Inverter for dorm fridge online; looks good (so far)

[rabbit]

Installed a Ramsond 1500watt pure sine wave inverter to power my 2.7 ft\3 dorm fridge in the Burro. It's on a sliding tray in the forward left hand dinette locker because next door to the fridge cmptmt and to make cable run to the battery as short as possible. I used pre-lugged 1/0, 6' length plus a pre-lugged 1' long cable on the hot side to allow putting the fuse block in the line. I probably could have got away with 5' but couldn't find it pre-lugged and I'm not running all over town to welding suppliers, etc. to make it cost even more.

To take the fridge off shore power, I unplug the fridge from the receptable behind under-sink door, go around to the lower fridge vent, and hand it up into the fwd locker; go back inside and plug it into the inverter. At this time, the fridge has been inverter-powered from a "warm" start (fridge not on or cooled down) for several hrs. I set the fridge on 4 on a dial marked 0 to 7. Five hours now and the idiot lights still showing 12.5 volts (multimeter says 12.53 at the last check). Ambient was only 65-69 degrees today so I was only present to see the motor kick in twice. Looks like the wattage draw surges to about 750 momentarily but the continuous draw is under 150 watts. Fridge draws .87 amps continuous so should be about 105 watts use. I'm only going down to 80% on the battery which is 12 volts or the next light down on the Christmas tree and I'll shut it down. It may be I'll find I need another 100 amp hr. battery to make this thing run for 24 but I'll need a sunny day to test the recharging rate of my 80watt solar panel before I contemplate that.

Think this inverter may have been overkill for this ap but at $259 free shipping it seem like a pretty good deal on a pure sine wave of that capacity. Cables cost me another $63 from Amazon; 50 for the six-foot run and 13 bucks for the short red wire. Counting the initial 72$ for the dorm fridge, I'm still well under the price of a small 3-way, I think I'll run 12 gauge SJ to the overhead locker in the rear master suite, break the jumper on my shore power duplex receptable and have both shore and inverter power from one receptable each. I have checked to see if my wife thinks we'll ever plug in anything else back there when on shore power. She doesn't think so so I won't have to cut any openings for more boxes. As for mounting the inverter in the locker. I will have to cut a rectangular opening in the locker door and add a plexi plate so I can see the idiot lights. I had contemplated other sorts of flush counterfront installs for this box but all involved cutting more holes in the glass inner shell and less than satisfactory ventilation. In the locker, there's plenty of air around the fins (the fans didn't even run today except on startup), and the locker connects to the fridge cmptmt. where I have a 120AC muffin fan on a strut which can also plug into the inverter without a big battery drawdown impact. I have photos but no time to post this evening. Maybe tomorrow evening.

jack

[Donna D.]

Originally Posted by rabbit

I have photos but no time to post this evening. Maybe tomorrow evening.

jack

Counting on it Jack bet this thread is gonna help others!

[rabbit]

Got 7 1/4 hrs. runtime yesterday. Shut it down when 12.5V idiot light was flickering. Multimeter read 12.2V so I was right at batt 20% down. Have to try solar recharge next. It would be great if I could run all day and have a fully charged battery to carry thru a summer nite but I doubt that's possible. Think 24 hr. sustainability is doing to demand a second deep cycle battery.

[rabbit]

. . . and some more:

[Tim Wood]

Nice looking installation.

[Thomas G.]

Originally Posted by Tim Wood

Nice looking installation.

Yea, tidy workmanship.

[ericw]

I looked into doing this and actually wired it up in my trailer (not permanently). The 120V fridge takes a lot of power. It was fine hooked up to the tow vehicle (but the charging of the battery was slow). It definitely was not going to last 24hrs on just the battery. We ended up going with a 12V/120V fridge. Cost was similar to the 3way but it is a little bigger, easier to install, and in my experience more reliable since there are less things to break.

I hope it works well for you. Let us know where the project goes from here.

[rabbit]

Our dorm frdige draws about 105 watts. Not a whole lot of power, but over 24 hrs. measured against the capabilities of a 100 amp hr. battery, it is too much power. If I finally have to get a couple of AGM batteries and put them inside to get them off the tongue, I guess that's what I'll have to do. Taking it one step at a time. At least I have a fridge that works great on the grid; that's more than I had with a "no-way".

jack

[rabbit]

I added a "view window" to my locker door so's I can monitor the Christmas tree lights on the inverter (pix below). I stripped the MBA vinyl so will have to recover. No biggy; takes about 10 minutes. 1/8" clear plexi screwed on the back of the door and the white ring is a large grommet of the sort commonly seen in computer desks. I call the door "Wallace."

It would be nice to have a remote eyebrow panel but I'm going to make do with this lowbrow viewing port. My wife says I sacrificed a very deep locker to the inverter. She didn't have to haul everything out of it to find the thing sought. I did and won't miss it a bit. There's another just across the way for hoses, stackajacks, and power cords.

[rabbit]

Test of the 80watt solar panel to "keep up" with the battery draw for the dorm fridge. Bright sunny day but we have a lot of large trees so was 9:30 before the sun came over the house and I could find a patch without partial shade. Battery was fully charged by the converter before test so at present the panel controller is indicating regulation or float charge. Most of the time I am not even getting an idiot light on the inverter indicating 150 watt so the draw once cooled is well under 150. Idea is to see the magnitude of the contribution of solar recharge. Certainly hoping for appreciable time increase over 7 hrs. without solar but I will shut it down on or before 11:30 PM depending. 14 hrs. would be encouraging but obviously not nearly enuf for round the clock refridgeration. We'll see.

