The Thinkpad T420 is one of the longest lasting laptops in terms of battery life. Sony Vaio S or Z can have an extended battery sheet (adding almost no thickness) that will make your laptop have ridiculously long battery life.
Laptop battery life depends on a variety of factors. Typcially Dell has higher rated batteries.
If you want any batteries to last longer then put the batteries in your fridge and that helps them to last longer!!
Frozen batteries last longer unfrozen batteries.
they are bigger
You can find good batteries that last a while on Best Buy and Fry's sites. But you should know that it also depends on your laptop brand and model on how long your battery will last.
After charging laptop it will 3 to 4 hours backup
alkaline
the most common non rechargeable battery is alkaline batteries. the more expensive batteries contain more lithium. the lithium batteries last a lot longer. you can also buy heavy duty batteries. although it sounds like they should last longer..they don't. heavy duty batteries are actually a step down from alkaline.
No, batteries should be stored at room temperature and extreme temperatures reduce performance. They do last longer for about 5%. And if there alkaline batteries, room temperature does just as well.
According to manufacturers, you should never remove the battery when the computer is plugged in. Removing the battery does not extend battery life because all batteries have "shelf" life and are no good after a certain time. Today's batteries actually will last longer if you keep it in the laptop.
Storing batteries in a fridge or freezer does not make them last longer, it's just a myth.
It depends on usage. But laptop batteries last anywhere between 12-24 months. My laptop battery needs to be replaced because it will not charge all the way and it is 19 months old. If possible, Replace it with a 9 cell for longer life and it will hold a charge longer too.