Solar Power/Batteries to run a caravan...
Submitted: Thursday, Mar 18, 2010 at 14:58
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Member - David J (VIC)
We have ordered an Off Road caravan. My biggest problem at the moment is choosing between a 3 way or compressor fridge. We want to be able to stop somewhere for a week and be self sufficient for power. No generators...
Any comments about the noise level of a compressor fridge in a small van?
Our power needs will be minimal except for the fridge (if we go with a compressor one). Just a pump for water and a few LED lights.
If we go with a compressor fridge it would probably be the Waeco CF110 with a rated consumption of 2.5Ah/h at 32 degrees. So assume 3 Ah/h for a total of 72Ah per day plus say, 10Ah for the rest, to a grand total of 82Ah. Call it 90Ah.
Question is, what battery and solar capacity do I need to keep that load from killing the batteries?
One suggestion was 1 x 130W panel per 100Ah battery and I tend to think maybe 2 x 100Ah batteries with 2 x 130W panels?
All suggestions and ideas gratefully received!
Cheers
Numb Thumbs ;))
Reply By: Mandrake's Solar Power- Thursday, Mar 18, 2010 at 15:21
Thursday, Mar 18, 2010 at 15:21
David ,
There is a neat
solar power calculator
here - Which will show you what that combination you mentioned will do for you ..
You certainly need 200 ah of Battery to be able to use up 90 aH without killing your batteries .. 90 aH of sun = 15 amps = 300 watts roughly..
But if you run out of sun - you're in trouble within 48 hours ..
Try the calculator out first and send me a PM if you need any help with it
Cheers
Steve
AnswerID:
409355
Follow Up By: Member - Scrubby (VIC) - Thursday, Mar 18, 2010 at 15:52
Thursday, Mar 18, 2010 at 15:52
G`day Steve & David,
David, I think your assumption of 72ah per day for the fridge is incorrect, 72 ah would be if the fridge run continuously non stop, of course it normally only runs about a third of the time, so I would think this figure should be 24ah.
Steve,....... Have another look at David's original post, I think he has that daily ah rate for the fridge wrong. My 80 lt Trailblaza only uses about 32ah... 35ah per day @ 5.? amps.
Please correct me if I am wrong.
I was wrong once before but that was many years ago. Hahahaha :>))
Regards,
Scrubby
FollowupID:
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Follow Up By: Member - David J (VIC) - Thursday, Mar 18, 2010 at 16:01
Thursday, Mar 18, 2010 at 16:01
I am going by the Waeco website - yeah, I know, never trust anything on the web! ;)) - but I have a Waeco 40 litre and the Waeco web site puts it at 0.87 Ah average, ans I have tested it at 0.86Ah so it seems fairly accurate!
And I would rather have too much power than kill the batteries in a few months of travel!
Cheers
Numb Thumbs ;))
FollowupID:
679308
Follow Up By: GerryP - Thursday, Mar 18, 2010 at 22:54
Thursday, Mar 18, 2010 at 22:54
Hey Scrubby - I thought I was wrong once too... but I was mistaken :)
Gerry
FollowupID:
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Reply By: Rangiephil - Thursday, Mar 18, 2010 at 15:31
Thursday, Mar 18, 2010 at 15:31
You could always get a fuel cell.
http://www.efoy.com.au/
They are expensive but are a great idea as they will top up the batteries automatically if the solar falls over.
Regards Philip A
AnswerID:
409358
Reply By: Battery Value Pty Ltd - Thursday, Mar 18, 2010 at 15:31
Thursday, Mar 18, 2010 at 15:31
Hello David,
the following figures are for a daily load requirement of 90Ah:
Your batteries will see a load demand of 60Ah during no or little sun.
A single 100Ah, will do this at a DOD of 60%, with no reserve for overcast days.
Add one 100Ah deep cycle battery for every additional day with no sun.
Solar panel:
to replace your daily 90Ah draw, you'll need a panel wattage of 433 Watts (taking into account a MPP voltage of 17.5V, 4 PSH and a battery charging efficiency factor of 0.9).
Pls note that your panel will have to face due north all the time, and it'll have to be mounted on an angle if you want to achieve this daily Ah figure.
An increase of 20 to 25% of panel output can be expected if the panel can be made to track the sun.
Hope this answers your questions?
Best regards, Peter
AnswerID:
409359
Reply By: Member - colin J (VIC) - Thursday, Mar 18, 2010 at 15:35
Thursday, Mar 18, 2010 at 15:35
Hi David,
I have just changed my 3 way fridge over to the Waeco CF110 The three way fridge does not cope in hot conditions and the boss was getting pretty cranky, but she is rapt with the performance of the Waeco. Very little noise with the compressor. I previously had a 100 watt panel and two 75AH batteries. They did not cope with the power requirements over summer so have added another 130 watt panel and changed the batteries to two x 130AH. No problems now. The 110 fridge is brilliant with a greater internal capacity for a similar sized 3 way fridge externally.
Regards from Big Col.
