Installation manual

D9124 Operation & Installation Manual
Page 31
© 1996 Radionics
74-06799-000-D 2/96
Figure 18: 24 VDC Standby Source Batteries
Choosing the Right Batteries to Meet 24V Requirements
The correct size of batteries connected to the system depends on the amount of current
that devices draw from the power supply and the standard that you are meeting. See the
Auxiliary Current and Standby Battery Requirements section, Calculations for 24 VDC
Devices for more information.
Table 10 shows the amount of current that 24 VDC devices can draw depending on the
battery amp hours that you have installed, and the amount of standby time that you need.
The calculations in Table 10 include current requirements for five minutes of bell time at
the end of the standby period.
For example, if you have 7 amp hours of battery capacity (two D126 batteries installed),
and you are required to provide 24 hours standby time, then 24VDC devices may draw
no more than 0.135A. In addition to the 0.135A of continuous current drawn, you may
also attach up to 3A of indicating devices (bells for up to 5 minutes) to the Bell Circuit
terminals on the motherboard.
The maximum standby current cannot exceed 1.5 amps, the maximum bell current
cannot exceed 3 Amps and the total current cannot exceed 4 amps. See page 38 for
further discussions and examples.
Table 10: Standby Power Requirements for 24V Devices
Installing the 24 V Standby Source Batteries
See the Safety Section before installing batteries.
1. Place the batteries on the top battery shelf (see
Figure 18 ).
2. Connect the black negative wires from battery
harness P7 to the negative terminals on the
batteries.
3. Connect the red wires from battery harness P7
to the positive terminals on the batteries.
4. Plug battery harness P7 into connector J7 on
the D9142 Power Supply.
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24 VDC STANDBY
SOURCE BATTERIES
D9142
24 Hour Standby 60 Hour Standby 72 Hour Standby
Battery
Amp. Hrs
Current
(Amps)
Recharge
Time (Hrs)
Current
(Amps)
Recharge
Time (Hrs)
Current
(Amps)
Recharge
Time (Hrs)
7Ah 0.136 10 0.030 12 0.012 12
12Ah 0.322 10 0.105 12 0.075 12
14Ah 0.397 11 0.135 12 0.100 12
17.2Ah 0.517 13 0.183 14 0.140 14
24Ah 0.771 18 0.286 18 0.225 18
36Ah 1.219 34 0.467 27 0.376 26
38Ah 1.294 37 0.497 29 0.401 28