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Small Cabin Forum / Off-Grid Living / mini fridge for solar
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MtnDon
Member
# Posted: 22 Aug 2016 15:26 - Edited by: MtnDon
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As I stated before, and creeky seems to agree, batteries and wire size. That inverter alarm is doing what it is supposed to do; warn of low battery voltage. When the large load is removed, no doubt the voltage recovers. The drop in voltage can be because the battery(s) can not deliver the amps or can be because the wires are too small, too long for the size, and can not deliver the wanted # of amps.

How old are the batteries? How have they been cared for? Lots of deep discharges? Left sitting part charged for days/weeks?

Do you have a hydrometer? If you have lead acid batteries with caps that are removable you should have one and know how to use it. One of the better, easier to read and temperature corrected hydrometers is the Hydrovolt.

Or the easy technological way out of the problem is to buy lithium (LFP) and a new charge controller and still change the wires from battery to inverter as they do appear too small a gauge for the capabilities of that inverter. How long is the run from battery to inverter?

Renegaderh
Member
# Posted: 22 Aug 2016 15:28
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One more question . I'm a little unsure about how to figure "my loads" weekends see the heaviest use for the 19 inch t.v. and swamp cooler. But both run at some point during the day everyday in the summer. . If I can run a fridge bigger than 1.7 cubic feet that would be really great. Can you point me in the right direction for figuring my loads?

MtnDon
Member
# Posted: 22 Aug 2016 17:28
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Kill-a-watt measures actual use over a period of time. There are a couple different models and many places that sell them.

The Killawatt tells you the energy used by the device. The AC energy out of the inverter. You still have to account for the internal DC to AC losses of the inverter and the loss inside the battery. At 25% for conservative calculating. IMO.


Is anything left running when the cabin is not in use?

Renegaderh
Member
# Posted: 22 Aug 2016 20:23
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Nothing is left running when i go to work. But the surge suppressor that the tv, bluray player and swamp cooler are all plugged into stays on. The batteries are about 18 months old. They fully charge everyday. I'll look into the hydrovolt and will up grade my wiring. I can eventually make the switch to ion batteries but it will take a while.

Renegaderh
Member
# Posted: 22 Aug 2016 20:26
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The batteries are on the floor and the inverter is on a shelf maybe 30 inches above the batteries? I'll be doing some remodeling soon and bring the inverter closer to the batteries. Already looking for a mppt charge controller.

Renegaderh
Member
# Posted: 22 Aug 2016 20:27
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I live in my cabin year round.

Renegaderh
Member
# Posted: 22 Aug 2016 20:30
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Again, I appreciate you guys getting me on the right track. I'll be happy if I can get this setup to run a fridge by next summer. Even a 4 cubic foot would be great. I'm not sure I have room in my 128sqft for a 10 cubic foot.

Renegaderh
Member
# Posted: 22 Aug 2016 20:45
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http://www.lithiumion-batteries.com/products/product/12v-20ah-lithium-ion-battery.php #

Would this be an appropriate size? They run about 289.00 ouch..

MtnDon
Member
# Posted: 22 Aug 2016 22:48
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IMO, No, that would not be a great choice. Better would be the larger "prismatic" type of cells that are available from a few sources. One source, and another. I note that one of the other online sources, balqon, seem to have gone out of business. At least their website is dark and their stock has a value of $0.00.

Those batteries that look like the lead acid batteries we know are often much more expensive per Ah than the prismatic variety. Or for the more adventurous there is the salvage li-ion cell/battery route as creeky did. I am having a serious look at the cells sold by the two links I provided. That is Not to be taken as a gold plated recommendation. Caveat Emptor!

Before spending too much time on looking at batteries though determine your needs in terms of how much energy storage is needed. And while doing that reconsider the entire package... 12 volt systems are generally only advised for small-ish systems. I do think 12 volt may be better with a LFP battery than lead, but there is still the issue of delivering higher numbers of amps compared to a 24 volt system through larger wires from battery to inverter. 12 volt systems need to deliver 2x as many amps to do the same work as a 24 volt system.

You have some time to sort things out and do some pricing.

Renegaderh
Member
# Posted: 22 Aug 2016 23:11
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You are the best! I appreciate your patience with all my questions.

Renegaderh
Member
# Posted: 22 Aug 2016 23:25
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I scrolled around both links, good lord who knew there were so many kinds of batteries. Hahaha

I'm going to upgrade my wiring, that I can do right now, and consider a 24 volt inverter. I found one for 400.00 . I've got a Kill A Watt meter coming so I can at least get an idea of energy consumption while keeping in mind the numbers you gave me. Fortunately I'm not trying to run lights, or washers and dryers and various other appliances. I live pretty simple and small.

Jroa1
Member
# Posted: 11 Jul 2021 12:51 - Edited by: Jroa1
Reply 


ok i got 1 deep cycle
battery and 2
75 watt solar panels and 300 invertor so will that a run a mini fridge someone please let me know if i will work

Brettny
Member
# Posted: 11 Jul 2021 14:34
Reply 


Yes it will but prob not for long enough to cool the fridge down.

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