I have a Dometic RM4223 fridge and a WFCO WF-8725P power center. With shore power plugged in and the fridge on 12v the pc cooling fan runs continually and after an hour or so the 20amp fuse for the fridge blows. If I unplug the shore power everything is ok, fridge keeps cooling of the onboard battery. It also runs ok on LP and 120v. I like to run the fridge on 12v even when on shore power because it does a better job of cooling. I have checked most of the wiring that I can get to without pulling the power center out and opening it up. Any suggestions?
Brad, the 8725 is a 25amp converter. Your fridge, running on 12vdc will pull over 20..So you have no extra capacity for much else that uses 12vdc, like your batteries.
That poor 8725 is running wide open all the time..Not good for it.
I would not recommend running on 12 vdc even if you had a converter that put out over 45.
I am surprised that your fridge is more efficient on 12vdc because the 12vdc heating element is lower in wattage than your 120vac heating element.
Read below from the RM 4223 manual.
1. AC/LP/DC refers are NOT to be run on DC only when camped even tho the owners manual does not state this. The DC mode is for IN TRANSIT operation only so the chassis alterantor can supply the needed voltage/amps to run the refer. NOTE that on DC there is NO tstat controlled operation. That is because the 12 volt DC element is a "maintainer" of cold, NOT a cold drop element.
2. The 12 volt element pulls 10.5 amps dc current
3. The refer IF connected to use the 12 volt option is supposed to be connected direct to the battery and NOT thru a Power Converter or the coach 12 volt fuse panel system. This is also from the installation manual
To prevent the refrigerator from being left on and
draining the battery when the vehicle's engine is not
running and charging the battery, it is recommended
that an automatic cutout relay be installed between
the battery and the refrigerator toggle switch so that
the refrigerator will not draw current when the
vehicle ignition is switched off. Alternatively, a suitable
plug and receptacle should be installed in the
12V supply line so that the refrigerator can be disconnected
from the supply, as necessary
In the case of the RM4223, the refrigerator works continuously
on DC operation (no thermostat control).
11. 12 VOLT DC CONNECTION
The 125 watt heating element operates the cooling unit
when the refrigerator is connected to the battery of the
vehicle. It has a current rating of about 10.5 amps; therefore,
the wiring from the battery to the refrigerator must
be of heavy enough gauge to carry this load satisfactorily
without undue voltage drop. To ensure this, the minimum
size of wire to be used is 14 A.W.G. The terminal
block for connecting the 12V supply cable to the battery
is positioned at the lower lefthand corner of the rear side
(G, FIG. 8). From this terminal, the connection to the
battery should be made using ring-type clamps with
tightening bolts to ensure good contact with the battery
terminals. Polarity is not important, therefore it does not
matter which wire leads to which battery terminal.
DO NOT connect lights or any other electrical components
to the same circuit that is used by the refrigerator