Helping people with computers... one answer at a time.

When I first got my laptop (8 mos. ago) my battery life was about 2 hours 45. Now after daily use (mostly with plug but using battery as well) it is down to 1.5 hrs which is basically useless. I have tried draining totally recharging etc and still only 1.5 hours. SO I am buying a new one. My question is how do I make my battery keep its charge so I can have it when I need it?

I originally wanted to title this article "Why does my battery life suck?", because I know that's exactly what it feels like when the battery life gets shorter and shorter. My oldest laptop has about a 20 minute lifespan, so in many ways the battery is really nothing more than a glorified UPS. Not that that's bad, but it does limit the laptop's portability.

I turned to a friend, Jerry Foutz, for some help on this one. Do a Google search for Power Supply Design, and Jerry's site, SMPS Technology, is the top result. Jerry knows power supplies.

It turns out that the single, most important aspect to maximizing battery life is something that I wouldn't have thought of: matching the battery to its charger. In Jerry's words: "Make sure your battery and charger match and you have a quality charger. About the only way you can maximize the probability of this happening is to buy both from the computer manufacturer for the exact computer model."

"...even small differences in output voltage of the charger can have dramatic impact on the lifespan of your battery..."

Apparently even small differences in output voltage of the charger can have dramatic impact on the lifespan of your battery, by either under, or over-charging. "If you get a low-cost charger and it is off by as little as 10 mV (millivolts, 1/1000 of a volt), you will also get less than optimum performance." An example Jerry shared is that a 4.1V cell charged at 4.050 V might be good for 4,000 charge cycles. Increasing the charge voltage to 4.250, a difference of less than 1/4 of a volt, can reduce this down to less than 100 cycles.

I had no idea that batteries were that sensitive.

I'm also glad that I've purchased my batteries, extra batteries, and chargers from the manufacturer at the time I got my laptop. That, further, minimizes any manufacturing differences that may occur over time.

The number two factor in battery life? Temperature.

The fact is that laptops just aren't designed for ... well, for laps. If you look at the bottom of your laptop you'll see it probably has feet (or more likely, bumps or rubber pads) that lift it off of any flat surface you might put it on. That creates very important space for ventilation. If you block that space, with say your lap, it's likely that you'll be causing the laptop to run hotter than it should. If you do this regularly, you'll likely shorten the lifespan of the laptop's batteries.

Again, in Jerry's words: "If you have your laptop on your lap and it is burning you, you are shorting the battery life and charge-cycle capability because you have interfered with its cooling system."

If you do like to use your laptop on your lap, there are various "laptop desks" out there that will provide you a flat, or even grooved surface (for even more space and air flow) on which to comfortably place your laptop. My wife and I actually each have a laptop desk from LapWorks.

Temperature cycling - allowing the laptop to become very cold and then warm, repeatedly - say by leaving it in your car overnight in cold weather regularly can also adversely impact the battery's life.

A concern that I've had for a long time is whether or not leaving a laptop plugged in for extended periods of time would harm the battery. Today's designs pretty much expect that type of usage, so it's not the issue I was afraid it might be. Good thing, too ... my laptop is plugged in and running pretty much 24x7.

Finally: "All this assumes a well designed power supply (including charger and battery). Unfortunately, not all designs are perfect and the layman has almost no way to judge the quality of the design. You pretty much have to trust the manufacturer and his reputation."

Thanks again to Jerrold Foutz for contributing to this article.

Article C2533 - January 26, 2006 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Jerrold Foutz
January 27, 2006 4:14 PM

Hi Leo,

Two important things that I did not mention when we talked about batteries are aging and storage.

