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Laptop Battery Charge Limiter


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#1
Anomaly

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Does anyone know of an application that will keep a laptop's battery from charging past a certain percentage?
My laptop has a nice little feature that lets me set a limit to the battery's charge (100%, 75%, or 40%) and it will not charge past that, even when the laptop is off. I understand that since it works while the laptop is off, it's definitely somewhat hardware-related, even though it is software-controlled. However, I would like to port this ability to other laptops, since both my own experience and my understanding of how Lithium-Ion batteries work tell me that limiting the charge will extend the overall lifetime of a battery. Is there an application, or Windows tweak (both Vista and XP) that will allow me to prevent laptop batteries from going past, say, 75% charge? I understand it would only work while the laptop was on and booted, but that's better than nothing.
And while we're at it, how about doing it on Ubuntu as well?

Thanks

Edited by Anomaly, 06 November 2009 - 02:50 PM.

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#2
Neil Jones

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Most laptops automatically stop charging at 100%, because realistically the whole point of a laptop is to be portable. If you only charge it 40% you're kind of spending more time charging it back to 40% every time rather than going back to 100% and letting it discharge normally and often getting a longer battery time to boot. Providing they don't get totally discharged (as in totally discharged, ie totally dead), a complete discharge (to a reported 0%, which is rarely the true charge rate anyway) and recharge is usually the best procedure for most batteries.

The feature in question is probably a BIOS option which means it will not be transferable to other units. Even if such a software solution was available for Windows, as soon as you shut the unit down the thing will carry on charging past whatever you set, making it, in my view, pointless.

Edited by Neil Jones, 06 November 2009 - 04:29 PM.

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#3
Anomaly

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Well, yeah, I understand they stop at 100%, that was just to say there was an option for a full charge. I also understand the point of laptops is to be portable. However, in my case, 95+% of my laptops' on-time is while plugged in. I also understand that it obviously wouldn't work while the computer is off, but that just means pulling the plug out upon shutdown, which is a very minor inconvenience.

I'm sorry if my language was confusing, but when I said longer battery life, I was referring to, for example, how many years before this battery becomes so bad that it needs replacing. I didn't mean how long it can last between charges.

My understanding of Lithium-Ion (what all my laptops have) batteries in general is that spending a long period of time at a full charge will degrade the battery's shelf-life much quicker than being stored at a partial charge. Since my batteries hardly get used, being on A/C power all the time, I thought i might try to extend their total lifetime (not their charge) by limiting the level to which they charge.

Anyways, I'd rather not debate the effectiveness or practicality of it, because in my specific case there is no real drawback, but just see if anyone knows of such an application.
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#4
Neil Jones

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My understanding of Lithium-Ion (what all my laptops have) batteries in general is that spending a long period of time at a full charge will degrade the battery's shelf-life much quicker than being stored at a partial charge. Since my batteries hardly get used, being on A/C power all the time, I thought i might try to extend their total lifetime (not their charge) by limiting the level to which they charge.

Anyways, I'd rather not debate the effectiveness or practicality of it, because in my specific case there is no real drawback, but just see if anyone knows of such an application.


Please bear in mind forums like these appear in Google, so whatever I say or you say will be read by somebody else in the future. Your situation may apply to somebody else who reads this in three years time. Therefore what I've said in the previous post may not be of any interest to you now, with all due respect, but a Googler in 2012 may find it useful.

With regards to prolonging battery life in a laptop, all batteries of this type decay as soon as they're made. The average life of these sorts of batteries is about 3 to 4 years under normal circumstances. All rechargeable batteries have a finite lifespan and will slowly lose storage capacity as they age due to secondary chemical reactions within the battery whether it is used or not. At a 100% charge level, a typical laptop battery that is full most of the time at 25 °C or 77 °F will irreversibly lose approximately 20% capacity per year.
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#5
Anomaly

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Before I reply, I'd like to say that I'm not trying to argue (I hate forum arguments, or arguments in any setting), but just trying to make a point that something which I asked would be useful to me, and perhaps to others that use their laptops in a similar way (plugged in just about every second it's on).

I realize the inevitable decay of batteries, and I'm not going to try to argue against it. I've had batteries decay and go bad on me. Yes, no battery will last forever. However, from everything I've read about prolonging the shelf-life of Lithium Ion type batteries, I think I can get maybe 1 or 2 more years out of it by keeping it at a lower charge level. Since in my case, it's just about always plugged in, I'd like these couple extra years. A point to add is that the recommended charge level to store lithium ion batteries at is 40% (not my number, but is from just about every source I can find). My battery is being "stored" (not actually being used, just sitting in my laptop while it's on A/C power) almost all the time.

