Thales 421, Эксплуатация и обслуживание, Страница: 163 / 256

non−metal
LLZ 421
Operation and Maintenance Maintenance
ILS 420
6−21
Ed. 01.10 SOAC
6.4.2 Care and Maintenance of the Lead Battery
6.4.2.1 Maintenance Accessories and Scope of Checks
The accessories below are required for monitoring and maintenance of the battery.
1 Acid syringe with areometer
1 Acid jug
1 Funnel
1 Container with specially purified water
Various cleaning agents (acid−resistant Vaseline, soda, cotton rags).
The maintenance chapters below refer to to the scope of check to be carried out. The checks and
related operations should be performed regularly every 2 to 3 months. The basic rules for handling
batteries (see 6.4.1.2.4 ) should be observed.
6.4.2.1.1 Keeping the Lead Battery Clean
The battery box with batteries, boxes, terminals and connections should be kept clean and dry. When
performing the regular check pay special attention to the poles and cell connections, since these are
particularly subject to acid aggression and susceptible to the formation of salt crystals, especially at
the plus−pole. The poles and cell connections should be greased slightly with an acid−resistant
Vaseline following cleaning.
6.4.2.1.2 Measuring the Acid Density (not for maintenance−free Batteries)
The acid density should be measured using the areometer. False measurements can be avoided by
observing the rules see 6.4.1.2.4 . The density of accumulator acid is 1.24 ± 0.01 kg/l at 20 °C when
the battery is charged. If the temperature deviates substantially from the reference temperature of
20 °C, this should be taken into account when measurements are performed.
6.4.2.1.3 Topping Up the Cells (not for maintenance−free Batteries)
The cells should be topped up in good time with specially purified water. A visual check of the cells
should be done approx. every 2 to 3 month. An acid level indicator with two markings 10 mm apart
is incorporated in one of the cells for determining the nominal acid level. If this indicator is missing,
the cells should be topped up to 15 mm above the top of the plates. It is not always possible to obtain
specially purified or desalinated water of the required quality at the point of installation.
In countries where the water quality is inadequate the specially purified or fully desalinated water in
stock should be checked before use in accordance with the handling specifications of the battery
manufacturer (test chemicals supplied if required). If the purified water does not meet the specifica-
tions, it must be post−treated (ion exchanger or distilling apparatus − supplied on request) or suit-
able water must be obtained.
CAUTION
The battery guarantee is only valid if the accumulator acid and water have the necessary
degree of purity.
6.4.2.1.4 Measuring the Cell Voltage
The nominal voltage of the lead cells has been fixed at 2.0 V. The no−load voltage is 2.04 to 2.1 V
depending on the acid density. The discharge voltage is dependent on the discharge current. The
higher the discharge current, the lower will be the cell voltage and vice versa.
Under normal operating conditions with trickle charging the cell voltage is 2.25 V. In case of a failure
or disconnection of the 230 V or 115 V mains voltage resulting in discharging of the batteries, the cell
voltage will be 2.1 to 1.75 V after about 5 minutes up to disconnection of the mains power supply.