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kittysmitty
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# Posted: 16 Jul 2024 18:22
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Working on a project for a friend with a boat. Not Small Cabin but defiantly off-grid. Does anyone have any experience in what the power requirements for a unit like this. When on shore power an AC to DC adapter is used, but I'm more concerned about DC usage. He's in the process of buying a cooler, batteries etc. and would like some info. Thanks
https://www.canadiantire.ca/en/pdp/mobicool-12v-cooler-34-l-blue-0370566p.html?loc=pl p
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razmichael
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# Posted: 16 Jul 2024 19:35
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ThermoElectric coolers are power hogs, both due to the way they operate (Peltier effect) and that coolers like this run 24/7 unless you modify them. on colder days they can end up freezing the food and on hotter days may not be able to keep up (not that this is any different from many off-grid type cooling systemswith limited power. They do have the advantage that you can use them for heating things (not cooking!).
Most of this general size use between 4-5 amps which kinda fits an answer in the questions section: "A: 6 hours on a full charged 24 Deep cycle (75AH) FLA battery, a little more than 50% charge remains." - and note that 50% discharge is as low as you want to go with FLA.
So I think your friend will need to do some calculations based on how big a battery he wants, how long the trips are and what other things he may need to power.
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paulz
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# Posted: 16 Jul 2024 21:02
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My cooler also uses about 4 amps at 12 volts but it is compressor based (not peltier) and doesn’t run very often, about like a regular house fridge.
https://img.saleyee.cn/Resources/GoodsAttachment//2021/202101/202101282127215709_988f 6568-6c38-46c9-8450-a30f21f22635.pdf
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ICC
Member
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# Posted: 16 Jul 2024 21:54 - Edited by: ICC
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A standard single stage peltier effect cooler can reach a temperature differential of 40 degrees F between the hot and vold sides of the unit. That is, if the ambient air temperature is 80 F the inside of the cooler box won:t cool any lower than 40 F.
An efficient compressor type can actually make ice on a hot day and use less power. Some have a split compartment. One half can be used as a freezer and the other for non frozen food. I have a 20 year old ARB that still works. It is a single compartment unit, and can make ice to be used in a Yeti cooler for days and weeks on end, as long as there is power available.
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ICC
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# Posted: 16 Jul 2024 22:09
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I believe the peltier is only about 5% efficient. A Danfoss compressor is well over 70%.
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gcrank1
Member
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# Posted: 17 Jul 2024 00:05 - Edited by: gcrank1
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I have two, one the size of a large cooler and the other a 'truckers' 12v about the size of a small + cooler. The only time I use the small one anymore is on a road trip when it will run off the alternator, Not Battery.
The big one runs on 12vdc or 120vac and is even more of a pig. As said, they seem to run 24/7 and will suck even a 100ah lfp down in under a day.
We also have a pretty big Yeti clone cooler, if we pack it 'right' it has gone 4 days with just some frozen food, diy ice bottles, cold food & drink. Toward the end the diy ice bottles still had about 1/2 ice and provided very cold drinking water.
I don't know how to calc the 'efficiency' of it.....but three years on we still like it.
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kittysmitty
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# Posted: 17 Jul 2024 11:03
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Thanks for all your comments, opened my eyes to the efficiency of peltier vs compressor. Like everything in life, if you want to play you got to pay. My recommendation would be to buy a good Yeti or clone, or if you have the cash something like this https://www.thecabindepot.ca/products/ecoflow-glacier-3-in-1-portable-fridge-freezer- ice-maker
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Brettny
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# Posted: 17 Jul 2024 14:33
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Once you start nearing the $1000 range for these special appliances just to use less/no power you dont end up saving alot vs just putting in more solar power.
My initial system cost $1200-1400 and could run a 4.5cuft mini fridge with plenty of power left. That price also included the fridge and 1kw inverter generator.
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redwolfguild
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# Posted: 17 Jul 2024 16:42
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Ice takes up space, and you have to continually buy it at marinas, they know they have you, so they charge you for it. I use this fridge for my small cabin and it runs around 100 watts on start up and then when running is around 60 watts. On average runs about 20 minutes per hour depending on temp, how many time its opened, etc, etc. For me, best $800 i spent. Load it at home and chill it on 120V then transfer to the truck on 12v, when I get to the cabin plug it into 120v from my inverter.
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Brettny
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# Posted: 18 Jul 2024 15:19
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A large mini fridge runs about 60-70w cycling roughly 50% of the time in a 85* building. There not nearly as portable but $200. You can buy alot of ice or solar for $600.
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gcrank1
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# Posted: 18 Jul 2024 18:07
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Fwiw, when I was trialing my absortion and later dorm size 'fridges I found that unplugging them at bedtime and back in at get-up worked decently. Not opening the door kept the cold in (checked the inside temp with a thermometer to know). That cut about 30% of the bat drawdown per day.
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redwolfguild
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# Posted: 18 Jul 2024 18:46
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Quoting: Brettny A large mini fridge runs about 60-70w cycling roughly 50% of the time in a 85* building. There not nearly as portable but $200. You can buy alot of ice or solar for $600.
My understanding is he is putting this in a boat so a mini fridge may not be that practicial.
I also look at my time as money, so not having to go and get the ice is worth it to me.
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gcrank1
Member
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# Posted: 18 Jul 2024 19:10 - Edited by: gcrank1
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Sounds like the solution is Go Big (pricey) or Stay Home; lol.
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Brettny
Member
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# Posted: 20 Jul 2024 19:56
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I have family that bought two of these powered coolers and pannels to run them on a sail boat for 30daya in the Bahamas. They ended up having to turn one off and use ice. There power hogs.
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offgrididaho
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# Posted: 21 Jul 2024 19:19
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Engel compressor coolers are awesome, fridge or freezer depending on setting, sip power. Not cheap though. ARB is another option although of the two I like my Engel better (ARB had trouble holding steady temp except when full on freezer). Always nice to run the unit off 12v in car until you get to you r off grid location.
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kittysmitty
Member
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# Posted: 21 Jul 2024 20:03 - Edited by: kittysmitty
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I went to the Engel website and downloaded this document. Makes perfect sense. Colder the setting on the dial and higher the outside temperature, the more power it uses, and the run cycle increases. No surprise, but interesting numbers.
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