Have you ever think about the problem, what the inside of a laptop looks like?
The images below shows the inside of a sony vioa laptop. The major components have been removed and highlighted. Their corresponding place on the laptop has been highlighted as well.
We can found that all the internal components are much smaller than those we have ever saw in conventional desktop PCs easily. what more . This is especially evident when comparing the Hard Disk Drive and the RAM. When assembled the keyboard fits across the middle of the machine, it sits on top of the processor , the processor heat sink , the ACER ASPIRE 3000 Laptop Battery and part of the Hard Disk Drive. This particular model does not have an internal CD ROM Drive to conserve space. A larger laptop would usually have space for a CD drive on the bottom left of the chassis. The Dell INSPIRON 6400 Laptop Battery is located on the reverse of the laptop - see second image.
Why are some laptop batteries so expensive?
Some batteries are specific to a manufacturer or laptop model, thus enabling the manufacturer to keep the price high. Batteries specific to one manufacturer or model will be made in lower volumes which will increase the production cost. In some cases the price of the original battery is kept high to motivate buyers to buy a new laptop.
Why are some laptop batteries so cheap?
Laptop batteries are often manufactured in very large volume production runs and as a result the cost saving is directly passed onto the end user.