A laptop that dies halfway through a meeting does not necessarily need a new battery. First separate battery wear from unusually high power draw. Compare runtime during a repeatable light workload: the same browser tabs, screen brightness, power mode and Wi-Fi connection. Unplug external displays and powered accessories so they do not distort the result.

Read the battery report in context

On Windows, run powercfg /batteryreport and open the HTML report at the path it prints. Compare design capacity with full charge capacity. A lower full charge capacity is expected as a battery ages, and an estimate from one report is not proof of a defect. Track the trend and compare it with measured runtime. On a Mac, start with Battery Health in System Settings.

Fix avoidable power drain first

Check whether an application is holding the processor or discrete graphics active, and whether an external monitor changes that behavior. Lower brightness during the comparison and temporarily pause large sync jobs. If the machine spends most of its life plugged in, look for a manufacturer-supported charge limit. Disable the limit before a travel day only if you need the extra runtime.

Know when to stop testing

Unexpected shutdowns at a substantial indicated charge or very short runtime after you rule out heavy workloads may justify a service assessment. A bulging case or lifting trackpad is different: stop using and charging the laptop, and contact the manufacturer or a qualified repair shop. Do not press the case flat or try to puncture the battery.