Notebook Battery Guide

Notebook Battery Guide
By Chris Yano​

Notebook batteries are a common topic of discussion, and the vast majority of questions about them deal with prolonging their lives. There is a lot of information about Lithium Ion (hereafter Li-Ion) batteries to wade through. There are a lot of misconceptions floating around as well. This simple guide addresses the most common notebook battery questions and concerns.

Quick Reference: Simple Guidelines​

Frequently Asked Questions:​

How long will my battery last?
Connected or Disconnected when on AC power?
How do I prolong my batteries’ life?
Battery Wear Estimates?
Considering a second battery?
Can I use a battery from another system in my new laptop if it fits? Can I use a generic battery in my laptop?
What about recalls and exploding batteries?​

 

How long will my battery last?​

Your notebook battery will deteriorate over time whether you use it or not. Although the Li-Ion industry does not publicize this fact, your battery’s clock began ticking the moment it was assembled. The elements inside your battery slowly react with each other, eventually rendering the battery unable to supply the required power to your notebook. In addition, your battery is rated to last between 300 and 800 charge/recharge cycles. It will gradually lose charge capacity rather than abruptly fail to power your notebook.

The general consensus is that notebook batteries last one to three years. While you can slow the battery’s aging and loss of capacity, you cannot stop either decline. The temperature of the battery, combined with the amount and nature of its usage contribute significantly to your battery’s lifespan. You can ease the aging process with some care and maintenance.

Temperature​

Lower temperatures slow down the self-discharge (loss of charge while disconnected) and aging process of the elements within your battery. Therefore it follows that higher temperatures shorten the life of your battery. Leaving your battery connected while on AC power causes the internal temperature of the battery to rise. Removing your battery and storing it in a cool, dry place will help to slow the aging process. Keeping your notebook in a hot environment is also detrimental to your battery.

Amount of Usage​

The Lithium-Ion batteries used in notebooks are rated to handle between 300 and 800 charge/discharge cycles. Some of these cycles are used when you leave your battery connected to your notebook while on AC power. On AC power, the notebook will routinely “top-off” the battery when its charge reaches predetermined levels (i.e. 95%). Removing your battery and storing it in a cool, dry place will help to preserve some of these cycles.

Nature of Usage​

Li-Ion batteries do not suffer from the memory-effect (requiring complete discharge before recharging to avoid loss of capacity) like older rechargeable batteries. Regular full discharge/recharge cycles result in an increased loss of capacity per cycle. A series of partial discharge cycles are better for Li-Ion batteries than a single full discharge. You should, however, calibrate your battery routinely.

 

Connected or Disconnected when on AC Power?​

Things to consider if:​

You are removing the battery while on AC power:
Pros:
• Preserves charge cycles
• Keeps the battery temperature lower thus slowing the aging process
Cons:
• Lose the battery as backup power during power outages and voltage drops
• Unsaved work will be lost and data may be corrupted without backup power
• UPS (uninterruptible power supply) needed to serve as backup power source

You are leaving the battery connected while on AC power:
Pros:
• Battery serves as backup power during power outages and voltage drops
• More convenient for “grab-and-go” use
• Battery doesn’t require sufficient warming time (as it would after being stored in the refrigerator)
Cons:
• Loss of charge cycles
• Battery’s temperature is higher on AC power resulting in accelerated aging

 

Prolonging your Battery’s Life​

• Calibrate your battery with a full discharge every 30 charges to help the battery’s fuel gauge remain accurate. Run the battery down to the automatic cut-off point of your notebook before recharging.
• Avoid repetitive and regular full discharges. Li-Ion batteries will lose less charge capacity when partially recharged. Recharging at a 10 to 20% charge level is recommended.
• Disconnect the battery and store it in a cool, dry place. The optimal charge level is 40% for prolonged storage. Storing the battery with a low charge will result in permanent damage or battery failure.
• If you store your battery in a refrigerator, use a sealed plastic bag to keep moisture out. Allow the battery to warm to room temperature before using or recharging it.

