Douglas (ScubaGuy) asked me to post this about their JC-Refrigeration Conversion. This converted their LP refrigerator to a 120v compressor driven refrigerator in their 1997 40' U320.
They hooked up a Kill-a-Watt meter to monitor actual power consumption. It has been in place for about 25 days. As of last night the second test has recorded 12.83 KWh used over the past 198 hours ( a little over 8 days). They are running the refrigerator at level 5 to achieve the measured interior refrigerator and freezer temperatures they want.
12.83 KWh for 198 hours is an average of 64.8 watts per hour. 1555 watts per day. For reference our 19 cu ft Samsung averages about 70 watts per hour.
What does that mean in AmpHrs?
If you have an older inverter that is about 88% efficient and your batteries are at 12.5 volts that is about 5.9 amps average draw on your batteries or 141 amp hrs per day.
Roger you are saying with no load my old freedom 25 drew 7 amps being on?
I don't know about all of the different inverter/chargers they used but the Prosine 2500 in my 2001 U320 drew about 7 amps when it was on inverter and no 120 v loads. That's what my meter said.
Documentation from that time frame says
No load current draw, inverter idle 60W
That is about 5 amps. The transfer switch at the foot of the bed is 120v as I recall and there ma have been some other hidden 120v loads (no icemaker was in use). The igniter on the stove, maybe the sat dish, maybe a TV. Not the Bose though, the base speaker alone was several amps at 120v.
My sw2812 uses 30 Watts. No load
Xantrex 3012 less than 3amps @12 volt. tuned on at idle.
The newer inverters use much less power at idle. My Victron 3000VA MultiPlus (94% efficiency) uses 20 watts at standby. That is just over 1 amp. The Magnum MS 2812 (88% efficiency) uses more than 2 amps just to be on. The Xantrex SW 3012 (90% efficiency) uses 3 amps just to be on. Not sure which one you actually have.
Many older coaches have the original inverters that were much less efficient and used much more power just to be on. My old Prosine used almost 25% more power to be on than our Samsung residential refrigerator uses. A good reason to consider an update to your older inverter/charger.
This thread is not about how efficient which inverters are or how much standby power they use.
If you are considering a 120v or 12v refrigerator conversion you need to know how much power the converted refrigerator will use. Once you know the power consumption then you can consider the best way to supply that power.
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is there a difference in power ratings to go with the different no load consumption?
This is easy to look up. Maximum power output does not seem to be related to no load standby power consumption except for the Victron inverters.
The Victron inverters uses less standby power for the 2000VA (11 watts) compared to the 3000VA (20 watts).
The Xantrex inverters appear to have the same standby power use for the 2012 or 3012. (37 watts)
The Magnum inverters appear to have the same standby power use for the 2012 or 2812. (25 watts)
Let's stay on topic. None of this inverter discussion has anything to do with how much power the refrigerator conversion uses.
The Victron takes 20 Watts no load. 2400 watt continuous. 50 amp transfer 40 pound machine
Sw2812 uses 30 Watts. 3000 watt continuous. 60 amp transfer. 52 pound machine
If that's ok that I post that on this thread? If not let me know.