Planning for inverter for elec. refrig, while driving

[PilgrimStill]

My dual fuel refrig in my 5th wheel doesn't keep things cool enough. I am going to replace it. Dry camping is a seldom done thing; we mostly travel, stopping in RV parks with elec. and water. I want to put a battery and inverter into my refrigerator swap out, so that the refrigerator will stay cold while we are on the road. I don't plan to charge the battery during the day. I'll recharge it in the evening, when connected to shore power. The refrigerator I am considering is the Avanti RA7316PST 2-Door Apartment Size. Supposedly, this draws 15 amps at startup. Will a 2000 Watt Continuous/4000 Watt Peak Power Inverter (Jupiter) connected to a deep cycle battery be sufficient? Any insight is much appreciated.

[azrving]

Did you notice that the installation instructions say this

"Allow 5 inches of space between the back and sides of the appliance, which allows the proper
air circulation to cool the compressor.

I installed THIS Whirlpool two years ago. It has a rear coil so the clearances can be much smaller. It pulls point .6 amps so the DC running amps are 6 to 7. I run it along with other items on a Xantrex Prowatt 2000 and it's 10.7 cu feet. It can accept an ice maker but I opted to make a freezer shelf out of plexiglass with a thin aluminum edge.

I dont recall but I think defrost pulls about 20 some amps DC and last 10 min or so and it's no big deal.


I dont see a defrost circuit in the Avanti wirig schematic but the owners manual says this.

" When
? For the most efficient operation and minimum energy consumption
, defrost the
appliance compartment when the frost on the appliance walls is excessive or ¼ inch thick.
There is no need to defrost the refrigerator, because ice depositing on the inner back wall is
defrosted automatically. Ice is depositing on the inner back wall during the compressor
operation; later on, when the compressor is not operating ice is defrosting and water drops
collect and drain through the outlet in the inner back wall into the drain pan situated above the
compressor, from where it evaporat
es.
•
How?
CAUTION
Do not use boiling water because it may damage the plastic parts. In addition, never
use a sharp or metallic instrument to remove frost as it may damage the cooling coils
and will void the warranty. We recommend using the plastic scraper.
•
Reset the thermostat to “
0” position and disconnect the power supply.
•
Remove the frozen food from the appliance and place it in a cooler to protect the food.
•
Leave the door open for a while so that you can easy scrape off the frost.
•
Use a plastic scraper
but be careful not to damage the inner surfaces of the freezer.
•
Wipe up the scraped frost and ice before it is completely defrosted.



It may be a manual defrost.

I dont recall exactly but I think I went 5 hours or so with mine shut off before the temps got lower than we like so I never bother shutting it off. No reason to as the solar more than covers it and battery charging. In your case if you have decent size wire in your vehicle (usually 12 gauge) you wont have any problem running it. If you want to overnight on your batteries I think you may need two 12 volts or go to 6's. During defrost it's a pretty good load load for one 12 volt so two may be better again if your vehicle is running it will probably be fine. My Whirlpool does a defrost at some interval but it also does a defrost each time I disconnect power and turn it back on so that cuts into any savings of shutting it off while traveling.

When you start the r&r consider the depth of where the front legs will sit as you may need some type of lumber to support the front. The frig will hang out of the hole about 4 inches so door can open.

Edit: I might also wonder that if the Avanti pulls 15 amps at start which is 150 amps DC that it might drop the voltage too low on a single battery.

[dons2346]

If you do from campground to campground, you do not need to worry about power to the refer. I have gone over 20 hours without power because of a bad transfer switch and the temps in the refer and freezer were still were within limits for food safety.

[Gdetrailer]

PilgrimStill wrote:
Awesome input! Thanks. I will do some research on all those suggestions. I get the inference that a PSW is preferable to a MSW. True?

Not all inverters have the same quality in engineering and parts and that includes PSW inverters.

PSW generally will provide a cleaner waveform that looks a lot closer to what your commercial utility provides and for SOME equipment it is better for.

However, not ALL equipment "needs" psw, in fact if it has a switching powersupply (like a computer or TV) there is zero reason to buy PSW because those supplies are designed to take pretty much any badly distorted waveform and keep ticking..

