Solar power

For a 40 l Waeco run at 4C full time and a couple of compact 12v fluoros we have 200 aH batttery bank. Does the job for 5-6 days off an initial alternator full charge. To extend the time beyond that experts advised a 120 w quality solar panel.

Depends if you are running the fridge as a freezer, or just all fridge.

If you are running it s a freezer then long term you need to keep food frozen at around minus 14 or so. This would sort of rule out shutting it off at night.

I have only got a 50 litre EVAKool that I run as a freezer and my 140 watt panel seems to handle that and the caravan lights with occasional telly OK.

I think your getting confused with amps and watts, batteries, are measured in amphours and solar panels in watts, the two are related but only distantly.

Solar panel rating base their output on the maximum achievable under ideal conditions, these conditions may only appear for a few hours a day and thats if your solar panels are tracking the sun correctly and are not off axis.

Assuming your 2.9AH fridge consumption is correct your using around 70Ah a day.

Again assuming your panels are 110W units and assuming you have bright sunshine at around 20C ambient then that's around 79Ah production and that will barely cover the fridge.

The above assume 100% efficiency which you won't have, if your in bright sunny condition for 10 hours a day then the ambient is most likely well above 20C and the panel will be producing well less than their 110W maximum, so bottom line is more watts required.

If your running the fridge as a freezer and don't wish to die from food poisoning I would suggest that you don't turn it off overnight.

Cheers
Leigh

Not sure where you got that 2.9 amp info. from (may be an ambitious average) but the Waeco 80 litre fridge freezer draws 7.5 amps, and with a duty cycle ranging from 40 to 70% (highest in hot ambient) you can expect your daily draw to be from 70Ah to 120Ah, the higher figure if using it as a freezer.
Whilst turning the unit off at night is feasible (the interior temperature if used as a freezer is unlikely to rise to dangerous levels) and may save a bit of battery overnight, you will still need to recover any gained temperature, and that will use the same amount of power.
This approach may work if you have excess solar capacity available to run the fridge during the day, but you don't.
The solar panel which I assume is a portable, can be expected to provide a maximum of about 40 to 50Ah per day provided you are very diligent about keeping it pointed at the sun. Expect the lower figure in hot weather.
So, at best the setup is down the drain by 20% and at worst by 80% after the first day, and it's all down hill from there.

Just remember that what you think is full charging off your direct alternator connection is highly unlikely to be so.
Direct alternator charging just does not fully charge remote/second batteries.
Sure, the initial charge rate is impressive, but have another look in twenty minutes and see what it is then and sure, at the end of the drive the terminal voltage may look good, but odds are that what you are seeing is only surface charge and the battery is far from fully charged.
The only way to ensure a good charge into that remote second battery is via a dedicated DCDC charger.

Once your research has you up to speed with the amp hours and watts etc., note also that the wattage figures on solar panels are their 'rated' output under perfect conditions...and such outputs are rarely achieved (70% of that rating is a realistic max). As for saving power at night...we often turn our fridge down a bit at night but run it hard during the day, as the solar comes in.

I travel quite a bit with a similar fridge/freezer.

I have never bothered with solar.

It is much cheaper just to run my 4wd for 15 minutes if the power in the second battery is getting to low.

I have set my fridge to run on a "low voltage" setting.

Hey escapesilv the best way to get the right information is not these forums, especially about solar panels etc, as you might have noticed lots of replies and no 2 agree.

Go to an auto electrician and speak to them as these people are trained in this field and can give you a no bullsh1t response the first time.

Phil

Hi
I had the same issue with my 80L
Run on -17 all day and -12 at night.
Have two accede batteries. 80a & 250a
Have just purchase a 195 foldable solar system and have no issue of getting absobtion with full sun in three hours

I am not technical as it took me 12 months to get this far as the conflicting information in surprising

I am also going to change my electrics to DC-DC

Hello guys, I went through this ordeal 12months ago. It was fun to get everyone's advice and I learnt a lot but in the end was getting nowhere and more and more confused! I found a good auto electrician, told him what I wanted to achieve ie what 12 volt items I wanted to run incl tv,lights,deep freeze/fridge ( Waeco) and PC. He set it all up and we have a system now that works. It cost about $300 for a separate cable from the car to the deep cycle battery in the Van,the battery itself, $250 and a 120'watt solar panel connected to the van $280. We haven,t yet ran out of power with careful use and the waeco keeps everything cold or frozen. My wife even has a hair dryer she runs for a few minutes!!! Go find a auto electrician that understands this stuff. It's a lot less stressful and in my case a bloody lot less confusing johno

Hi Rob - I Have had the Waeco 80 ltr for about 8 years now.

In the end this is what I needed to keep it running on Fridge/Freezer for extended times at rest in a camp no Alternator. In case of issues I have the Yamaha 1kva 4 stroke Genset and have needed it a couple of times because of Battery and Regulator issues.

I have 2 x 115 amh Deep Cycle Batteries specifically for the camper lighting and fridge (very few lights) - These have a feed from the alternator.

I run the fridge on High during the day when the sun is shining and turn it down to low overnight. I keep some type of insulation over the freezer being careful to still allow the flow of air to the fridge.

I have an 80w fixed Solar panel and a 120w folding panel which I move with the sun during the day.

This is the only way I can camp knowing I can run the Waeco 80 ltr, anything less and it just did not get there!

One full day and maybe a night I would get with only the 80w Fixed Panel and alternator Charge, mostly it would switch to fault low charge before the morning. Not until I added the 120w folding panel did I have success in running independant of a generator and alternator.

Hope that helps Regards Tony

Hi Rob,

I am far from technical, but below is what I have/used. I only used the solar panels for the first time over this Xmas break & I didn't run out of power at all. Used LED's most nights & the fridage was in the back of the ute with temps outside hovering around 28 degrees most days.

I have a 50ltr Waeco that I run on about minus 4, my 2nd battery is 110 amp/hr & my solar panel are 140 watts.

All the above posts are a tad confusing for me & it took me ages just to get the general gist of solar/amps/watts....

Good luck with it all!
Cheers :)

As mentioned, I am far from technical. But a few points;
My fridge was run at minus 4 as a fridge, not a freezer. When operating as a fridge/freezer it is set to minus 18.
Whilst 28 degrees is not that hot, that temperature increases dramatically inside a car sitting in the sun.
The above comment was made in relation to a 2 week stay where the car would have been lucky to have done 80km's
Yes, the fridge has a cut off and the dual battery an isolator.
I guess waiting for the "big trip", that does not include those already done (the Simpson x 2, Cape York & 3 weeks around SA ex Sydney), will test my system.
My post was not a recommendation, merely a comment on my current experience based on my set up and fridge.

Cheers,