How is battery health percentage calculated?

Battery health is calculated by dividing the current Full Charge Capacity by the original factory Design Capacity, then multiplying by 100: (Full Charge Capacity / Design Capacity) * 100. For example, if a 50,000 mWh battery now charges to 40,000 mWh, its health is 80% with a 20% wear level.

Why doesn't the live Web Battery API work on my browser?

Some browsers (like Firefox and desktop Safari) disabled navigator.getBattery() to prevent cross-site fingerprinting. Chromium-based browsers (Google Chrome, Microsoft Edge, Opera, Brave) fully support it. You can still use our built-in Wear Calculator regardless of browser.

How do I generate a battery report on Windows 10/11?

Open Command Prompt (cmd) or PowerShell as Administrator and run 'powercfg /batteryreport'. Windows generates a detailed HTML file showing design capacity, full charge history, and recent cycle counts.

When should I replace my device battery?

Manufacturers (including Apple, Dell, and Lenovo) recommend replacing a lithium-ion battery once its maximum health drops below 80% (typically around 500 to 1,000 full charge cycles), or if your device experiences unexpected shutdowns under load.

⚡ Real-Time Battery Telemetry & Capacity Wear Diagnostics

Battery Health Check: Monitor Status & Calculate Wear

Inspect real-time battery charge levels, calculate capacity degradation, check charge cycle counts, and generate official Windows and Mac battery reports with zero downloads.

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Detecting Battery...

Calculating charge/discharge telemetry...

📊 Battery Capacity Wear Calculator

Original Design Capacity (mWh):

Current Full Charge Capacity (mWh):

Cycle Count (Optional):

Battery Health 85.0%

Wear Level 15.0%

Lost Capacity 7,500 mWh

Health Rating Good

How to Get Exact Battery Capacity on Your Device

Windows contains a hidden utility that generates an official HTML battery health report. Run this command in Command Prompt (CMD) or PowerShell:

powercfg /batteryreport

After pressing Enter, Windows saves battery-report.html to your user folder. Open it in any browser to copy your exact DESIGN CAPACITY and FULL CHARGE CAPACITY into our calculator above.

How to Test & Maintain Battery Health in 3 Steps

Extract Design & Full Capacity

Generate your device's battery report (e.g. powercfg /batteryreport on Windows or System Information on Mac) to retrieve original vs current capacity.

Calculate Wear Percentage

Enter the values into our wear calculator. Above 80% is healthy; below 80% indicates degraded battery life and potential performance throttling.

Practice 80-20 Charging

Avoid keeping lithium-ion batteries at 100% on chargers or discharging to 0%. Maintaining between 20% and 80% doubles cycle lifespan.

The Science of Lithium-Ion Battery Degradation & Longevity

Rechargeable lithium-ion (Li-ion) and lithium-polymer (Li-Po) batteries power modern laptops, smartphones, and tablets. Unlike memory chips or processors, batteries are consumable electro-chemical components that naturally degrade over time.

How Battery Degradation Occurs at the Molecular Level

During discharge, lithium ions travel from the graphite anode across an electrolyte solution to the lithium-cobalt or lithium-iron cathode. During charging, they return to the anode:

Solid Electrolyte Interphase (SEI) Thickening: Each charge-discharge cycle causes chemical side reactions that consume active lithium, forming a resistive crust on the electrodes that permanently reduces capacity.
Electrode Micro-Cracking: High voltages (above 4.2V per cell at 100% charge) exert mechanical stress on cathode crystal lattices, causing physical micro-fractures.
Thermal Acceleration: Heat is the primary enemy of lithium chemistry. Operating above 35°C (95°F) drastically speeds up parasitic side reactions and accelerates capacity wear.

Why the 80-20 Rule Triples Battery Lifespan

Depth of Discharge (DoD) directly dictates cycle durability. Cycling a battery from 100% to 0% provides roughly 300 to 500 total cycles before reaching 80% health. By contrast, cycling between 80% and 20% (60% DoD) minimizes high-voltage stress, allowing batteries to deliver 1,500+ usable cycles—effectively tripling physical lifespan.

Battery Health Ratings & Cycles Matrix

Industry standard battery health ratings and cycle thresholds across modern consumer electronics:

Health % Range	Wear Level	Average Cycles	Operational Status	Recommended Action
90% – 100%	0% – 10%	0 – 250	Optimal (Factory Condition)	Continue standard 80-20 charging habits
80% – 89%	11% – 20%	250 – 500	Good (Normal Aging)	Normal runtime; avoid extreme heat
70% – 79%	21% – 30%	500 – 800	Service Recommended	Noticeable battery drain; consider replacement
50% – 69%	31% – 50%	800 – 1200	Degraded / Throttled	Device may shut down unexpectedly under heavy load
Below 50%	> 50%	1200+	Failing (Urgent Service)	Replace battery immediately; risk of physical swelling

Frequently Asked Questions

Is it bad to leave my laptop or phone plugged in overnight?

Modern devices feature smart battery management controllers that stop charging at 100% and bypass current directly to the system. However, keeping a battery constantly at 100% voltage (especially in hot environments) creates sustained chemical stress. Enable 'Optimized Battery Charging' or limit maximum charge to 80% if plugged in continuously.

Does draining a battery to 0% recalibrate it?

Draining to 0% does not improve physical battery chemistry; in fact, deep discharge strains lithium cells. However, doing a full cycle (0% to 100%) once every few months can recalibrate the software fuel gauge microcontroller if your percentage jumps erratically.

How can I tell if my battery is physically swollen?

Signs of a swollen battery include a laptop trackpad that no longer clicks properly, a bulging keyboard deck, or a smartphone screen separating from its frame. Swollen batteries pose a thermal runaway hazard—stop charging and seek professional replacement immediately.