How do they measure a laptop's battery life?

[Turkish]

You know they claim some high numbers in IBM ads, like 7 hours on a couple ones.... How do they measure this? To they just measure the time that laptop can stay on without any apps running? Someone enlighten me.

/ / / Xiety

 

[notfred]

They turn on every single power saving feature, turn the screen contrast down, leave the machine on and time how long it takes for the battery to run out.

 

[hoyaguru]

I sell laptop batteries for a living (batteryfuel.com) and as far as I know, they just make it up. You can find the exact same battery on 5 sites and they will show 5 different run times. It's impossible to say how long a battery is going to last, it depends on so many different things. Someone watching a DVD movie is going to get far less time than someone typing a letter or surfing the internet. Screen size, how much memory you have, and several other factors will affect the time you get. Case in point, the biggest battery we sell (an external) will give you between 10 and 14 hours run time, so some sites will tell you 10 hours, some will tell you 14. I say 10, so the customer isn't disapointed.

 

[Turkish]

cool.. thanks guys....

my laptop supposed to have 2,5 hours of battery time when i bought it.. but the battery is weak... it lasts only around 30 minutes when I am using Word... the laptop is 3 years old.. but still... this just sucks.

 

[hoyaguru]

The average laptop battery lasts about 2 years (or about 400 charges), 30 minutes of life after 3 years is actually pretty good. If you are looking for a new battery, try to find one with the highest amperage (the amps or mAH listed on a battery is what is going IN, not what is coming OUT), you'll get more time out of it. The average battery is 14 Volts, 3.5 Amps, but some manufacturers will make higher amperage batteries, you might get lucky and find a double capacity.

 

[Eli]

Originally posted by: hoyaguru
The average laptop battery lasts about 2 years (or about 400 charges), 30 minutes of life after 3 years is actually pretty good. If you are looking for a new battery, try to find one with the highest amperage (the amps or mAH listed on a battery is what is going IN, not what is coming OUT), you'll get more time out of it. The average battery is 14 Volts, 3.5 Amps, but some manufacturers will make higher amperage batteries, you might get lucky and find a double capacity.

Huh? That is incorrect.

The mAh spec of a battery is telling you the energy capacity of the battery. It means milliamp-hours; that is, how many milliamps the battery can release in an hour(fully drained).

A 2200mAh AA battery can supply 2.2 amps for 1 hour, or 1.1 amps for 2 hours, or 733mA for 3 hours... etc.

 

[hoyaguru]

Originally posted by: Eli

Originally posted by: hoyaguru
The average laptop battery lasts about 2 years (or about 400 charges), 30 minutes of life after 3 years is actually pretty good. If you are looking for a new battery, try to find one with the highest amperage (the amps or mAH listed on a battery is what is going IN, not what is coming OUT), you'll get more time out of it. The average battery is 14 Volts, 3.5 Amps, but some manufacturers will make higher amperage batteries, you might get lucky and find a double capacity.

Huh? That is incorrect.

The mAh spec of a battery is telling you the energy capacity of the battery. It means milliamp-hours; that is, how many milliamps the battery can release in an hour(fully drained).

A 2200mAh AA battery can supply 2.2 amps for 1 hour, or 1.1 amps for 2 hours, or 733mA for 3 hours... etc.

Yers, the mAh is showing you the energy capacity of the battery. The higher the mAh, the higher the capacity of the battery. Again, this is showing the amperage going in, not coming out. I think we are both saying the same thing here.