AnswerID:
409360
Reply By: gottabjoaken - Thursday, Mar 18, 2010 at 15:53
Thursday, Mar 18, 2010 at 15:53
David,
My inexpert view is that your fridge calculation is about on the ball, but the battery and solar sizes too light.
To support a compressor fridge you would need about a 150ah battery wired to the fridge only, and three 120/130 watt panels. The amount of solar there is not for the sunny days, but for the overcast and rainy days when you will need as much as you can get.
The other current draws would be ok with an 80ah battery - you didn't mention tv/dvd/sattv. If you are using those, then make it at least 120ah, with one 120/130watt panel.
Use two solar controllers, one at least being a Morningstar Duo to charge the fridge battery at 90% and the other at 10% from three panels, and the other using one panel to charge the house battery.
This way, you are not putting the batteries in parallel - poor practice - and getting the most out of the solar performance.
This approach will no doubt be howled down by the "experts" who run their Engel on a single 80w panel and an old starter battery, but at least you will have had the opportunity to think it through and seek advice on what consumption and what solar input you can really achieve.
ps. don't plan to draw a battery down more than 50% of its "capacity". ie, if your fridge is going to take 72ah in a day, and the sun don't shine one day, your 100ah battery will be slowly dying from that day on.
happy travels
Ken
AnswerID:
409361
Reply By: Member - David J (VIC) - Thursday, Mar 18, 2010 at 15:54
Thursday, Mar 18, 2010 at 15:54
In my case, SWMBO - and I! - are fed up with frozen lettuce and tomatoes on a cold morning from our 3 way fridges! You can
cook a frozen tomato, but a frozen lettuce is just a sloppy pile of green slime once it thaws!
How are your panels mounted - flat or can you angle them?
How about having to park the van in the sun to get the power to the panels? I'd be attaching the panels flat on the roof of the van and I have a spare folder panel to put out in full sun if I needed to. The panel has "6.67 Amps) on the baclk and claims to be a 120W panel but I have my doubts...
Cheers
Numb Thumbs ;))
AnswerID:
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Reply By: Maîneÿ . . .- Thursday, Mar 18, 2010 at 15:56
Thursday, Mar 18, 2010 at 15:56
Numb Thumbs,
If your "biggest problem at the moment is choosing between a 3 way or compressor fridge" then you have no problems at all ha ha
I use ~200 Watts
solar power and ~200 ah AGM Deep Cycle batteries and have no problems running a 70Lt Reefer Fridge/Freezer 24/7 with some lights etc.
I would not use anything under 200 watts solar for the CF11O and to make life easy you need a large battery capacity so 200 ah would be good, but 240 ah would be better.
Maîneÿ . . .
AnswerID:
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Reply By: Member - Ian W (NSW) - Thursday, Mar 18, 2010 at 15:58
Thursday, Mar 18, 2010 at 15:58
Comments re noise of a compressor fridge.
We run a 110 ltr Waeco in our small (14' internal), off road van. Whilst in bed on a very quiet night we can barely hear it. During the day with a little background noise I need to go outside to the vents to hear if it is running.
As far as batteries and panels are concerned. I originally went with 2 X 140W panels (thank you Mandrake), and the original 100 ah Calcium Calcium battery.
I was not happy with the depth of discharge on the one battery and had concerns as to battery length of life. When I was offered two 100ah VRLA's that had never been cycled in their two year life I jumped at it.
Our last trip was 15 days in February where other than one night at
Grafton we free camped the entire trip. We ran lights, water pump, fridge, range hood and watched a couple of hours of T.V. each night when we had reception. From memory the latest the batteries were back into float was just after midday after a morning of intermittent rain showers.
I merely recount our experience. There will no doubt be an expert along to tell you what you should do. Should you not feel comfortable with their advice just wait a while, there will be another with a flat contradiction.
regards.
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Follow Up By: Member - Ian W (NSW) - Thursday, Mar 18, 2010 at 19:30
Thursday, Mar 18, 2010 at 19:30
One point I neglected to mention.
Our van is of course fitted worth the ubiquitous Andersen Plug.
After fitting the Solar Panels the Andersen has been cable tied to one side. The only input to our batteries is from the solar panels.
Ian
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Reply By: Member - David J (VIC) - Thursday, Mar 18, 2010 at 16:04
Thursday, Mar 18, 2010 at 16:04
Ian
That kind of information is very handy. The real world tends be more helpful than theory and tables...
Our van will be 13' internal.
Cheers
David ;))
AnswerID:
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Follow Up By: Member - Ian W (NSW) - Thursday, Mar 18, 2010 at 19:40
Thursday, Mar 18, 2010 at 19:40
David,
Which ever fridge you go with, and I suggest the Waeco, there are a few little tips to improve performance.
Prior leaving
home pack as much as you can into the fridge and run it off your
home mains power for as long as you can to establish what I call, for want of a better description, a "cold bank".
If you don't fill the fridge use one or two litre bottles of water to take up any empty space, you will find much less variation in cabinet temperature by doing so.
