Deep Cycle Lead Acid Battery Charger 12V Longer Lifespan

1) Relationship between Open-Circuit Voltage and Electrolyte Concentration of Lead-Acid Batteries:
The curve showing the relationship between open-circuit voltage and H₂SO₄ concentration in the electrolyte is shown in the figure. During discharge, the H₂SO₄ concentration gradually decreases. Recharging is required when the H₂SO₄ density drops to 1.2 g/cm³.

2) Internal Resistance of Lead-Acid Batteries:
The larger the plate area and the smaller the distance between the positive and negative plates, the lower the internal resistance. The active materials in the positive and negative plates, electrolyte density, and temperature also affect internal resistance. During discharge, the decrease in H₂SO₄ concentration in the electrolyte increases resistance. In particular, as discharge time increases, the active materials transform into lead sulfate, a poor conductor, causing internal resistance to gradually increase. Temperature also significantly affects the internal resistance of lead-acid batteries. When the temperature is below +25°C, the internal resistance increases by 1.7-2.0% for every 1°C decrease in temperature.