It isn't always possible to be near an outlet to keep a charger running. A laptop is supposed to be portable. But a user may still need to be on their computer more than just 2 or 3 hours their batteries allow them. That can turn into a real problem if the person can't keep their computer running because lithium battery stocks its battery just died.
The processor goes up to 75-85C while under pressure but rarely dips below 40C when idle. Everything else is a bit cooler of course, but 40C in the computer case is rather common even with good air-flow. If you plan on using your notebook from the charger, remove the battery first left at 40% charge. Use an air-tight plastic bag and put lithium facts it into the fridge. Do not freeze.
The lithium-ion battery is light years ahead of the earlier batteries and considerably better than the Nickel-cadmium (Ni-Cd) or the nickel-metal hydride (Ni-MH) batteries which are still being used. These batteries are less expensive but the Li-ion batteries are far superior in three ways.
Also keep in mind that when your iPod mini battery does die, it requires a proper funeral inside a proper container. No you don't need to buy a casket and a plot but you do need to adhere to local lithium bettery stock laws when it comes to battery disposal.
Li-ion cells have a good peak output current and low source resistance. When you overload the tool, the voltage stays up, and they just keep pumping current into the motor. Power tools have thermal overload trips in the motors, and that's a good thing with Li-ion batteries, if they didn't they'd just burn the motor out!
Recharge the battery to full again and repeat the above steps a few more times. This will allow you to use the battery for a longer time and you can do this no more than once a month. Replacement batteries can be expensive and stretching out their use when you are on a budget can help.