49
3
UPS Operation
Alpha Technologies
3.10
Battery Discharge States
The batteries go through several states as they power the loads. Knowing how long they last for
your conditions will help you manage the loads when the line is unqualified.
1) Battery Mode
The unit is providing backup battery power to the loads. How long it stays in battery mode depends upon
the size of the loads and the capacity of the batteries. Perform a run-time test (Section 5.1) to learn how
long the batteries can power your loads.
TIP: The operator should shut down unnecessary loads to extend battery backup time.
2) Low Battery Warning
The batteries still power the loads, but they are almost discharged and cannot power them much longer.
3) Low Battery Shutdown
When the battery has a voltage of 42.5 Vdc for 3 seconds, the unit automatically goes into this state. The
batteries are considered fully discharged and can no longer power the load, but they have enough power
to keep the unit’s monitoring and control circuits active. This state can last several days, depending on
the battery’s capacity.
4) Low Battery Disconnect
When the battery has a voltage of 42.5 Vdc for 10 seconds, the unit automatically goes into this state.
The batteries are disconnected from the unit to protect them from a damaging deep discharge. Both LEDs
and the LCD are OFF, showing the unit is shut off. The unit stays off until line power or a backup
generator is available or fresh batteries are connected.
NOTE:
Not to scale. Perform a battery backup time test (Section 5.1) to learn how long each state lasts for your operating conditions.
Figure 3.10.1
Battery Discharge States
1) Battery Mode Starts
NOTE: The battery voltage level
drops when the load is connected to it.
3) Low Battery Shutdown
2) Low
Battery
Warning
4) Low
Battery
Disconnect
(At Aprx. 42 Vdc)
NOTE: The battery voltage level rises
when the load is disconnected from it
because of the shutdown.
Output
LED
Flashing
All LEDs and
LCD OFF
Output LED off
Output and Alarm LEDs Flashing
B
a
tt
er
y
V
oltage
53 Vdc
42.5 Vdc
Time