User Manual
15
SPECIFIC GRAVITY
The specific gravity of electrolyte in a battery is the most accurate measurement of actual
state of charge. To determine if the batteries have reached full SOC, testing should be done
when the charge cycle has been completed and the battery bank is resting a Float voltage.
The specific gravity (SG) reading should remain constant for 3+ hours for an accurate 100%
SOC reading.
*Test and record specific gravity readings regularly to confirm charging parameters are
properly programmed and to avoid possible over/undercharge, cell damage and/or battery
failure. Rolls Battery provides a Flooded Deep Cycle Battery Maintenance log book
to track these readings and includes reminders to perform regular system inspections.
Request a copy from your Rolls Battery Distributor or Dealer.
Recommended testing: every 45-60 days
Minimum: every 90 days
Routine testing of specific gravity in Flooded models provides an opportunity to quickly
identify any notable changes in battery performance caused by charge-related issues
such as over/undercharging, sulfation buildup, capacity loss or cell/battery performance
or failures. Regular testing and tracking offers peace of mind and is expected as part of
the normal maintenance procedures. When monitored, necessary system adjustments
may be made to quickly correct & prevent any further issue or damage.
NOTE: Failure to adhere to ongoing maintenance requirements, including routine testing
and logging of specific gravity and voltage readings, may result in denial of a filed warranty
claim where the performance history and cause of cell/battery failure cannot be determined.
FIGURE 6:
Temperature
Sensor
% Charge Specic Gravity* (SG)
100 1.255 - 1.275
75 1.215 - 1.235
50 1.180 - 1.200
25 1.155 - 1.165
0 1.110 - 1.130
NOTE: Specific Gravity is dependent on the electrolyte temperature. These values are
for a temperature of 25°C (77°F). To adjust, add/subtract 0.003 for every 5°C (10°F)
increase/decrease.
TABLE 3: Specific Gravity vs State of Charge @ 25°C (77°F)