Duty
Minimum end voltage
5 min ≤ t ≤ 1h
1.65V
1h ≤ t ≤ 5h
1.70V
5h ≤ t ≤ 8h
1.75V
8h ≤ t ≤ 20h
1.80V
Temperature
Float Voltage
Recharging Voltage
0°C to 10°C
2.34Vpc
2.45Vpc
10°C to 20°C
2.31Vpc
2.40Vpc
20°C to 30°C
2.28Vpc
2.35Vpc
30°C to 40°C
2.25Vpc
2.30Vpc
Temperature
Float voltage range per cell
0°C
2.33-2.36V
10°C
2.30-2.33V
20°C
2.27-2.30V
25°C
2.25-2.28V
30°C
2.24-2.27V
35°C
2.22-2.25V
40°C
2.21-2.24V
Voltage
State of charge
2.14Vpc
100%
2.10Vpc
80%
2.07Vpc
60%
2.04Vpc
40%
2.00Vpc
20%
3
Charging
n
Commissioning charge
Before use, the batteries should be charged at a constant charging voltage (with a
charging current limited to 0.1C
10
) with one of the following method:
•
Charge during 96 hours with the floating voltage between 2.27 and 2.30Vpc
in ambient temperature range between 15 to 25°C.
•
or charge with the 2.40Vpc boost charge voltage during minimum 24
to 48 hours maximum to reduce the commissioning charging period (the
battery will then be switched over to float charging, maintain the battery
under floating voltage for 24 hours before any discharge test, see hereafter).
If the battery is to be subjected to a discharge test, in this case the test will be
performed imperatively after that the commissioning charge has been carried
out. Check that the battery is fully charged.
n
Float voltage
The recommended float charge voltage is 2.28 volts per cell at 20°C.
Following a commission charge and after 6 months continuous charge at the
recommended float voltage, individual cell voltages will stabilise within ±4.5% of the
mean applied voltage.
However, immediately following commissioning and for the initial 6 months of
continuous float charge, individual cell voltage values outside the above tolerance
may be observed without adverse effect. There is no relationship between a cell’s float
voltage and its discharge capacity. Cells are perfectly capable of giving their discharge
capacity even when outside the ±4.5% range.
After 6 months service, should any individual cell or monobloc show a continuing
reduction or increase in voltage outside the above limits over 3 successive monthly
periods, Enersys
®
should be contacted for advice.
When the average ambient temperature deviates more than ±5ºC from the reference
temperature (20°C), it is necessary to adjust the float voltage as follows:
If the charger does not permit an adjustment of float voltage in relation to the
temperature, it is possible to set a float voltage value according to the temperature
ranges as indicated in the last table of this publication.
n
Charging current
A discharged VRLA battery will accept a high recharge current, but for those
seeking a more economical charging system a current limit of 0.08 C
10
: 0.1 C
3
(A) is
adequate.
n
Fast recharge
Increasing the charge voltage to 2.40Vpc with a current limited to 0.1 C
10
: 0.125 C
3
(A) can reduce recharge times. Fast charge should be stopped afterapproximately
10 to 15 hours. This charge regime, in order to achieve a normal service life, must
not be used more than once per month.
n
Float charge ripple
Excessive ripple on the D.C. supply across a battery has the effect of reducing life
and performance. It is therefore recommended that voltage regulation across the
system, including the load but without the battery connected, under steady state
conditions, shall be better than ±1% through 5% to 100% load.
n
State of charge
The battery state of charge can be determined approximately by measuring the
open circuit voltage after the battery has been at rest for a minimum of 24 hours
at 20°C.
Discharging
SuperSafe
®
T batteries must not be left in a discharged condition after
supplying the load, but must immediately return to float recharge mode.
Failure to observe these conditions may result in greatly reduced service life.
n
Accidental deep discharging
For optimum operation the minimum voltage of the system should be related to
the duty as follows:
In order to protect the battery it is advisable to have system monitoring and low
voltage cut-out.
Deep discharge will produce a premature deteriation of the battery and a
noticeable reduction in the life expectancy of the battery.
n
The effect of temperature
- on capacity
Correction factors of the capacity, according to the temperature, are as follows:
Discharge
Time
0°C
5°C
10°C
15°C
20°C
25°C
30°C
35°C
40°C
5 mins to
59 mins
0.80
0.86
0.91
0.96
1
1.04
1.06
1.09
1.1
1h to 24h
0.86
0.90
0.94
0.97
1
1.03
1.05
1.06
1.07
- on life
Operation of valve regulated batteries at temperatures higher than 20°C will
reduce life expectancy. Life is reduced by 50% for every 10°C rise in
temperature.
Maintenance/Checks
SuperSafe
®
T are maintenance free, sealed, lead acid batteries and need no
water addition.
The containers and lids shall be kept dry and and free from dust. Cleaning must
be done only with a damp cotton cloth without man-made fibres.
WARNING - Do NOT use any type of oil, solvent, detergent, petroleum-based
solvent or ammonia solution to clean the battery containers or lids. These
materials will cause permanent damage to the battery container and lid and will
invalidate the warranty.
Check monthly that total voltage at battery terminals is (N x 2.28 V) for a
temperature at 20°C. (N being the number of cells in the battery). Make annual
readings of the voltages of cells making up the battery.
Keep a logbook to record values, power outages, discharge tests, etc.
An autonomy control can be done once a year.
Technical
n
Data when charging with a constant voltage
If the charger does not permit an adjustment of the float voltage in relation with
the temperature, it is possible to set a float voltage value and a recharging
voltage value according to the temperature ranges as indicated in the table
below:
Open circuit voltage variation with temperature is 2.5mV per 10°C.
