Need to upgrade.

Lefty Wright · August 2008

I'm pretty much a minimalist, 3 seldom used 20W circline fixures, 13W CFL's (seldom more than one on at a time) and no refigeration.
I've got 4 KC120's and will be replacing my golfcart batteries with something better.

But I want a refigerator!

I figure a 1000W exeltech sinewave inverter would run a reefer just fine. But I don't like the 20W idle current. That would mean one hour of sun just to satisfy the inverter's idle current each day.

How big an inverter does it take to run a modern energy star reefer?

I just need a small reefer but have found no energy star units in small sizes. Is it really worth it to convert a small freezer?

Besides the reefer I don't think I ever dissipate more than 40W at any one time. And winter storms don't bother me because It's cold enough from November to June to not need artificial refigeration.

niel · August 2008

Re: Need to upgrade.

my old roper nonenergy star 20cu in(sorry that's cubic feet and i'm leaving my error here cause that's a lulu;)) refridgerator i measured with a kill-a-watt meter at using a total of 1.5kwh a day. energy star could be as low as about 1kwh per day. may be higher during summer months if no ac and even moreso if you go in and out of it alot. the math is somewhat variable due to circumstances, but you can get a ballpark idea from it as to what you will need.
i think a 600w sinewave may run it as the surge current is the little monkey wrench that necessitites larger inverters. others can give more factual data on the startup needs better than i and the extra umph couldn't hurt even if only for expansion possibilities.

n3qik · August 2008

Re: Need to upgrade.

Some food for thought, I have a Magic Chef 4.0 Cu. Ft. Compact Two Door Refrigerator. Currently running it on a 1000W Xantex MSW inverter. The only problem is the inverter shuts down/faults at 15 volts. Once it goes into fault mode, it will not restart, needs a manual restart.

To follow up on niel's post, I also have a 600W pure sine wave inverter with softstart. It will not run the this refrigerator.

niel · August 2008

Re: Need to upgrade.

15v? is that due to charging your batteries that high or is that a typo meaning a much lower voltage that the batteries draw down to under load and it's kicking it off?

crewzer · August 2008

Re: Need to upgrade.

Link to previous (and very popular) thread on freezer-ro-fridge conversion: http://forum.solar-electric.com/showthread.php?t=9

HTH,
Jim / crewzer

n3qik · August 2008

Re: Need to upgrade.

niel wrote: »

15v? is that due to charging your batteries that high or is that a typo meaning a much lower voltage that the batteries draw down to under load and it's kicking it off?

15 VDC is correct. The Optima Yellow Top's can be charged from 13.8-15.6v as long as they are below 125 F. I set the C60 controller bulk to 14.5vdc, but on partly cloudy days, as the sun goes in/out the voltage will spike to 15-15.3v.

SolarJohn · August 2008

Re: Need to upgrade.

Lefty,

The exeltech 1100 (with the X2 option) uses only 10-watts of idle current. IMHO this is better than using an inverter that "sleeps". My exeltech 1100 watt inverter easily runs my big Sears (energy-star-rated) refrigerator with no start-up problems.

I use an automatic transfer switch for my two power sources (batteries and grid), and I have had no problems so far. I was concerned that when the compressor motor was under load, and the power source would switch, that it might cause problems, but it has not. The exeltech can handle whatever surges might be occuring. I wouldn't want to try this with a 600-watt inverter though.

Others may have different opinions, but I consider the 10-watts of overhead as the price I have to pay for the reliable and safe operation of my loads.

John

niel · August 2008

Re: Need to upgrade.

crewzer,
you had a 600w exeltech did you not? without my rummaging through the old fridge posts, did you ever try running a fridge with it?
general,
it has been noted that many smaller fridges do draw as much or more than their larger counterparts do. the constant draw from mine is about 140w. i also have one of those real small fridges (danby and guessing cuft to be about 1.5, but i don't remember) that i never bothered to check for its draw. i will place my kill-a-watt meter on it now and see what that draw looks like. in fact i'll see what it does over a 24hr period and update this post with my results.
initial kickon i saw well over 400w and this meter does not hold the peak. it settled to 90w.
after a day i looked and the total is 310wh. far less than i had expected. i guess it doesn't run as much as indicated by that 310wh 1 day total in light of the 90w draw i saw on it.

Lefty Wright · August 2008

Re: Need to upgrade.

Checked out the link to the previous reefer postings and Jay and Wayne have done excellent work.

My only question now is the exeltech 1100 with option X2. I can find nothing on the exeltech site about it except that it lowers the idle power consumption to 10W.

Is this option still available? NAWS sells the inverter but says nothing about option X2.

icarus · August 2008

Re: Need to upgrade.