Lithium-ion batteries start to deteriorate from the day they are manufactured. The mechanism is an increase in internal resistance. For a spare battery the ideal storage conditions are at a 40% charge at 0C (32F). In practice, store it in the refrigerator (not freezer) in a sealed bag after you discharge it to 40% of capacity as measured with the fuel gauge in your laptop. At these ideal conditions, the battery will still have 98% of its capacity after a year storage. But store it with a 100% charge and it is reduced to 94%. If you store it just above room temperature at 25C (77F) with 100% charge you drop to 80%. This is the way I stored my spare before I knew better. This capacity loss is non-recoverable. The capacity is gone forever. If your computer is always on and in use, the battery temperature may sit in an environment of 30C (86F) and drop to 65% capacity in a year. If it reaches 40C (140F) you can drop to 60% capacity in only three months! You get the idea why keeping your battery cool is so important. From the battery perspective, removing the battery while on AC power would reduce its temperature and help battery life, but from a power supply designer's perspective, this is not recommended. The presence of the battery provides substantial design margin to your laptop as well as protecting it from power surges and sags.

The increased internal resistance has an additional effect besides increasing internal battery temperature when current is drawn. When there is a current surge caused by hard-drive access or heavy CPU usage, the surge of current working against the age-increased internal resistance can drop the terminal voltage so that the protection circuits trigger and won't let you use it. There is still capacity, but you can't get to it in an aged battery.

An excellent website on batteries for your readers is the Battery University. This is the source of the percentages I quote above.

Jerrold Foutz
January 29, 2006 9:42 PM

Great article thanks

January 30, 2006 7:28 PM

> If you have your laptop on your lap and it is burning you, you are shorting the battery life and charge-cycle capability because you have interfered with its cooling system.

To say nothing of your own libido and fertility, if you happen to be male!

Take care, Leo!


Khurram Ali
January 31, 2006 2:51 AM

I think using the laptop battery in complete cycle helps. Meaning to charge it fully, then discharge or use it fully, then charge it again.

Charging every 30 minutes or for short time, many times uses up the cycles of the battery.

I have increased the life of my mobile phone battery this way, even after 5 years my Nokia 3100 gives me 24 hours charge.

I only charge it when it is down to its last hours and charge it fully.

February 12, 2006 1:18 AM

Actually, Khurram, Lithium batteries life decreases after every full cycle, aka discharging to 10% or less and then charging to 100%.

Lithium batteries do not have the memory problems that NiCd and NiMh had.

Full cycles are NOT reccomended :)

May 6, 2006 9:16 AM

How can I increase the power of the generic batteries such as Energizer, Duracel, or Enercell 9V?

June 12, 2006 4:16 AM

is there a software to keep ur battery charged for a considerably longer time????

July 2, 2006 11:43 AM

I see replacement batteries that say they will match my laptop but they have higher voltage. For instance, my battery says DC10.8v and 400 mAh. Replacement that says it will work for me is 11.1 and 450. I do not use an external charger, jsut recharge within my laptop...

October 15, 2006 1:19 AM

Great article, Leo (with appreciation from Jerrod, of course)! I just ordered a new Dell Inspiron E1505, and I'll take the advice given on this page to heart. Thanks, guys!

January 4, 2007 3:37 PM

I purcahsed this refurbished HP DV5224NR laptop on boxing day 2006 from futureshop. I have two problems with it. The short battery life and the used up harddrive space.
The battery life lasts a maximum of 1.5 hours - 2 hours under regular usage of surfing the internet and maybe listning to music at the same time. I have noticed that roughly every 1 minute, a percentage of battery is used up.
Secondly, the avaliable harddrive space to use when first opening the computer is approximately 50 GB. The 30 GB that is used up is the 12 GB taken up in the recovery partition and the rest in the programs that come pre-installed from HP.
These are my two cons, if anyone has the same peevs, please share.
Otherwise, so far the laptop is going well.

Jeff White
February 12, 2007 3:19 PM

Can zinc-air cells (hearing aid) be recharged? How do I extend their life?

