Inverter Question

Hopefully the 3.9 is startup amps as my 21cu ft draws 1 amp AC/8 amps DC while running. Start up amps can be four or five times running amps. Several people have reported running their Samsungs on 500 W inverters.

Ivylog wrote:
The reason the Samsung do well on modified sine wave power is because they have DC compressors... not AC. They are popular units to replace the NoCold 1200 because they are much the same size although they are 6 inches taller. They will also come through the front door of many motorhomes as they are counter depth units.

And only draw 3.9 amps.

The reason the Samsung do well on modified sine wave power is because they have DC compressors... not AC. They are popular units to replace the NoCold 1200 because they are much the same size although they are 6 inches taller. They will also come through the front door of many motorhomes as they are counter depth units.

I don't know what brand fridge you have but Samsung says our RF197 will run okay on a modified sine wave inverter. We did that for a couple of years with a 1000 watt one that came with the fiver without any problems. I just wasn't comfortable with it so I changed to a 1000 watt pure sine wave, upgraded the wiring from the batteries to the inverter to a heavier and recommended gauge, added a circuit breaker between the batteries and the inverter and installed a transfer switch that automatically changes from battery to shore power and vice versa. May have been totally unnecessary but I feel better about it.

joanw2947 wrote:
It would have been nice if the manufacturer had put a pure sine wave inverter in to begin with but that would have cost a few extra dollars.

Yeah.. they wouldn't ever want to do that.

Thanks so much for taking your time to reply and help me out. I wanted to put the question out there in case there were red flags that I wasn't thinking about. There is always such knowledgeable advise on this board. I am leaning toward replacing the inverter just in case it is a little easier on the fridge. I'd have more options in case I need to run something else also. It would have been nice if the manufacturer had put a pure sine wave inverter in to begin with but that would have cost a few extra dollars. Thanks again for the replies. They were very helpful.

"Most AC motors will run on MSW inverters with an efficiency reduction of about 20% due to the harmonic content." If you do not boondock... hooked to shore power most of the time, keep what you have, but I would add a transfer switch so it is running on shore power when you are hooked up.

I went with a 1000W PSW inverter (500W would do it) because we do boondock often. Our 21 cuft refer runs at 100W and takes 4-5 times that to start. The extra power is used to power a Sat dish, DVR/receiver, and TV so it will record saved programs.

If you decide to do something, I would probably just add a PSW inverter to increase your power to 1500-2000W.

Our 1500 watt pure sine wave (PSW) inverter is only used to power the residential fridge when not connected to shore power. It's been absolutely trouble-free.

When in transit, the 5th wheel batteries are charged through the umbilical between the truck and 5th wheel by the truck's batteries and alternator via the +12VDC source (pin #4) in the truck's 7-pin Pollak receptacle, so the inverter and fridge can run indefinitely without discharging the 5th wheel batteries.

Rusty

Since you already HAVE that MSW inverter and evidently have been running that residential fridge on it which surprises me, as I'd expect such a unit to have a higher starting draw than a mere 1,000 watt inverter could deliver, but evidently I'm wrong about that in this case, either because your fridge doesn't draw as much as I'd expect or because your inverter has a higher surge capacity than I'd expect.

In any case, if you've been running it that way, and nothing bad has happened, I wouldn't worry about it. There are two parts to any fridge, the compressor or heating element in the case of an absorption RV fridge, and whatever controls said fridge has associated with the thermostat. Both the motor and the heating element should work without issue on MSW power as well as PSW. It is the controls that might have an issue, and only some of those would have trouble. Either way, trouble, if it were to occur, ought to happen fairly quickly, that is, within minutes, or at most a few hours, of beginning operation. If the fridge has a fairly simple thermostat to turn the compressor on and off, this should be no issue. It is pretty much only if the fridge is a fancy, multi-function unit that it ought to be an issue.

Let's put it this way: With MSW, most things will run. With PSW, all things will run.