Ian
FollowupID:
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Follow Up By: Member - David J (VIC) - Thursday, Mar 18, 2010 at 19:56
Thursday, Mar 18, 2010 at 19:56
Ian
Yes, I always run the fridge for at least a day if not several on 240 volts to get it nice and cold. I have also worked out that a full fridge works better than an empty one - thermal mass and all that. When i
test a fridge I do it empty to stress it as much as possible!
Cheers
Numb Thumbs ;))
FollowupID:
679347
Reply By: MEMBER - Darian, SA - Thursday, Mar 18, 2010 at 16:13
Thursday, Mar 18, 2010 at 16:13
Re the noise - our Vitrifrigo 2 door 150L compressor fridge can easily be heard running at night (mainly the cooling fan) but has never kept us awake. I was expecting it might be an issue (I'm often a light sleeper), but no. Re support - we have 2 x 130W Kyocera panels and 3 x 100Ah deep cycle batteries - yet to be properly tested in a static
camp scenario, but indications to date in mild sunny weather suggest the panels will have no trouble keeping up. Without any sun in cool weather, my solar calculator suggests the run down time to a safe low battery level will be a bit less than 2 days - then it's out with 1Kva gennie (situation allowing, that is :-o).
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Reply By: Member - DAZA (QLD) - Thursday, Mar 18, 2010 at 17:02
Thursday, Mar 18, 2010 at 17:02
We have not been on an extended trip as yet, only no more than a five days, at the moment we run two 120amp Deep Cycle Batteries which we use for the Lights/ Pumps/ Tv, and the Three Way Dometic Fridge and Hot Water System runs on Gas, as yet we have never ran out of power for our needs, and when I have checked the batteries on the Electronics Board in the Caravan Boot they have never been below half charge, the van is wired up for Solar, and we have the Gennie if we need it, when we go on an extended trip I will consider getting the Solar Panels installed, but at the moment our power needs are sufficent.
Cheers
AnswerID:
409373
Reply By: titl4 - Thursday, Mar 18, 2010 at 18:28
Thursday, Mar 18, 2010 at 18:28
David - sounds to me like you have it covered with enough in reserve. A variation to think about would be to upsize the batteries to 2 x 120ah AGM - more in reserve, quick to charge, but at a cost.
We have 2 x 85 w panels and 2 x 120ah AGM plus a 100ah calcium aux in the tug, 2 chest type compressor fridges (39 litre Engel + 55 litre Bushman), sat tv, LED lights etc. The batteries are also charged by the alternator when moving. In a month away the batteries never looked like dropping to 50%. On another trip with a few stationary days at over 40 degrees the fridges certainly chewed some juice but the panels 'just' managed to top up the batteries each day. (We can turn & tilt the panels but didn't need that extra sun). You're looking at 36% more input than us. A good solar regulator is
well worth the extra $$$.
We have a Honda generator but not having needed it in years no longer take it with us. If desperate we'll use the alternator but that hasn't happened yet.
Re fridges - we have had both 3 way and compressor. While both have advantages we won't go the 3-way route again. A big down side of course is the need to park in or at least near the sun when stopping for long.
Cheers ........ Alan
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Reply By: Wyoming - Friday, Mar 19, 2010 at 15:14
Friday, Mar 19, 2010 at 15:14
David,
For what it's worth, I would go with the compressor frige every day. I had a 80 litre in my previous camper and that was driven by 2 x 100Ahr gels. Power was monitored with a . During really hot weather, I could go for 6 days before the batteries were screaming for help and duribg those 6 days, the fridge cooled a lot of cans. Noise was not a problem at all - it gave out a rather comforting "hummmm", cycling on and oss during the night. I recently sold the camper and purchased a van.
The fridge in the van is another storey. It's a 160 litre 3-way fridge which is useless on battery, despite drawing 15 Amps. On a hot day, it's not much better on AC or gas. I'm so disappointed with it that I will probably pull it out and replace it with 2 x 80 litre compressor fridges.
Hope this helps - Neil
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Reply By: Motherhen - Friday, Mar 19, 2010 at 17:20
Friday, Mar 19, 2010 at 17:20
Hi Numb Thumbs
I have been away for a couple of days and thought i replied to you before i left.
I am surprised that an off road van manufacturer would consider a three way fridge, and it would be unusual to find one being built without a lot of
solar power.
With our previous camper, which we purchased when rather old, we threw out the three-way, put in an upright 12/240 of around 120 litres, one deep cycle battery, a controller and an 80 w panel put on a stand to put outside when we set up
camp. This ran the fridge and a couple of fluro lights. We had no pumps, television or chargers for phone and camera batteries in those days.
Solar power is of benefit to more than fridges - if gives you the independence which is needed for long term
bush camping.
Our fridge is virtually silent and cannot be heard running when in the caravan unless we open the cupboard door where the compressor is - sometimes even putting my hand on the box to feel for vibrations.
Our present caravan now has 4 x 130 w panels and 4 x 110 a/h batteries and regardless of the weather, batteries pretty
well maintain full charge; really overkill for what we use.
Motherhen
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