Notebook Battery Guide

My Laptop says it has a reduce cycle pattern program to stop short cycles and heat build up while pluged into the AC adapter ... The manufacturer (ASUS) says it completely disconnects the battery using a software sensor program in the BIOS when running on the AC adapter to reduce heat build up. In fact ASUS says the danger of connector damage and additional battery connector wear exceeds any gain removing and storing the battery out side of the Laptop would give.

My questions are:

#1. Have you heard of this kind of software switch?

#2. Do they really work?

#3. How long is "prolong running on the AC adapter" (such as a contentious 4 hours or more) & How long of a shut down period is required to start a new "prolong running" period (several hours such as 5 to 8 or does it have to be longer than 24 hours)?

#4. In your opinion, should I still remove and store my battery when running on AC power for longer than 3 to 4 hours with out a several hour shut down?

 

This sounds like marketing talk, because all Li-Ion batteries are treated like this. Li-Ion batteries can't be trickle charged - if they are, the battery can be damaged and become dangerous. Once the battery is fully charged, the charging circuit turns off. Then, while on AC power, there is no power sent to the battery until it self-discharges to defined point (95% or 96% in the laptops I have checked). The battery is charged again and the cycle repeats. If the laptop is on AC all the time, this probably happens twice a month.

To answer the questions:

#1 - To me it sounds like something that every laptop has, but ASUS might have added something to it. As batteries get warm when charging, they might have done something so that there is less heat build-up during the charging cycle, but this will probably mean the charging is slower. In case there is something different, do you have a link to the details?

#2 - Don't know as I am not sure if it is anything different to what every other laptop has.

#3 - Is that "prolonged running on the AC adapter"? If so, than to me, we are talking about days or weeks. I think that if you shut the laptop down at night, then you are never reaching "prolonged running". But, you are probably really worried about being connected to AC whether the laptop is running or not. The battery charge cycle I described above is happening whether the laptop is booted or not.

#4 - My opinion is to put the battery in the laptop, and use the laptop however you want to. The battery is there so you can disconnect whenever you need to and it also acts as a UPS. To me, the only reason to remove it is if you know the laptop will not be disconnected for weeks. Even then, I would only do it if the battery was being kept hot by the laptop as heat is the real issue for shortening the overall life of the battery. This is dependent on the design of the laptop (position of the battery and hot parts of the laptop). With the laptops I have owned, this hasn't been a problem (though I haven't checked my new Samsung).

 

And that is why Acer guarantee their batteries for erm . . how long ?

 

I am looking for a replacement battery for my lenovo R61 7732 laptop. Currently I have a 4 cell battery FRU 42T4552 with the following specs 14.4V , 2.6AH. I would like to go for a higher cell/capacity battery. I have checked many websties but can't find one with the same specs. They have batteries with 10.8V. Will these batteries be compatible with my laptop?

 

Appreciate the OP

Quick question, first, this is my charge habit. I use the laptop on battery for about an hour until I plug it in to charge it. Not a full charge but some charge. I then run on battery again to repeat the whole process. Is this okay as far as battery wear goes?

 

If I understand what you are doing, that is a bad idea.

It sounds like you are in a place that you have power available to you, but are running on battery half the time. If this was my laptop, it would mean the battery was dropping to about 50% and then being recharged. That would mean that every four hours of use, there would be a full discharge/recharge cycle. That would mean two cycle most day and four today (watching Australia play Ghana and hoping that a penalty doesn't knock Australia out of the World Cup twice in a row). As Li-Ion batteries are rated for between 300 and 500 recharge cycles, this means a lot of wasted cycles and wearing the battery out a lot faster.

If there is a reason you need to do this, then do it. But, if you are doing it because you think it will extend the life of the battery, then stop. It will do the opposite.

David

 

Appreciate your input David, do you think this is a better idea?

I will try to run the battery down to 20% before I recharge. Rather than pluggin in and out every chance I get. As in 95 to 100% 97 to 100%

 

Unless you store in a fridge I think you are spinning your wheels. But whatever you wanna do. No correct answer.

 

It isn't any better or worse if you are doing what I said. Partial cycles are cumulative - ten 10% cycles are the same as two 50% cycles or one complete cycle.

My real question is why are you doing it this way? Or I have misunderstood what you are doing?

David

 

First time poster here. I thought I'd add a bit of info to the original post. (I'm a hardware/software/firmware engineer going wayyy back )

Q: Is battery recalibration dangerous?

A: No. However...

Recalibrating too much is hard on your battery. Follow the OP's recommendation; I never recalibrate more than 2-3 times a year max.