The problem starts when you buy the cheap stuff, even cheap PSW inverters may not work well, the reason for that is it takes more parts and engineering to properly form a perfect sinewave. More parts and engineering makes the inverter cost more.

MSW gets a bad rap because of the cheap imports like the HF stuff, not all MSW inverters are bad..

Really cheap MSW inverters can often make the induction motors run hotter than they would on PSW and some just simply cannot even start an induction motor.

There are high quality MSW inverters, you will pay more than even some of the low cost PSW inverters.

To get any inverter of sufficient quality that will be able to deal with the inductive startup kick of a fridge compressor you WILL want to put the money into a good one the first time..

Very few inverters publish the surge time, Tripplite is one of the very few that does.. Most do not and the reason for this is many of those inverters that surge current is milliseconds.. Inductive loads can have a startup surge of several seconds..

Induction motors can present a very large inductive voltage spike back INTO the inverter, cheap inverters (MSW AND INCLUDING LOW COST PSW) may not be able to handle these voltage spikes.

Sure, you can over buy on a cheap inverter like a 2000W to get around the short surge time but you are not going to be happy when that inverter fails at the wrong time due to it seeing the inductive voltage kick back.

It is your rig so do what you want.

[PilgrimStill]

Awesome input! Thanks. I will do some research on all those suggestions. I get the inference that a PSW is preferable to a MSW. True?

[theoldwizard1]

PilgrimStill wrote:
My dual fuel refrig in my 5th wheel doesn't keep things cool enough. I am going to replace it. Dry camping is a seldom done thing; we mostly travel, stopping in RV parks with elec. and water. I want to put a battery and inverter into my refrigerator swap out, so that the refrigerator will stay cold while we are on the road.

If you are on shore power overnight and you NEVER open the door to the refrigerator until you are plugged back into shore power and you are on the road for less than 10 hours per day, you really do not need an inverter.

Now that I said it, I would get a name brand 2000/4000 pure sine wave inverter and TWO 6V golf cart batteries. Samlex makes a nice inverter/charger. I like it because of it simple wiring. Get rid of your old converter (keep the DC distribution panel and wire it directly to you house battery bank). The shore power connects to the inverter/charger and there is a built in transfer switch so you use shore power when connected and inverter power when not connect WITHOUT OUT HAVING ANYTHING TO SWITCH ! It will also accommodate a generator and input from solar panels.

You really should have your house battery bank hooked to your tow vehicle battery via a DC-DC charge. Read this regarding charging a house battery from a vehicle alternator.

DC-DC battery charging

EDIT : Samlex 1200W/3600W inverter/charger (no separate generator input; plug the generator into the shore power plug)

[Gdetrailer]

Ivylog wrote:
I'm powering a 21 cuft Whirlpool with a 1000W PSW inverter. While running it only draws 8 amps DC...96 Watts. I can boondock 24 hours with two batteries before needing to recharge. You do not need that big an inverter and one battery is plenty for 12 hours...you can go 12 hours without it running if you keep the door closed.

The inverter the OP specified is a Harbor Freight MSW inverter, it WILL take most if not all of that cheap import inverter and may even smoke it in the process.

With your 1000 PSW inverter, it may have a bit more quality parts in it and may be able to handle the inductive kick of the compressor.

most cheap Chinese import MSW inverters will let out the smoke packets when treated to heavy induction motor kicks..

When it comes to cheap stuff, it is a go big or go home thing, super size it to make sure you have enough..

But personally, in cases like this, I like to go with heavy duty quality type overkill like the Tripplite I mentioned..

[Ivylog]

I'm powering a 21 cuft Whirlpool with a 1000W PSW inverter. While running it only draws 8 amps DC...96 Watts. I can boondock 24 hours with two batteries before needing to recharge. You do not need that big an inverter and one battery is plenty for 12 hours...you can go 12 hours without it running if you keep the door closed.

[2oldman]

PilgrimStill wrote:
..connected to a deep cycle battery be sufficient?

