TYPE 4208 “Y”
AUTOMATIC BATTERY CHARGER PANEL
INTRODUCTION
The “Y” panel monitors the charge level of the
standby battery and supplies the necessary charge
to keep the battery at its proper potential.
The “Trickle Charge” circuit operates during
normal conditions. When the battery voltage falls
below 90% of the full charge, the panel automati-
tally transfers to the “Fast Charge” circuit.
An AUTO/MANUAL switch is provided to over-
ride the automatic charge circuit. This allows the
battery to be charged periodically
as
specified by
the manufacturer’s maintenance recommendations.
The “Y” panel includes two door mounted
meters: a milliammeter to indicate the trickle
charge rate, and a voltmeter to indicate the battery
voltage level.
CIRCUIT OPERATION (FIG. 28)
TRICKLE CHARGE CIRCUIT
In normal operation, a trickle charge is applied
to the battery. Current flows from the negative
side of the rectifier, through resistor R2, the
TRICKLE RATE ADJ. switch (OFF position), the
AUTO/MANUAL switch (AUTO position) to ter-
minal OV (-BAT). (The trickle charge rate can be
monitored by placing the TRICKLE RATE ADJ.
switch to the ON position.)
When the battery is fully charged, relay Kl is en-
ergized and relay K2 is de-energized. Current flows
from terminal OV (-BAT.), through relay Kl,
con-
tacts K2A (5 & 1), resistors R5 and R3 to terminal
+24VDC.
FAST CHARGE CIRCUIT
If the standby battery voltage falls below 90% of
full charge, relay Kl de-energizes and its contacts
transfer.
The transferred Kl A contacts complete the cir-
cuit through relay K2. Relay K2 energizes and its
contacts transfer. Current flows from terminal OV
(-BAT.), through relay K2 (energizing K2), con-
tacts K 1 A (6 & 4) to terminal +24VDC.
The K2B contacts complete a path for a fast
charge (2 amp) to be applied to the battery. Cur-
rent flows from the rectifier, through resistor Rl,
the TRICKLE RATE ADJ. switch (OFF position),
contacts K2B (7 & 6) the MANUAL/AUTO switch
(AUTO position) to the battery via terminal OV.
The K2A contacts break the circuit through re-
lay Kl and Kl remains de-energized until the bat-
tery voltage is high enough to break down Zener
diode D 1.
When the battery becomes fully charged, Zener
diode Dl breaks down and completes a path to en-
ergize relay Kl . Current flows from terminal OV,
through relay K 1 (energizing K 1), Zener diode D 1,
resistor R4 to terminal +24VDC.
When relay Kl energizes, its contacts transfer
and break the circuit for relay K2. Relay K2 de-en-
ergizes and its contacts transfer.
The transferred contacts K2B (4 & 6) break the
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