12v Refrigeration - What size do you use?

[Cosmo]

Prototype. More data is needed about run time.
I think it will work.
=Cosmo

[featherliteCT1]

Looking good!

[TimC]

[color=#0000BF][size=150]Prototype. More data is needed about run time.
I think it will work.
=Cosmo

Thanks for the plug Cosmo. You're doing all the hard R&D! Fun project and I like how you are documenting the progress. That's a neat and useful little meter...

Tim

[Socal Tom]

These small fridges do not have a fan in them to circulate air.

https://www.amazon.com/gp/product/B01E5 ... UTF8&psc=1

Cosmo, I like the idea of a small fan. I'm curious if one of the below fans with some fabrication of a case would work to circulate air in the fridge. I get that I don't want massive air movement. This one has 2.3 cfm which is even higher than necessary I think. What do you think? I'm a tinkerer and don't have any problem either wiring with a battery (there are many small 12v batteries on the market) or wiring direct to the input to the fridge, or, there are versions of this that are 5 volt. I've also run an 12v, 80mm case fan on a 9v battery with sucess. This fan runs on 6/100 amp, so, I think it would last quite a while on a charge. Maybe even one of those rechargable battery packs that you use for a phone backup. OK, I'm rambling. Can you tell I like the idea of adding a fan to the fridge?

https://www.ebay.com/itm/12V-25mm-Mini- ... 0047.m2108

Tim

Or just get this
Valterra 3-Volt FridgeCool Fan, Refrigerator Fan for RV and Camper https://www.amazon.com/dp/B002N5W8Q4/re ... rDbEXJS58G

[Cosmo]

Hi Tom,
Check these links. TimC and I are playing around with small fans. The 25mm Fan looks like it will work for me. The 25mm moves air it does not provide much force when it moves that air. But we dont need force we just need to move air. I believe it will be fine for moving air from the bottom of my ONE CUBIC FOOT FRIDGE to the top so is circulates and evens out the temp. The Camco does this quite well in my fridge and I expect the tiny one inch 25mm to work just fine FOR MY NEEDS. Might depend on how large your fridge is.

https://youtu.be/SQ1yEv4T2IM
https://www.amazon.com/gp/product/B07NC ... UTF8&psc=1


Perhaps this is just the tip of the iceberg...
I have used coolers in the past. One problem there is the food above the water in the air does not get very cold (convection cooling) . If the food is not in direct contact with the ice (conduction cooling) even butter gets soft in the warm air pocket above the ice and water. Some sort of fan in the cooler might help keep things cooler but would probably melt the ice quicker.

There is the problem of the coldness trapped in the water which cant be transferred into the air. I air circulating to cool food. I have had a big chunk of ice on the water and its very cold down there while up above in the air space its not cold at all! Fish pump blowing cold bubbles? Some sort of convection improvement. I am pretty sure only block ice could survive very long in with a fan. I imagine cue ice might melt pretty quick.

=Cosmo

[TimC]

[/quote]Or just get this
Valterra 3-Volt FridgeCool Fan, Refrigerator Fan for RV and Camper https://www.amazon.com/dp/B002N5W8Q4/re ... rDbEXJS58G[/quote]

Now Thomas... why would we buy something when we can Rube Goldberg the heck out of this?

[Socal Tom]

Or just get this
Valterra 3-Volt FridgeCool Fan, Refrigerator Fan for RV and Camper https://www.amazon.com/dp/B002N5W8Q4/re ... rDbEXJS58G[/quote]

Now Thomas... why would we buy something when we can Rube Goldberg the heck out of this? [/quote]
Been there done that...

[TimC]

In a kind of related subject...

I'm thinking I will try to maximize my solar generation even when parked where i can get 110v power. But, I'm wondering if having a Noco G3500 as a backup for night time use will offset what the fridge will consume at night. It sounds like 3.5a will cover the fridge to keep the batteries from being depleted. My 100w panel is producing an amp or two during the day with cloud cover and I will soon have two of them to double generation.

Not sure if it would be a waste of money as I mostly boondock and rarely stay in campgrounds with 110v hookups.

[TimC]

Received the fridge yesterday. Pre cooled it then plugged it in to a kill-a-watt meter. According to my crude measurements of the fridge running twelve hours on 110v it used 1 amp. At twelve volts that would be 10 amps, Correct? Not sure my calcs are correct.

