batteries and charging for camper trailers

Submitted: Friday, Apr 09, 2010 at 12:50
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I have just spent 5 days away in my camper trailer, I carried 2 x 70w batteries and a 120w solar panel. Running a waeco CF 50 fridge and 2 x 1amp flours. flours where only on for 3 hours every night my fridge on low about -4 degrees. During the day my solar was plugged into the battery with good sunlight and getting around 4-6 amps which I thought having 2 batteries I would have heaps of power. Well no it let me down.
Could anybody have any suggestions on how I can operate my system over this period of time

Thanks
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Reply By: Member - Jeff P (SA) - Friday, Apr 09, 2010 at 13:07

Friday, Apr 09, 2010 at 13:07
A couple of questions, by 70w do you mean 70 amp hour batteries? and are they deep-cycle batteries?
You would need to know how much current your fridge is actually drawing while it is running, waeco claims less than 1 amp/hr @ 5 degrees, so in theory your fridge should run for at least 100 hours nonstop on your batteries without recharge. Why do you have yours at -4 degrees? are you using it as a freezer? it will use more power at that setting by running longer. Are you sure your solar panel is actually charging the batteries?
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Follow Up By: PHayes - Friday, Apr 09, 2010 at 15:56

Friday, Apr 09, 2010 at 15:56
Thanks Jeff

Yes I do mean 70amp, the fridge will draw 4.5 amp/hr while running @ 4 degrees thats the info from waeco.
I was running the fridge @ -4 degrees as I had frozen meats to try and keep, but I was told that this was to high and yes would pull to much juice out of the battery. the solar panel was putting into the battery as I have a monitor fitted to say what I am using and what the solar is putting in

Cheers Paul
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Reply By: Mandrake's Solar Power- Friday, Apr 09, 2010 at 13:48

Friday, Apr 09, 2010 at 13:48
I have the same fridge , a 140 watt solar panel on the roof of my Jeep and a 100 aH AGM to power it ( No lights ) this set up works very well until you get 4-5 days of cloudy rainy weather ...Otherwise it lasts as long as the sun shines !!
The CF50 at -4 is probably using 3.5 - 3.8 amps while running which it problably does for 20 minutes every hour --
Maybe you open the lid too much ? ;-)

Cheers

Steve

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Follow Up By: PHayes - Friday, Apr 09, 2010 at 15:58

Friday, Apr 09, 2010 at 15:58
Thanks Steve

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Reply By: Moose - Friday, Apr 09, 2010 at 14:01

Friday, Apr 09, 2010 at 14:01
Maybe you started off with flat batteries.
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Follow Up By: PHayes - Friday, Apr 09, 2010 at 15:59

Friday, Apr 09, 2010 at 15:59
Moose thanks,
The batteries were fully charged
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Follow Up By: Moose - Friday, Apr 09, 2010 at 16:09

Friday, Apr 09, 2010 at 16:09
Absolutely sure? Sometimes they can appear charged but aren't full - use of a multi-meter can fool you. If they are wet cell you need to use the "turkey baster" on them to be absolutely cerrtain. If sealed then I don't know how to check.
Assuming they were fully charged at the start then you are losing heaps of power somewhere. Fully charged at start plus heaps of sunshine should have kept them charged for the duration.
You never said how they let you down.
Have you had them load tested since you've come back? Maybe one or more dropped a cell during your time away!
I suspect we need some more information here to solve the problem.
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Follow Up By: Glenndini - Friday, Apr 09, 2010 at 16:35

Friday, Apr 09, 2010 at 16:35
From what you have written you have 140 aH of battery and in 24 hrs you run 2 x 1 amp lights for about 3 hrs, 1 x 4.5 aH fridge for 24 hrs.

That means you are consuming something like 114 aH in 24 hrs.

Your panels running at 6 amps for say 12 hours gives you a maximum of 60 aH recharge every day.

You are therefore running at a deficit of about 50 aH per day. More out than in.

After 3 days you wouldn't have much if any charge left.
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Follow Up By: Maîneÿ . . .- Friday, Apr 09, 2010 at 19:01

Friday, Apr 09, 2010 at 19:01
Glenndini,
no, the fridge and lights use ~42ah per day (24 hours)
with ~50 going in, there is some power added to the batteries daily.

Why the batteries go flat is not because of the 'maths' but maybe the cabling, regulator or the batteries are not holding their charge for other various reasons.