 

Battery Wear Estimates​

Hardware utility applications such as Notebook Hardware Control can estimate the amount of wear your notebook’s battery has experienced. Many are alarmed when their two-week-old battery registers a 16% battery-wear-level. Understandably, they are concerned that their battery is dying and will not be useful for long. Unless you were given an older battery with your new system, you can take those alarmingly high figures with a grain of salt.

Unless the application you are using was designed with the exact specifications of your notebook and battery, it is a generic program that estimates battery wear levels. There are countless variables that can affect the outcome of this estimate (notebook-specific configurations, BIOS and software settings, battery specifications, etc.). The utility can not possibly communicate perfectly with every notebook system and battery model available, so it takes what information it can and calculates its best guess. To give you an idea of how inaccurate these figures can be, my five month-old battery has 0% battery wear according to Notebook Hardware Control.

 

Considering a Second Battery?​

As mentioned above, the elements inside your Li-Ion battery will deteriorate over time regardless of what you do. This is why you may want to consider delaying that second battery purchase – to stagger the aging process of multiple batteries. You may find that you do not need a second battery after all. If you do find that you need an extra battery, however, it is recommended that you buy only when needed for this reason.

 

Can I use a battery from another system in my new laptop if it fits?
Can I use a generic battery in my laptop?​

Li-Ion cells are permanently damaged when their charge drops below certain levels. If the voltage gets too low, the battery will stop working and become unsafe to use. Therefore all systems powered by Li-Ion batteries have a predefined threshold set to shut down at certain levels of discharge. As a result, Li-Ion batteries are made to the exact specifications of the systems they are designed for, and vice-versa. This is where batteries from another system or low-cost generic batteries may not be compatible. If the thresholds of the system and battery do not match, there is a risk of power cutting off at the wrong moment. This may lead to unsaved work being lost, data corruption, or irreversible battery damage.

In addition, generic low-cost batteries are not made with the high safety standards of official batteries. Main-brand batteries use only approved safety circuits in their battery packs whereas there is no regulation of off-brand battery production. This, as well as attempts by notebook manufacturers to ensure approved batteries are used, is responsible for the higher cost of official batteries. There have been reports of notebooks rejecting generic batteries (to avoid usage of potentially dangerous batteries) without software changes (bypassing the security system). Some generic batteries even fail to work altogether.

There are subtle differences in design, manufacture, and the operation of generic and official batteries which may or may not cause problems for you. For every person that has had problems using generic batteries, there is another who has had no problems whatsoever. You must decide if saving a little money on a replacement battery is worth the potential risks.

 

What about recalls and exploding batteries?​

Recently there were a number of reports of exploding batteries. Naturally, you may be concerned about the safety of your notebook’s battery. The cause of recent battery explosions has been traced to metal particle contamination of internal components in batteries produced in certain factories. A recall is in place for the batteries at risk of suffering from this defect.

Here is the recall list from October 23, 2006, where you can check to see if your battery is at risk.

 

Quick Reference: Simple Guidelines​

• Heat is your battery’s worst enemy. Avoid keeping your battery in hot places such as your car during the daytime.
• A full discharge puts more strain on your battery than several partial discharges. You do not need to worry about battery memory with Li-Ion batteries. Get into the habit of recharging the battery when it reaches 10-20%.
• Never discharge your battery to 0% – as this can render your battery useless.
• Calibrate your battery’s fuel gauge by doing a full discharge every 30 cycles. Run the battery to the cut-off point in your notebook to keep the battery’s fuel gauge accurate.
• If you will be on AC power for an extended period of time, you can prolong your battery’s lifespan by removing it and putting it into prolonged storage.
• Prolonged storage should be done with a 40% charge-level and in a cool, dry place. Some experts recommend you place the battery in your refrigerator. Use a sealed plastic bag to keep moisture out if you do this.
• Do not freeze your battery.
• Allow a stored battery to warm to room temperature completely before using or recharging it.

