how long until computer runs out of battery?
Just about any gadget that keeps track of the time will have a battery. In your computer (as well as other gadgets), the battery powers a chip called the Real Time Clock (RTC) chip. The RTC is essentially a quartz watch that runs all the time, whether or not the computer has power. The battery powers this clock. When the computer boots up, part of the process is to query the RTC to get the correct time and date. A little quartz clock like this might run for five to seven years off of a small battery. Then it is time to replace the battery. 6 Easy Ways to Keep Your Computer Cool Without Using Electricity.