Forgetting to recharge at the end of a calibration discharge could definitely "kill" the battery. But unless the battery is already almost dead, it would take weeks for it to lose its remaining charge and go into the "protective shutdown" mode.

Q: What is actually measured during recalibration?

A: The amount of power used from full-charge to empty.

Q: Is there a right or wrong way to recalibrate?

A: Definitely.

Your battery has a "high" and "low" charge-trigger point that determines whether any given discharge cycle is considered a valid recalibration. The battery will recalibrate as long as you have charged enough to hit the "high" mark, and then discharge all the way to the "low" mark without plugging in the laptop.

So what? Consider this: unless you ensure the battery is 100% completely charged at the high end, and 100% discharged (as far as you can get it) at the low end, then you may have just calibrated your battery to think it has less power available than it really has.

Personally, when recalibrating I charge until it stops charging, then pull the battery for a few seconds and charge some more, repeating 2-3 times to be sure it is at the very top.

At the other end (remember to disable all auto-shutdown functions!) I run until the laptop powers down, then pull the battery for a few seconds and attempt to power up into the BIOS, repeating until I get tired of it (or until the laptop only stays on briefly.)

Note too that discharge rate does have an effect. Don't recalibrate with the laptop in a very high performance mode: fast discharge tends to run the battery into the ground too quickly. Batteries have a bit of memory effect... a slower discharge rate, or even letting it sit a half hour after it first hits zero, may give it some more power to be used up.

I've seen batteries "recalibrated" repeatedly, accidentally, that showed half of their real capacity.

Q: How can I tell what the battery capacity is?

A: There's a handy Windows utility called BatteryMon by Passmark. It's commercial software but has a 30 day free trial last time I looked. It shows all the data from within your battery, has a nice charge/discharge graph, and can even log the battery state every few seconds during a recalibration.

If anyone knows of a capable free alternative, I'd love to hear about it!

Q: How do I know if my battery needs recalibration?

A: Watch the charge level while running on battery. A properly calibrated battery will run smoothly from 100% down to zero. And with auto-shutoff disabled, will NOT run for a long time at 1-3 percent.

A badly calibrated battery typically shows one or more of the following effects:

- Doesn't charge to 100%
- Discharges smoothly at first then suddenly drops all the way to 0-5%
- Once it hits 0-5%, with auto-shutoff disabled it continues to run fine for quite a while (I've had batteries that go to 1% within ten minutes, but then could power the laptop for 90 more minutes!)

Q: I recalibrated but that didn't fix it. The power level still jumps down.

A: Many batteries have a limit to how much their "full charge" level will adjust after each recalibration. A typical value is 512 mWh per recalibration.

If you have an older battery that has never been recalibrated, you may want to recalibrate several times. In this case, I highly recommend:

a) Do this gently. Heating up the battery by extensive rapid drain and recharge cycles is very hard on the battery. Drain slowly, let it cool, recharge, let it cool again for a few hours before repeating.

b) Use something like BatteryMon to see that the Full Charge level is actually changing. You do NOT want to recalibrate more than necessary.

Q: I recalibrated and now my battery is dead!


A: I'm sorry for your loss. Really. However, I've never seen this happen except under two circumstances:

1) The battery was already on life support. It was going to die very soon and you just put it out of its misery.

2) Forgot to recharge after recalibration. "SMART" Lithium Ion batteries (ie laptop versions) always have a protection circuit that shuts down the battery if its charge level goes too far below what you see as zero percent. That's to prevent a fire when it recharges (remember those scary stories and recalls on defective batteries?)

Q: My battery won't recalibrate no matter what I do

A: Unfortunately, some laptop manufacturers ignore the need for recalibration. They set the BIOS to shutdown the laptop before the battery hits zero. Your only recourse is to disable auto-shutdown and be careful when your battery level gets low.

I've seen this on several Dell laptops, and my current Toshiba laptop. Very frustrating!

For what its worth, I'm just now replacing my latest laptop after four years, with the same battery. It hibernates every day on the way to and from work, and I use it on battery for an hour every weekend (minimum.) The battery doesn't show much capacity (10% of original) but it still runs for an hour!

My greatest battery-wish: that laptop manufacturers would provide better support for battery recalibration.

 

Sorry but i'm a complete junior with computers.
I'm pretty confused here and i'm hoping somebody could help clarify things.

So when you say to charge your computer once you reach 10-20%, do you leave your battery connected once you plug your charger in? I already read your post about the pros and cons of leaving your battery connected when your ac adaptor (which i assume is what i call the thing that charges the battery) is connected to your computer, but what concerns me is that didn't you also say that when taking out your battery out, it is best for the battery to be charged to 40%? Or is that just for when your taking your battery out to store for a long period of time?