Maîneÿ . . .
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Follow Up By: Glenndini - Friday, Apr 09, 2010 at 19:54

Friday, Apr 09, 2010 at 19:54
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Follow Up By: Maîneÿ . . .- Friday, Apr 09, 2010 at 20:11

Friday, Apr 09, 2010 at 20:11
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Follow Up By: Glenndini - Friday, Apr 09, 2010 at 20:17

Friday, Apr 09, 2010 at 20:17
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Follow Up By: Maîneÿ . . .- Friday, Apr 09, 2010 at 20:28

Friday, Apr 09, 2010 at 20:28
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Follow Up By: Glenndini - Friday, Apr 09, 2010 at 21:16

Friday, Apr 09, 2010 at 21:16
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Follow Up By: Member -hamo (NSW) - Friday, Apr 09, 2010 at 21:32

Friday, Apr 09, 2010 at 21:32
Glenndini no need for that rubbish
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Reply By: Staffee - Friday, Apr 09, 2010 at 16:17

Friday, Apr 09, 2010 at 16:17
You really don't need to keep your meat frozen when going away for 5 days, I throw it in frozen and let it defrost over time. I run an engel set on fridge and the thermo usually runs between 1 - 3 degrees, if you are worried about your meat and are going away for longer you could get it "vacuum sealed" by the butcher.

120W solar panel charging for say 10hrs of effective sunlight at best, recharging 40-60 amps a day into batteries. Your fridge set on freezer pulling as you stated around 4.5A at -4 for 24hrs 108Amp/hr + 6amp/hr lighting at night pulling a total of 114Amp/hr a day, you can start to see why the setup was failing.

You could always turn the fridge off at night (i admit works better in winter :) to save a little power. If you intend on using the setup then maybe you need a generator style charger, but even if you get a decent 12Amp one you would still need to run it for 10hrs a day to keep up with demand....

If they state that at 5 degrees it pulls 1 Amp I would be setting it around that or a little lower myself, then your system would be pulling 24Amp + 6 totallying 30A which is way more manageable for your system.

Regards
AnswerID: 412268

Reply By: Alloy c/t - Friday, Apr 09, 2010 at 16:41

Friday, Apr 09, 2010 at 16:41
Do the math , your cf50 will use around 48amp hrs per 24hrs and you are using 6 amp hrs per night for your lights = 54amp hrs from your batts total of 140amp hrs , your recharging at peak sun hrs =36/40 amp hrs in 24 so your at a deficiet of a minimum 14 amp hrs per 24 hrs, 14x5days = 70amp hrs from 140 = batts only 1/2 charged,,,,, shifting the panel 5/6 times a day to get absolute peak power allday every day is 1unpractical way , another panel is another , ,,, yamaha or honda +25amp ctec another lol.
AnswerID: 412271

Reply By: Steve and Viv - Friday, Apr 09, 2010 at 19:40

Friday, Apr 09, 2010 at 19:40
We have a CF 60 that we run at -1. We don't freeze our meat, we use a sunbeam vacuum seal device and get 2 weeks out of a steak at that temp so maybe look to do that as a side option.

We have a 105 ampH deep cycle battery and with out the Solar we get 3 days out of the 60. Are you confident that your wiring loom is up to scratch? You may only be loosing half a volt but that will rob you half to more of a day.

Also make sure you don't top drinks up during the day if you can help it. The fridge inside temp will rise to high and depending on the model may run in turbo mode until it gets down to close the set temp. It is an automatic thing that try's very hard to lower the temp. You can also turn it up a bit over night as you don't need beers at 0c at midnight - do you, maybe you do :-) Then turn it down again in the morning. I also turn it all the way down if going for a short or an hour or so drive, even if it means you get a bit of ice on a beer. Then turn it back to your set temp back at camp

With the solar (85watt) we get about a week but we do go for day drives so that helps. You must move the panel around and follow the sun to get the most out of the panel.

For example. We spent the weekend at Cape Laveque and it was 37 in the day and 31 over night. Our CF50DZ run fine for the 3 days of 156ampH at -14 and the CF60 Ran fine for 2 days off 105ampH. I then had to put the 60 on my 40ampH Power Tank while the solar panel did it things. The 6o is the drinks fridge as was used a lot down on the beach with 4 adults and 2 kids in and out.
AnswerID: 412286

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