Tim and Tom, your nice comments shamed me to tidy up the battery cables to the inverter. I spiraled them together to avoid interference with TV and radio and added wire ties inside and out. It was raining the day I did the hookup and I was antsy to see it operate. I still have to get a tube of flexible caulk for the access hole thru the floor. Sometimes I wish you could get caulk-gun tubes with about half the volume of material; such a waste over time no matter how you deal with keeping the nozzle open. I always insert a nail or bolt or something but it cures anyway in time. I hate cutting the tubes open and messing about. I wonder why they've never figured out the "hypodermic" clearing of the nozzles that you can do with 5-minutes epoxy dispensers? Tim, I read that you will have the Parkliner at Williamsport in late June. Wonder if they have "new trailer" smell and if that's a good thing considering the construction

jack

[rabbit]

2:30 PM here. Doing great on a sunny day and have "six bars" on the inverter battery monitor (13volts)! Controller on the solar panel indicates it's on regulation or float so that also indicates that the battery is being kept "topped up." So at a quick appraisal, it appears that the rig with only the one battery would support the fridge draw indefinitely IF the sun shone strong every day AND all nite. Better result than I expected. I kicked in the FantasticFan on high a couple times. Didn't even blip the watt meter. Recovered the locker door this afternoon and added a big Burro logo to the front window gravel guard. Got it at work from a guy in the grfx dept. He also did our spare cover for el Gordito. In return, I said I'd help him install base shoe and ranch casing in his basement rec room. No shipping on barter!

jack

[Thomas G.]

Awesome. Keep up posted as I'm sure this will be more popular as solar panels come down in price and compact refrigerators become more efficient.

[rabbit]

Pix from today. The locker door looks better covered.

[rabbit]

Shut down the fridge at 11:30. 12.5 V light still solid; multimeter showed 12.36 V. There were moments during the day when I had 6 or seven lights on the voltage monitor (13 to 13.5 volts) but it was obvious that the dropoff in output by the panel would be very noticable if I were not around to reposition every 2 or 3 hrs. Bright sunshine on the longest days of the yr. just might produce enuf juice for a long enuf time to allow the setup to approach the hrs. of darkness with a decent charge level and keep the fridge cooling for 24 hrs. Considering I chose the 12.2V level of discharge as that which assures optimum no. of duty cycles from the battery, choosing or allowing a deeper percentage discharge would also improve the outcome of the sustainability test, but it's obvious that my rig is a weather dependent and marginally-effective power generation source for a 100watt continuous load. More batteries and more amp hrs? More panels? As almost everyone who examines this question realizes, those are answers up to the capacity of the trailer to carry them and the tug to pull them. There is no way around limited no. of sun days per yr.

jack

[MCDenny]

Jack, I just speced out the electrical system for my Lil Snoozy with the goal being indefinite dorm fridge operation and a little lights, water pump, computer recharging, etc.

I am puttiing two Trojan T105 6v 220ah batteries on the tongue but pushed aft far enough so that the 124 lbs of lead only puts 80 lbs on the tongue. I ordered a 600w Samlex TSW inverter (fridge only draws 100 w but I want some extra power to cover starting loads) and a 30 amp Iota battery charger. Operating my Honda EU2000 genny for 4 hours a day will put 120 ah into the battery each day. If the fridge runs 50% of the time the genny is not running (I hope it runs less) that's 83 ah drain so I should be in the ball park.

I also ordered a Victron BMV600 battery monitor so I will be able to see the actual amp hours in and out and know when to run the generator.

[dylanear]

Update? Very curious about running that kind of appliance off batter/solar. If I can run my fridge off solar just during peak sunlight rather than LP it will help make LP last longer. I killed a small propane bottle pretty quick with the fridge running on gas.

[rabbit]

I'm running a cheap Black & Decker AC dorm fridge which draws approx. <1amp. Unfortunately, as electric heads better than mine will tell you, that translates to 8amps DC. My best swag is that with 2 group 27 batts and a sunny summer day and 80watts solar I might get around the clock once before reaching 50% DOD. My best run from battery at full charge at fridge startup and charged by solar during run is 16 hrs. Voltmeter said 12.3volts when I shut down. This with a single group 27. I really don't have 6-9C dollars for an efficient DC fridge. Good things about this one is it cost 69 bucks, it's a great fridge on shore power, and I have a convertible ice chest. Before I had a defunct 3-way and a convertible ice chest. Better to have something riding in the 3-way's spot that performs well at least on the grid. I am also told that creating DC by inverter is inefficient. Better to find a DC fridge probably.

jack

[dylanear]

I am not building a solar system to run refrigeration, but I am curious how well it can work. I have the 3 way Dometic. I wonder how well it would work in 12V mode with 300ish watts of panel and 240ish amp hours of battery? May be useful when LP is not easy to come by.

Sort of a learning experience. I want to build a sustainable house someday, getting an idea, experientially, of what it takes to collect, store and use the energy needed for various tasks has a strong appeal.

[Thomas G.]

Originally Posted by dylanear

........ I wonder how well it would work in 12V mode with 300ish watts of panel and 240ish amp hours of battery? ...........

I believe the 3 way refrigerators draw about a steady 10 amps on 12 volts. So, that would be 240 amp hours a day. Did I read a guestimate of total output in amp hours per day to be equal to one full hour at maximum outout, or 25 amp hours in the case of 300 watt panels?

[Raz]

Originally Posted by dylanear

Update? Very curious about running that kind of appliance off batter/solar. If I can run my fridge off solar just during peak sunlight rather than LP it will help make LP last longer. I killed a small propane bottle pretty quick with the fridge running on gas.

Dylan, I am not sure what you mean by a small bottle but I run my fridge for weeks on a 20 lb tank. If you are going through a 20 lb tank quickly, you may have a leak. Just a thought. Raz