Laptop batteries are essential if you use your laptop on the move. The amount of operating time a battery provides between charges varies depending on the model of laptop you have, but overtime all laptop batteries become less efficient.

The main reasons for buying a laptop battery are:

To replace an exhausted laptop battery.

Exactly how long a laptop battery will last depends largely on usage and the type of battery, but as a general rule you should replace the battery every 18 - 24 months.

To extend the battery's operating time

In some cases it is possible to replace the original laptop battery with one with a higher capacity, which will give more time between charging.

To use as a back-up or spare battery

If you constantly use your laptop away from access to mains power then one battery may not be enough to ensure the performance required.

If your existing laptop battery isn't providing power or isn't lasting as long, then it's probably time to replace it. It is recommended that your change your laptop battery around every 2 years but this varies depending on use.

You should also consider purchasing a laptop battery as a spare. This particularly applies if you need to run your laptop off the battery for extended periods.

Before you buy a new laptop battery, check that an exhausted battery is definitely the cause of the fault:

• - Check the battery hasn't become disconnect from the laptop
• - Try cleaning the contacts to ensure a good connection between the laptop and battery
• - Make sure the laptop battery is installed correctly
• - Check the laptop runs correctly using the mains AC adaptor

Q: What are the advantages of Lithium Ion batteries compared to other rechargeable batteries?

A: Lithium-ion batteries have several advantages: They have a higher energy density than most other types of rechargeables. This means that for their size or weight they can store more energy than other rechargeable batteries.

They also operate at higher voltages than other rechargeables, typically about 3.7 volts for lithium-ion vs. 1.2 volts for NiMH or NiCd. This means a single cell can often be used rather than multiple NiMH or NiCd cells. Lithium-ion batteries also have a lower self discharge rate than other types of rechargeable batteries. This means that once they are charged they will retain their charge for a longer time than other types of rechargeable batteries. NiMH and NiCd batteries can lose anywhere from 1-5% of their charge per day, (depending on the storage temperature) even if they are not installed in a device. Lithium-ion batteries will retain most of their charge even after months of storage. So in summary; lithium-ion batteries can be smaller or lighter, have a higher voltage and hold a charge much longer than other types of batteries.

Q: How long should my new rechargeable battery last?

A: The life of a battery operating under normal conditions should be between 500 to 800 charge-discharge cycles. This translates into one and a half to three years of battery life for the average user. As your rechargeable battery begins to die, you will notice a decline in the running time of the battery. When your two hour battery is only supplying you with twenty minutes worth of use, it is time for a new one. NiCad and NIMH batteries have an average shelf life of three to four years. When a battery is not used for extensive periods of time it should be removed from the computer and stored in a cool, dry and clean environment. Self-discharge will occur when the battery is not used for an extended time period. Fully charge the battery before use after storage. Long term storage will have no permanent effects on the battery's capacity.