Bosch BAT 645 - 5.2 Switching On; 5.3 Charging Mode

¶ Never disconnect the terminal clips while a battery
is being charged.
¶ Never disconnect the battery from the vehicle
electrical system whilst charging is in progress.
¶ Never short-circuit charging clips.
i In the event of incorrect polarity and terminal
short-circuit no charging voltage is applied and an
failure indication appears.
5.2 Switching on
1. Connect the BAT 645 to the mains voltage system
via the power supply cable.
2. Switch on the BAT 645 via the on/off switch (fig.1,
item1).
 The red LED (fig.1, item7) lights up if the bat-
tery is connected or flashes if it is not connected.
i After switching the device on or after resetting it to
factory settings, the "Language settings" menu is
displayed automatically.
i After the BAT 645 is switched on, the voltage is
displayed when the battery is connected or if the
battery is not connected, the message "no battery
connected" appears.
i The BAT 645 automatically detects whether a 12V
or a 24V battery (series connection of two 12V
batteries) is connected.
Minimum voltage by mode 12V 24V
No mode (e.g. after switching the device on) 3V 17V
Charging 3V 17V
Charging (LFP) 9V 18V
Back-up 3V 17V
Buffering 9V 18V
Tab. 1: Battery detection
5.3 Charging mode
Charging characteristics
Various charging characteristics and charging
parameters are stored in the BAT 645, depending
on the battery type. The figure below is an example
which shows the principle of a battery charging
characteristic.
t
U
U
I
I
t1
t2
U
1
I
1
I
2
U
2
U
3
t3
Fig. 3: Charging characteristic
Characteristic values for UNI battery type
I
1
= 20% of set battery capacity
I
2
= 2 of set battery capacity
U
1
= 14.0V (12V), 28.0V (24V)
U
2
= 14.2V – 14.8V (12V), 28.4V – 29.6V (24V)
U
3
= 13.5V / 27V
Phase 1 (t1): Main charging, green LED flashes
rapidly
The charging current I
1
is approx. 20% of the set
battery capacity (60% with LFP batteries). Once the
battery has attained the charging cut-off voltage U
1
,
the charging current I
1
starts to decrease. Approx. 65%
of the battery capacity has then been attained. The
battery is ready for use as a starter battery. Phase1 is
over when the charging current I
1
drops below approx.
2% of the battery capacity. The battery is then approx.
97% charged.
Phase 2 (t2): Secondary charging, green LED flashes
slowly
The charging current I
2
is approx. 2% of the set battery
capacity. The charge voltage is limited to U
2
.
Phase 3 (t3): Trickle charging, green LED lights up
The charging current is always activated when the
battery voltage drops below U
3
. The charging current
remains active until the charging voltage U
1
is attained
again.
i If the message "Time out" is displayed, a charging
phase could not be completed. This indicates that
either the parameter was entered incorrectly, or
that the battery is defective.
| 18 | BAT 645 | Operationen
1 689 989 233 2022-01-24| Robert Bosch GmbH