So far it fits everything I need for a long weekend trip with room to spare. Waiting on the fan install until Cosmo gives his results of the 25mm fan and usb battery bank.



Opps, forgot to pack my two cans of Widowmaker...

[absolutsnwbrdr]

It looks like the Alpicool CF35 is rated at 45W, so when the compressor is running it is pulling about 3.75A (on 12VDC), or 0.375A (on 120VAC).

Hypothetically speaking, on 120VAC, if the compressor kicks on for an average of 15 minutes per hour for 12 hours, your total (Ah) usage might be only be 1.125Ah. (.375A)*( 15min/60min)*(12hours) = 1.125Ah in a 12H period. So yes, if you were testing in an air conditioned house the cooler didn't need to work very hard, the 1Ah reading you got was probably correct.

On 12VDC, that would be... (3.75A)*( 15min/60min)*(12hours) = 15Ah used in a 12H period.

In real-world conditions (hot car or campsite) the compressor will need to cycle significantly more, so significantly more power will be consumed. How often the compressor cycles will depend on the ambient air temp, the desired cooler temp, and the efficiency of the cooler insulation.

[Cosmo]

I agree with absolutsnwbrdr power analysis. The duty cycle (amount of time the fridge is actually running) is short once the fridge is cooled.

I hooked up a 10 amp hour USB Lithium power battery - the type you charge a phone with. to the tiny fan. It moves adequate air. The battery lasted 4 days of continuous running. U have to compare this with the Grapefruit sized Camco fan that runs a month on 2 D cells and figure out what works best for you. I'm either ambivalent or apathetic on this. i don't know which and I don't care. Either way I am chilling.

Tim if you have the fan - throw it against the wall and lets see what sticks! The fridge will run fine with no internal fan - the fan is just icing on the cake to keep temps even in the fridge.

I have to say - the fridge you purchased looks VERY similar to the Dometic. The controls, internal light, cage and layout. The space in mine seems to hold quite a bit if I unwrap stuff and pack it carefully. I will be curious how it works for you and power consumption on battery power. I have not been able to get a direct connection between the power my fridge draws on AC vs DC. I believe my fridge draws about .45 amps an hour average on 12 volts which is amazing.

I have always wanted to drill into the lid and fill it with foam but I dont want to mess with it. I believe the lid is just filled with air.

Enjoy the cooling and do report back.

=Cosmo

[KTM_Guy]

Your calcs are correct. If you convert to watts you are at 110 watts on AC and 120 watts at 12v. But if you only used 1 amp over 12 hours that is incredibly efficient. My Snomaster draws 2.5 to 5 amps when running on 12 volts. It’s 56 liters and has two compartments, can be fridge/freezer, fridge/fridge, or freezer/freezer. It is hard to get numbers on real power usage because the conditions vary so much. I used it from 30 degrees to 120 degrees. And I’m still trying to figure it out. But at 110 day temps and 90’s for the lows a 100 watt panel will not keep up.

I would say use what you have in real situations camping then add more solar as needed.

Todd

[absolutsnwbrdr]

Cosmo, I was thinking the same thing in regards to the Alpicool vs Dometic. It looks VERY similar, at less than half the cost.

I know my Dometic is advertised @ 0.79Ah per hour, (set at 41°f with and ambient air temp of 90°f). So in a 24 period at those conditions, I expect to use nearly 20Ah of battery capacity. I usually have it set to about 32-35°f just to be sure things are nice and cold.

[Cosmo]

TimC can you post a photo of the display buttons etc. for comparison?

I set mine for 33 and with the fan it does keep everything inside at exactly 33. The temp on the display (air temp in the firidge) varies between 30 and 38 but the food is always exactly 33. Great technology. Without the fan you get a slight temperature zone system Butter and eggs on shelf area on mine will be about 40 temp. With fan- 33

For the data obsessed this meter will give cumulative power consumption which factors in the duty cycle on off and give a true picture of power use. There are many other solutions too!
https://www.amazon.com/dp/B01LVTST80/ref=dp_cerb_1

=Cosmo

[TimC]

I'll get back to y'all in a couple days. No signal where I was parked last night ( I think I was in heaven). It's been an interesting trip so far as far as the fridge. Plug falls out of the socket e very bump in the road. And I don't mean big bumps. More, and pics of control panel later. I'll need further good advice and confirmation of what I'm seeing.