Allmand Brothers MB 6200 - Manual (Page 52)

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The batteries on the system can become discharged for a number of reasons, for example:
•
Operating conditions during the “winter” months of November through February, when the power
provided by the PV array is reduced.
•
Improper maintenance, such as not cleaning the PV array.
•
Loose or corroded battery terminal connections.
•
Improper position of the system where the PV array in the shadow of an object, or tilted away from the
sun.
•
Prolonged cloudy weather where the system is operating.
Maintenance of batteries, especially the proper voltage level, in the above situations should be performed as
required. In some instances, it will be necessary to provide multiple recharges from an external source or
replace with fresh batteries.
Use the following table to determine the status of each battery in the system:
6-Volt Battery 12-Volt Battery Specific Gravity State of Charge
6.36 or more 12.72 or more 1.295 or more 100%
6.15 to 6.36 12.30 to 12.72 1.250 to 1.295 75% to 100%
6.00 to 6.15 12.00 to 12.30 1.200 to 1.250 50% to 75%
5.85 to 6.00 11.70 to 12.00 1.175 to 1.200 25% to 50%
5.70 to 5.85 11.40 to 11.70 1.120 to 1.175 0% to 25%
1. Check the voltage levels with an approved digital voltmeter and the specific gravity with an approved
hydrometer.
2. Before taking any readings, run the system off the batteries for a few minutes. This removes any minor
surface charge on the battery plates. The surface charge will affect the accuracy of your readings.
3. Service or replace any battery with a specific gravity that is ten percent higher or lower than the aver-
age.
Additional Information for Storing and Handling Batteries
The electrolyte in discharged batteries may freeze if the outside air temperature drops below the freezing
point of w a ter: 32 °F (0°C). When a battery is discharged, the electrolyte solution in the battery is mostly
water. The electrolyte in a fully charged battery has a much higher concentration of sulfuric acid and
therefore freezes at a much lower temperature.
The Specific Gravity/Freeze Temperature chart provides information on specific gravity verses freezing
temperature for the batteries used in the system.
Specific Gravity Freeze Temperature
1.250 –62°F (–52°C)
1.200 –16°F (–27°C)
1.150 5 °F (–15°C)
1.100 19 °F (–7°C)
If the specific gravity of one battery cell is less than 0.020 or more than 0.050 the specific gravity of the
other two cells, use the AC charger’s equalize feature during charging. If the differences remain after
charging, replace the battery with an exact replacement.