how long will the battery last before it’s no longer an effective battery? That’s pretty much the same for all modern laptops — about 300–500 full charges. That’s what you can expect from today’s Li-ion batteries. The answer also can vary depending on how you use it. Your laptop battery should last for at least four hours of continuous usage and up to 12 hours with intermittent usage. As you use your laptop, the battery will drain gradually until it's completely out of power and shuts down.