Peltier broken!?

[jeroen]

I picked up one of these made-in-China rebranded 12v/120v ac/dc mini fridges (https://www.amazon.com/Avanti-SHP171...rds=12v+fridge) today from a guy of CL.

The fans ran (and still run) when I plugged it in, so I figured it was all good. As far as I understand it those are the only moving parts. The two fans are on the inside to move the air around the cold part of the peltier element, and on the outside to get the heat away from the hot side of the peltier element.

I've had it running on 120v for 2 hrs now, and it's at 48f in a 70f room. Does anyone have any idea what could possible be not working? Peltier elements either work, or they don't as far as I know, and the fans definitely work.

Any idea on where to start/what to do/what to fix?

[Mike Magee]

It has achieved a 22 degree reduction in 2 hours. It is working, at least to some degree. Put some beverages inside it and leave it overnight, then check it again. If it does not meet expectations, hopefully you can return it.

[madjack]

...let it run overnight and see the temp in the morning...keep in mind, on the best of times, the peltier unit will cool at most is 40 degrees below ambient...my opinion is, after owning several, you would havvta pay me to take one and then, I would either sell it or toss it in the dumpster...YMMV...............
madjack

[jeroen]

Does anyone make a compressor type one that runs on 12v and doesn't cost 800 bucks? I'm going electric only. I guess I could just get a conventional mini fridge and a pure sine inverter. I like my beer cold....

[madjack]

https://www.compactappliance.com/sea...ortable+fridge

...best prices I know of...I have a few friends with an Edgestar and they are very happy with them...Engels are probably the best(and priciest) of the bunch...Dometic makes one as well (pricey).................
madjack

[jeroen]

Yeah, I guess pure sine inverter plus conventional it is...

[madjack]

...keep in mind, when going from 120vac to 12vdc, there is a tenfold increase in amperage draw...in other words, if the fridge draws 3amps on 120vac, then it will draw 30 amps on 12vdc, plus the inherent losses from the inverter...not very workable in most boondock situations..........
madjack

[Mike Magee]

If you have about $500-$600, invest in a Truckfridge, Edgestar, or similar refrigerator with Danfoss-type compressor. They are the least power hungry 12V fridges and you can regulate the temp, even to the point where you can keep ice cream in one.
Home Page for TruckFridge : Built-In and Portable Refigerator/Freezers

[Raspy]

Mike has the best answer of all ^^^^^^^^^

The peltier unit will never be suitable for cold beer.

[jeroen]

Well, I put some beverages in it out of the fridge yesterday. The were 40F when I put them in, and they're still 40F. I guess it's working, but I'll need something more powerful. A regular mini fridge uses about 85 watts when running, but a whole lot more to get started. Still, a 1000 watt invertor with 2000 peak should be able to handle that. Question is how long it will last. Fortunately they're only 59 dollars at Walmart, so if it does break after a year or 2 I could just get another one.

[The Minimalist]

Originally Posted by jeroen

Well, I put some beverages in it out of the fridge yesterday. The were 40F when I put them in, and they're still 40F. I guess it's working, but I'll need something more powerful. A regular mini fridge uses about 85 watts when running, but a whole lot more to get started. Still, a 1000 watt invertor with 2000 peak should be able to handle that. Question is how long it will last. Fortunately they're only 59 dollars at Walmart, so if it does break after a year or 2 I could just get another one.

Does your TV's tongue weight limit allow that many batteries??

[jeroen]

Originally Posted by The Minimalist

Does your TV's tongue weight limit allow that many batteries??

A 105Ah deep cycle battery at 12 volt gives me 1260Wh. With a cheap invertor at 80% efficiency this gives me 1008Wh. I don't want my battery to discharge more than 80%, so 806Wh. A 85 Watt mini fridge would run 9.5 hours on that single battery. Now if I add a second battery I get to 19 hours. I don't plan on living off the grid in my 13' camper, so the only time when I need to run on battery is when I'm driving to a camp ground, where I can plug it in on AC and recharge my battery.

Is my math wrong?

[dbdbgriggs]

Dometic Coolmatic CR-1065U/F 2.3 CU. FT. 12/24 Volt DC & 110/220 Volt AC Built-in Refrigerator Freezer With Flush Mount Frame

Got this one for $600 this spring, it uses only about 40w when running, is very quiet and I can attest that it cools beer magnificently, and it fits in the hole from the old dometic 184 3-way

[Johnny M]

You can get a dorm fridge for under $100 and a used one for less than $50 and an inverter for 12v to 110v can be found on the cheap to...you just need a good battery bank for it and solar or generator to top off the batteries....

[Johnny M]

Originally Posted by jeroen

A 105Ah deep cycle battery at 12 volt gives me 1260Wh. With a cheap invertor at 80% efficiency this gives me 1008Wh. I don't want my battery to discharge more than 80%, so 806Wh. A 85 Watt mini fridge would run 9.5 hours on that single battery. Now if I add a second battery I get to 19 hours. I don't plan on living off the grid in my 13' camper, so the only time when I need to run on battery is when I'm driving to a camp ground, where I can plug it in on AC and recharge my battery.

Is my math wrong?

If you figure in the amount of time that the unit cycles off you may find you get more run time that you expect...you could also add an EZ start device same as used on a/c also know as a hard start capacitor

[jeroen]

Originally Posted by Johnny M

You can get a dorm fridge for under $100 and a used one for less than $50 and an inverter for 12v to 110v can be found on the cheap to...you just need a good battery bank for it and solar or generator to top off the batteries....

Yes, that's what I'm thinking about doing. I only need to run on battery for a few hours at a time, so I'm not too concerned about battery capacity. Yeah, it would be great to get a system that can keep my beer and steaks cold for several days, but not for 600+ dollars. I guess I could just takes a cooler and a 3 dollar bag of ice with me if I go to a place without hookups.

[Raz]

We use propane when camped as we seldom camp where there is power. Water bottles mostly frozen and topped off with water keep things cold on the way. They work very well but do use up space. If you camp with power a dorm fridge is the cheapest route. Off grid my rm2193 on propane is hard to beat. For beer get a cooler. Nothing beats ice.

[Mike Magee]

Running a batt much below 50% will begin sulfation. You only have about half as much capacity as your numbers suggest.