Laptop Repairs

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Care of laptop batteries

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Laptop batteries have a definite lifetime. Often they are one of the first major components to fail in a laptop, especially if you usually use the laptop when it is not connected to mains power.

There are currently two types of batteries commonly used in laptops, Ni-MH (Nickel-Metal hydride) batteries, or Li-ION (rechargeable lithium) batteries. Ni-MH batteries are really the lower power, cheaper alternative for laptop batteries. They develop what is known as voltage depression, which is more commonly, although incorrectly, referred to as the memory effect. When this occurs Ni-MH cells will not fully recharge or discharge, causing a considerable drop in operating lifetime. Li-ION batteries, while considerably more expensive, do not develop a memory effect, and do not degrade as quickly or as severely as Ni-MH batteries. They are also capable of holding a higher capacity while being considerably lighter in weight. While they last longer, eventually they too will start to degrade, often as a result of the way they are charged and discharged and the type of environment in which they operate.

Battery in cradle

Ni-MH batteries will eventually degrade no matter how well they are cared for and how they are recharged. To help reduce the speed and severity of the degradation, it is best to completely discharge and then recharge the battery at least once every few months, as well as avoiding recharging the battery when partly discharged. As well, Ni-MH batteries are not as good at absorbing overcharge as Li-ION batteries. This is because Li-ION batteries usually contain circuitry that prevents the cells from being overcharged.

Modern laptops that use Ni-MH batteries often have a bios feature called "Battery Calibration". This feature can be used to help maintain the battery cells' ability to hold charge and to give an indication as to when the battery should be replaced. This automates the process of completely discharging and recharging the battery, and also often indicates the remaining capacity of the battery. A Ni-MH battery will last between 6 to 18 months.

Li-ION batteries will generally last longer, with a usual lifetime of one to three years depending on how they are treated. Unlike Ni-MH batteries, they do not develop a memory and hence do not degrade as quickly or severely, and can therefore be recharged without ill effect at any time. From personal experience, I have found it does seem to help to discharge a Li-ION battery to about 30% of capacity maybe once or twice every few months.

Battery slot

Continually keeping the battery charged does tend to cause it to degrade more quickly. This is most likely due to some overcharging or more likely, the heat generated through the process of continual charging.

Li-ION batteries will degrade over time even when not in use, and this will occur more quickly if they are stored at a low charge.

If the laptop is not going to be used for some time, it is best to remove the battery. If it is left in the machine it will slowly discharge and will degrade more quickly. Batteries should be stored at approximately 50% charge, and should be stored in a cool, dry place. While Li-ION batteries need no on-going attention, Ni-MH batteries should be checked, discharged and recharged about every six months to prolong their stored lifetime.

Although some manufacturers advise that the battery be removed if the laptop is not going to be moved, I believe it is better to leave them in, as while it may cause the battery to degrade faster, it helps iron out power spikes and brownouts which may damage the laptop.

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