HandKey II Installation and Operation Manual
Revision 2.0
Page 15
Battery Backup Operation
The Hand Reader uses an internal switching regulator to obtain internal operational
power. It accepts input voltages from 12 to 24 VDC or 12 to 24 VAC at 50 to 60 Hz.
An optional power-fail protection circuit board can be attached to the main circuit
board to provide and control battery backup. The design of the internal power supply
is such that any range of the above input voltages may be used and still provide proper
battery charge voltage and battery backup operation. Switch-over to battery power is
automatic and occurs when the input voltage falls to approximately 10.5 volts. At that
time the internal battery charger is disabled to save power and uninterrupted operation
continues on battery power.
When input power is restored, the Hand Reader switches off of battery operation and
the battery charger is re-enabled to recharge the battery. Battery charge voltage is set at
approximately 13.65 volts, and battery charge current is limited to approximately 50
mA. A fully discharged battery requires approximately 12 hours of charge to fully
recover.
Additional options installed and specific configurations within the Hand Reader make
it difficult to predict precisely how long battery support will last, but in general two
hours of battery operation can be expected. While operating on battery backup due to
loss of main input power, the battery output voltage is constantly monitored by
internal circuitry. If the battery voltage reaches approximately 9.5 volts the Hand
Reader automatically shuts down. This is done to prevent full exhaustion of the
battery. A yellow indicator on the top panel illuminates to indicate that the Hand
Reader is running off of battery power. This indicator extinguishes when main input
power is restored.
Shunt J7 which is located immediately in front of the DIP switches on the main logic
board (see Figure 3-3) enables or disables battery operation on those Hand Readers
equipped with optional battery backup. If a Hand Reader does not have the optional
battery backup package installed, J7 is not used. On Hand Readers equipped with the
battery backup option, J7 allows service personnel a mechanism for disabling battery
backup operation before removal of main input power. To fully power down a Hand
Reader equipped with battery backup, remove or reposition shunt J7 so that the two
pins protruding up from the main logic board are not connected to each other. This
effectively opens the circuit, removing the battery from any internal circuitry. Main
input power can then be removed and the Hand Reader will fully shut down. Once the
Hand Reader has fully shut down, shunt J7 may be reinstalled. The design of the
power supply is such that main input power must be reapplied to re-enable the battery
protection mechanism. If shunt J7 is not properly installed, the internal backup battery
will not be charged, and in the event of a main input power loss, the Hand Reader will
shut down.
