Detailed Explanation of Battery Full Charging Time

Theoretical Calculation Formula

• Efficiency factor: 1.1~1.2 is used to compensate for energy loss during charging.
• Practical application: For a 48V12Ah lead-acid battery (common output current 2A), charging time ≈ 12 ÷ 2 × 1.2 ≈ 7.2 hours.

Charging Time Comparison by Battery Type

Key Factors Affecting Charging Time

1. Battery Capacity and Charging Current

• Larger capacity leads to longer charging time (a 48V20Ah battery takes about 2 hours more than a 48V12Ah one).
• Higher current results in shorter charging time (ordinary chargers with 3-5A take 6-8 hours, while fast chargers with 5-8A only take 3-5 hours).

2. Differences Between Battery Types

• Lead-acid battery: Slow chemical reaction and low charging efficiency, usually requiring 6-10 hours.
• Lithium-ion battery: High energy density (150-250 Wh/kg, compared to only 30-50 Wh/kg for lead-acid), fast charging speed, supporting 2-3 hour fast charging.

3. Remaining Battery Level

• From 0% to 100%: About 8-10 hours for lead-acid batteries, 3-5 hours for lithium-ion batteries.
• From 30% to 100%: Approximately 60-70% of the full charging time (e.g., about 4-5 hours for lead-acid batteries).

4. Impact of Ambient Temperature

• Summer (25℃+): Charging time shortens, 6-8 hours for lead-acid batteries and 2-3 hours for lithium-ion batteries.
• Winter (below 0℃): Charging time extends, 8-10 hours for lead-acid batteries and 4-6 hours for lithium-ion batteries.
  • Principle: Low temperature reduces battery activity, and the charging efficiency of lead-acid batteries drops to 60-70% of normal temperature at 0℃.

5. Charging Phase Characteristics

• Constant current phase (0-80%): Fast charging with stable current.

• Constant voltage/trickle phase (80-100%): Charging slows down to protect the battery, taking about 1-2 hours.

Practical Charging Time Reference Table

Charging Recommendations

1. Lead-acid Battery

• Float charge for 1 hour (summer) to 2 hours (winter) after full charge, with a total time not exceeding 10 hours.
• Avoid over-discharging; it is recommended to start charging when the remaining power is about 30%, and charge for 6-8 hours.

2. Lithium-ion Battery

• Unplug immediately after full charge, or float charge for only 30-40 minutes, with a total time not exceeding 6-8 hours.

• Avoid overcharging and over-discharging, which helps extend battery life (up to 1800 cycles, about 8 years).

Summary