Function and structure
Batteries_Rail_Power_Manual_en02.docx
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5.4.3.
Battery charging characteristics
Like all chemical reactions, the charge / discharge processes in the cell are subject to a
temperature effect. In general, chemical reactions run faster with rising temperature and
slower with falling temperature. For this reason, temperature compensation is used for the
charging voltage.
This compensation is applied equally to the one-stage (IU) and two-stage (IU0U) charging
method.
Note
Depending on the special operating mode of a vehicle and the resulting special requirements for
the charging, individual values may differ from those listed below.
5.4.3.1.
One stage, temperature compensated charging (IU-charging)
For rail. power batteries, a temperature-compensated charging characteristic is required to
avoid excessive currents at high ambient temperatures and to fully charge the batteries at
low temperatures. Starting from the charging parameters at design temperature, the
charging voltage is increased or decreased depending on the measured battery
temperature.
The figure below shows the charge voltage per cell as a function of the battery temperature
monitored by the charger. It shows the temperature-compensated charge with -4 mV/°C per
cell based on 20 °C for rail. power batteries referred to a single-stage constant voltage
charge with current limitation.
The recommended maximum charge current is 1.0 x I
5.
Charging voltage at 20 °C: 2.27 V per cell
Charg
ing
V
o
lta
ge
[
V
]
Elektrolyte temperature [°C]
