EternaCell BLSe 12-100, Operating, Installation, Maintenance Instructions

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8.3 Charging in Service
Once put into service, Eternacell (B)LSe standby power batteries should be charged according to
the following sections.
8.3.1 Float Charge at Constant Voltage
To maintain the battery in fully charged condition during normal battery operation or, after
a discharge, to recover 90% of nominal capacity within 20 hours, a recommended float
charge must be applied.
Recommended float voltage is 2.23 V/cell with 1.240 SG electrolyte at 77°F (25°C).
The effective charge current will be very low. However, charge current increases as a
function of temperature and age of the battery. Gassing and water consumption are
minimized at this voltage.
To verify the charge efficiency of the battery, the constant control of the electrolyte
specific gravity and temperature is essential.
Decreasing specific gravity is a symptom of insufficient charge.
Increasing specific gravity and decreasing electrolyte level are indications of excessive
charge or that the cells should be topped up.
For comparison of electrolyte specific gravity vs. temperature, please refer to section 9.0.
8.3.2 Equalize Charge
Chargers usually have two adjustable voltages: one for the “float” and one for “equalize”
(also known as "boost" or "high rate").
The equalize charge is generally required:
•
when the total voltage spread between the cells is greater than 0.04 V under float
charging conditions
•
for fast recharging after a discharge
•
after addition of de-ionized water to assist in mixing the acid and water
•
for float charge using voltages below 2.22 volts per cell (see table below)
Float V/cell
Equalizing required at
these Intervals
2.22 - 2.23 Never
2.20 Every 6 Months
2.17 Every 3 Months
2.15 Every Month
Equalizing may be carried out at voltage settings above 2.30 V/cell.
Recommended values of equalize voltage are 2.33-2.4 V/cell.
The length of equalize charging required depends on the depth of discharge, electrolyte
temperature and normal float voltage level. The best guideline is to continue equalizing
until the specific gravity of the acid in the designated pilot cells remains constant for at
least 2 hours.