DCU20
User Manual rev. 21
Page 12/29
Battery capacity: between 1.2Ah and 150Ah (see §5.2.4).
Battery charging voltage: provided by the battery manufacturer (see §5.2.5).
Battery charging current: provided by the battery manufacturer (see §5.2.6).
Battery deep discharge voltage (see §5.2.7).
The battery charger automatically reduces the current to avoid exceeding the maximum input current
(20A) in case of high current load. For example if the load is consuming 19A and the charger current
is set to 3A, the charger current is automatically reduced to 1A to avoid the 20A input current limit.
The charger voltage is independent on the input voltage (power supply), and is user settable.
Time
Current
Voltage
Constant current
Constant voltage
Maintenance
User settable charge
User settable charge
voltage
current
Figure 8: Battery charging algorithm
The battery charge terminates in case at least one of the following conditions are satisfied:
Low current:
The measured battery current is lower than 10% of the “Battery charge
current”.
Timer:
the charge is terminated after the battery has been charged for a predetermined
amount of time. The value is automatically calculated by the device.
For Nickel batteries only the following conditions are also checked:
Temperature Cutoff (TCO):
The battery temperature if higher than the
“Battery maximal
temperature
” (§5.2.11) minus 3°C for more than one minute. For example if the maximal
battery temperature is set to 60°C, the charge terminates in case the temperature is higher
than 57°C.
Rate of Temperature Increase (
ΔT/dt):
The battery temperature is rising at a rate equal or
superior then 1°C/min.
To avoid unattended end of charge don’t place the system on an
ambient with rapid changes of temperature (for example exposed to direct sunlight).
Warning: In order to avoid potentially hazardous situations including fire hazard, safety
recommendations must be followed. Only authorized staff can install the unit.
Warning: For Lithium cells the balancing and protection circuit must be included in the
battery pack.
For nickel batteries the use of the external temperature sensor is mandatory. The sensor
must be placed in contact with the battery.
3.7 Coulomb counter
DCU20 measures the current flowing from/to the battery to keep track of the capacity available on the
battery. The capacity is measured in Ampère Hours [Ah]. The value shown is based on the following
assumptions:
