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Ivylog · 08-25-2020, 05:28 AM

Finally some good info: “ On my 10 cu ft Magic Chef (2017 model HVDR1040B) I measured a start surge at the batteries of about 100 amps for about 2 seconds. At 12.6VDC (batteries just off the charger) the wattage was 1260 watts.”
A 1000W inverter can handle a 26% overload/surge, a 500-600W can NOT handle a 100+% surge. A Samsung refrigerator does not have this high startup surge because of the DC compressor they use... will work well on a 600W MSW inverter.

Ice maker: my 21 cuft goes from DC 8 amps to 32 (400W) when the ice maker harvests the ice. Took me awhile to figure out why the EMS (when on poor power 108-9 V) who shut the rig down. Turning the ice maker off solved the problem.

My “new” rig came with a residential refrigerator and a 3000W PSW inverter. Yes, it’s overkill for a refrigerator that needs 100W when running, but to add a 1000W inverter to save a few amps, even while dry camping, is not worth it for me. I could turn the inverter off at night as the temperature only increases 4-5 degrees overnight, but I have 880 AH of batteries and can charge 200+ amps on generator power in the morning when making coffee.

Sbrownstein · 08-25-2020, 06:02 AM

Samsung refrigerators do not use DC compressors. Just like a whole bunch of Energy Star reefers, Samsung uses a variable frequency inverter built into the unit to power the compressor. That means they convert the AC to DC and then send the DC through the inverter that makes AC to run the compressor at variable speed. Same for Frigidaire and a lot of modern high end reefers. BTW this is the same as "inverter" A/C split air conditioning systems as well.

Ivylog · 08-25-2020, 12:07 PM

Strange ^^^, Samsung calls their compressors “BLDC (brushless direct current) inverter compressors”. Guess I should only use dc instead of DC.

Sbrownstein · 08-25-2020, 12:35 PM

Quote:

Originally Posted by Ivylog

Strange ^^^, Samsung calls their compressors “BLDC (brushless direct current) inverter compressors”. Guess I should only use dc instead of DC.

"Brushless DC electric motor (BLDC motors, BL motors) also known as electronically commutated motors. Rigid BLDC inverter compressor is powered by DC electricity via an inverter or switching power supply, which produces an AC electric current to drive each phase of the motor via a closed loop controller."

Sort like a big stepper motor. Inverter runs polarity and voltage to motor coils to make it move and vary speed while managing torque. Like square wave drive. Definitely not a DC motor. Interesting that in one sentence they say DC electricity and AC electric current.

To make it even more confusing, most are referred to as 3 phase motors.

jcussen · 08-25-2020, 03:54 PM

Re my question on venting a residential fridge in the motorhome, think I will go with the vented theory. I have a free standing fridge in my garage, and when I put a couple of warm 6 packs in it, the compressor runs for a while and the condenser tubing at the back gets quite warm. Of course it dissipates in the garage eventually. The fridge will be sealed in its compartment with only condenser surfaces exposed to the vented compartment, so outside temps should not affect interior temps in the motorhome. Gets pretty warm in south texas, so every bit of heat you can remove from the coach, will make it easier on the roof airs.

FIRE UP · 08-26-2020, 06:34 PM

OK Gang, OP here.
Well, I just got off the phone with the technical staff at MCA appliance, the owners of Magic Chef. I had TWO specific questions for that tech:

1. What is the START UP AMPERAGE DRAW on that fridge?

2. What is the RUNNING AMPERAGE DRAW on that fridge?

The answer for #1 is: 1.4 amps

The answer for #2 is: 1.3 amps.

He re-itterated both answers saying these are very efficient fridges. the model number of ours is: HDMR1000ST The last two letters represent the color. Ours is *Platinum Stainless Steel*.

So, as little as I know about PSW Inverters, at this point in time, I'm pretty darn sure that a 1000 watt PSW inverter WILL do for my situation.

Now, keep in mind folks, the primary goal of this mission, should I decide to accept it (old Mission Impossible cliché) is for this potential new inverter to simply handle keeping that fridge, at an already cold status, in between or, traveling between I should say, full hookup campgrounds/RV parks.

I know, I know, some folks suggest that I don't worry about keeping it cold during travel time. They say it will REMAIN cold for hours, almost days, between it being powered up by shore power. Well, I don't have enough experience with this situation to argue, one way or the other. All I know is, a lot of our trips/traveling, is in the summer time. And, that means we're galivanting around this country, IN HOT WEATHER!

That means it's gonna be WARM inside that coach since, I don't run the gen and house A/C all that often. It also means THE OUTSIDE OF THE COACH IS GONNA GET HOT TOO!!!!!!!!!!! What all that means is, due to close wall proximity to the sides and back of that newly installed residential fridge, radiant heat is gonna try and heat that fridge up while we're motoring down the road.

I didn't go through all the change from an RV fridge to a residential fridge and any fitment work etc. just to be lazy and let food get even a bit warmer, moving from camp to camp. I'm real close to pushing the button on a 1000 watt PSW inverter that a great member on here has lead me to. I'm gonna get a remote for it too so that I can control it due to that inverter's gonna be mounted in a space that's inconspicuous.

I will still consider a *transfer switch* also. However, and this may be rather important, concerning both an inverter and or, a transfer switch.

In the owners manual of that particular fridge, it states on page 8:

" If the unit is unplugged, has lost power, or is turned off, you must wait 3-5 minutes before re-starting the unit. If you attempt to restart this unit before the time delay, the refrigerator-freezer will not start".

