Datasheet

PRELIMINARY
UB20.241
U–Series
24V, 20A, DC-UPS
Temperature effect:
The temperature has the most impact in the service life. The hotter the temperature, the earlier the wear-out phase
of the battery begins. The wear-out results in a degradation of battery capacity. See
Fig. 27-1 for details.
Effect of discharging cycles
The number as well as the depth of discharging cycles is limited. A replacement of the battery might be necessary
earlier than the calculated service life if the battery exceeds the numbers and values of
Fig. 27-2.
Other effects which shortens the service life
 Overcharging and deep discharging shortens the service life and should be avoided. Thanks to the two
battery chargers of the UB20.241, the end-of-charge-voltage can be set very precisely to the required value
and thereby avoiding unnecessary aging effects.
 Charge retention is important to get the longest battery life. Stored batteries which are not fully charged
age faster then charged batteries. Batteries which are not in use should be recharged at least once a year.
 Excessive float charge ripple across the battery has an effect of reducing life and performance. The UB20.241
does not produce such a ripple voltage. This effect can be ignored when the battery is charged with the
UB20.241.
Guidelines for a long battery service life:
 Place the batteries in a cool location: E.g. near the bottom of the control cabinet.
 Do not place the batteries near heat generating devices.
 Do not store discharged batteries.
 Do not discharge the batteries more than necessary. Set buffer time limiter to the required buffer time.
 When choosing the batteries capacity, always try to get the next higher capacity than required. The depth of
discharge reduces the service life of the batteries and limits the number of cycles. See
Fig. 27-2.
Example for calculating the service life and the required replacement cycle:
Parameters for the example:
 two 26Ah battery with a design life of 10-12 years is used
 The average ambient temperature is 30°C
 One buffer event consumes approx. 25% of the achievable buffer time.
 One buffer event every two days
Calculation:
Ambient temperature influence:
According to
Fig. 27-1 curve C, a 5 years service life can be expected for an ambient temperature of 30°C.
Number of discharging cycles: 5 years * 182 cycles = 910cycles in 5 years.
According to
Fig. 27-2, curve C has to be used (only 25% of battery capacity is required). 910 cycles have only a
negligible influence in a battery degradation and can be ignored.
Result:
The battery shall be replaced after 5 years.
Please note that the battery degrading begins from the production date (check date code on the battery) which may
shorten the replacement intervals.
September 2012 / Rev. 1.3 DS-UB20.241-EN preliminary
All parameters are specified at an input voltage of 24V, 20A output load, 25°C ambient and after a 5 minutes run-in time
unless otherwise noted. It is assumed that the input power source can deliver a sufficient output current.
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19/23