solar success

Gday everyone I have read on this forum many times people asking how long you could run an engel 40 litre fridge for on solar well I have just built my system I have 2 60 watt panels permanently mounted horizontal on my offroad trailer I used a 15 amp Morningstar Prostar regulator and my batteries are 2 x 6 volt 200 amp agm wired in series to produce 12 volt at 200 amp my fridge has been running now for 2 weeks in the backyard and the batteries are still full and the fridge is empty so one would asssume that it would be drawing more current than if it was full I used 6 B&S wire the proper MC4Y connectors to parallel the panels many people cut of the original fittings on the panel and use anderson plugs or some type of junction box but unknowingly they are voiding the warranty on there panels and for anyone wondering at what latitude I am well I am in Mt Gambier down south not the sunniest place in Australia and I have had 65% cloudy days and partial shading early morning and late afternoon from neighbors trees all up the system cost me $950 and after 2 weeks of testing my conclusion is that the fridge will run forever or atleast until the batteries need replacing which will hopefully not be for 8 years as this is what the manufacturer has stated the design life of the battery is.
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Reply By: Member - John - Saturday, Feb 25, 2012 at 12:51

Saturday, Feb 25, 2012 at 12:51
G'day, you seem to have done your homework with your system.

I was going to run 2 x 6 volt batteries also, but decide against it after careful consideration. If you do happen to have a cell go faulty or what ever on one of the batteries, you lose all your power storage. With 2 x 12 volts batteries, if one goes bung, you still have another to supply power.

Good luck with travels. John
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Follow Up By: Swaggy1963 - Saturday, Feb 25, 2012 at 13:32

Saturday, Feb 25, 2012 at 13:32
Gday John I did do my homework I just thought i would inform other people who were maybe thinking of building there own system and were apprehensive about it like i was as I have seen this question asked so many times b4 and usually the first person to reply to the post is some clown with a dual battery setup that doesnt camp in the one spot for more than 2 days.
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Follow Up By: Swaggy1963 - Saturday, Feb 25, 2012 at 16:29

Saturday, Feb 25, 2012 at 16:29
Also John I forgot to mention that I have planned for such an event I simply connect an anderson plug that i have put on the drawbar of my trailer that is wired to the battery input terminals on the regulator and connect this to the anderson plug on the back of my car and the current is redirected to the car battery and the load on the regulator will now be running of the car battery should work in an emergency I think should I lose all capacity from my battery bank I wasnt advocating 6 volt over 12 volt was simply saying what I have and based on the fact that my sister has 4 x 6 volt batteries in a series paralell producing 12 volt at 500 amp in there caravan and their batteries are coming up 7 years old I cant say that I really share your concern.
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Follow Up By: Member - Kevin S (QLD) - Saturday, Feb 25, 2012 at 17:37

Saturday, Feb 25, 2012 at 17:37
Quote: "With 2 x 12 volts batteries, if one goes bung, you still have another to supply power".
For this to be the case you will need your batteries set up separately, won't you? I ask this question as I lost 2 12V batteries at the same time. One went and took the other with it.
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Follow Up By: Swaggy1963 - Saturday, Feb 25, 2012 at 17:59

Saturday, Feb 25, 2012 at 17:59
Yes very true Kevin also batteries in paralell dont accept the charge as well as batteries in series because 2 batteries in series are acting as one battery my mate had a dual battery set up in his toyota and he wired the isolator incorrectly and his auxilary battery was weak and he couldnt figure out why his main battery was flat all the time it ended up being that the weak battery was sucking all the juice out of the good one because his isolator was wired wrong anyway thats enough about batteries I was just letting people know how long a fridge would run for if you were camped in the one spot for a long time in the end you have to make a decision on what you are going to buy based on the information you have at the time.
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Follow Up By: Crackles - Saturday, Feb 25, 2012 at 20:02

Saturday, Feb 25, 2012 at 20:02
I agree John, I also like the idea of keeping all the batteries of a similar size that way if the starter battery failed you could swap out one from the camper.
Going on several others setups 120 watts appears to be about right to keep up with a small compressor fridge although in real life running where the fridge is often opened & additional drinks cooled down (along with a few camp lights running) a few more watts may be required. At least with 200ah it gives a good buffer. The best part Swaggy, no generator required ;-)
Cheers Craig.....
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Follow Up By: Swaggy1963 - Tuesday, Feb 28, 2012 at 11:14

Tuesday, Feb 28, 2012 at 11:14
Gday Craig well if I did have a starter battery failure whilst camped my plan was to charge it enough to start with the generator and battery charger and if the alternator is ok this should get me out of trouble and if 2 batteries in series causes you concern then there are a lot of trucks around with 2 x 12 volt batteries in series producing 24 volt you think they would be using 2 x 24 volt batteries in parallel if that was the superior set up.
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Follow Up By: Swaggy1963 - Tuesday, Feb 28, 2012 at 12:15

Tuesday, Feb 28, 2012 at 12:15
What are the advantages of 2 6-volt batteries in series vs two 12 volt batteries in parallel?

We just attended a seminar on this subject. For house batteries the 12v models just don't have the plate thickness necessary to make them good for a deep-cycle application. As stated above, stick with the 6 volt deep cycle batteries.

The advantage of 6VDC batteries is first of all cost per unit. Second is the fact that 6VDC batteries with very high Amp Hour Ratings can be purchased in pairs for less than one 12VDC battery that comes close in Amp Hours.The 6VDC Batteries will discharge and recharge more times than 12VDC batteries will, so their life span is greater.

For the same ampere hours, if you could get it all in one 12 volt battery, there would be no difference - a 12 volt battery has two 6 volt batteries in series inside it.
BUT for the same ampere hours, if it is going to take two batteries to do it because of size, weight, availability, etc., then rather than two 12 volt in parallel you are better off with two 6 volt in series.
Why is that you ask?
Because batteries in parallel, even if twins from the same manufacturer''s batch, will never be exactly identical, so one will always be a little weaker than the other and when charging ceases, the weaker one will discharge, or steal some of the charge from the stronger one through the parallel connection. This may be minor when they are new but as they age, the problem will get worse.
On the other hand, batteries in series can''t discharge into each other, so for that particular setup, the pair of 6 volt will be better.
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Reply By: P2D2 - Saturday, Feb 25, 2012 at 21:29

Saturday, Feb 25, 2012 at 21:29
Remember this is summer and getting 5.92 solar hours a day. In mid winter you will only get around 2.5 solar hours and while your fridge uses less power in winter, proportionately it is not as much reduction as the solar hours. You may not have sufficient solar panel capacity for winter if relying completely on solar. 40L fridge is very sensible realistic size, and in the main 120W will scrape you through. With the Morningstar easy to see when the battery is near fully charged and state of the battery under load. Excellent product and reliable.
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Follow Up By: Swaggy1963 - Tuesday, Feb 28, 2012 at 11:00

Tuesday, Feb 28, 2012 at 11:00
Hi there well the plan is that I will be somewhere sunny come winter I also do have another 120 watts of solar that I can use portably and angle for best performance so I should have ample power to run a laptop and lighting at night I also have a 1000 watt inverter generator and a 10 amp 7 stage charger but I dont think that I will have to use it very often and yes I thought the Morningstar regulator was my pick I was tossing up between a steca , plasmatronics or morningstar but went with morningstar as they were awarded the patent for highly effective battery charging algorithm based on true PWM switching and constant voltage charging there are many other cheap regulators claiming to be PWM regulators but they are using different algorithms and are not truly PWM I also should mention that the 2 panels that I am using portably are not included in the $950 cost for the permanent set up on the trailer.
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