Lead Acid Battery

Overview

Engineering reference data for Lead Acid Battery in material science and properties.

Key Formulas

Stress

$\sigma = \frac{F}{A}$

Force per unit area.

Strain

$\varepsilon = \frac{\Delta L}{L_0}$

Change in length per original length.

Hooke's Law

$\sigma = E \varepsilon$

Stress proportional to strain in elastic region.

Thermal Expansion

$\Delta L = \alpha L_0 \Delta T$

Length change due to temperature.

Variables

State of Charge Indicators

Understanding the relationship between specific gravity and state of charge (SOC) is essential for lead-acid battery maintenance:

Temperature Effects on Battery Performance

Lead-acid battery performance is significantly affected by temperature:

• Efficiency: Battery efficiency decreases as temperature drops, with optimal performance typically around 25°C (77°F)
• Specific Gravity: The specific gravity reading in a fully charged battery varies with temperature and must be temperature-compensated for accurate readings

Specific Gravity Temperature Compensation

The specific gravity of a fully charged lead-acid battery varies with electrolyte temperature. Standard specific gravity values (typically 1.265 at 25°C) should be adjusted:

$SG_{corrected} = SG_{measured} + 0.0007 \times (T_{reference} - T_{measured})$

Where:

• $SG_{corrected}$ = temperature-compensated specific gravity
• $SG_{measured}$ = specific gravity reading at measured temperature
• $T_{reference}$ = reference temperature (typically 25°C or 77°F)
• $T_{measured}$ = actual electrolyte temperature

This compensation is critical because specific gravity readings taken at temperatures significantly different from 25°C can be misleading when assessing state of charge.

References

• Original Source