July 31, 2007 6:56 PM

Verizon is about the only place you can get the authentic RIM product and matching door. Most other sites are out of stock and even when they are in stock they have the black battery door which looks like crap.
We supply a large range of rechargeable Laptop Battery packs for your Laptop , All Laptop Battery in our are made with high quality cells.

lory battery
August 7, 2007 5:53 PM

Verizon is about the only place you can get the authentic RIM product and matching door. Most other sites are out of stock and even when they are in stock they have the black battery door which looks like crap.
We supply a large range of rechargeable Laptop Battery packs for your Laptop , All Laptop Battery in our are made with high quality cells.

July 23, 2008 7:53 AM

I have a Hp Pavilion and my battery have never lasted longer than 15 minuts. I paid $1,300.00 for my computer. I bought it from Best Buy. What happened?

Sounds like you got a bad battery. I'd take it back.


August 29, 2008 11:54 PM
Text blatantly copied from another website in violation of copyright has been removed.
August 16, 2009 7:32 PM

It is very detail for the extend laptop battery life, maybe you can write a article about how to calibrate the laptop battery.

September 4, 2009 11:42 AM

Is true if I remove the battary from my laptop it will last longer.

My laptop

windows XP

Dell Vestro 15

December 10, 2009 9:33 PM

I just got my warranty replacement battery thru best buy, HP pavillion dv6700, the battery is from HP and I got a new charger at same time. the battery is large, actually makes my laptop sit at a nice angle and when I first charged it two weeks ago it lasted 6+ hrs, I never do more than surf the web or word processing when on battery power, and use power save mode, but now 2 wks later my battery lasts only 3 hrs.. is my battery a bad?

January 12, 2010 8:37 AM

Try to avoid leaving the charger in the laptop when the battery is at 100%. This overcharges. If you know you're using mains and the battery is at 100%, slide the battery out! The laptop still works.

May 7, 2010 1:04 AM

Usually a new laptop battery comes in a discharged condition and it must be charged before use (refer to your computer manual for charging instructions).

May 7, 2010 1:05 AM

laptop battery

June 23, 2010 9:56 PM

A good article on same topic which is worth a read:

September 16, 2010 12:57 PM

Sorry but this article tells me nothing about how to maximize my battery life. Charger? What are you talking about?? The laptop IS the charger! I don't buy chargers for laptops. This didn't say anything about power settings, charging/discharging, expected lifetime/charging cycles, nada, nothing, zip. Total waste of time!!

September 17, 2010 7:17 AM

My batter-life power save is about 1 minute? If that.. How do I get it back up to 6 hours again?

Stu Berg
October 3, 2010 6:16 AM

I've read articles about the upcoming electric vehicles that will use lithium-ion batteries, similar to what is in laptops. These articles say that the auto industry is struggling with the problem that whenever the charge in lithium-ion batteries goes below 40% the life of the batteries is reduced. Therefore, I assume the same is true in laptops.

pc repairs brisbane
September 17, 2011 1:08 AM

I like your article that guide me to increase the battery life of laptop. Mobile computing has got better with lighter components, better chips and faster processor. To get rid of this we should, we have to follow these point that are Reduce your monitor brightness, Do one thing at a time, Shut down services you don't need and Keep it cool. Thanks a lot .

April 24, 2012 4:08 AM

I have a cochlear implant for my hearing. I have four batteries which have to be charged daily i.e one every four days (they are used one at a time, not together). These batteries are still going strong after four years. What a shame laptop batteries are not made of the same stuff. Mind you they are £100 each

Charlie Pelissier
May 1, 2012 1:24 PM

A more practical comment would address the consequences of overcharging by leaving the charger connected beyond full charge. Why don't charges automatically shut down when they recognize a fully charged battery ?
How can you know for how long to charge a battery?

Many chargers do these days.
travis hermes
June 10, 2012 8:46 PM

what do i do if i get a message saying something about my battery life at startup everytime i start my laptop? what do i do??? please help

It depends entirely on what the "something" is that it's telling you.
August 23, 2012 12:23 AM

Awesome post! Referring to ( shall give you detailed overview of similar destinations, featuring best tips on how to maximize laptop battery life.

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