batteries and charging for camper trailers

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?

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

Maybe you started off with flat batteries.

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

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.

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.