Basically my whole reason for doing this is to get an extra 1-2 years out of a battery before replacing it, because that matches up better with how often I buy a new laptop. Not having to shell out $150 for a new battery (darn those expensive suckers) for each laptop would be nice.

At a 100% charge level, a typical laptop battery that is full most of the time at 25 °C or 77 °F will irreversibly lose approximately 20% capacity per year.


And a typical Lithium Ion battery (the kind my laptop uses, and I believe are very common in them) that is kept at 40% charge at 25 °C will irreversibly lose approximately 4% capacity per year. Jump the temperature up to 40 °C (closer to laptop temp, in my opinion) and a 100% charge loss is at 35%/yr, and a 40% charge loss is at 15%/yr.
Source: http://www.batteryun.../parttwo-34.htm

That said, does anyone know of just a utility I asked for in the first post?

Edited by Anomaly, 12 November 2009 - 03:13 PM.

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#6
dsenette

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point blank...no...there's no such utility that i know of...that HAS to be a custom function of your laptop (make and model?) and i've never seen an app that would control charge levels and that MUST require some form of hardware intervention to accomplish (you can't stop a battery from charging without stopping the electricity from going into it...so there has to be some form of redirection going on with the power supply)...even if the computer is on, there's no application or tweak that would allow for this if the hardware doesn't exist

if you're worried about your batteries getting "used" when they're not really being used (i.e. while plugged in) simply pull the battery out while the computer is plugged in. problem solved it won't be receiving electricity and can't stay at 100% charge. your computer will run fine without the battery in place as long as the power stays on (of course, if you have a power outage then the thing is going down)
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#7
Anomaly

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I'm positive that there IS a hardware component to it, being that my laptop has a button on it that allows override of the limit, even if powered off (laptop is a Sager NP2090. I don't think that exact model is made anymore, but there may still be the similar NP2092). My question was for a software solution, but from the strength of the "no, there isn't one", I'd now assume that Windows has no control over when it starts/stops charging, but rather just gathers charge data and reports it on-screen. I'll have to stick to the pulling-out-the-battery one. Having it automatically stop was just so much easier tho... Oh well, thanks anyways!
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#8
McWheels

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Well DANG! I had to register and make this my first post here. I wonder if Anomaly is still reading this forum.

It's only a few days away from 2012 which was referred to in the previous posts and I have been searching for a long time to find exactly what he was looking for as well.

I am thinking along the same lines as Anomaly and have been pulling the battery out of my laptop on occasions but even that, after time, gets to be a pain in the butt. I do have my power supply plugged into a UPS so brown-outs and failures don't pose any difficulties for me but it's still a pain to stick the battery in every time you want to unplug the computer to move it around.

I'm on an HP Pavilion dv6 right now because it's my favorite but I'm setting up a Lenovo for a friend and it came with that power management feature he described that limits the charging to 40%. I can definitely see where that feature can help as HP has already had to send me a new battery under warranty because this one dies in 11 months because it was plugged in 99.9% of the time.

So, it will be interesting to see if this generates any further discussion.
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#9
psybathatha

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I also registered in order to reply to this forum. I am looking for the exact same thing that Anomaly is looking for. Thank you Anomaly for asking this question.
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#10
Crazycamel

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Make me the third person that register only to answer this specific question.

Well, I'm using a lenovo G470 series provided by my office to do my work. It came with an application called Lenovo Energy Management. This application can maintain battery charge level around 48%-51% when its set to the mode "best battery health".

I am looking for a similar application, because i want other laptop to be able to at least prevent a fast degradation.

So basically, i'm on the same boat as Anomaly.

Hope someone can build this nice little application fast.
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#11
ChickenSheep

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Make me the FOURTH person to register to only reply to this specific question. Aside from the random Googler in 2012 comment and having read 10 minutes prior to looking at this site the webpage on the Battery University website linked to by Anomaly, I can also relate to McWheels, as I too am currently running an HP Pavilion dv6. My previous laptop was a Lenovo which came with the Lenovo Energy Management described in the posts above. According to my brief research, Sony also has a similar program for their laptops, however it would be nice if there was some freeware available to download for other laptops.
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#12
cfdp

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Also interested after purchasing a Samsung laptop for my girlfriend, seen the 80% charge thing. I tried installing the Lenovo ThinkCenter tools on my Dell but it cannot detect the battery :(
As anybody would say after all of us wanting a utility for this, just buy a laptop that is capable of that, right? Well find me a new laptop with a 1920x1200 screen resolution and I'll switch! I'll stick to my 4 year old Dell Studio 1535 for that reason alone. I hope Dell will catch on in the future and add a similar option/utility. Unless they want us to keep paying their (and most) outrageous battery prices. Maybe the farmer's still at the Dell racking excess money too busy to notice.. Dude, I'm not getting another Dell otherwise sorry..
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