A notebook's battery has a finite number of recharges before its performance degrades, or even stops holdll1g a charge. An early sign of a battery neanng the end of its life is the requirement for more frequent recharging. Although the notebook manufacturer will happily sell you replacement (or spare) batteries, it's wOl1h shopping around to find the best price. Most modern batteries degrade from the day they are made, so buying secondhand isn't generally recommended .