If you’re like every other user I've run into, your laptop battery never has enough life. You'll start using it and before you know it the system starts beeping at you “Battery low, plug in AC power to avoid shutdown” and some equivalent message meaning “I need more power!” Well, the following should help get the most from your battery.
For starters, the more devices you turn off the more life you’re going to get. For instance, most laptops today have either a physical or software switch that will disable the wireless card. Even if you’re not using the wireless at that particular moment the card is still searching for wireless services in the area and as such expending power to do so. If you have any PCMCIA cards plugged in or a memory stick in the card reader, if you have a card reader, it is also using power. Any USB devices will pull power; use the track pad instead of an external mouse. Above all, don't try to use the optical drive to watch movies, play a cd, or burn a disk while on battery, you'll run the battery in half the time of anything else you do. All these extra devices use up power and this power is needed for other purposes.
Another thing to remember is not to recharge when the battery is already partially charged. Use the battery up completely, if at all possible, before recharging. Anytime you recharge a partially charged battery you lessen the endurance of that battery per charge. Yes, there are steps to return the battery to a longer life, but it is a long and drawn out process, and it will never get you fully back to maximum life. If you have a battery that has a short life span, charge it for eight hours, then run it on battery until it is fully discharged even to the point of turning it back on a couple of times after it shuts itself back off. If you do this 4 or 5 times you should start noticing that it lasts a little bit longer each time you try it. If it does not get any more life back, then you've probably already damaged the battery and should replace it.
Another thing I find is that most people will have a laptop, because of its size, they have little room, and they are retired and live in an RV (again space is an issue), etc… And they never actually use it off battery. Then when they try to use it off battery, suddenly it has very little life span and they can't imagine why. Well, even though the Laptop knows when it is charged and will reduce the charge to a trickle rather than a full flow, the battery is still getting juice. As such, it's like an atrophied muscle, it's there and it looks big but it just doesn't have the endurance. Once the battery reaches that point it is dead, replace it. My suggestion is when you first get the laptop, charge the battery fully. Follow whatever the manufacturer’s suggestion is for the first charge; usually they want you to charge it for a solid 10 or 12 hours. Then use the laptop solely from battery until the battery is fully discharged. Then let it charge overnight again, at least 8 hours. Then pull the battery from the unit if you plan to use it from AC. This way the battery knows the charge it's suppose to have, and as your not using off battery there's no need to have it in the machine. When you do use the battery, use it on and off from battery until the battery discharges again, then charge overnight again, and remove again when done. Note! You will need to use the battery at least once every other week or so, again like a muscle it needs to be exercised to stay in good health.
As for battery saving settings, many modern laptops know the best settings for their power consumption. If you use the products built in ability to conserve power you will usually get a better battery performance from the system. If you consult your user’s manual you should find the manufacturers recommendations.
I would also suggest purchasing a spare battery. If the need for true mobile computing is important to you that you should always have a backup. When you do, you'll want to rotate batteries often to maximize performance. You might also consider an external charging device. Not all batteries have one, but when they do, it can make your life so much easier.
Temperatures are also a factor. The colder the better, however it's a pain on the fingers. Being to hot, though uncomfortable to you, can cause serious effects not only on the computer but on the battery itself. The hotter the temperature the more the fan has to spin to try and cool the unit off, which means the more juice the battery has to supply generating more heat, forcing the fan to spin more, and…. you get the idea, a self defeating course of action. So, try to keep the area around the laptop as cool as possible. I've seen many people decide to use the laptop on their laps while lying in bed with a blanket between them and the laptop. Well, yeah the blanket insulates your legs from the heat of the laptop, but your also covering up the vents the fan needs to cool off the system, causing the fans to spin faster and longer to try to suck air through the vents to cool, causing the battery to expend more power generating more heat, which needs to be cooled off, and… You see the cycle all over again. I suggest, for those people, getting a board or platform, balsa wood works, to set under the laptop. This gives it a solid surface to sit on without adding unnecessary weight on your legs, and still gives you the convenience and comfort of sitting in bed, or the couch, or futon, etc…
Hopefully one or more of these suggestions will help you gain a better mobile computing experience, and just might safe the life of another poor unfortunate battery.