In other words, i'm just a little confused about which would be the best route to take. In addition, having my netbook conveniently on the go is not one of my concerns so i don't take as a factor that could affect my decision.

A) using my computer till 10-20% of batter is left, then charging my laptop with the battery connected
B) using my computer till 40% of the battery is left, then taking out the battery to charge my computer
OR
C) Another option that i did not take into consideration because i am a confused, helpless, technology-silly person

And also, would continuously taking out my battery affect it's health? And how exactly does my ac adapter charge my computer when the battery is out? Cause i always thought all that energy was going into my battery, but apparently it's not? Or is it just that when it's connected to the charger, my laptop is using the energy from there but not retaining any..?

haha sorry for so many questions.

 

You cannot actually "charge" your computer (we usually use the term as a convenient shorthand, since most people don't take the battery out, and charging the battery usually means the battery is in the computer); if you take your battery out, there is nothing to charge, because most (practically all consumer) computers do not have a secondary built-in battery. Thus any reference to "charging your computer" really means "charging the battery that is in your computer." There do exist separate battery charging devices that you can plug in and then plug your battery into, however, these tend to be somewhat rare and most people find it much easier to simply put the battery into their notebook and charge it that way. And yes, the AC adapter is the plug that you plug into the wall, which goes to a blocky transformer (commonly called the power brick), which then goes to a plug that usually plugs into the side or back of your notebook.

What usually happens is that your AC adapter (should) provide enough energy to both power your computer, as well as enough extra to also charge up your battery at the same time. This is why, if you turn off your computer, your battery will charge faster, because the power that would normally be running your computer can be used to charge your battery instead. If you pull your battery out (or if your battery is full), your computer will draw only enough battery from the AC adapter to run, since it doesn't need the "extra" power to charge the battery.

The 40% figure (it really should be more 40%-60%) is only for long term storage in a cool dry place. Even then, you'll probably want to pull it out and test its capacity every few months, just to make sure it hasn't deteriorated too much (all Li-ion batteries will self-discharge, you want to make sure it hasn't dropped below safe levels).

If you're going to be using your battery, then A) is just fine. If you don't plan to use your battery at all, then B), and then pulling out your battery at the 40% or so mark for long-term storage outside your computer will be better. Just remember that if you use option B), you'll never be able to use your computer without plugging it in, which for many people negates the point of having a notebook.

 

Thanks for this nice job (sorry for my franglish),

I have an Asus Eee Pc 1005 HA. I bought it because I will need it when I will be in India for my studies (more than three months).

I have to consider electricity problems there. I will buy an UPS (probably Eaton Protection Station 650 (tell me please if you know a better choice)). I think if I bring it in cabin lugage I can face problem with the security (Air India Paris - Delhi and Kingfisher Delhi-Dabolim) in the planes. So I have to put it probably in my big bag in the store-room (I don't know the right name).

Will it not suffer to much by the cold ?

Thanks for your answer

yatri

 

That's not the usual sort of question we see here.

I had a look at the specs and the battery is "Replaceable sealed lead-acid batteries". I know little about these batteries except that that there is one under the bonnet in my car. A quick look at Battery University, found this. The table on that page has the operating temperatures for lead acid from -20ºC to 60ºC. In general, the storage temperatures range exceeds the operating range, but I don't know by how much. Also, I don't know what the expected temperature are for an aeroplane hold are. I think it should be OK, but can't be sure.

 

Now I am sure I will not face a temperature problem. It will be minimum 10° celsius (50° farenheit).

But I don't know if the air pressure could affect the Ups's battery. I read a story about somebody who brought some small pieces of chocolat with a bubble of calvados (french - normandy alcohol) inside. After the travel no more bubble, only chocolate... Explosion of the bubble !

Thanks, davidfor,

yatri

 

Chocolate with bubbles of Calvados. Sounds delicious. Umm, now what where we talking about?

Sorry, I can't help you with the pressure issue. There might be more on the Battery University site discussing it, but I don't remember seeing anything about it.

 

Well, I just bought a new Dell XPS 15 with a li-on 96Whr battery.. I'm interested in prolonging my battery life, and I'm going to have it plugged in 95% of the time.

Question:

If I remove the battery and store it at 40% charge, as suggested by this forum and other online guides, what do I do with the gaping hole that results? Does anyone make a battery cover?

Mark

 

I haven't seen one recently but I do remember at least one company selling them a long time ago (at least five years). I have seen a suggestion of getting a dead battery and removing the cells.

