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 « »

A version of this article that can be republished without cost is available at ArticlesByLeo.com terms).

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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.

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Recent Comments
31 Comments
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 .

KEITH PATERSON
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.
Leo
01-May-2012
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.
Leo
11-Jun-2012
Barkha
August 23, 2012 12:23 AM

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