Further Reading
• Battery University Homepage
• Batteries in a Portable World
• Wikipedia
• laptopbattery.net Maintenance Tips

 

Wow, that's pretty thorough. Without getting into the science and chemical reaction involved with Li-Ion batteries that's about all you need to know.

One thing some manufacturers are offering now is "Express Charge", specifically Dell. While I like that feature, a word of warning, Express Charge can be a killer on the battery as the faster you charge a battery the more it tends to warp the cells. So in the long run a trickle/slow charge of a battery is better. However, tell that to the guy that has an hour layover in an airport and needs to charge a battery as fast as possible. I kind of wish notebook makers offered a way to toggle how fast the battery charges so you could trickle charge when it doesn't matter and fast charge when you really need to charge the battery fast.

Anyway, that's a bit off topic. I have nothing else to add to this very thorough post, but if someone has some more pointers here please post!

 

Please feel free to contribute additional information. I will make updates to this guide as more information becomes available.

If you are submitting new information, please include a link to your source.

Thank you.
Chris

 

An awesome job you've done there, Chris. Proper care and maintenence of Li-Ion batteries is essential... this definitely warrants a sticky.

 

I will sticky it shortly. Thanks!

 

Fantastic job Chris, this is easily one of the best guides on the forums. I learned a few things about batteries I hadn't been aware of before. You learn something every day.

 

A larger battery will run cooler because of I^2R losses. Several companies offer a larger battery as an upgrade including dell hp compaq and toshiba

 

Good job! That is a very thorough review! Thanks for your efforts.

 

Are you saying we should recharge our batteries when they are at 10 or 20% remaining?

 

I believe so.

Matt

 

The basic idea is that you do not want to run your battery down completely every time. Recharging at 10-20% charge level is ideal.

 

Now thats real nice.
Props and Thanks

 

Thanks for your great work, chrisyano!

Please forgive me if I missed this, but you mentioned battery "cycles" several times in your guide. What exactly is a cycle? When you say to calibrate the battery’s fuel gauge by doing a full discharge every 30 cycles, does that mean doing this once per month is sufficient? Thanks in advance for your answers and thanks again for the guide!

 

A cycle generally refers to a discharge and a recharge. I wouldn't consider a discharge to 90% and then recharging a cycle, but discharging to 10% and recharging would be a cycle.

 

A discharge/charge is considered a cycle, yes. Once a month should be OK, but some do recommend every two weeks. The idea is just to help your battery's fuel gauge stay accurate--otherwise if it's always at full it will lose some of its ability to do so.

CalebSchmerge is correct about that. And while I also wouldn't consider a discharge to 90% and then recharging a cycle either, it does count somewhat in the overall equation of the battery's lifespan. Definitely not as much as the 10% example he gave above though. Remember that full discharges will always take more long-term capacity away from your battery than a series of partial discharges, so try to recharge before your battery hits empty as much as possible.

 

Great guide! It would be neat if something was mentioned about different battery specifications. Like the # of cells in the battery and how that affects battery life. Also the mAH #’s found on batteries and what that means etc. And the Whr's (watt hours) of a battery… And lastly, some information on the voltage of different batteries. Perhaps also mention the older ni-cad batteries and how they compare to ni-hm, and the future of fuel cell batteries.

Another simple thing to add would be how to improve your battery life... Like: turning off Wi-Fi, disabling the optical drive, unplugging things from the USB, screen brightness, cpu settings, undervolting etc. And then maybe even some information on external batteries.

 

the most important things affect battery life is the stuff of the cells, next is the PCM (protection circuit module) that avoiding overcharging and overdischarged,

 

So what do you guys do when you're using your laptop plugged in the wall ? Leave the battery connected or not ?

 

i left mine connected.
I look at the battery as an UPS (uninterrupted power supply) - just in case the power goest out, i do have a few hours backup

cheers ...

 

That's what I was thinking.

Thanks bro!

 

Thanks, this is a very informative guide.

