AMER-EN-TM-ODY July 2021
www.odysseybattery.com
B. UNDERSTANDING STATE OF CHARGE
Like all batteries, it is best that AGM
2
batteries be kept at a high SOC. It is important to understand
how to determine the SOC of AGM
2
batteries correctly. The approximate SOC value is found by
measuring the battery’s Open Circuit Voltage (OCV) with a high-quality voltmeter. The voltage read-
ing must be taken at least four hours after the battery finishes charging or at least 30 minutes after it
finishes a discharge. Measurements will not be accurate if adequate rest time is not allowed. Table 4
below shows the typical relationship between OCV and SOC.
C. STORAGE AND SELF-DISCHARGE
Even if batteries are not installed in an application and are being stored, their SOC declines over time.
The rate at which a battery loses charge depends on the temperature. The warmer the temperature the
shorter the storage time before a freshening charge is required. Cooler temperatures slow down the
rate of self-discharge. A good rule of thumb to use is that for every 18°F (10°C) rise in temperature the
storage time is cut in half. This means that the storage time at 95°F (35°C) is half the storage time at
77°F (25°C).
If stored at 77°F (25°C) or lower, ODYSSEY
®
AGM
2
batteries should be given a freshening charge a
minimum of at least once every two years or when the OCV drops to about 12.2V, whichever comes
first. This OCV corresponds to a SOC of about 50%. Batteries should always be fully charged before
they are stored. The warmer the temperature the more frequently OCV should be monitored. Table 5
below shows how temperature impacts the rate of self-discharge.
SOC
OCV
100%
12.9
75%
12.6
50%
12.2
25%
11.9
0%
11.5
Table 4
Table 5
Storage Temperature
Storage time (Months)
41°F (5°C)
48
59°F (15°C)
36
77°F (25°C)
24
95°F (35°C)
12
113°F (45°C)
6
8
Содержание NSB-AGM
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