Extenting Your Laptop Battery Life

Laptop batteries are generally Lithium-ion batteries, they work buy moving Lithium Ions from the negative electrode to the positive when being used and the opposite when they are charging. They are often used for laptops as they have the best energy-to-weight ratio of all the battery types and only slightly loose change when not in use (about 5-10% per month).

They do, as many of you will know, have several disadvantages, the most prominent being their shelf life. When you charge a Lithium-Ion battery it causes deposits in the electrolyte (much like limescale in your kettle). These deposits reduce the total charge of the battery as well as increasing internal resistance. This is why your laptop batteries eventually die and why laptop manufactures do no cover batteries under warranty, classing them as consumables.

The main driving force for this deposit build up is heat, the hotter the battery the more deposits build up, this table shows the approximate irreversible loss of charge per year depending on the heat of the battery:

Temp Loss
0°C 6%
25°C 20%
30°C 35%
At 100% Charge

As you can see, the higher the temperature the faster you’ll loose your total charge, if you could manage to keep your battery at 0°C it would last 15 year as apposed to 2 year at 30°C. There is one more factor, and that’s the change the battery is kept at. When a battery is at 100% charge the particles are more excited then at 30% and therefore more likely to cause these deposits. So if your battery is kept at a lower charge then it will last longer, see this below table:

Temp Loss
0°C 2%
25°C 4%
30°C 15%
At 30%-60% Charge

so at 30%-60% the battery is likely to last between 50 & 5 years. This is much better then the 15-2 years at 100% charge. So what practical ways are there to increase the lifespan of your Lithium-Ion batteries:

  • Use the battery regularly (at least once a week), even if this means running the battery at your desk.
  • Allow the battery to discharge fully at least once a month.
  • Don’t let the battery get too hot, clean any dust from vents, keep the vents clear and keep the laptop on a flat surface.
  • Don’t leave it in direct sunlight or areas where it will be exposed to extreme temperatures such as your car on hot days.
  • If you don’t use your laptop for a period of time (longer then a week), make sure it has about 30% charge.
  • Use a laptop cooler (especially useful if laptop spend allot of time on your desk lap)

These simple steps should help keep your battery running in peak condition and hopefully last much longer then the 2 year average.

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