2.3. Charging with external charger
Charging must only be carried out with direct current. Chargers with
IU-, IUI- or W-characteristics according to DIN 41773, DIN 41776 and
DIN 41774 may be used.
2.3.1. IU (or IUU) characteristics
Starting with a given initially constant charging current ("I") the cell or
battery voltage reaches the given final value which depends on the
charging requirement by the application. The charger automatically
switches then to constant operating voltage ("U"). As long as the final
voltage is not reached, the charging current is limited by the charger only.
Typical values for constant currents are 0.5 to 2.0 times I10. Typical
constant voltages are 2.23, 2.25, 2.30, 2.40 V/cell. The different voltages
are given by the application. The IUU characteristic provides a switching
point after a higher first constant voltage to operating voltage.
2.3.2. IUI characteristics
This characteristic is a very effective method in order to recharge batteries
in short time and to crack sulphations. At first, an IU characteristic is
applied to the battery. After a given time held out at constant voltage, the
charging method is then extended by using a reduced constant current
("I"). This current is limited to 5 A/100 Ah C10. The cell or battery voltage
reaches values between 2.60 and 2.75 V/cell. Check if loads have to be
disconnected before, in order to prevent damage. On exceeding the
maximum temperature of 55°C/131 F, the charging has to be either
stopped or proceed with reduced current or be switched to float charge as
per item 2.3.3 in order to allow the temperature to drop. The fully charged
state is reached, when the cell voltages have not risen for a period of 2 h.
2.3.3. Float charge (float voltage)
A battery is float charged, when the electrodes are sufficiently polarized in
that quantity that the floating current compensates the self discharge rate
of the battery. A fully charged battery remains at 100 % SOC while being
floated. The float voltage depends on acid density. Please take the values
from following table:
2.4. Charging with alternative power supply
When using an alternative power supply, the battery charger is not always
able to supply the maximum load current. The load current can exceed
the nominal current of the battery charger. The battery supplies power
during this period and the battery will not fully charged. The charge
voltage has, therefore, to be set at 2.23 - 2.35 V per cell ±1% x number of
cells.
At regular discharges of approx. 0.2 x C10 a charging voltage of 2.30 V to
2.35 V per cell has to be used.
At regular discharges from 0.2 to 0.3 x C10 the charging voltage should
be 2.35 V to 2.40 V per cell.
In accordance with item 2.5 the charging time at those increased voltages
shall be limited to maximum 72 h. If no discharge follows then switch to
standby operation.
At standby operation without cycling the batteries should be operated at
float charge with 2.23 V/cell ± 1 % per cell.
After deep discharge or after inadequate recharging an equalizing
charging as per item 2.5 is necessary.
2.5. Equalizing or boost charge
Charging method with increased gassing activity at higher cell voltages
(>2.33 V/cell), done with either increased constant voltage (e.g. 2.33 to
2.40 V/cell) or constant current. The application of this method shall be
time (max. 72h) and temperature (max. 55°C (131 °F)) limited. Please
take the values from following table:
On exceeding the temperature maximum, the charging must either be
stopped or proceeded with reduced current or be switched to float charge
to allow the temperature to drop. The equalizing charge, if executed with
constant current is completed, when the individual cell voltages does not
increase longer within 2 hours.
2.6. Ripple currents
During recharging up to 2.40 V/cell the RMS value of the AC ripple current
may reach temporarily max. 20 A/100 Ah C10. After recharging and at
standby (float) or buffer operation the RMS value of the ripple current
must not exceed 5 A/100 Ah C10.
3. Battery temperature and related charging voltage
All technical data refer to the nominal temperature of 20°C (68 °F).
The ideal operating temperature range is
20 °C ± 5 K (59 °F to 77 °F). The recommended operating
temperature range is 10 °C (50 °F) to 30 °C (86 °F). Higher
temperatures reduce the working life. Lower temperatures reduce
the available capacity. Exceeding the temperature limit of
45 °C (113 °F) up to 55 °C (131 °F) is acceptable only for short
periods. Exceeding the temperature limit of 55 °C (131 °F) is not
permissible. A temperature-related adjustment of the charging
voltage within monthly averaged battery temperature of
10 °C (50 °F) to 30 °C (86 °F) is not necessary. Below 10 °C (50 °F)
in the monthly average the charging voltage should be increased
(-0.003 V/cell K) for a faster recharging. Above 30 °C (86 °F) in the
monthly average voltage may be reduced (-0.003 V/cell K) to
reduce water decomposition and corrosion.
4. Electrolyte
The electrolyte is diluted sulphuric acid. The rated specific gravity of
the electrolyte in the fully charged state is based on 20 °C (68 °F)
and the “MAX“ electrolyte level with a maximum deviation
± 0.01 kg/l. The rated specific gravity is printed on every type label.
Higher temperatures reduce the specific gravity of the electrolyte,
lower temperatures increase it. The temperature correction factor is
-0.0007 kg/l per K.
Examples: Electrolyte specific gravity 1.23 kg/l at +35 °C (95 °F)
corresponds to 1.24 kg/l at +20 °C (68 °F). Electrolyte specific
gravity 1.247 kg/l at +10 °C (50 °F) corresponds to 1.24 kg/l at
20 °C (68 °F).
5. Maintenance
To avoid leakage currents and the associated risk of fire keep the
battery dry and clean. Cleaning with clear water, no solvents, and
no detergents. Avoid electrostatic charges. If the electrolyte level
has dropped to the „MIN“ mark, purified water as specified under
DIN 43 530 Part 4 (maximum conductivity 30 µS/cm) must be used
to top up the electrolyte level to the „MAX“ mark.
To be measured and listed every 6 months:
•battery voltage
•the voltage of some cells/block batteries (pilot cells)
•the temperature of the electrolyte in some cells/block
batteries (pilot cells).
Every 12 months:
•The voltages and densities/temperatures of the electrolyte
in all cells/blocks have to be measured and listed.
•Connectors, racks and ventilation have to be visually
checked and restored if necessary.
Should the float charge voltage in single cells deviate more than
+0.10 V or -0.05 V from the average value (see item 2.3.3), the
customer service should be called.
6. Testing
Tests must be conducted according to DIN 43 539 Part 1 and 4 and
IEC 60896 - 11. Special test instructions, e. g. to prove operational
safety in accordance with DIN VDE 0107 and DIN VDE 0108 must
be observed.
7. Storage and taking out of operation
If filled lead acid accumulators are to be taken out of operation for a
longer period of time, they must be placed fully charged in a dry,
frost-free room. To avoid damage periodical equalising charges
(every 6 weeks) or permanent float charging have to be made.
8. Transport
OPzS.solar block batteries and cells are protected against short-
circuit. They are not subject to the German Regulations on
Dangerous Goods carried on road and railway (GGVS, GGVE,
ADR), if they show no damage, are protected against sliding, falling
over and damaging and are piled up on pallets appropriately
(ADR, Annexe A, Chapter 3.3, Special Provision 598).These
cells/batteries are dangerous goods on sea and air transport.
Declaration and packaging must comply with the requirements of
IMDG-Codes or IATA-DGR. Cells/batteries without electrolyte are
generally no dangerous goods on all kinds of transportation.
