory effect. For long term storage (3 months or more at once), yes, 40%...., but for anything else, just leave it in the computer.

Wow, roor beat me to it by a few seconds.

 

haha, but your post was a little more in depth, if mine wasnt so short and to the point you would of probably been first.

 

Yes it has a smart chip but the AC power will top-off the battery constantly. Now I agree that this has a minimal impact on the battery and that's why I leave mine in all the time (and it's always plugged in).

? I'm not sure why you said that. They don't have a memory effect meaning they don't need to be discharged completely (and shouldn't be) before being charged again. But they still do have a number of cycles.

Buy a second battery once the first one dies or else you have two aging batteries.

 

even if you buy a second battery when the first one dies its still degrading while its sitting in the box waiting for you to buy it

 

Yes, but we can assume that the battery was "newly" manufactured and that it hasn't been sitting around for a few years.

 

so, now you're claiming it DOES loose cycles but it's NOT bad?
funy ^^

 

I never claimed that it didn't lose cycles or that it wasn't "bad".
"Bad" just depends on the person. The way I see it is that it's a battery, it should be used and will eventually die out anyway. I'm not really worried about my battery and I don't care too much about it since I rarely use it. I posted information from the battery guide and answered questions that were asked. Now you (and the others who asked questions) can decide if removing your battery and storing it is worth it or not. Some people will care about the small battery loss that will be due to leaving it in all the time (to them it's bad) and others won't see it as a big deal.

 

you can turn it any way you want
but, if it looses cycles, it's bad ... but not everybody will care, that's true

 

That's why I'm now saying "bad".
I never said it was good did I? I just said I didn't care.

 

It just goes into "float charge". The voltage applied is just enough to balance out self discharge. Moisture loss in float charge is minimal.

It's better to leave it on float charge than to top it off. The top-off voltage is high enough to cause significant moisture loss. It does, however, help equalize the cells which is why it is done. (There is an even higher "equalization charge" that is done for certain UPS batteries, where the electrolyte levels are checked, a high voltage applied, and the electrolyte levels checked again. Obviously, it is never done for hermetically sealed batteries.)

 

Also remember that the notebook doesn't run at full clock speed when its plugged into the a/c adapter without a battery. On my T61 I've noticed that it'll only reach 1.2 ghz when on a/c without battery, when I plugged in the battery it would clock up to 2.0 ghz. It would stay at 1.2 ghz even at full cpu load.

 

Really?
I don't understand why it would do that.

 

It's common to use the battery as a very large capacitor. Perhaps it underclocks because there is not enough capacitance to reliably operate at full speed.

 

That's an interesting thought. My AC adapter only provides 65W DC. Is it possible that AC adapters don't provide enough juice for power hungry notebooks under load, and thus turn to the battery for additional energy when required?

 

OT: Tailic that appears to be just a Lenovo thing.