Lead-acid battery performance is evaluated based on several professional parameters. These parameters provide insights into the battery’s capacity, efficiency, durability, and overall suitability for various applications.
- Capacity (Ah):
- The capacity of a lead-acid battery is measured in ampere-hours (Ah). It indicates the amount of electric charge the battery can deliver at a specific current over a specified period.
- Voltage (V):
- Nominal Voltage: The standard voltage of a fully charged lead-acid cell is 2.1 volts. Batteries are often composed of multiple cells, with common configurations including 6V, 12V, 24V, and higher.
- Operating Voltage Range: The voltage range from fully charged to fully discharged state, typically between 2.1V (fully charged) and 1.75V (fully discharged) per cell.
- C-rate:
- The charge or discharge current relative to the battery’s capacity. For example, a 1C rate for a 100Ah battery is 100A, and a 0.5C rate is 50A.
- Energy Density (Wh/kg):
- The amount of energy the battery can store per unit of weight, usually expressed in watt-hours per kilogram (Wh/kg).
- Specific Energy (Wh/kg) and Specific Power (W/kg):
- Specific Energy: The energy per unit mass.
- Specific Power: The maximum power output per unit mass.
- Cycle Life:
- The number of complete charge-discharge cycles a battery can perform before its capacity falls below a specified percentage of its original capacity (typically 80%).
- Depth of Discharge (DoD):
- The percentage of the battery’s capacity that has been used. A deeper DoD can shorten the battery’s cycle life.
- State of Charge (SoC):
- The current charge level of the battery as a percentage of its total capacity.
- Internal Resistance (mΩ):
- The resistance within the battery that causes a voltage drop when current flows. Lower internal resistance indicates better performance, especially under high load conditions.
- Self-Discharge Rate:
- The rate at which a battery loses charge when not in use. Lead-acid batteries typically have a self-discharge rate of around 3-5% per month.
- Charge Efficiency:
- The ratio of the energy put into the battery during charging to the energy that can be extracted during discharge. Lead-acid batteries typically have a charge efficiency of around 85-90%.
- Float Charge Voltage:
- The voltage at which the battery is maintained after being fully charged to keep it in a ready state without overcharging.
- Equalization Charge Voltage:
- A higher-than-normal charging voltage used periodically to ensure all cells in the battery are equally charged and to reduce sulfation.
- Temperature Range:
- The operational temperature range over which the battery can safely operate. Extreme temperatures can significantly affect battery performance and lifespan.
- Cold Cranking Amps (CCA):
- The amount of current a battery can provide at 0°F (-18°C) for 30 seconds while maintaining a voltage of at least 1.2 volts per cell. This is particularly important for automotive batteries.
- Reserve Capacity (RC):
- The number of minutes a fully charged battery can deliver a specified load (usually 25A) before the voltage drops below a specified limit (typically 10.5V for a 12V battery).
These parameters are critical for assessing the suitability of a lead-acid battery for specific applications, ensuring optimal performance, and maintaining safety and longevity.
