9
The Battery Backup Option allows the unit to switch to using a connected battery as a power
source in the event of external power failure.
The DC power output normally supplies the load while the battery is maintained at full charge by
a 1A trickle charger built into the unit. In the event of an input power failure, the load instantly
switches over to using the battery as replacement power source, running until either the battery
is fully discharged or the load goes into low voltage shutdown. Once power is restored, the DC
output will resume supplying power to the load and the trickle charger will recharge the battery.
To set up the Battery Backup:
1. Connect the Load to the output terminals labelled
OP+
and
OP-
2. Connect the Battery to the output terminals labelled
Batt+
and
Batt-
3. Turn the unit ON
Battery Backup (Optional)
27.2V
1A Charger
In
Out
Main PCB
Chassis
DC Output 28V
-
+
Battery
To Load
+
-
27.2V
Batt -
Batt +
OP -
OP +
The Battery Backup circuit is designed so the battery is normally reverse biased. Essentially,
whichever source has the higher voltage will take precedence in supplying power to the load. If
the Voltage Output (V
Out
) is greater than the Battery Voltage (V
Batt
), current will only flow from V
Out
to the load. The path of this current is indicated in
red
.
If V
Outt
drops below V
Batt
, the current will flow from the battery to the load. The path of this current
is indicated in
blue
. The configuration of the schottky diodes prevents this current from feeding
back into the unit.
TIP:
Size your batteries correctly.
Choose batteries with enough amp-hour capacity to power the load for the required
amount of time in a power outage.
Note: The diagram shows the voltage settings for a 24V system, but this option is
available for every standard output voltage.