One battery? Not sure that will handle the startup surge without a significant voltage drop.

[Gdetrailer]

15A startup surge is a bit on the high side, most home fridges use the same compressor which is typically 1.1A-1.2A running draw, I measured the surge of my 10 cu ft fridge I used in my TT at about 10A-11A startup surge with .9A run current.

With that said, I would highly recommend not skimping and using a cheapo Harbor Freight inverter..

Instead, spend a bit more and get a BETTER built inverter designed from the ground up to handle the startup surge of a heavy inductive load like a fridge compressor.

I highly recommend a Tripplite PV1250FC which is a industrial MSW inverter built like a tank which is the inverter I used in my conversion.

Right now you can get it for about $235 through Amazon (ship and sold by Amazon) HERE. That is not all that more money than the cheapo HF inverter at $169...

1250W continuous output with an honest 1875W surge for up to ONE HR and 2500W surge for TEN SECONDS!!! No other inverter out there can match what this Tripplite offers.

"Harness your vehicle's battery to efficiently power office equipment on the road or power tools at a work site. Continuously supplies up to 1250 watts of 120V AC power to 2 AC outlets from any 12V battery or automotive DC source. Frequency control locks AC output at 60Hz for operating stability of motor loads. Includes a set of high current DC input terminals for simple permanent installation. Highly reliable large transformer design specializes in powering motors and other inductive loads with high-current startup needs. PowerVerter Plus Inverters acmodate "peak surge" demands by delivering more output power than their continuous rating. Compare the "Continuous" and "Peak Surge" wattage ratings and you'll find PowerVerter Plus Inverters supply up to double their output to easily handle equipment start up and motor cycling requirements. A DoubleBoost feature provides up to 200% of the continuous output for up to 10 seconds providing the extra power needed to cold start heavy-duty tools and equipment. An OverPower feature delivers up to 150% of the continuous output for up to 1 hour. Primary InformationPower Device Type : Power converter Power Device / Form Factor : External Voltage Provided : AC 120 V +/- 5% Voltage Required : 12 V Power Provided : 1.25 kW Input Connector(s) : 2 Output Connector(s) : 2 x power NEMA 5-15 Enclosure Color : Black Width : 8.7 Inch Depth : 9 Inch Height : 7 Inch UNSPSC CodeUNSPSC Code : 39121006 "

It is big and heavy weighing in at 24 lbs..





Also is about 90%+ efficient, the HF inverter is something like only 82%-87% efficient meaning you will get more run time from your batteries..

And even better the PV1250 also has a power save feature called "load sense" which allows the inverter to detect if there is a AC load or not ans the inverter will turn on/off for the AC load demand! Saves a lot of battery capacity!

I would highly recommend that you use very heavy gauge wire, I used 1/0 on mine, fused at 200A and the fuse needs located within 18" of the battery.. You NEED to locate the inverter CLOSE as possible to the batteries, mine is only three feet from the batteries for a total of 6ft of 1/0 wire..

I would recommend getting Extra flexible 1/0 wire, you will need to order this since Home Depot and Lowes only stocks building wire which is NOT real flexible. Welding wire can be used which is extra flexible but not cheap for this size..

There are some mail order outfits which do sell at good pricing..

1/0 Entertainment/stage lighting cable for $2.35 HERE which is a deal compared to 1/0 welding cable or even building wire..

Then you run normal Romex wire from the inverter to the fridge for the 120V..

You NEED to consider some GOOD batteries, I used a pair of 6V GC batteries wired in series to get 12V for my setup, gives me about 20hr-24hrs without needing to recharge and since we run light on other battery draws it works great for us.

Sam's club or Costco is a great source for 6V GC batteries..

[Lwiddis]

“My dual fuel refrig in my 5th wheel doesn't keep things cool enough.”

Why not avoid all this and repair your current fridge or get a new RV fridge? RV fridges work well.

[time2roll]

2000 watt rated inverter should start anything with a regular plug. I recommend sine wave for most items... especially a motor.

I think you could easily use the existing battery in your trailer for this purpose. Small charge on the road is already set up and recharge at the destination would be automatic.