Battery Charging With Sitop Psu3800 - Siemens SITOP PSU8200 24 V/20 A User Manual

Applications

9.7 Battery charging with SITOP PSU3800

9.7 Battery charging with SITOP PSU3800
The SITOP PSU3800 power supplies are optimized for charging lead batteries. For a U-I
characteristic curve set to parallel operation (DIP switch "A" at "ON", see Section Figure 2-6
Selector switch A/B (Page 18)), the battery to be charged is charged with a constant current
until approximately 95 % of the set SITOP output voltage is reached (set using a potentiometer,
see Section Figure 2-4 Potentiometer (Page 13)). The charging current then decreases
continuously from 1.2 × rated current at 95 % of the set voltage to approx. 0 A or the self-
discharging current of the battery at 100% of the set output voltage, i.e. the resistance
characteristic in this range (see Figure 6-15 Output characteristic 6EP3436-8UB00-0AY0
parallel operation (Page 66), Figure 6-16 Output characteristic 6EP3424-8UB00-0AY0
parallel operation (Page 66) and Figure 6-20 Output characteristic 6EP3437-8UB00-0AY0
parallel operation (B OFF) (Page 67))
Note
The value recommended by the battery manufacturer (dependent on the battery temperature)
must be set as end-of-charge voltage. A lead rechargeable battery temperature of 20 ... 30 °C
is ideal; in this case, the recommended end-of-charge voltage is normally approx. 13.5 or 27 V.
Note
As protection against back emf and as polarity reversal protection, we recommend that a
diode rated for at least 1.2 × rated current of the power supply with at least 40 V blocking
voltage is connected in series to the "+" output (connect the anode with "+" output of the
SITOP PSU8200/3800 and the cathode with the plus pole of the battery). The output voltage
of the power supply under no load must be set to the end-of-charge voltage plus the voltage
drop at the diode. For an end-of-charge voltage of, for example, 27.0 V DC (usual for 20 ... 30 °C
battery temperature, although the specifications of the battery manufacturer must always be
observed!) and 0.8 V voltage drop at the diode, the power supply without load should be set
to 27.8 V.
LEDs and a potential-free signaling contact indicate the associated charge state of the
battery (see Section Figure 2-5 Operating display and signaling (Page 15)):
Green LED ("12 V O.K.", "24 V O.K.") lit
Signaling contact (13, 14) closed
Yellow LED (OVERLOAD) lit
Signaling contact (13, 14) open
102
Battery voltage > approx. 10 V or > approx. 20 V
Battery voltage < approx. 10 V or < approx. 20 V
Manual, 05.2018, C98130-A7638-A1-6-7629
SITOP PSU8200/3800 3ph