How does the battery health report say excellent while it dies at 30%?

“Excellent” doesn’t rule out a battery problem. Health ratings often reflect estimated capacity, while an ageing or weak cell can suffer a sudden voltage drop under load. The charge gauge can also be inaccurate, so the displayed 30% may not represent usable power.

First, distinguish an abrupt power cut from Windows showing a low-battery warning and hibernating. For the latter, check Power Options > Advanced settings > Battery for an unusually high critical-battery threshold.

If it suddenly loses power, back up your work and run the manufacturer’s battery diagnostics. Check for model-specific firmware updates, and use a calibration procedure only if the manufacturer recommends it. Repeatedly draining it until it cuts out isn’t a reliable fix.

If it keeps happening—especially if it runs normally on AC power—have the battery checked even if the health rating stays “excellent.” If you notice swelling or unusual heat, stop using it and arrange service.