A refurbished laptop arrived with a perfect screen and a battery that worries me

I bought a refurbished laptop for evening classes because a new model with the same memory was outside my budget. The listing promised a tested, working machine and allowed returns. It did not promise a new battery.

The laptop looks better than expected. The screen is clean, the keyboard feels good, and it handles my browser, video lectures, and spreadsheets without complaint. The problem is battery life. During a two-hour library session with ordinary use, it dropped from full to 18 percent. The case was warm but not painfully hot, and the percentage did not jump around.

I can live near an outlet most days. I also know that “refurbished” covers different conditions, and a used battery is not automatically defective. But I do not want to normalize a problem during the return window and regret it halfway through the semester.

Before deciding, I plan to record three repeatable runs: similar brightness, the same set of apps, no operating-system updates in progress, and start and end percentages. I will save the listing, the seller's battery language, the return deadline, and the machine's built-in battery information. I will not open the case or install mystery diagnostic software while return rights still matter.

The choices are not simply keep or return. I could ask the seller whether the result meets its grading standard, request an exchange, price a future battery replacement, or keep it because the total value still works for my use. What I need is a decision threshold, not a promise that every used laptop should last a particular number of hours.

Would you judge this mainly against the listing, against the work I need it to do, or against the cost of replacing the battery later? What evidence would you collect during a short return window so the decision is based on a pattern instead of one anxious afternoon?