Best operating temperature for Lead Acid Battery

How does temperature affect battery voltage?

As the temperature increases, the equilibrium voltage of the lead acid battery, EMF, or open circuit voltage also increases. This is 2.5 millivolts per °C

when electrolytes have the specific gravity range commonly used in lead-acid batteries. Another factor that affects blood pressure is acid sp gr. With increasing temperature, the acid expands and sp gr decreases. The extension is about 5%. This is the reason for the decrease in specific gravity. Based on the above 2 factors, the change (correction) in OCV is 3 millivolts/degree Celsius (mV/°C)

This is of concern when the electrolyte temperature exceeds 25-27 °C to 35°C and higher. The charging voltage should be set to a lower value, i.e. reduce the charging voltage by 3 mV for every 1 °C rise above 27 °C. Otherwise, battery life will be reduced due to higher gas content and network corrosion. At higher temperatures the float voltage decreases and at colder temperatures increase the float voltage 3 mV per °C