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

[cpaharley2008]

Nice job, a small suggestion would be to add a small round air vent on side to help keep the inverter cooler=more efficient.

[rabbit]

Heat has not been a problem with that inverter. It's located in a locker that connects to the area of the old fridge vents. Once the tasteful wood-grain divider or bulkhand was removed, it was in a position to benefit from the muffin fan which is located behind the upper vent. Actually, it hasn't even had a workout with the fridge; only get the internal fans on startup and just barely warm to the hands.

jack

[dylanear]

Originally Posted by P. Raz

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

Interesting. Good data point.

It was a really small tank. 1 gal, 5lbs. I did use some for heat that day too, maybe it didn't get filled entirely. I use that little tank on the tongue on the move and put the big cylinder on the floor near the axle when underway. The thinking was to use it to keep the fridge going while moving, but I know how controversial that is. I just need to figure out how to get more current to the trailer from the TV, I don't seem to get much juice from the TV, perhaps I just need bigger wire.

[dylanear]

Originally Posted by Thomas G.

I believe the 3 way refrigerators draw about a steady 10 amps on 12 volts. So, that would be 240 amp hours a day.

Wow, that's not very effecient. I was just looking at this little fridge/freezer, 30 watts (2.5 amp), 60 amp hours a day.

http://dometic.com/enus/Americas/USA...ctdataid=90084

Originally Posted by Thomas G.

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?

I dunno, did you read that?

I hope to have up to 320 watts of panel, they are 12v panels, but apparently 17v is typical output, 320w/17v= 18 amps. So if 1 hour a day is a good rule of thumb, not sure how people with 50 or 80 watts of panel are reporting getting a good charge on a 80 amp/hour battery in a day.

Why didn't I ever take physics.

[honda03842]

Dylan,

I did major in Physics and it does help one every day of one's life.

Regardless I do have an 80 watt panel and it does the job not because it puts our tremendous amounts of power but rather because I use little power. I think that's a big part of successful solar installations.

I think minimizing usage is the key. I'm installing one on my son's trailer today and he needs to replace his power hungry incandescents with LEDs. His incandescent load with all lamps on represents 16 amp hours alone.

Our load with all LEDs on would be about 1.6 amp hours though we typically only have a couple on probaby less than 0.5 amp hours and generally only on at night for a few hours.

Our water pump draws a lot but really is only on a few minutes an hour.

Our TV draws about 1.5 amp hours and is only on early in the morning and at night.

My computer draws about 1.5 amp hours whan charging and runs for about 7-9 hours on a charge, it's a small netbook yet does the job well. Phones and e-books are barely worth mentioning.

We have made it easily on 80 watts....

I must admit we typically travel during periods of 'long hours' or are in sunny climates in the winter. I'm sure that helps. The 10 percent efficiency earlier mentioned in the thread I'm sure does not apply in Yuma, even without tilting panels. I'm sure the same can be said for any where in the southwest.

Now that we're in the NW where the Sun is extremely rare at this time of the year, it's at least bright for 15 hours a day. Though parked in our son's yard and plugged in does not require much DC. Howver we do not have our converter on and are using the panel to charge.

Our experience is that 80 can be enough. Certainly 320 should do the job.

Safe Travels and sunny days,

[Raz]

"Regardless I do have an 80 watt panel and it does the job not because it puts our tremendous amounts of power but rather because I use little power. I think that's a big part of successful solar installations.

I think minimizing usage is the key."

BINGO

[dylanear]

Originally Posted by P. Raz

"Regardless I do have an 80 watt panel and it does the job not because it puts our tremendous amounts of power but rather because I use little power. I think that's a big part of successful solar installations.

I think minimizing usage is the key."

BINGO

I hear that loud and clear.

But I'm still going to make and store all the power I can.

