Lucent Technologies Victory Class Batteries WP-93936
Issue 1 May 2000
Operation 7 - 3
Effect of
Temperature
Electrolyte above 77°F (25°C) will result in a lower observed specific
gravity reading approximately equal to a loss of 1 point (0.001) for each
3°F (1.67°C). In contrast, electrolyte below 77°F (25°C) will read
approximately 1 point (0.001) higher for each 3°F (1.67°C). Higher
temperatures expand the volume of electrolyte, which reduces the
observed specific gravity, while lower temperatures condense the
electrolyte, which increases the observed specific gravity.
emperatures
The lead-acid battery is an electrochemical device. Heat accelerates
chemical activity; cold slows it down. Normal battery operating
temperature is considered to be 77°F (25°C). Higher-than-normal
temperatures have the following effects on a lead-acid battery:
• increases deliverable capacity
• increases discharge rate capability
• increases self discharge or local action losses
• lowers cell voltage for a given charge current
• raises charging current for a given charge voltage
• shortens life
• increases water usage
• increases maintenance requirements
Lower than normal temperatures have the opposite effects. In general,
at recommended float voltage, a battery in a cool location will last
longer and requires less maintenance than one in a warm location. If the
operating temperature is something other than 77°F (25°C), it is
desirable to modify the float voltage as follows:
For temperatures below 77°F (25°C), add 2.8 mV (0.0028 volt) per °F
(5.0 mV/°C).
For temperatures above 77°F (25°C), subtract 2.8 mV (0.0028 volts)
per °F (5.0 mV/°C).
Example:
Victory Class Battery nominal float @ 77°F is 2.20 Vpc
Corrected float @ 67°F is 2.228 Vpc
Corrected float @ 87°F is 2.172 Vpc
At higher than normal operating temperatures, for every additional
15°F (8°C) battery life is decreased by 50 percent. Therefore, continued
operation at an average cell temperature of 92°F (33°C) will reduce
battery life to 50 percent of that typical at 77°F (25°C).