Okay, I removed my battery, but now there is a hole on the bottom of my laptop... not only that, but one of the rubber feet was on the battery, so now my laptop is not very stable. Anyone know if I can get a plastic cover to put there? I have a Dell Inspiron 6400. The battery type is GD761. I called Dell and they said they didn't have anything like that to send me. I searched online and didn't find anything for my particular computer.

 

There was a poll about that in these forums not too long ago. Last I checked leaving the battery connected when on AC power was way ahead. I personally like the added convenience a notebook battery provides. If it gets too weak, I'll buy another if I'm not already on to my next system.

You're welcome. And thank you.

I think you're going to have to custom-make something there. You can be as simple (books, perhaps?) or as creative as you want (fashioning some sort of custom-fit cover/stand).

 

if our laptop plugged in the wall and Leave the battery connected , it will charge into 100%
so what we do when it reach 100% , remove the AC adapter then using it until it drop to 10-20% and charge again or still leave the laptop plugged into the AC adapter ?

sorry for my bad english

 

No don't do that, you're just discharging your battery for no reason.

What Chrisyano is saying is that you should discharge to 10-20% and remove the battery, and only use the AC. Store the battery in a cool, dry place until you need it again. Some people put theirs in a plastic bag, then drop it in a corner of the refrigerator. A much more appealing option is just put it in a drawer. Remember, partially charged + dry + cool!

 

Your English is fine. I understand you completely. The 10-20% refers to when you are using the notebook on battery power (unplugged and away from your desk or power source). The Li-Ion battery will respond better over time to being regularly recharged at those levels than being completely discharged all the time (run down to the point of automatic shutdown).

Your charger should sense when the battery is fully charged. At that point it will stop charging the battery. But, over time the battery will lose some charge and when it hits a certain point (i.e. 95%), the charger will top it off and bring it back up to 100% automatically.

If you want to prolong your battery's lifespan a bit, you can do this. Personally I prefer to leave the battery in and replace it if need be in the future.

One note though: the optimal charge level for prolonged storage is 40%. 10-20% charge level is ideal for recharging after using the notebook on battery power.

 

thanks a lot for the reply to both chrisyano and gatordude123

 

Hi chrisyano,

Nice job with this post. Why 40% though? Why not 100%. Then you'd have to recharge it fewer times and also there is less of a chance the battery will discharge fully before you recharge it.

 

Studies have been done with different charge-levels in prolonged storage. These studies have shown that 40% is the optimum state-of-charge for putting your battery into prolonged storage.

The additional stored energy (when storing the battery at higher charge-levels such as 100%) is actually harmful to the cells over time, causing permanent damage and thus decreasing its lifespan.

 

Rock on! Thanks.

 

Hi,

I just bought second (main) battery, so I want to ask how to use two batteries.

I am keeping my battery in while on AC. So, when I use one battery to 10% (for example) and I will use only the second one for next few days - is it better to:

a) keep the battery on 10%
b) charge it to 40% (probably not)
c) charge it to 100%
d) charge it to 100% and run it down to 40% (this should be better for battery storage, but it is a waste of cycles...)

It will be 1 to 3-4 days without usage.


Also one battery is 6-cell the new is 9-cell - if it matters what battery should I prefer to keep in or recharge...


Thanks for reply.

 

Personally, I'm not a big fan of the prolonged storage for Li-Ion batteries. I prefer the convenience of a built-in backup and can accept the fact that I may eat up a few extra charge cycles here and there along the way. If my battery ever gets too weak, I'll simply buy a second battery like you did.

Questions:
1) Is one of your batteries an older battery that is starting to show signs or aging? or
2) Did you buy the second battery because you need extended battery life while out and about? and
3) Do you think you will be needing both with you most of the time?

If we're only talking about a few days here and there, I don't think you need to go to all the trouble of putting one battery into prolonged storage while using the other. You can just stick the first battery in your bag while you use the second.

I'd caution against putting the first battery into prolonged storage with a 10% charge though. And I wouldn't consider a few days prolonged storage--so you'll be fine until the second battery wears down and you can recharge both of them. So in that case, answer a should be fine for you. And it doesn't matter which one you use more often.

