Want your iPhone battery to last years longer? Enable “80% Limit”.
Go to Settings… scroll down… tap Battery
Now open Battery Health & Charging
Turn on Optimized Battery Charging. This slows charging at night and keeps your battery around 80% until you need it.
Some iPhones also show 80% Limit. Turn that on to stop charging past 80% — the safest level for long term battery health
🔋 Why 100% Is Bad for iPhone Battery Health
🟥 1. High voltage stresses lithium‑ion batteries
At 100%, the battery is held at its maximum voltage, which accelerates chemical aging.
Lithium‑ion cells prefer the middle range (20–80%).
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🟧 2. Staying full generates heat
When the battery is full, the charging system repeatedly “tops off” the battery.
This micro‑charging creates extra heat, the #1 battery killer.
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🟨 3. Overnight charging keeps it at 100% for hours
Even with Optimized Charging, many people still keep the phone plugged in long after it reaches 100%.
Long exposure to full charge = faster wear.
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🟩 4. Apple’s own documentation warns about high charge levels
Apple states that batteries age faster when kept at full charge + warm temperatures.
This is why Optimized Charging exists.
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🟦 5. Charge cycles wear faster at high voltage
A cycle at 100% is more stressful than a cycle that stays between 20–80%.
Same number of cycles, but more wear.