Typical charging times for lithium-ion batteries depend on their capacity, the charge rate (expressed as C-rate), and the charging method used. Here is a detailed overview:
Charging Time Based on Capacity and Charge Rate
- Lithium-ion batteries are commonly charged at rates between 0.5C and 1C, where 1C means charging the battery fully within one hour. Charging at 0.5C typically takes about 2 hours for a full charge, and charging at 1C takes about 1 hour.
- For example, a 1Ah battery charged at 1C will take approximately 1 hour to charge from empty to full, whereas at 0.5C it will take about 2 hours.
Charging Stages and Their Impact on Time
- The typical charging process involves two stages:
- Constant Current (CC) stage: The battery is charged at a fixed current until it reaches a specified voltage threshold.
- Constant Voltage (CV) stage: The charger maintains a constant voltage while the charging current gradually tapers off until it reaches a cutoff level, signaling full charge.
- The CV stage prolongs the total charging time because the current reduces progressively, especially as the battery approaches full capacity.
Charge Time vs. State of Charge (SOC)
- Charging to around 80-90% capacity is faster and generally recommended for regular use to extend battery life.
- Achieving 100% charge takes longer due to the extended CV stage needed to fully saturate the battery.
- For example, the following table shows charging times related to cell voltage (rough approximation for SOC):
| Charge Voltage (V/cell) | Approx. Capacity (%) | Charge Time (minutes) | Capacity with Full Saturation (%) |
|---|---|---|---|
| 3.80 | ~40% | 120 | ~65% |
| 3.90 | ~60% | 135 | ~75% |
| 4.00 | ~70% | 150 | ~80% |
| 4.10 | ~80% | 165 | ~90% |
| 4.20 | ~85% | 180 | 100% |
- This reflects a charge time of about 2-3 hours for typical lithium-ion cells to reach full charge at standard charging rates.
Fast Charging
- Fast charging can charge lithium batteries to about 80% capacity within 30 minutes using high-power DC charging and higher current.
- However, fast charging puts more stress on the battery, potentially reducing lifespan compared to slower charging methods.
Slow Charging
- Slow charging uses lower current over extended periods (6-8 hours), which is gentler on the battery and helps maximize longevity.
Summary Table of Charging Time vs Capacity (typical for a 1C or 0.5C charge rate)
| Battery Capacity | Charging Method | Typical Charging Time |
|---|---|---|
| Small (e.g. 1000mAh) | 1C (fast) | About 1 hour full charge |
| Small (1000mAh) | 0.5C (standard) | About 2 hours full charge |
| Larger batteries | 1C | 1 hour per Ah capacity |
| Larger batteries | 0.5C | 2 hours per Ah capacity |
| Fast charging (high power) | Quick charge to ~80% | ~30 minutes |
| Slow charging | Low current AC | 6-8 hours full charge |
In general, charging times increase with battery capacity if charging current remains the same. Using higher charge currents (up to 1C) shortens charging times, but with a tradeoff in battery life. Charging to about 80-90% is a good balance between speed and longevity.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-are-the-typical-charging-times-for-different-capacities-of-lithium-ion-batteries/
