Use the following settings. Temperatures are averaged over one month:
For Stand-alone systems:
Controller type
Setting
-20 to 0°C
0 to 15°C
15 to 35°C
>35°C
Constant Voltage – one
step
Vr
2,37V
2,35V
2,30V
2,27V
Constant Voltage – two
steps
absorption
maximum 2 h per day
2,40V
2,40V
2,35V
2,30V
float
2,35V
2,30V
2,25V
2,25V
On-off
High voltage (Vr)
2,40V
2,35V
2,30V
2,30V
Low voltage (Vrr)
2,20V
2,20V
2,20V
2,20V
For hybrid systems:
when only PV is engaged: use settings as in “Constant Voltage – one step” case above
when only diesel is engaged (continuously): reduce the previous settings by 0.05V each.
3.4. Temperature limits
All technical data apply for the nominal temperature of 20
o
C. The ideal operating temperature range is 20
o
C to
25
o
C. The recommended operating temperature range is 15
o
C to 35
o
C. Higher temperatures reduce the working
life. A maximum temperature of 45
o
C must not be exceeded. In hybrid applications the yearly average of battery
temperature should be less than 30°C.
Subzero temperatures may cause electrolyte freezing and irreversible damage when the battery’s state of charge
(SoC) is low. The minimum safe temperature Vs SoC is given below:
SoC (% to C10 – DIN value)
0% – 40%
40% – 60%
60% – 80%
Freezing point
-30
o
C
-20
o
C
-15
o
C
The system designer/installer shall consider countermeasures like thermal insulation, increasing the battery
capacity or increasing the minimum system voltage. In Stand-alone systems it is recommended to use controllers
with adjustable LVD setting to the battery temperature (higher LVD for lower temperature).
During operation, the temperature difference between individual battery cells should be below 3
o
K.
3.5. Current limits
The maximum charging current during the bulk charging is 0.2 x C10, while the battery voltage is below the
gassing voltage of 2,40V x number of cells.
3.6. Ripple currents
During recharging up to 2.40 V/cell, the effective value of the AC ripple current may reach temporarily at
maximum 10 A /100 Ah C10 nominal capacity. After recharging and at float charge in stand-by or buffer
operation, the effective value of the AC ripple current must not exceed 5 A /100 Ah C10 nominal capacity.
4. Battery Maintenance
To avoid leakage currents and the associated risk of fire, keep the battery dry and clean. Clean with clear water
and do not use any solvents and detergents as they can cause permanent damage to container or lid. Avoid
electrostatic charges.
To be checked and listed every 6 months:
battery voltage
voltage of some cells (pilot cells)
temperature of the container in some cells (pilot cells)
confirm daily DoD per cell
confirm max DoD per cell does not exceed the allowed limit
confirm charging factor is within acceptable limits
confirm that charge settings correspond to the recommended ones
finally check if corrective equalizing is applied according to 3.2.2.2
Check and list every 12 months:
The voltages and temperatures in all cells.
Connectors, racks and ventilation.
