Laptops – Portable computers almost.
If you were to say ‘laptop' to someone thirty years ago, he or she would have thought that one was referring to a grandchild to be bounced on his grandpa's knee. Now a laptop is a computer, which would have been difficult to imagine thirty years ago as well, because computers at that time resembled large electronics closets that weighed several hundred pounds. If one were to put such a behemoth on one's lap at that time, one's lap would have been crushed and the laptop user would not have ideal use of the computer, as he or she would be laid up in the hospital nursing broken legs. That is why the term 'laptop' became common currency only when computers got small enough to allow people to put it on their laps without hurting themselves. Laptop computers give one the ability to use the power of those computers of thirty years ago without getting in one's car and driving several miles to the computer center to make things happen. And everyone now can use a cheap laptop - price is no longer the barrier that it once was to a laptop user. Laptop batteries have gotten so good that one can put a computer on one's lap and use it without access to electrical current for several hours at a time. Cheap laptops do not mean cheap batteries, as the amount of competition in the computer market means that at all price levels there are lots of options and performance will remain relatively good.
Laptop batteries can be expensive, however, relative to the other parts of a laptop computer. That's because, while the cost of other components has come down nearly exponentially, the price of the components and manufacture of laptop batteries has not kept pace. While the lithium and the other components of the battery are relatively inexpensive, the manufacturing techniques to make them last a long time and be relatively safe can be very difficult. Witness Sony's difficulty in the last few months with battery fires, which were caused by some design flaws. The engineers were looking for a way to extend battery life, and may have pushed things a bit too far on the side of performance and not far enough on the side of safety.