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gringostar

Solar barely runs refrigerator

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Hello 

I bought my Toy with an awesome solar power set up. I have one solar strip of panels on the roof, a huge Duracell deep-cycle battery, and 2300 watt inverter.  When there is sun, the solar panels charge up the battery to 13 volts, no problem.   But, when the sun goes down, with the refrigerator on, the battery dips to 11.1 volts.  I pretty much can't run anything else at that point.  If I want to run anything else, I have turn the refrigerator off first.  Questions (please):  Should I get a smaller refrigerator (cube), another solar panel, a smaller inverter, another battery, or maybe a lithium battery, or all of the above?  Obviously, cost is my number one concern. Thanks.  

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I'd start by testing the battery. Get it fully charged with either your solar or alternator. Let it sit for a few hours with nothing switched on and test the voltage before and after.

It sounds like you own a multimeter. :)

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Remember that using an inverter means that your amp draw is around 10 to1. A small refer draws about 1 amp that means your inverter is drawing about 10 amps from your battery.

 

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How many amp hours for the battery. Check the fridge for excessive drain. Sometimes they are faulty and run constantly instead of only when needed. Have you checked the water in your battery. Does it immediately go to 11 or drain down to that. Instant 11 means you have something wrong with the system somewhere. Messed up inverter can cause drain too

Linda S

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In the sun with a solar setup the battery should be 13.5v +.

Check all wires for good contact.

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the reason most frigs run on propane is that propane offers the most energy for the weight.

 

going from 12 dc to 120vac is inefficient in itself.  

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The last time I checked a 120 volt fridge heater it was around 175 watts that's a good chunk of power even at 120 volts. So that's pushing 15 amps DC granted the figures are less than exact but close enough so if it runs half a day on DC you will suckup 180 amps of battery! It should be used on DC only while you are driving. The amount of energy in a jug of propane is probably more than you could store in at least 10 batteries. I  left my fridge on for about 2 months once running on propane it was nice and cold when I went to fill it for a trip!

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Things are getting confused. So Gringo are you running a 115v ac dorm refer or a RV refer??

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They do make efficient DC fridges read expensive even a dorm fridge is a bit hard on batteries if it runs half a day it too can suckup 100 amps DC.

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6 hours ago, WME said:

Things are getting confused. So Gringo are you running a 115v ac dorm refer or a RV refer??

I'm running a 115 v dorm refrigerator.  

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Now that we know what your doing some questions

1. Does the refer work right when plug into 115 v at home? Compressor cycles and all that.

2 What size and type is the battery.. 24 or 27 size, flooded cell or AGM?

3. Is the controller good. Float voltage should be 13.5v, bulk charge voltage is around 14,6

If all is good then more solar and battery might be the answer.

General WAG math if the compressor runs 30% of the time your need 80 amp hours (AH) a day. A 27 battery has a safe discharge of 50 AH. A 100w panel will out put around 45 AH a day. If you drive every day then the alternator should give you a fully charged battery and you will only need to run 10 hr a day on battery. It might work out, but a couple of days boondocking and you have warm beer.

So start  with your local Craigs list and look for a 2 way rv refer. Have them plug it in for 6 hours before you go to look at it

 

 

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Half a day is 50% load the dorm fridges are cheap and not real efficient or insulated you are pushing the limits. A 100 watt panel on the equator at noon will give you about 8 amps max that's how they are rated moving north or south will reduce the solar gain so will panels on the roof. An inverter switching supply is pretty efficient but still has a good 3% loss and there is no getting around the conversion from 12 to 120 volts a good DC fridge is around $600 in my line of thinking you would be better off buying a propane fridge or not getting too far from the power lines. There is a romantic notion of going solar but no one seems to mention the cost.

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Have you thought about adding a marine wind turbine to your system?  I have been kicking around the idea but have not done it.  It could mount on the old TV antenna mount.  A marine wind turbine (when there is wind) will probably give one 5 to 10 times the charge rate, over the solar panel.

Edited by bufbooth

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Marine wind turbines are not real small and the ones that are are only about 85 watts and need a great deal of wind speed to reach that figure. They are only about 25 watts at around 25 MPH. I'm also wondering how they would stand up to  60+ MPH winds on the top of a MH, would require a pretty substantial mounting. 

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