A laptop battery can be charged 300-1000 times. The actual number depends on the way it has been treated. In the last post of this series, I outlined the influence that the temperature has on a battery’s lifespan. Today, I will explain how a battery should be charged and discharged with care.
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Fully discharge a new battery and then re-charge it. This calibrates the battery.
Calibrate the battery every 30 charges, i.e., fully discharge it and charge afterwards.
Avoid frequent full discharges. In contrast to NiCd (Nickel-cadmium) and NiMh (Nickel-metal hydride) batteries, Li-ion (Lithium-ion) batteries show no memory effect. That is, it will do no harm to the battery if it is re-charged before it is empty. Full discharges will strain the battery.
Avoid total discharges. Total discharges, i.e., to the cut-off point, can destroy battery cells. Not all cells in a laptop have the same voltage. Your laptop’s battery gauge only displays the state of the whole battery. If a cell goes below a certain voltage it will be destroyed. Therefore, it is safer to stop working when your battery level reaches 20%. The low battery level can be configured under Vista in the advanced power settings applet. Vista will warn you when the battery reaches the low battery level.
Avoid high discharge rates. High discharge rates also strain the battery. Therefore, I would avoid power intensive tasks while working on battery. Some laptops come with special power management software that can disable unused components. Every piece of hardware that is active produces heat and wastes precious battery capacity. I also recommend checking out Vista’s advanced power management features. You will find many ways to reduce the power consumption. For example, I always set the maximum processor state to 1% while working on battery. You will be surprised at what a modern CPU can accomplish with 1% of its capacity.
Avoid full charges. Fully charged batteries deteriorate faster, especially at high temperatures. Monitor the battery icon in the systray and disable charging before it is fully charged. I guess this is not really a practical advice. Hence, it is only something for battery life-saver enthusiasts.
Avoid charging. This might sound like a rather unrealizable piece of advice because an empty battery has to be charged so it can be used again. The problem is that a lithium-ion battery only allows a limited number of discharge/charge cycles. If you are working on main, Windows will try to charge the battery whenever it falls below a certain level. This procedure is the worst thing that can happen to a battery. Usually, power management is set to high performance while the laptop is connected to AC. This increases the heat in the laptop while the batteries are being charged. One option is to disable charging while working on main. A far better option is to remove the battery if you don’t need it for the next couple of days.
In the next and final post in this series, I will give some tips on how a laptop battery should be stored to extend its lifetime.