Don't worry about saving every little spark of life in your batteries. Just enjoy .

 

My first battery is 7 months old, it lasts almost the same as when it was new... It is the 6-cell battery - so I bought another because this lasts only 2 hours and that is too short for me (don't ask about the notebook selection, I was looking for performance primarily because notebook is my only computer).

I think I will be using the 9-cell battery more, but probably I will take both to school... I'll see when next term begins I'll be using the 6-cell on AC, because heatsink is close to battery and the battery gets warm on one side (which is not good for it )...


You're right about the "new battery strategy" - I think it is better to have some comfort and buy a new battery later, than to worry constantly about it .

 

I think you'll be fine with the unused battery in your laptop bag. If at some point you find you are only using one of them, you can choose one and put it into prolonged storage. That is unfortunate that your notebook heats up the battery, I agree.

I had two batteries for my first notebook, but rarely had the need for the second one. I kind of regretted spending $150 or more on it, but on the few occasions that I did use it--it was definitely nice to have .

 

I understand having the notebook in the vehicle in the summer time (excessive heat) can be dangerous for the laptop battery (and possibly other components?), but what about keeping it in the vehicle during the winter? Likely between 1 - 2+ hours lets say? I've heard from someone that it took longer to boot-up, but i'm not sure about the dangers/cost of doing so.

 

I think in the winter (assuming you live where it gets cold in the winter), your main issue is going to be theft when leaving a notebook in a car. I would probably prefer to take it with me, or at least put it in the trunk for safety (less visibility) and lower temperature. If it's a sunny day though, there may be chance of a "greenhouse effect" in the passenger compartment of your car.

 

Great article!
How often should I use my battery to keep in a "good state"? I mainly use my notebook at home and may need the battery 1-2 times a year. I have stored it 40% charged as advised

John

 

I actually have two batteries for a 7+ year-old notebook, and they're both still pretty decent after going about 4-5 years between uses. They still hold their charges pretty well too.

I'd say you may want to bring the battery out every 2-3 months or so to give them a calibration cycle before putting it back into storage. Keep in mind though--that the active elements within the battery are still reacting with each other, albeit at a slower rate while in prolonged storage. As mentioned, you can slow down the aging process, but you cannot stop it.

 

Thank you Chriyano

John

 

thanks a lot

 

I have a Toshiba Satellite A10 (very old, yes). Its battery is a model PA3284U-1BAS (Li-Ion). It has a lifetime of approximately 7 minutes. However, Windows detects it as having a life of approximately 2.75 hours (which is about what it had new). But it is really strange - it'll go 100 - 99 - 98 - 97 - 96 - 3 - 1 (it goes to 1 really fast). Notebook Hardware Control reports it as having 0% ware, and it takes roughly the same amount of time to charge it (to read 100%) as it did when it was new. but it never touches anywhere from 9 - 91%. Is there any way to get it to hold some charge?

 

The elements in your battery have probably been degraded to the point where the internal resistance is high enough to prevent the cells from providing the necessary power to your notebook for more than a few minutes. I'm afraid there is nothing that can be done to your battery--it has simply aged to the point of being borderline useless.

Much of the reasons why are discussed above, and there is a dedicated section in the guide about why battery wear estimates are not likely to be accurate.

 

The big danger with near feezing and below temps would be the LCD, if it gets very cold, then warms up too quickly, it WILL crack, I've seen it happen, I was visiting a friend in Denver, we were at a coffee shop waiting in line, all of a sudden we hear this short pronounced "crunch" sound, I turn and the fellow behind us looks white as a sheet, pulls his laptop out of his bag, and the screen was toast. It was around 20 F outside, and around 80 F inside, he said the laptop had been in his car around 3 hours, he was in the coffe shop for less than 10 minutes and didnt even power it up, it was still in the bag, since then I have avoided exposure to non temprature controlled environments whenever possible

technically I "heard" it happen, I know someone was going to point that out sooner or later