Puls UBC10.241, UBC10.241-N1 Application Note
U–Series
UBC10.241, UBC10.241-N1
24V, 10A, DC-UPS
28. APPLICATION NOTES
28.1. BATTERY REPLACEMENT INTERVALS
Batteries have a limited life time. They degrade slowly beginning from the production and need to be replaced
periodically. The design life figures can be found in the individual datasheets of the batteries and usually is specified
according to the Eurobat guideline or according to the manufacturer’s specifications.
The design life is the estimated life based on laboratory condition, and is quoted at 20°C using the manufacturer’s
recommended float voltage condition. According to the Eurobat guideline, design lives have been structured into the
following different groups:
3 - 5 years:
6 - 9 years:
10 - 12 years:
A battery failure within the specified design life of the battery usually results in a complete loss of the battery
function (broken cell, defect connection, …) and will be detected and reported by the periodical battery tests which
are included in the UBC10.241 DC-UPS control unit.
If the operational parameters differ from those which are specified for the design life, an earlier change of the
battery might be necessary. The “real life” is called service life and is defined as the point at which the cell’s actual
capacity has reached 80% of its nominal capacity. At the end of the service life the capacity degrades much faster, so
that a further use of the battery is not recommended.
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. 28-1 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. 28-2.
Other effects which shorten the service life
Guidelines for a long battery service life:
This group of batteries is very popular in standby applications and in small emergency equipment.
This represents a 4 years design life with a production tolerance of ±1 year.
This group of batteries is usually used when an improved life is required.
This represents a 7.5 years design life with a production tolerance of ±1.5 years.
This group of batteries is used when in applications where longest life and highest safety level are
required. This represents a 11 years design life with a production tolerance of ±1 year.
Overcharging and deep discharging shortens the service life and should be avoided. Thanks to the single
battery concept of the UBC10.241, the end-of-charge voltage is precisely set automatically 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
UBC10.241 does not produce such a ripple voltage. This effect can be ignored when the battery is charged
with the UBC10.241.
Place the DC-UPS in a cool location: E.g. near the bottom of the control cabinet.
Do not place the DC-UPS near heat generating devices.
Do not store discharged batteries.
Do not discharge the battery more than necessary. Set buffer time limiter to the required buffer time.
The depth of discharge reduces the service life of the battery and limits the number of cycles. See Fig. 28-2.
May. 2008 / Rev. 1.1 DS-UBC10.241-EN
All parameters are specified at an input voltage of 24V, 10A 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.
www.pulspower.com Phone +49 89 9278 0 Germany
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U–Series
UBC10.241, UBC10.241-N1
24V, 10A, DC-UPS
Example for calculating the service life and the required replacement cycle:
Parameters for the example:
A 5Ah battery with a design life of 3-5 years is used (e.g. Yuasa battery which is used for type UZB12.051)
The average ambient temperature is 30°C
One buffer event consumes approx. 25% of the achievable buffer time.
One buffer event per day
Calculation:
Ambient temperature influence:
According to Fig. 28-1 curve A, a 2 years service life can be expected for an ambient temperature of 30°C.
Number of discharging cycles: 2 years * 365 cycles = 730cycles in 2 years.
According to Fig. 28-2, curve C has to be used (only 25% of battery capacity is required). 730 cycles have only a
negligible influence in a battery degradation and can be ignored.
Result:
The battery shall be replaced after 2 years.
Please note that the battery degrading begins from the production date (check date code on the battery) which may
shorten the replacement intervals.
Fig. 28-1 Service life versus ambient
Service Life in Years
10
9
8
7
6
5
4
3
2
1
20°C
temperatures, typ *)
C
B
A
Ambient Temperature
30°C 35°C
25°C
Design Life
of Battery
A:
3-5 Years
B:
6-9 Years
C:
10-12 Years
40°C
45°C
Fig. 28-2 Cell capacity degradation vs. discharging
Cell Capacity
120%
100%
80%
60%
40%
20%
A
0
200
cycles *)
C
B
Depth of
discharge
A:
100%
B:
50%
C:
30%
Number of Discharging Cycles
400 600 800 1000 1200
*) datasheet figures from battery manufacturer
28.2. PARALLEL AND SERIAL USE
Do not use the DC-UPS in parallel to increase the output power. However, two units of the DC-UPS can be paralleled
for 1+1 redundancy to gain a higher system reliability.
Do not use batteries in parallel, since the battery quality test might create an error message.
Do not connect two or more units in series for higher output voltages.
Do not connect two or more units in a row to get longer hold-up times.
May. 2008 / Rev. 1.1 DS-UBC10.241-EN
All parameters are specified at an input voltage of 24V, 10A 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.
www.pulspower.com Phone +49 89 9278 0 Germany
22/23
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