Lefty,

I don't know what your living situation is (full time off grid or what) but if you are not living full time off grid, you might consider a good Propane fridge. They can be had used from RV's and if you add insulation and a low draw fan, they will run a long time on a gallon of propane. My 8 cu ft Dometic burn 1500 BTU/hour. They run ~ 50% of the time in the summer, perhaps 25% in the winter. You can do the math, but in rough numbers that is ~ 50 hours per gallon at 100% burn time.

In the long term, more panels/batteries and a energy star 120vac fridge may make sense if you are living off grid full time.

Tonty

Lefty Wright · August 2008

Re: Need to upgrade.

Tronty, I live in the largest off grid community in California. It's 3½ square miles with 800 property owners. Only about 50 full time residents though.

Most folks do have propane refigeration but the cost of propane has really gone up in my area. It was costing my nearest neighbor about $20/week to run his propane refer so he shut it down and now uses a freezer.

Not a freezer conversion but an unmodified freezer. I think he makes ice and uses that to store things he doesn't want frozen.

Any one know about this X2 option for the Exeltech 1100? My only experience with inverters has been with the cheap msw inverters.

BB. · August 2008

Re: Need to upgrade.

It probably would not hurt to call the Exceltech and ask about the X2 option--And post the answer here... There is nothing on the Exceltech website other than to mention the option.

I also did not find any answers elsewhere either.

-Bill

icarus · August 2008

Re: Need to upgrade.

Lefty,

$20 a week is indeed excessive, that would be 5 gallons @ $4 per gal. As I said, my usage is ~1 gal per week, that at about 80f. One key that is often over looked is venting the coils. An ammonia absorption fridge works best when it has a very well designed cooling draft over the coils. Most people who use Rv fridges just tuck them up to the wall and forget them. A small muffin fan over the coils with a proper exhaust, coupled with intake air low behind the fridge, baffled such that the (cooler) air coming in is forced over the coils and then vents to free air on top. Doing this can increase the efficiency of a fridge ~50%. Adding insulation to the outside of the cabinet can add another 25-50% depending on how much you can add. I have my cabinets insulated with 2" of foam board.

Good luck,

Tony,

PS, I like my new handle,,Tonty! I think I will keep it! Aren't typos great!

westbranch · August 2008

Re: Need to upgrade.

Tronty....he he he, good one, sounds like you need a horse next...;)

Say do you have a pic you could post of your fan setup? I could probably use it at my cabin.

ej

icarus · August 2008

Re: Need to upgrade.

Eric,

I don't have a picture, but it is pretty simple.

I have a snap thermostat that is adjustable on switch, 20f differential, I have it set to come on at ~120f then off at 100f. This is wire tied to the coldest end of the perk tube. (Farthest from the flame) This is the last spot before it goes into condenser (finned coils). (I couldn't put it on the fins since I couldn't mount it easily). The fan is mounted on a bracket on the fridge over the evaporator coils, or in on case on the wall behind. The fan is a small 4 watt muffin fan.

The important thing to remember about absorption fridges, is that they work due to natural convection. All the fan does is help that convection along. You also need a source of cool air at the rear of the fridge down low, ideally cooler outside air. The fan then draws this cooler air up and over the coils. A baffle (made out of wood, or tin, or formica or such, or a built in cabinet, forces the air up instead of allowing it to leak out the sides of the fridge if this makes sense.

At the top of the fridge, if you live in a warm climate, you can baffle the fan forced air out a vent (out of the building). In cooler climates, a baffle (or cabinet) extending above the fridge can be used to direct the air out into the room above the fridge. (I close my low intake vents in the winter to keep the cold air out, and let the fridge draw room air from the cabinets)

If none of this doesn't make sense, let me know and I will try to clarify. If I have to remove the fridge someday, I'll take a picture to show how it works.

In my experience, the best Absorption Fridge information is found here: http://www.rvmobile.com/

They have a very good technical support section, as well a user forum. There is also a great section on proper venting. http://www.rvmobile.com/Tech/Trouble/vent.htm

Tony AKA Tonty!

PS. It goes without saying, but always make sure that the flue of any LP fridge is vented out the building. Venting it out from behind the fridge does two things. The first of course is that it gets any C0 or C02 out of the house, and secondly, it gets the combustion heat away from the cabinet and the coils.

Lefty Wright · August 2008

Re: Need to upgrade.

I called Exeltech about the X2 otion for the 1100 sinewave inverter.

The option costs $14 and is mainly a ferite core or loop that somehow cuts the idle power to 10W for the 20W normal loss.

With this option there is no sleep mode. The inverter is on all the time.

Interesting stuff about propane refers. It's quite possible my neighbor's frige has not had it's coils cleaned in it's lifetime. He has excess PV capacity and seems happy using his AC freezer.

BB. · August 2008

Re: Need to upgrade.

Thank you LW--Good information.

-Bill

Need to upgrade.

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