BÜTTNER ELEKTRONIK – Batt erie-Control-Booster MT BCB 30/30, MT BCB 40/40, MT BCB 60/40
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4.7. Charge progress on the board batt ery
A new, complete main charge cycle for the BOARD battery begins,
• after the alternator has stopped (or the control signal “D+” has disappeared), or a
mains power failure
• after the reset voltage drops below 12.75 V (lead battery) or 13.10 V (LiFePO
4
) for 30 s
1. The main charge takes place with maximum constant current (CC) in phase I (Bulk) from
the medium voltage range up to close to the U
1
(CV) phase. Deep discharged batteries
are gently pre-charged starting from 0 V with initially reduced current and charging
current interruptions for regeneration up to approx. 9 V. The Main Charging LED lights
up, approx. 75 % of the capacity (approx. 90 % for LiFePO
4
) is recharged. The duration of
the CC-phase depends on the battery conditions, the load from consumers and the state
of charge. For safety reasons, the I (CC)-phase is ended after a maximum of 15 h (in the
event of battery cell defects or similar).
2. When the voltage rises, the charging current is somewhat reduced to protect the battery
and subsequent switched to the constant voltage (CV) phase U
1
(Absorption). During
the U
1
(CV)-phase (full charge, cell compensation charge, the battery voltage is kept
constant at a high level, the green LED Battery Full flashes (only briefly, with increasing
charge, flashing interval increases). The duration of the constant voltage phase depends
on the battery type and the depth of discharge. The LED Main Charging will be extincted
at the end of the U
1
(CV) phase.
3. The U
2
(CV)-phase (Float) then takes place at reduced voltage and variable current in
parallel operation with consumers. The LED Battery Full is illuminated continuously.
Depending on the battery type, the U
2
(CV)-phase is limited to 24 to 48 hours.
4. The subsequent U
3
(CV)-phase at reduced charging voltage (Storage charge) is used in
long- term operation on mains power without further discharging (e.g. long breaks in
use or hibernation) to minimize battery gassing and harmful battery cell plate corrosion
effects.
5. For battery regeneration (avoidance of electrolyte stratification and sulphation), the
charger carries out a constant voltage (CV) phase U
1
twice a week for a short time (max.
1 h). This is followed by a direct return to the U
3
(CV)-storage charge.
Note:
In all charging phases U
1
-U
3
(CV) (battery full), almost the entire possible charger current is avail-
able for additional supply of consumers without discharging the battery!
deep
discharged
battery
1
(CC) phase
bulk charge
2
U1 (CV) phase
absorption
charge
3
U2 (CV) phase
fl oat
charge
4
U2 (CV) phase
storage
charge
U1
1 h
charging
time
100 %
100 %
<100 %
<75 %
<10 %
100 %
State of charge
Charging
voltage U
Charging
current I
