People just seem to keep forgetting the easiest things about notebooks.
Especially the battery is a continuing point of frustration. How many times hasn't it happened that when you pull out your notebook, the battery is dead, even if you've just recharged it a few hours before.

Well, it's time to take care of that!

Next are a few tips and tricks to both extend the life of your battery and to make sure that you can work as long as possible on a single charge, so that you can save energy and make sure it takes just a bit longer until you have to throw your battery away, which is good for the environment.

Step 1: First Things First...

In order to take care of the battery, it might be useful to know a few things about them.
Notebook batteries can be made of 3 types of chemical compositions.

The first ever notebook batteries were Nickel Cadmium (NiCd). In that time, they had a high energy output and they could be charged quite quickly, which is very convenient in a notebook.
The NiCd, however, isn't used as much in electronic devices because the later types have yet a higher energy output.

The second type of batteries, were the Nickel Metal Hydride (NiMH) batteries. These batteries are still widely used and particularly known for a drawback, namely the memory effect.
These batteries needed to be completely discharged in order to keep its capacity at a maximum.

UPDATE: thanks to Flea i syarted to research a bit more on the memory effect and apparently the memory eefect occurs mainly in the NiCd batteries, as Flea said. NiMH still suffer from this phenomenon though in fewer cases.

The newest type of batteries and the ones that are dominating the market by now, are the Lithium Ion (LiON) ones. These batteries have solved the memory effect found in the NiMH batteries. Instead their capacity is to be held at a maximum by only partially(!) discharging it.
The only problem is that the calibration may turn out a bit off. How to solve this is mentioned later in this instructable.

Step 2: Save Your Battery – I Like Mine Extra Crispy

The first and probably the most important thing to prolong the life of your notebook battery is to take care of it.
By this I mean don't just let your batteries linger around, especially not in extreme conditions like humid places or places with extreme temperatures.
The latter means for instance a hot car in the summer (a greenhouse effect). This is a very easy but important tip that just seems to keep being forgotten.
By the way, an exposed notebook in a car is like Christmas to thieves.

Step 3: Save Your Battery – Plugged In

Another very easy thing to do (in most cases) is to simply remove your battery when working on fixed power.
The reason for this is that when the battery is placed in while you work on fixed power it is in a constant state of dis- and recharging. Seeing that for instance a LiON battery has about 300 - 500 recharge cycles before the internal resistance becomes too high, it's better to only charge it when you are really want to charge it, instead of just letting it warm up (which is also bad).
When you want to charge it, don't use the notebook until it's charged, or unplug it first.

Of course, in a desperate attempt to make notebooks look better and are smaller, some notebook manufacturers build in their batteries which can be removed by doing a lot of effort (and probably voiding some warranties) or you make it a bit easier for yourself and just don't get it out with the risk of seeing your battery die just a bit earlier.
A very good example of this trend is the Macbook Air. A very sleek design, but with a built in battery. In order to get it out, you have to expose the notebooks innards and therefore it might not be the best choice if you don'thave a lot of experience.

Step 4: Save Your Battery – the Sooner the Better

A funny thing about LiON batteries is that they keep their maximum capacity by charging it when its just a bit discharged, rather than when it's completely discharged. The latter was necessary with the older NiMH batteries due to their memory effect.
However, there is a bit of a nag. When you constantly charge these batteries when they are just a bit drained, your computer will probably give you wrong information about the battery. This can be solved quite easily. Just completely discharge your LiON battery about every 30-50 cycles and the info should be right once again.
Also, when you just got a new battery, you are best to fully charge and discharge it a few times to gain maximum capacity and longer cycles.

Step 5: Use Your Battery – Unplugged

Again a rather simple solution. Only turn on what you need!
The more devices that are up and running, the more power you drain from your battery.
Let's start with the easiest ones. Unplug every USB device, express card or the older PC card that you don't really need. These devices keep draining power, even if you aren't using them at the moment.

