A battery is considered in good health when its capacity is 80% or above relative to its original design capacity.
Understanding your device's battery capacity is crucial for knowing its health and expected performance. While a battery's original capacity (often measured in milliampere-hours or mAh) indicates how much energy it can hold when new, the relevant metric for ongoing health is the percentage of that original capacity it still retains.
What is Battery Capacity Health?
Battery capacity health refers to the current maximum charge a battery can hold compared to its capacity when it was new. As batteries age and undergo charge cycles, their ability to hold a charge gradually diminishes. This is a normal part of lithium-ion battery degradation.
According to information from Backmarket's Help Center, a widely accepted benchmark for battery health is 80%.
"If the capacity is 80% or above, your battery is in good health."
This means if your battery, when fully charged, can still hold at least 80% of the charge it held when it was brand new, it's generally considered to be performing well and is in good health.
Why is 80% a Key Threshold?
- Manufacturer Standard: Many device manufacturers consider a battery to be performing within acceptable parameters until its capacity drops below 80%.
- Warranty Often Applies: Some warranties may cover battery replacement if the capacity falls below 80% within a certain timeframe (e.g., one year).
- Noticeable Performance Drop: Below 80%, users often start noticing a significant decrease in how long their device lasts on a single charge, impacting daily usability.
Checking Your Device's Battery Capacity
Most modern smartphones, laptops, and other portable devices offer ways to check the battery's current maximum capacity health.
- Smartphones: Often found in the battery settings (e.g., Battery Health on iOS, Battery settings on Android, sometimes under device maintenance).
- Laptops: Can usually be checked via built-in battery health tools or command-line interfaces.
Example:
| Original Capacity | Current Max Capacity | Percentage Health | Health Status (based on >80%) |
|---|---|---|---|
| 3000 mAh | 2700 mAh | 90% | Good Health |
| 3000 mAh | 2400 mAh | 80% | Good Health |
| 3000 mAh | 2250 mAh | 75% | Below 80% (Degraded) |
When your device reports its battery health percentage, you can use the 80% threshold as a guide to understand if the battery is still performing optimally or if it's significantly degraded. A battery below 80% capacity will provide noticeably shorter usage time between charges.
