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Post by robbo3 on Jan 1, 2011 18:56:52 GMT 10
I'm after a bit of technical advice.
I have a 100 amph deep cycle battery,suntec stp085 solar panel purchased second hand from a local market and a 60 ltr Engle fridge with bag.
Problem the fridge works fine for about 30 hours,before the internal temperature rises, the fridge seems to keep cycling but not cooling. Whilst I was away a bloke put some sort of meter on the solar panel which was putting out 14.2 volts. But the battery was down to 10+ volts. This chap had no idea what could be wrong. The battery is about 3 years old and I'm starting to think this could be the problem. I had the fridge checked out by the local Engel fellow who advises it is in perfect working order. Before I go and buy another battery I thought I would run it by you guys.
Anyone have any theory's?
Any input would be greatly appreciated.
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Post by empyrean on Jan 1, 2011 19:42:34 GMT 10
Hi Robbo,
A solar panel like that in the sun and not connected to anything should have an open circuit volatge of around 20 volts. If it doesnt then something is wrong with the panel.
!0 volts on a battery means flat/dead battery. The fridge will not operate correctly.
If the solar panel is connected directly to the battery then their voltages should be the same unless you have a bad connection somewhere.
If there is some kind of regulator in between the solar panel and the battery then that could change things depending on whether the regulator is allowing charge or not.
It seems that you have a flat battery. The cause could be either a faulty battery (dead cell), a faulty solar panel (low open circuit voltage) or a faulty regulator if you have one (not allowing the battery to charge), or a dodgey connection.
You could try and charge the battery with a mains powered battery charger to see if the volts come up and it runs the fridge.
If you have any other information that could be helpful in determining the fault.
Cheers
Martin
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Post by robbo3 on Jan 2, 2011 10:55:31 GMT 10
I've been watching youtube on how to test solar panels, been down bought a multi meter and tested in accordance with yt direction. The panel produces 20.1 volts in normal sunlight , it is then run through a regulator (20 amp 12v) the reading on this side is 14.4 volts The fridge isn't 60 ltrs as I was advised my brother during the sale but 32 ltrs ,the engel people suggest it uses .5 -2.5 amps max I assume per hour. I have removed the battery on put it on a charger and will take it to be tested tomorrow. But with my extremely limited knowledge of electrics, it looks as thought the battery will be the problem.
Thanks again for you assistance.
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Post by drylander on Jan 2, 2011 23:09:12 GMT 10
you will probably find out the fridge uses more than what was stated .... but even at 2.5 amps thats 751mps used means you pulled the battery too far down. You need to put another panel up so the battery doesn't drop too low as that will kill them.
Do a search for Collyn Rivers as he has some great books re solar for vans & motorhome about 45oxford scholars but very informative. Its Australian based as well
Cheers
Pete
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Post by Daggsey on Jan 3, 2011 0:31:26 GMT 10
Hi robbo3,
From personal experience, a couple of points:
1. What wattage is your solar panel? I'm assuming from the serial number you quoted it is possibly 85 watts......if that is the case, from annecdotal evidence (from gray nomads), your Engel shouldn't drain the battery in 30 hours.....it should last a few days.
2. A solar regulator is a must.
3. What setting have you got your fridge on? The higher your setting, the more power that is required. We were told in Mackay on our travels (when our Waeco was doing the same thing) that the fatal mistake that is made with fridges (portable & residential), is that people turn their fridges up when the outside temperature increases. This ices up the inside of your fridge, which in turn acts as an increased insulator and makes the fridge work overtime, subsequently requiring more power, which ultimately flattens a battery quicker.
We ran a 20 watt solar panel which struggled to keep the batteries charged. Having said that, we had 2 deep-cycle batteries wired in tandem. On the West Coast Spring Tour in October, we only had one battery and the solar panel seemed to keep up with that OK, which sort of proved to me that we were initially trying to expect too much from the solar panel.
Just my two roberts worth
Daggsey
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Post by robbo3 on Jan 3, 2011 13:08:02 GMT 10
Daggsey,
The solar panel is 85 watts,it puts out 14.4 volts after the regulator, I had the engel on about 5 from memory which is quite cold. It has flattened the battery ,I have recharged the battery and it now ready 14 volts. I will take this to a battery place tomorrow and have it tested. I have learned a lot these past few days about electronics I note I should have an in line cut off to stop the fridge at 11 volts , I will look into purchasing one tomorrow also.
I have a 30 year old finch three-way fridge that I run on gas when I get to the fishing destination that works a treat. The engel is mainly to transport to and fro and it's just about taken what hair I had left. Thanks for your assistance.
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Post by DC3Td on Jan 3, 2011 16:40:41 GMT 10
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Post by smiles on Jan 3, 2011 19:39:16 GMT 10
On the Propert's maiden voyage, we went to Flat Rock camp site which has no powered sites. We were in a relatively hot campsite in late Oct. We took our fairly new 40l Engel & a battery out of the ride-on to run it. The battery is about 45amp/hours. We had no solar panel but managed to run the fridge for almost 3 days on the battery & still start the ride-on first go on Sunday arvo when we got home.
How did we do it?
We put a frozen 5l plastic water bottle in the Engel right from the start, then set the Engel at just over 1 (setting "ref"). Setting 5 is "freeze" so you may have been trying to freeze everything & run the battery down, with the fridge running continuously. We turned the Engel off at night & then ran it for about 2-3 hours in the mornings & evenings. We opened it sparingly during the middle of the day when we had it turned off. It was just an experiment to see how little power we could use & still get a cold beer! In the future we'll have a solar panel to run the fridge. I've read that an 85watt panel should do the trick (apart from cloudy weather.
Oh yeah, we also ran 2 led lights no trouble on the battery.
Hopefully you've got the battery fully charged now & it will hold the charge in future.
Good thing about the Engels is the thermometer, no reason to freeze everything if you just want it to be a fridge.
Rob
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Post by robbo3 on Jan 4, 2011 13:02:04 GMT 10
I have just had the battery tested, my suspicions were correct it is 3 years old and the capacity is down to 55 amp hours.
So I guess this is a major part of my problem a new 95 amph battery is $259 or an american 105 amph which needs to be topped up is $290.
Something to ponder whilst I pay off some of the Xmas bills.
Once again thank you all for the day to day tutorials, I have learned a lot.
At least now I have some idea of what goes on.
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