Securitron EXD - Manual (Page 12)

PN# 500-13350
Page 12 Rev. E, 11/11
FIG. 5: CHART FOR SELECTION OF BATTERY PACK SIZE
MIN 1 HR 2 HR 4 HR 8 HR 16 HR 24 HR 48 HR 72 HR UL STD.
150 MA
300 MA
500 MA
1 A
2 A
3 A
4 A
5 A
7.5 A
10 A
4 AH
4 AH
4 AH
4 AH
4 AH
4 AH
4 AH
4 AH
4 AH
4 AH
4 AH
4 AH
4 AH 4 AH 4 AH 4 AH
4 AH 4 AH 4 AH 4 AH
4 AH
4 AH 4 AH 4 AH 4 AH
4 AH 4 AH
4 AH 8 AH
8 AH
8 AH
8 AH
8 AH
8 AH
12 AH
16 AH
20 AH
12 AH
12 AH
16 AH
16 AH
20 AH
16 AH
20 AH
16 AH
20 AH
12 AH
20 AH
12 AH
20 AH
8 AH 8 AH 12 AH
12 AH 16 AH
16 AH
24 AH
36 AH 24 AH
24 AH
36 AH
28 AH
28 AH
24 AH
36 AH
48 AH
36 AH
44 AH
72 AH
100AH
24 AH
32 AH
40 AH
60 AH
72 AH
52 AH
72 AH
84 AH
130AH
180AH
48 AH
72 AH
100AH
120AH
180AH
240AH
48 AH
100AH
150AH
200AH
240AH
360AH
480AH
72 AH
150AH
240AH
300AH
360AH
480AH
720AH
BACKUP TIME DESIRED
T
O
T
A
L CURRENT
DRAW
N
"MIN" TIME REFERS TO FACILITY USING EMERGENCY GENERATOR WHERE THE
BATTERIES ARE ONLY REQUIRED TO OPERATE THE SYSTEM
U.L. STANDARD REQUIRES 4 HOURS OF BATTERY OPERATION FOLLOWED BY
A 24 HOUR RECHARGE PERIOD AND THEN A SECOND 4 HOURS OF OPERATION
STANDARD SECURITRON POWER SUPPLIES CAN ONLY CHARGE UP TO A 20AH PACK.
FULL RECHARGE FROM A FULLY DEPLETED BATTERY PACK REQUIRES 32 HOURS
FOR EACH 4 AH OF BACKUP UP TO 20 AH. FOR LARGER PACKS,
THE FACTORY CAN QUOTE THE RECHARGE TIME.
MODIFIED EQUIPMENT. LARGER PACKS ARE SHOWN IN ITALICS IN THE CHART.
IF A LARGER PACK IS CALLED FOR, THE FACTORY MUST BE ALLERTED TO SUPPLY
BATTERIES MUST BE SEALED LEAD ACID OR GEL CELL TYPES.
DRY CELLS WILL NOT RECHARGE AND WILL BE DAMAGED.
THIS CHART IS ONLY VALID IF BATTERIES ARE OPERATED
AT ROOM TEMPERATURE. IN A COLD ENVIRONMENT, CAPACITY IS REDUCED.
BATTERIES SHOULD BE REPLACED AFTER 5 YEARS OF USE.
FOR A FEW MINUTES UNTIL THE GENERATOR TAKES OVER
To implement battery backup, it is necessary for the installer to correctly determine the proper
size for the battery pack which varies with the current drawn by the complete load and the
backup time desired. The power supply must also be able to charge the pack. All BPS series
power supplies provide a current limited charging circuit. The reason that the charge current is
limited is that otherwise a recharging battery after a power failure would take current away from
the locks which must also operate during battery recharging. Charge current on standard
supplies is limited to 250 mA and this amount of current is capable of charging up to a 20 Amp
Hour battery pack. If a larger pack is needed, Securitron can supply a modified power supply
with a larger maximum charge current. Naturally, the greater charge current means that the
supply loses load operating capacity. For example, a standard supply rated at a maximum total
output current of 3 Amps can only supply a maximum of 2.75 Amps to the load as 250 mA is
reserved for battery recharging (up to 20 Amp Hours). If the supply is modified to provide a 1
Amp charge current, which allows an 80 Amp Hour battery pack, only 2 Amps remain to be
allotted to the load.
Figure 5 is a chart which allows calculation of the correct size battery pack to provide a range of
backup times in concert with a range of possible total system load currents. Selection of backup
time will depend on the history of power outages in the area and on the level of security
required for the facility. The information in the chart is valid for 12 or 24 volts although,
naturally, the battery voltage must match the power supply voltage. As a rough guide, consider
a single door EXD system to draw 200 mA at 24 VDC and 400 mA at 12 VDC. For multiple door
systems, the total current must either be calculated or measured with an ammeter. Be sure to
carefully read all of the notes at the bottom of Figure 5.
6.2.5 HIGH ENERGY HAZARD
It is often assumed that electrical installations running on low voltage are inherently safe. Low
voltage installations do not pose an electric shock hazard but can pose a high energy hazard