waeco CB-40 /solar query (1 Viewer)

[scotzsue]

I have, in my new to me doblo camper, the above fridge only have one leisure battery, but it only needs to run the internal lights all low energy.
Battery is 85amp. Believe the drain from the fridge is pretty high and i really want to go off grid, well to fun rallies, what is the best way for me to keep the battery topped up. it is fully charged according to voltmeter and charges when hooked up ok.
How much solar would I need to keep it going and would a crocodile clip to battery be enogh or do i need a regulator as well. power management system is a PMS 3V

 

[Theonlysue]

If battery is 85 amp all being well, you have half availabke, say 42 amps.
Fridge uses 3.75 amps an hour.
In 10 hours 37.5 amps, max.
Doesn't give you a lot left.
You may need extra batteries as well as solar.

 

[tonyidle]

It depends on a number of things: how many days / nights off EHU; do you camp off-grid in late Autumn, Winter, early Spring; etc. My view is that you will need as much battery capacity as you can fit and as much solar as you have room on the roof. You will need a regulator and given your need to maximise solar it should be a decent MPPT device. Or a generator ..................

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[scotzsue]

It depends on a number of things: how many days / nights off EHU; do you camp off-grid in late Autumn, Winter, early Spring; etc. My view is that you will need as much battery capacity as you can fit and as much solar as you have room on the roof. You will need a regulator and given your need to maximise solar it should be a decent MPPT device. Or a generator ..................

got one of those, but takes up too much room, is smelly, heavy and noisy, think I would prefer to leave fridge switched off
Thanks for the calculation chart Theonlysue but it wont be running constantly surely.
this is a tiny van and we manage with 1 battery and 160W solar for the coachbuilt. (except sometimes in winter for the diesel heating)
Think it will be frozen milk and water a few cool blocks and warm beer.

 

[Lenny HB]

How much solar would I need to keep it going and would a crocodile clip to battery be enogh or do i need a regulator as well. power management system is a PMS 3V

Don't even think about using croc clips unless you are planning to turn your van into a bonfire dangerous things.

Any panel above 10 watts needs a regulator.

The spec and manual on your fridge only gives power input at 45 watts it does not give power over 24 hours. Someone with a compressor fridge will know the right answer but if we took a guess and said it ran for 20% of the time 216 watts over 24 hours approx 17 a/h. If only using lights you could probably survive for 2 days just on the battery if it is fairly new and in good condition.

With your size van you will never get enough solar on the roof for winter use.
A 100 watt panel will be fine in June but nowhere near enough in April or September unless you get loads of bright sunny days.
Just fit as much solar as you can get on the roof and buy a good quality MPPT regulator either a Votronic or Victron.

 

[Misterg]

we manage with 1 battery and 160W solar for the coachbuilt.

160 W of solar and a decent MPPT controller has been running our CRX 50 fridge constantly since March (uk). A few cloudy days and the batteries don’t fully re-charge, which suggests that this is about the minimum you could get away with. A bigger battery bank will give you a better buffer against higher than expected usage or a run of overcast weather.

The fridge uses a lot more power in sunny weather when the inside of the van gets hot - something like 40AH per day, so you’d need to keep a close eye on your 85AH leisure battery and make sure to top the charge up with driving or EHU if solar alone wasn’t doing the trick.

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[scotzsue]

Thanks for all the information and input folks, knew that these fridges take a lot of juice but hadn't realised it would be that much. There is enough room on the roof for one or 2 good sized panels, but not sure i will use the van off grid enough to justify the expense, it will also take it over the 2.1M height limit unless I can find some paper thin ones. suitcase solar and regulator is a possibility I caan barely lift our genny so wont be using that, even if I could put up with the smell. will just need to try the van off grid and see how i fare.

 

[Lenny HB]

Have you got space for a 2nd battery as that might be the cheapest option to give more time off grid.

 

[DBK]

We have a compressor coolbox of a similar size and as already mentioned it won't run all the time. If it's cool outside it might run for 5 minutes then sit silent for 15 but it will run almost constantly when you load it with stuff which isn't already cooled. A three litre box of wine has ours running for at least four hours.

I suggest just give it a go and see how you get on. Ours has a low voltage cut-off and this prevents it flattening the battery. Yours might as well. You could also try turning it off when you go to bed to save further power.

Until you've given it a go you won't know if you need solar, you probably do and the flexible panels are very thin but aren't cheap. A good MPPT regulator is essential. I would avoid the suitcase options, too much hassle and they take up internal space.

On the plus side compressor fridges just shrug off hot weather. We have a small gas fridge and the compressor cool box. Guess which one gets the responsibility of keeping the wine and beer cooled in the current temperatures of high thirties in France at the moment?

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[scotzsue]

DBK wanted to like and thank you for the post, not really got enough room for another or even a larger battery. think the try it and see is a good idea, but don't think a 5 day rally is a good tryer outer might still go ahead if i can persuade a fellow camper to freeze a couple of blocks for me each day, seems to keep stuff fairly cool even when switched off. It does cut out if level gets too low. Can always use a torch for lights and drink warm beer.

 

[scotzsue]

Have, after a bit of testing, discovered that the on/off temperature switch wont turn off. Put it to zero and it flicks back to 1 GRRR nothing in manual helps. It was a lovely 11 in the fridge while inside van was 26.5.
Bonus I know it works.