Batteries
Since laptops and other portable devices are built to be used "on the road", there might not always be a power outlet available to plug a unit in. To solve this problem, batteries have been incorporated as an integrated component of portable systems.

Originally, portables used Nickel Cadmium (Ni-Cad) batteries that were in an external battery pack that would attach to the portable device. The average amount of time Ni-Cad batteries would operate a device was around two hours, depending on power consumption. Since the amount of time it takes to recharge these types of batteries is nearly a day, better batteries have gradually replaced them.

More recently, Nickel Metal-Hydride (NiMH) and Lithium-Ion batteries have been used in portable devices. These batteries are usually constructed in a plastic holder that can be easily inserted into the portable device. These batteries usually last for a little over two hours, depending on their size and the power consumption by the device. Also, it only takes three to five hours to recharge them, a considerably shorter time than it would take for a Ni-Cad battery. One drawback for portable systems is that there are currently no industry standards in place for the power supplies. Therefore, a battery in one portable device may not be compatible with a different portable device.

Hard Drives
As with most components of a portable device, hard drives have been specially developed to be smaller and use less power to accommodate size and power limitations. The size of hard drives in portable devices range dramatically. Power issues have also been addressed with hard drives by powering them down once they have not been accessed for a certain amount of time.

PCMCIA Cards
The Personal Computer Memory Card International Association (PCMCIA) card, introduced in 1989, is a special expansion card type designed primarily to accommodate the needs of the portable computer market. Recently, the term PCMCIA has been used less often and has been replaced by the more easily spoken PC Card. There are three types of PCMCIA slots and cards. These include the following:

• Type I cards are 3.3mm thick and used as memory expansion units.
• Type II cards are 5mm thick and are used for any expansion device except hard drives.
• Type III cards are 10.5mm thick and designed to be used solely for hard drives.
   

Memory
Most portable computers do not use a standard type of memory. With nearly any laptop, to upgrade the memory, the owner will need to seek out the manufacturer website or their user manual for more information. Even within the same manufacturer, memory types can vary between different products or different versions of the same product. This calls for careful research before upgrading a portable's memory.