Data Sheet

UB20.241
UB-Series
24V, 20A, DC-UPS
battery chargers and the temperature tracking feature of the UB20.241, the end-of-charge-voltage can be set very
precisely to the required value and thereby avoiding unnecessary aging effects.
- Discharged batteries:
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.
- High ripple voltage:
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.
Recommendations for achieving 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. 23-2.
Fig. 23-1 Service life versus ambient
temperatures, typ *)
Fig. 23-2 Battery capacity degradation vs.
discharging cycles *)
20°C
10
30°C 35°C
40°C
45°C
8
6
4
2
Ambient Temperature
25°C
1
3
5
7
9
Service Life in Years
Design Life
of Battery
A: 3-5 Years
B: 6-9 Years
C: 10-12 Years
A
B
C
0
120%
100%
40%
20%
Number of Discharging Cycles
200
60%
80%
Cell Capacity
Depth of
discharge
A: 100%
B: 50%
C: 30%
400 600 800 1000 1200
A
B
C
*) Datasheet figures provided by the battery manufacturer
How to determine the replacement intervals:
Example:
- Two 26Ah batteries with a design life of 10-12 years are 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 (=182 cycles / year)
Calculation:
A) Ambient temperature influence:
According to Fig. 23-1 curve C, a 5 years service life can be expected for an ambient temperature of 30°C.
B) Number of discharging cycles: 5 years * 182 cycles = 910cycles in 5 years.
According to Fig. 23-2, 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.
Feb. 2016 / Rev. 2.1 DS-UB20.241-EN
All parameters are specified at 24V, 20A output current, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
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