UB40.241
UB-Series
24V,
40A,
DC-UPS
Jun. 2020 / Rev.0.1 DS-UB40.241-EN All values are typical figures specified at 24Vdc input voltage, 40A output current in
power supply mode at 25°C ambient, no charging and after a 5 minutes run-in time unless otherwise noted.
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6.
B
ATTERIES AND
B
ATTERY
C
HARGING
The battery is not included in the DC-UPS. The battery is one of the most important parts of a DC-UPS system, which needs to be
carefully selected while also paying close attention to storage, charging and environmental conditions. Select the proper battery
capacity according to the required buffer time and select the right battery quality to achieve the requirements for changing intervals.
Batteries are service parts and need to be replaced periodically and also need to be replaced when the internal battery tests of the DC-
UPS report an unexpected failure.
The device has a battery size selector included, which allows an optimal use of different battery sizes.
Batteries smaller than 12Ah are only recommended when the load current is below 20A.
Charging:
During charging, the DC-UPS consumes additional current from the input. The supplying power source must be able to deliver the
additional internal current consumption (including the charging current) specified as input current in the table in the chapter
“Input and
Output Characteristic”
.
A special feature of this device is the automatic reduction of the charging current to 2A when the input current reaches 40A. This should
help to prevent an overload of a 40A power supply.
The device charges the batteries in a constant current / constant voltage (CC-CV) mode.
When the battery center-tap connection is installed, the two 12V batteries are charged with a balancing function. This adaptive charging
mode enables up to 1A more in charging current for the battery which require a higher current to get fully charged, while the other
battery gets up to 1A less. This results in a faster and more efficient battery charging and makes matched (paired) batteries unnecessary.
The center-tap connection is optional and if not installed, both batteries will be charged with one common charging voltage. The device
automatically recognizes if the center-tap connection is present or not.
When c
harging is approximately 85% completed, the individual green “Ready” LED f
or the specific battery stops flashing and is on solid.
When the temperature sensor (PT1000) is installed, the end-of-charge-voltage is temperature compensated. The device automatically
recognizes if a temperature sensor is connected or not. A list of suitable PT1000 temperature sensors from different vendors can be
provided.
In case no temperature sensor is installed, the end-of-charge-voltage is fixed to a value which corresponds to a battery temperature of
40°C.
Frequent charging below +5°C (41°F) reduced the lifetime of the battery and should be avoided. Low temperatures increase the battery
impedance and also change the battery characteristic
s. This could result in a false “r
eplac
e battery” signal or an unexpected interruption
of a buffer event, especially with small batteries. For this reason, the charging current is reduced at low temperatures depending on the
battery size.
