WFCO WF-8740P - Manual (Page 3)

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Converter Operation Modes
All WFCO power converters are automatic three-stage switching
power supplies. The converter senses which mode it needs to be in by
checking the RV system voltage.
The three modes/stages of operation include:
Absorption mode/Normal operation
Nominal battery charge and supplies power to appliances
Bulk mode/Charge mode
Fast battery charge and supplies power to appliances
Float mode/Trickle charge
Trickle battery charge during storage
Absorption Mode: During this mode, the converter output is in the
13.6 Vdc range. This is the normal operation mode. This mode
provides the 12 Vdc and current required by the 12 Vdc RV appliances,
as well as slow charging the battery.
Bulk Mode: In this mode, the output voltage of the converter will
switch to 14.4 Vdc for a maximum of four hours. If the converter
cycles between “Absorption and Bulk mode,” there could be a
shorted battery cell or other issues.
Float Mode: In this mode, the converter is charging the battery with
a trickle voltage of 13.2 Vdc. When the converter senses a demand
(by turning on lights), the converter automatically returns to the
“Absorption mode”.
(Figure. 3)
ATC style
M A IN
B R E A K E R
OFF
ON
WF-8735
“Littelfuse “ Type 257 fuse ®
Troubleshooting
MODEL NUMBER
FUSE
F1
R1
LED1
F2 R1
LED2
F3 R1
LED3
F4
R1
LED4
F5
R1
LED5
F6 R1
LED6
REVERSE BATTERY
PROTECTION FUSE
FUSE
Before checking the converter output voltage, it is necessary to disconnect
the battery cables at the battery (as shown below). Make sure the converter
is plugged into AC source (105-132 Volts). Check the converter output
voltage at the battery with a voltmeter. Place the probes on the disconnected
battery cables; place the Positive (red) meter probe on the + positive red
battery wire and place the Negative (black) meter probe on the -Negative
black wire on the battery cable. Be sure you have good connections at the
cables. If the voltage reads 13.6 Vdc (+/-.2) with no load, the converter is
functioning properly.
If the reverse polarity fuses are blown, it means the RV battery was
accidentally connected in reverse, either at the battery or at the converter.
Reconnect properly, then replace the fuse with the same type and amp rating
as the original “Littelfuse ” Type 257 automotive-style fuse.
IMPORTANT: These fuses protect the converter from damage in the event
thatthe RV battery is accidentally connected in reverse. A reversed battery
connection, even for a second, is the reason that these fuses will blow.
The fuse rating that the manufacturer suggests for the output fuses will be
marked on the unit. Replace only with same type and rating.
If the converter output voltage at the battery reads in the 0.0 Vdc range,
or the battery is not charging, check for:
- an open inline fuse in the battery wire (if installed by OEM)
- an open wire between the converter and the RV battery
- loose ground connection
- improper torques
If the converter fuses and AC voltage are good, but the converter output still
reads zero volts, the converter is not functioning properly.
Contact Cheng USA, Inc. Tech Support at 1 (877) 294-8997.
®