OK, there are MANY variables that go into how long your battery lasts but nearly ALL laptop batteries are Lithium Ion with Cobalt Oxide cathodes. Here are the factors that effect their life 1. DoD, Depth of Discharge, the deeper you discharge the battery the shorter it's cycle life (cycle life is defined as being over when the battery only holds 80% of it's original capacity) discharging to ~40% is optimal. Conversely charging the discharging to ~40% is optimal. Conversely charging the battery to 100% also shortens the life, most laptop bats are actually at 90% when they show 100% and stop charging. battery to 100% also shortens the life, most laptop bats are battery to 100% also shortens the life, most laptop bats are actually at 90% when they show 100% and stop charging. 2. C rate. A 10 amp hour battery producing 10 amps is discharging at 1C. A 10 ah battery producing 20a is discharging at 2C. Anything above 1C starts to decrease the cycle life of the at 2C. Anything above 1C starts to decrease the cycle life of the battery (though not all chemistries are like this, this figure is for li-ion with cobalt oxide cathode) battery (though not all chemistries are like this, this figure is for i-ion with cobalt oxide cathode) 3. Temperature, higher temperatures increase the amount of energy available for a given charge (to a point) but decrease the cells cycle life, temps over 40deg C have an exponentially ncreasing (with T) negative affect on cycle life. Also if temps are below or near freezing you lose cycle life and the energy available per charge is decreased. THE EFFECTS OF #2 AND #3 ARE MULTIPLIED, A HIGH C RATE AT HIGH TEMP IS THE WORST 4. There are many other smaller factors specific to exact chemistries I have heard rumors that it is good to vary the chemistries I have heard rumors that it is good to vary the DoD. Simply leaving the battery in a really hot place (car in the sun) or operating a laptop with poor cooling that heats up a lot will decrease the batteries life even when it is not in use.