Modern day notebooks also have a lot of built-in features. Especially built-in Wi-Fi is an energy sinkhole. This and other built-in features can be turned off.
Follow the pictures to see how.
Tip: A lot of modern notebooks have either shortcuts or physical switches to turn Wi-Fi or Bluetooth on or off. Consult your notebook's manual to see how or where.

It's also best to use your touchpad instead of an external mouse. Maybe it isn't as easy (though practice makes perfect), but it's definitely more energy-efficient.

Step 6: Use Your Battery – Turning It Down

I seem to be repeating myself, because once again, this is a simple solution.
In order to work longer on a single charge, just turn down a few settings.
Probably the most famous solution is screen brightness.
Usually you don't need the full brightness of your screen (except when you are working with the sun reflected in your screen). Especially with LCD screens, which use a backlight that is constantly on, this can make a lot of difference.

There are still some other options to turn down. For instance you can lower or completely mute your sound. Besides, who needs those annoying windows sounds?

Step 7: Use Your Battery – Mirror on the Wall

This might be a bit more challenging for those who have never done it before.
In order to save energy, you can create an image of a CD or DVD. This helps save energy because a hard disk requires a lot less energy than an optical drive.
You can find information everywhere on the internet (even on instructables) on how to make an image, but I will give a quick summary.
In order to create an image you must first download a bit of software.
For example: older versions of Nero Burning Rom can be found on various locations (try to Google the name).

Once downloaded and installed, you start up Nero Burning Rom and instead of your usual burner drive, you choose the image recorder from the list.
Specify a folder, the type of image (ISO is about the most known one) and start the virtual burning.
What's happening now is that the program makes a copy of the CD or DVD on the hard disk, rather than on another disc.

Please note that this is quite an exact copy and the file will take up as much space as used on the disc. In case of a double layer DVD, up to 8 GB.

When you are done ripping the disc, you have to install yet another tool. There are many image readers such as Daemon tools, alcohol 120% etc.
These tools install a virtual drive on your system on which you can play your image files. Just mount your images in your virtual drive and enjoy the programs you otherwise would have run from a disc.

Note: these images are usually quicker than optical drives too, because the transfer speed of a hard disc is much higher.

Step 8: Use Your Battery – Theatrical Tuning

Another thing to remember is to avoid multimedia applications whenever possible.
Videos, games, etc. actively drain your battery by putting much more strain on the internal hardware.

For instance: a videogame is probably a lot harder to run than simply WordPad or something like that. It occupies the processor which needs more power to run properly.
Also, these applications produce a lot more heat, so watch out when you're doing something intensive with your notebook on your lap.

Step 9: Use Your Battery – Going Soft

Last but certainly not least, there are some software tweaks that will help your battery last longer.
Most of you probably know this already, but windows has a built-in power management console.
Just open your control panel and search for Power Options.
Tip: pres P on your keyboard to highlight the first icon with a name that starts with P. Tapping P repeatedly will highlight every icon beginning with P in turn.
Once you've opened this, you can select energy schemes or adjust everything yourself. This is up to you (though windows has some good notebook schemes).
Follow the pictures if you don't know what to do.
Except for the power options, other programs can be tweaked as well. For instance, you can turn off the auto save feature in Microsoft Word, resulting in less use of the hard drive and lower energy use.

Step 10: Final Notes

Please remember, most of these tips only lower your power usage a small bit. It's when they are combined that you can sometimes work minutes (to be pessimistic) longer.
Like mommy allways said, every little bit counts.

Also, I know that I haven't mentioned every possible tweak to save power. That would be virtually impossible. It's up to you to go and search for more tips if you don't find these sufficient. I just hope these tricks will help you enjoying your notebook more and less batteries find their way to the dump (Newer batteries can often be recycled to new batteries though. Just don't toss them away with your common household thrash. Take them to a recycling point instead!).