Sooooo, not sure about some of this stuff. My plan was/is, until I procure a transfer switch, un plug the fridge from the standard receptacle behind the fridge and, plug it into the inverter. Then, go and turn the inverter ON. But, I might have to remind myself to delay that 3-5 minutes BEFORE I actually turn that inverter ON.

But, if I procure a transfer switch, THEN WHAT? Meaning, what about the requirement for the time delay, if a transfer switch is used? I guess it could be that, I'd still wire things up for the use of a transfer switch but, just not turn the inverter on 'till the time delay has passed. Hmmmm.
Scott

TJHUB · 08-26-2020, 06:40 PM

Scott:

I used my Kill A Watt to measure my same fridge as yours, and start up and running was 66 watts! My mini fridge in my lower compartment was 380 watts at start up, and 312 watts running. I'm thinking the 1,000 watt PSW inverter I have coming Friday will be way more than adequate.

Both fridges are off for tonight. I plan to test start up tomorrow and time to cool down for both.

**CountryFit** · 08-26-2020, 07:40 PM

Quote:

Originally Posted by FIRE UP

" If the unit is unplugged, has lost power, or is turned off, you must wait 3-5 minutes before re-starting the unit. If you attempt to restart this unit before the time delay, the refrigerator-freezer will not start".

This tells you that it has a built-in delay timer to protect the compressor from load-start burn-out. You will not see it running within 3-5 minutes after you plug it in or power on.

twinboat · 08-27-2020, 05:46 AM

Just plug it into the inverter forever.

My 8 c.f. boat fridge has run on PSW inverter power for 12 years now. Happy and cold.

Ivylog · 08-27-2020, 06:32 AM

The only way the start and run amps can be within 0.1 AC amps is if it has a Samsung BLDC compressor that doesn’t have a 3 minute wait time...1.4 A start amps is BS. Takes a really good meter to measure start amps because it doesn’t last very long. As I’ve posted 3 times, you need a 1000W PSW inverter for a non Samsung refrigerator.

A transfer switch works fast enough that the compressor’s motor doesn’t even know it lost power. Now electronics (TV & Sat receiver) may turn off when switching to inverter power... happens to me about 30% of the time when I turn the generator off. SIDE NOTE: I may try turning the 50A circuit breaker off instead of the slower loss of power shutting the generator off as it takes 10 minutes for the Sat receiver to reboot.

tripntx · 08-27-2020, 06:49 AM

The Power Dynamics 1,000 watt PSW inverter we installed is powering our fridge, 43" QLed TV, Motorized TV lift, sound bar, and subwoofer. It has an internal transfer switch. It switches from shore power / genny power to battery power extremely quick, and the power swap is not seen nor heard on TV or fridge. We have not had a single issue with freezer not coming on when it is swapping between power sources.

**CountryFit** · 08-27-2020, 10:00 AM

Quote:

Originally Posted by Ivylog

The only way the start and run amps can be within 0.1 AC amps is if it has a Samsung BLDC compressor that doesn’t have a 3 minute wait time...1.4 A start amps is BS. Takes a really good meter to measure start amps because it doesn’t last very long. As I’ve posted 3 times, you need a 1000W PSW inverter for a non Samsung refrigerator.

A transfer switch works fast enough that the compressor’s motor doesn’t even know it lost power. Now electronics (TV & Sat receiver) may turn off when switching to inverter power... happens to me about 30% of the time when I turn the generator off. SIDE NOTE: I may try turning the 50A circuit breaker off instead of the slower loss of power shutting the generator off as it takes 10 minutes for the Sat receiver to reboot.

Agreed. MC doesn't have a technology to compress the start up current to just 0.1a above running current. Go with the number on the compressor label.

The quality of the ATS plays a role. Our Magnum inverter internal ATS does a good job - all electronic devices are working seemlessly (microwave clock doesn't get reset) when power sources swap.

FIRE UP · 08-27-2020, 01:13 PM

Ok,
I called MCA again and, talked with a different tech. *She* looked up the specs on my model number, based on what the factory sends her and, she confirmed, this model fridge is rated at 140 watts. And that the start up amperage is, 1.4A and the running amps are, 1.3. I told her about the *LRA* sticker that's on the compressor that states: LRA 6.5A and she was not too keen on what that is. So, she's gonna find out more.

She called me back, very shortly after we hung up in the first place and, tried to explain what the *LRA* is. Not sure she's all that adept at this kind of stuff. But, again, she assures this fridge is 1.4A startup and 1.3 running. She also stated there's a spec sticker on it someplace that also will tell the startup amps and running amps. I'm gonna have to pull it to find that sticker. Stay tuned.
Scott

P.s. Ivylog, if you read my post, I AM ABOUT TO BUY A 1000 WATT PSW inverter. I'm awaiting info from another member who's in the same predicament as I am, before I commit.
Scott

P.S. II
By the way, I looked up LRA and here's what I found. In reality, it has nothing to do with the regular startup and running amps. At least that's what this link states.
Scott

https://www.real-world-refrigeration...eration-1.html

miatawnt2b · 08-27-2020, 10:28 PM

Does your magic chef fridge have the condenser coil exposed on the bottom or back of the unit? If so, you can wrap the outside of your fridge with either foam board insulation or a hot water heater blanket. This will help keep it cool inside when you're unpowered and it's hot in the coach.
However, if your condenser is not exposed, it's covered by the side exterior case (which blows my mind because it's highly inefficient) but you should not wrap this style of fridge.