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2.2. Back-up Battery
An external lead-acid battery with the same nominal voltage as the power
supply may be connected directly in parallel with the output terminals, or to
the BAT terminal (on units with the LVD option “B”) to provide a DC
backup capability. Use appropriate wire, over current protection and
disconnect device as outlined in the Installation section. Your load will
then be powered from the external battery if the AC input power should fail,
and the battery will recharge from the supply output when the AC power
returns. Choose your battery size (Ahr capacity) so that it can provide power
to the connected loads for the duration of a typical loss of AC power.
For both battery configurations the external battery will be charged with a
constant current (the supply output current setting) until the float voltage
(supply output voltage setting) is reached, and then will be held at a constant
float voltage as long as the Digital Series supply is powered on.
WARNING!
Potential for personal injury, or damage to property and
equipment due to overcharging of the external battery!
The supply output voltage must be set to a voltage level suitable
for the external battery used. Check the float voltage rating of
your battery and set the supply output voltage accordingly
before connecting the battery to the system.
The battery may be charged at a rate up to the maximum output
current rating of the power supply. Ensure the battery used is
capable of being charged at this rate.
Heavily discharged batteries will initially be charged with a small trickle
current on LVD equipped units when connected to the BAT terminal. When
the battery voltage is greater than the LVD Reconnect voltage (user
adjustable) the internal LVD contactor will close connecting the battery to
the main power supply output and the load, allowing the battery to charge
and be maintained at its float voltage level. If the AC power fails during
normal operation the battery will remain directly connected to the output
through the LVD contactor and able to power the load with no delay or
transition time. As battery voltage falls to the LVD disconnect level (user
adjustable) the LVD contactor will open to help protect the battery from
excessive discharge. The contactor will re-close once the battery voltage
rises again to the LVD Reconnect threshold (user adjustable) due to
charging from either an external source, or when AC power is returned to
the power supply.
