Rockwell Automation Publication 1606-RM008A-EN-P - November 2021
15
DC-UPS - 24V, 20 A, 480 W Reference Manual
Buffer Time
The buffer time (sometimes also called autonomy time) is the maximum time
for which the battery can maintain the required output current. The buffer
time mainly depends on the capacity and quality of the battery and the output
current in battery mode.
The following times are typical values for a new product and the aging effect
during operation is not included.
Figure 11 - Buffer Time Definition
IMPORTANT
• The following buffer times apply for a battery temperature from
20...30°C and a buffer voltage setting of 22.5V. At higher voltages, the
buffer time is correspondingly shorter. Furthermore, with a wire length
of 2x1m (equal 1 m cord length) and a cross section of 4 mm
2
(or AWG 12)
between the battery module and the DC-UPS.
• Due to long-term aging effects of batteries consider a buffer time
reduction of 30…50% over time.
• The shown buffer times only apply for Rockwell Automation battery
modules or from Rockwell Automation recommended batteries.
• The buffer time is defined for a fully charged battery. The buffer time
can be 10…20% shorter for buffer events, which start immediately after
the “Ready” signal becomes active.
Buffer Time
Battery
Size
7 Ah
12 Ah
26 Ah
Notes
Typ
1 d: 17 h: 40 m: 0 s
2d: 22 h: 50 m: 0 s
6d: 19 h: 53 m: 20s
At 22.5V,
0 A
Typ
17 h: 13 m: 20s
1d: 6 h: 41 m: 40s
2d: 20 h: 03 m: 20s
At 22.5V,
0.2 A
Typ
5 h: 16 m: 40s
9 h: 51 m: 40s
21 h: 43 m: 20s
At 22.5V,
1 A
Typ
2 h: 32 m: 0 s
5 h: 17 m: 59 s
11 h: 27 m: 30s
At 22.5V,
2 A
Typ
46 m: 30s
2 h: 2 m: 55 s
4 h: 26 m: 40s
At 22.5V,
5 A
Typ
19 m: 11 s
46 m: 2 s
2 h: 10 m: 0 s
At 22.5V,
10 A
Typ
10 m: 35 s
27 m: 34 s
1 h: 17 m: 40s
At 22.5V,
15 A
Typ
06 m: 45 s
16 m: 47 s
55 m: 00s
At 22.5V,
20 A
Typ
4 s
4 s
4 s
At 22.5V,
30 A
Battery
Charge
100%
80-90%
"Ready" signal threshold
t
t
Battery
Mode
Buffer Time
