Battery Health & Test — Free Online Test
The Battery Health tool reads your laptop's live battery data through the browser's Battery Status API and analyzes charge/discharge trends in real time to estimate battery wear, remaining runtime, and health score. It also includes an optional stress test that spikes CPU load and measures the resulting discharge rate — a much more meaningful indicator of battery capacity than a manufacturer's spec-sheet mAh number. The entire test runs client-side; no data leaves your device.
How to use the Battery Health & Test
- Open the tool with the laptop unplugged so we can observe the discharge trend.
- Let it run for at least 2-3 minutes to collect enough samples.
- Optionally start the Stress Test to force a heavier discharge rate for accurate wear estimation.
- Watch the live level chart and health score update as data accumulates.
- Plug in and re-run the test in charging mode to check charge speed.
- Export the report as a text file for your records or warranty claim.
How to interpret your results
A healthy battery shows a steady, linear discharge curve and a health score of 85+. A score of 70-85 is normal wear for a 2-3 year old laptop. Below 70 indicates significant capacity loss — you'll likely notice much shorter runtime than when the laptop was new. Wildly fluctuating discharge rates or sudden capacity drops during light load usually indicate a failing battery cell.
Common issues and what they mean
"Battery API not supported"
Safari and Firefox have removed the Battery API for privacy reasons. Use Chrome, Edge, or Brave for full readings.
Runtime estimate keeps changing
The OS recalculates constantly based on current load. Give the test 5+ minutes at a stable workload for a reliable estimate.
Charging speed feels slow
Most laptops charge at 60W-100W. If yours is much slower, check that you're using the original charger and a certified cable; USB-C PD requires both sides to negotiate the correct wattage.
When to run this test
- When shopping for a used laptop — always test the battery before buying.
- When your runtime is much shorter than expected.
- Before a warranty claim (to document the wear level).
- Every 6-12 months as preventive check-up.
Frequently asked questions
How accurate is browser-based battery testing?
Useful for observing discharge/charge trends in real time. Less accurate for absolute wear — the browser cannot read the design-capacity value directly. For that, combine our test with vendor tools (Dell Power Manager, Lenovo Vantage, macOS "coconutBattery").
What is a normal battery cycle count?
Most modern lithium-ion laptop batteries are rated for 500-1000 full cycles before dropping below 80% capacity. Laptops used daily typically hit 300-500 cycles per year.
Can I improve battery health?
Yes — keep charge between 20% and 80%, avoid heat, and use manufacturer's "battery care" or "conservation mode" if available.