 

Kinda defeats the purpose of a portable, don't you think? In any event, that procedure should work out fine.

The gaping hole is on the bottom so you won't see it. If anything, it will allow greater cooling, so leaving it uncovered should be of benefit.

 

Just passing by to confirm that the 40% trick does a magnificent job!!!
I've been using my Gateway P-7811FX for over 27 months now (manufactured July 2008) and I did a battery test last week, just wi-fi and some heavy browsing (like 20 tabs open) along with MS Word typing, brightness at around 75%... well... I got 2,5 hours on the battery!!! Next day I was on the train and I watched a 2-hour bluray movie from the internal hdd and there was still quite some charge left! Of course 2 years ago I would get nearly 3,5 hours with the same usage, but to get 2,5h after 27+ months when I see people replacing their batteries within the first or second year is a relief to say the least.
Oh, the gaping hole doesn't bother me, surprisingly it is the only part of my laptop that never gets dusty.

 

I trust you realize that's not a scientific comparison? The aforementioned "two" year replacement may well be from a continuous recharging application. While you're is comparatively low recharging. Which in my estimation, is the greatest determining factor in battery longevity.

 

Joe270 asked for an update on my situation:

I can't really afford to buy a new battery right now, so I'm just running it with the A/C power cord. It works fine except for the battery not charging. I switched over to Windows 7, in hopes it might be some sort of software issue, but it didn't make any difference. I rarely used the computer away from home, anyway; it's just a little more convenient to be cordless.

I did have several people tell me that my battery had probably just reached the end of its lifespan. It's still strange to me that it could work perfectly right up until the moment it wouldn't power on. No sign at all that it was "going bad."

Best of luck.

 

my battery is failing.as i NEVER use laptop unless its plugged in to AC should this concern me?charge light on permanently,max charge held 91%.

 

It might mean the battery is failing. How old is the battery? What happens when you try to run the laptop on the battery?

 

battery is failing,however it is NEVER run on battery.always AC.if i run battery, very short life.i use a netbook as portable.can it stay like this?

 

battery 2 years old.

 

this machine is left permanently connected to AC.with battery in its bay.

 

Li-Ion batteries age. This means that over time they lose capacity. This happens whether they are used or not. By "used" I mean running the laptop on the battery. A drop of 50% capacity after two years is not unusual and more is not uncommon.

Get one of the tools that show battery wear. This is the measure used for aging. I like BatteryBar but something like HWMonitor will show it along with a lot of other things. The higher the wear, the lower the capacity and the more aging the batter has suffered.

If you never run the laptop on the battery, you can ignore this. You can also pull the battery out and run only on AC power. Personally, I would only do this if the battery had zero capacity and the laptop turned off immediately when the AC power was removed.

 

when i run battery test,results ambivalent.if i run it whilst the machine is charging,i get ok result.if i run it when machine is on its maximum(90%-91%) i get ;battery faulty.
is this perhaps a calibration issue? if so,how to re calibrate?
thanks for any help.

 

i have left the battery in as surge protection and because sometime i relocate machine to another power point.

 

Some laptops have an app to calibrate the battery or an option in the BIOS. Use this if you can. Otherwise, run on the battery flat until it turns off (about 5% left) and then turn it on and go into the BIOS and leave it there until it turns off again. Then charge the battery and repeat.

And they are very good reasons to keep the battery in the laptop. I normally use the laptop on the battery for my commute (though I haven't been carrying one lately) but my wife only uses her laptop around the house. Having the battery in means she can move from the bedroom to the lounge to the table with no problems. Yes, this isn't good for the battery, but it will eventually run out and the convenience far outweighs the shortening of the battery life.

 

@davidfor
i will try the calibration procedure as per your instructions.
thank you very much

 

@davidfor
it seems that my battery is not good,however as i do not rely on its storage function is there any reason that i should replace it ?

 

If you are not planning to run the laptop on the battery, don't worry about it. It won't harm anything in it's current state. Or, you can remove it if Windows is making annoying notices about it.

 

@davidfor, big thanks.

 

I'd like the approach of leaving the battery always on the laptop, even if it is used almost always at home.
I have question, though: I'm unplugging the power supply when I switch off the laptop, just to save it from consuming when it is not needed (the trasformer sucks something). I have noticed that when I plug it back it looks like retriggering the charge again, even if it was for few hours.
Is this normal? The laptop is quite new hp dv6.

Any comment appreciated.
Thanks,
g.

