Contents
1. How Much Capacity Do Lithium-Ion Batteries Actually Lose Each Year?
2. What Normal Capacity Loss Looks Like
3. The Two Main Types of Capacity Loss
4. Temperature: The Biggest Enemy of Battery Life
5. Charge-Discharge Cycles and Depth of Discharge
6. Storage State of Charge Matters More Than You Think
7. High Charging Voltage Accelerates Aging
8. Typical Yearly Capacity Loss in Real Use
9. How to Check Your Own Battery Capacity Loss
10. Simple Ways to Slow Down Capacity Fade
How Much Capacity Do Lithium-Ion Batteries Actually Lose Each Year?
Most people want a straight number: on average, a well-treated lithium-ion battery loses 4%–8% of its original capacity per year in typical consumer use (phones, laptops, power tools, electric bikes). Under harsh conditions—constant heat, deep discharges, or full charges—the loss can easily reach 15%–20% a year. Knowing the real range helps you plan replacement time and avoid surprises.
What Normal Capacity Loss Looks Like
When a battery is new, it delivers 100% of its rated capacity. After one year of daily use, most batteries still hold 92%–96%. After two years, 85%–92% is common. By year five, a good battery usually keeps 75%–85%. Once capacity drops below 70%–80%, you really feel the reduced runtime. These numbers come from thousands of real-world tests on NMC, LFP, and LCO cells in phones, EVs, and energy storage systems.
The Two Main Types of Capacity Loss
Capacity loss happens in two ways:
• Calendar aging – the battery ages simply sitting on the shelf or in your device, even when not used. Heat and high state of charge drive this.
• Cycle aging – every charge-discharge cycle causes tiny damage that adds up. Deeper cycles cause more damage per cycle.
In the first 2–3 years, calendar aging usually dominates in phones and laptops because people charge to 100% and leave them plugged in. In power tools and e-bikes, cycle aging takes over because of frequent deep discharges.
Temperature: The Biggest Enemy of Battery Life
Heat kills lithium-ion batteries faster than anything else. Every 10°C rise in average temperature roughly doubles the aging speed. A battery kept at 25°C may lose 4% per year; the same battery at 40°C can lose 12%–15% per year. That's why phones left in hot cars or server rooms age so quickly. Cold is much less harmful for long-term capacity—batteries stored at 0°C age very slowly, though power output drops temporarily.
Charge-Discharge Cycles and Depth of Discharge
A “cycle" is using 100% of the capacity, but it doesn't have to be in one go. 50% today + 50% tomorrow = one cycle. The deeper the average discharge, the fewer total cycles you get:
• 100% depth (0%–100%) → ~300–500 cycles to 80% capacity
• 50% depth (25%–75%) → ~1,200–1,500 cycles
• 20% depth (40%–60%) → ~3,000+ cycles
Phones rarely go below 20%, so cycle aging is slow. E-bikes and power tools often go from 100% down to 10%–20%, so they wear out faster.
Storage State of Charge Matters More Than You Think
If you store a lithium-ion battery for months, the charge level you leave it at decides how much capacity you lose. The worst choice is 100% charge—calendar aging can reach 15%–20% loss per year at room temperature. The best choice is 30%–50% charge in a cool place (refrigerator is fine, not freezer). At 40% and 15°C, high-quality cells lose only 2%–4% per year.
High Charging Voltage Accelerates Aging
Most cells are rated 4.2 V per cell for maximum capacity, but that voltage also speeds up degradation. Many modern phones and laptops now limit regular charging to 4.1 V or 4.15 V (85%–90% shown capacity) to extend life. Fast charging above 4.25 V or high C-rates also increases heat and stress, adding a few percent extra percent loss each year.
Typical Yearly Capacity Loss in Real Use
• Smartphone (daily charge to 100%, 25–35°C) → 6%–10% loss year 1, then 4%–7% per year
• Laptop (often plugged in, warm environment) → 8%–12% per year
• Electric bike (deep cycles, outdoor temperature) → 10%–18% per year
• Power bank stored half-charged in drawer → 2%–4% per year
• EV battery with active cooling and 20%–80% charging habit → 3%–5% per year
How to Check Your Own Battery Capacity Loss
On iPhone: Settings → Battery → Battery Health → shows “Maximum Capacity" percentage.
On Android: dial *#*#4636#*#* (works on many phones) or use free apps like AccuBattery or 3C Battery Monitor.
On Windows laptop: run “powercfg /batteryreport" in Command Prompt → opens an HTML file with “Design Capacity" vs “Full Charge Capacity".
On Mac: hold Option key → click Apple menu → System Information → Power → “Charge Remaining" / “Full Charge Capacity" ratio.
Simple Ways to Slow Down Capacity Fade
1. Avoid heat—don't leave devices in hot cars or direct sun.
2. Charge to 80%–90% most of the time instead of 100% if your phone allows it.
3. Use the device until 20%–30% before recharging instead of topping up all the time.
4. For long-term storage, charge to ~40% and keep it cool.
5. Turn off the device or enable optimized charging features.
Following these habits can easily cut yearly capacity loss from 10% down to 4%–5% for most consumer batteries.