5
1
PRODUCT FUNCTION
1.3.3 Optional External LED
To provide charge status and error feedback away from the main unit, a basic 3V
LED can be wired as show in Figures 2.7.1 and 2.7.2.
If used, this external LED is either OFF (BCDC not charging), ON (BCDC charging)
or FLASHING (see error codes in Section 1.5 Error Codes). A “12V” LED (3V with
integrated resistor) will not operate correctly if installed.
1.3.4 Charging Process
Voltage
Float
Absorption
Boost
Current
Charging Process
Soft-Start
When the Charger is turned on, it will start ramping current from 0A up to the full
rated current, this is called
Soft-Start
and usually takes around 30 seconds. Once
the full rated current is reached the charger will move into
Boost
stage. The
Boost
stage maintains a constant current until the battery voltage reaches its Absorption
Voltage.
The current in
Boost
stage may vary during operation in order to maintain safe
operating temperature, or to limit the difference between input and output voltages.
The Charger will then move to
Absorption
stage which maintains a constant voltage
level for a predetermined period of time or until the current being drawn by the
output battery drops to less than 4A for 30 seconds; after which the Charger will
enter
Float
stage.
Float
stage maintains 13.3V (13.6V for LiFePO
4
) on the output battery, keeping the
battery topped up. This counteracts the battery’s self discharging or loads applied
to the battery. When the battery loses charge, the Charger will move back into the
Boost
stage.
When using the Battery Charger to charge a Lithium Iron Phosphate battery, only
batteries that feature an inbuilt battery management system featuring inbuilt under and
over voltage protection and cell balancing are suitable.
Figure 1.3.4.1 - Charging Process