 

Yes, this is normal. All Li-Ion batteries will self-discharge, so the fact that you have it unplugged means that the battery loses charge over time, and when you plug it back in, it charges briefly to regain that lost charge.

 

I had my battery unplugged but didn't realize I set it in the exhaust field of the fan. It was there for probably 1.5 hours (about 6-7" away from the vent). Should I be concerned about any potential loss of charge capacity?

The battery was a little warm but not hot, and during that time my usage was minimal (web browsing mainly). Still, a bit foolish of me.

 

It probably won't be enough to matter, maybe a percent or two of extra wear, I'd guess. That's just a guess, though.

 

I'm using Dell XPS 15 , I drain my battery between 25 - 30 % everytime and then i let it 100 % charge everytime & When it charges completely i unplugged it. Is it Okay to let it drain that much and charge it ? or Should i just drain little bit only ?

 

So reading this thread, I understand that it is impossible to overcharge modern Li-ion batteries. Once the battery is at 'full charge' your power management system will cut off the power supply to the battery. The battery won't recharge until the battery is below a certain level (say 95%).

Is the above correct?

If so, how do I check/change the level where the AC power will kick in again and start charging (eg. I want to change it from 95% to say 80%). Is there an optimum level to start this recharging? The reason I ask is that I have a constant access to AC power supply, and only use the battery as a UPS. If I can reduce the number of charge cycles, this will increase my battery-life, yes?

 

Great thread! Thanks!

 

Yes, it is correct.

You can check the level by trial - unplug, run the battery down a percent, plug in and see if charging starts.

I have never heard of a laptop that allowed this to be changed. Some allow the maximum charge level to be set but this is dependent on the laptop. This means that the laptop stops charging the battery much lower than 100% (My Samsung r780 can be set to 80%)

If you are counting cycles, this doesn't help. When on constant AC power, the drop is the battery charge level is due to battery self-discharge. As Li-Ion cells suffer no problems from partial charge cycles and the partial cycles are cumulative, if you could set the recharge point to 80%, one of these would be the same as four going down to the standard 95%.

 

très détaillé. en effet, on m'a dit comment faire à mieux utiliser une batterie, mais les méthode m'assommes beaucoup. OK， i have a question, now i want to change my replacement batterie, but my last batterie can just work about 2 hours, now i want to buy a 12 cell replacement batterie, someone tell me that a 12 cell can last about 5 hours. give me some advice, because you are an expert. ths for your help, my laptop is Pavilion dv6000

 

Assuming you are replacing a 6 cell battery and the 12 cell battery has the same quality cells, it will last approximately twice as long. You should check the power rating for the two batteries. The difference can be used as a guide for how long the new battery will last.

 

Hi, I have Acer Iconia Tab W501p (Windows 7) with non-removable battery. Everywhere I use it I have access to AC outlet. I want to use the laptop only on AC power thus not adding cycles to the battery. But this involves turning on and shutting down the laptop while plugged in the outlet. Is it bad to turn on and shut down laptop while plugged in AC power?

 

There is absolutely no problem doing that.

 

Using the computer under strict AC power (and turning it on and off) will not hurt your system.

However, your batteries 'cycles' will be consumed whether you use them or not: it is not only a matter of charge/discharge cycles that determine a specific battery's lifespan - it is also a simple matter of time. Plan to need replacing it in 2-3 years - even if used 'strictly' in AC mode.

I would simply use the system as I needed (on battery or on AC, depending...) and try to limit the charge cycle to about once a day or less. Further, when the battery is fully charged - I would unplug the system from the AC (if you are finished using the notebook for the day). This will 'exercise' the cells 'optimally' and you'll probably get more battery life (not less) than by using strict AC power everywhere.

Good luck.

 

That is correct. Li-Ion batteries age and after two or three years will need to be replaced. Using them a lot will speed this up, but there isn't that can be done to extend the life a lot.

This is the advice I always give. Use the battery when you want to, charge it when you can.

This doesn't do anything. Once a Li-Ion battery is charged, the charging turns off. It doesn't turn on again until the battery charge drops below a certain point. And as this is not controlled by the OS, it doesn't matter if the laptop/tablet is powered on or not. Unplugging the AC when the laptop is off overnight will not have any affect on the battery life.

Of course, unplugging the AC adapter from the wall when not in use, will save a bit of electricity.

 

Thanks, guys. One more question. I read a lot of different opinions on that: should I wait while the battery is fully depleted and then recharge it, or there is no rpoblem to recharge it while it is not fully depleted? I know that Li-Ion batteries don't have "memory effect", but still some people recommend full discharge before charging. Which practice to use in order to maximally extend the overall battery lifespan?