[rabbit]

I pulled up my old thread on dorm fridge for an interim report on "real world" use. May have minimal interest for the "dries" and minimalists and also for the "full hookup" crowd but anyway a report:

Friday, June 29 was a near record setting hot day in the northeast. We cooled down the dorm fridge on AC Thursday before heading for Nittany Mtn. KOA in Williamsport. PA. Inverter powered off a fully charged group 27 for the 4 1/2 hr. trip. Multiimeter said 12.3 volts on arrival in early afternoon. Set up in 97 degree temp. and I'd say the little fridge had its work cut out to make ice and was contributing to cabin temp. On a sunny site which would have allowed me to recharge on solar contribution. With the shore power, that wasn't a necessity. Muffin fan behind the upper vent helped exhaust compressor heat; would also help with inverter heat from locker comptmt. which is also open to the vent but I didn't detect much heat in the fins probably because getting some Venturi principle exhaust while moving. Saturday was perhaps ten degrees cooler and overcast; little fridge was freezing everything so I turned it down. Return trip Sunday fridge again inverter fed; multimeter read 12.45 volts on arrival Sunday afternoon. I'm satisfied that this level of performance has some utility for short weekend trips. The "They drive by night and seek refuge at Walmart" scenario might not be as satisfactory if not punctuated by some shore power (and water) sites. Unfortunately, may not be ideal recharge system as we think we're fringe season campers (if there is a fringe season in northeast). I'm taking the something is better than nothing view for now. I continue to be overly optimistic about the capacity of the greywater tank. Did not use shower but apparently we are pretty lavish about rinsing dinner dishes. Bought a 15 gallon wasterwater tote from Amazon Monday.

jack

[Thomas G.]

Originally Posted by rabbit

I pulled up my old thread on dorm fridge for an interim report on "real world" use. May have minimal interest for the "dries" and minimalists and also for the "full hookup" crowd but anyway a report: .............
jack

Thanks for the update. It is an interesting experiment, given the huge price difference between a 110v dorm compressor refrigerator and a 12 volt compressor refrigerator of the same size.

[MCDenny]

I've got my dorm fridge in the Lil Snoozy running off the battery with a Samlex 600 watt inverter providing 110v AC. Works fine and the Samlex only draws 0.4 amps (48 watts) with nothing plugged in so it is not costing me much in electrical overhead.

There is a remote switch with a pilot light on the wall next to the outlets tied to the inverter to make it easy to turn on and off. I only waste the 48 watts when necessary.

[Byron Kinnaman]

Originally Posted by MCDenny

I've got my dorm fridge in the Lil Snoozy running off the battery with a Samlex 600 watt inverter providing 110v AC. Works fine and the Samlex only draws 0.4 amps (48 watts) with nothing plugged in so it is not costing me much in electrical overhead.

There is a remote switch with a pilot light on the wall next to the outlets tied to the inverter to make it easy to turn on and off. I only waste the 48 watts when necessary.

I'd like to make a small correction to the above. The Samlex is only drawing 0.4 amps in idle mode from you 12 volt battery that's 4.8Watts not 48 Watts. Better than you thought.

[rabbit]

Tom, I'm still thinking about another 68lbs. of group 27 on the tongue. On recent trip we carried a 20lb propane tank (38 lbs. full) rather than our huge 40 pounder (69 lbs. full). Based on filled wgt. the difference of 31 lbs. would offset some of the wgt. of the second battery. I wish I had an accurate tongue wgt. but we have made a number of interior mods which added wgt. forward since I tried the plank, fulcrum and household scale method more than a yr. ago. I'm going slow on adding the additional battery for now; I have a "smart" converter to replace the Newmark whizbang in our burro (same converter that Per Walthinson put in his) and that's first in the queue.

Denny, I'm interested in knowing how "far back" you can push those golf cart batteries before you run into trailer? Our original configuration is tank bracket forward of the battery which may be for the best but I still don't have generous room for two 27s behind the tank. I think I may have to fabricate a battery box or use two bracket mounts and make a splash cover which would only protect the fwd side of the batteries and the terminals and pigtails and jumpers and fuses on top. Does anyone know if a two-piece battery box is 1) a necessity weatherwise, 2) a necessity legality-wise?

jack

[cpaharley2008]

Jack,
I'll bring my Sherline scale to Burn't Cabins if you make that one and you are welcome to use it.

[rabbit]

Thanks Jim. If we're still mobile (or at least motile) by fall and the cricks don't catch on fire, we'll be there to take advantage of the opportunity and see the Escape. Have to look up Sherline scale to check if that's what Frederick "the trailer weigher" uses.

jack

[cpaharley2008]

Jack,I think Frederick uses some sort of truck scale because he works for a commercial weigh company.

[MCDenny]

Originally Posted by Byron Kinnaman

I'd like to make a small correction to the above. The Samlex is only drawing 0.4 amps in idle mode from you 12 volt battery that's 4.8Watts not 48 Watts. Better than you thought.

Oops. Thanks Brian.