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geoffbeaumont

Running an Electric Cool Box in Camp

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Okay, I’ve done a bit of searching and found various related topics but not quite what I’m after.

When we’re camping we use an Outwell electric cool box - it’s not a proper compressor fridge or anything like that, but it can be cooled off the mains before leaving and be kept cool in the car off 12V.

However - it’d be nice to be able to run it in camp rather than having to keep changing cool packs (if the site offers that), and using a good deal of the space for them. 

I’m trying to figure out what the most economical setup that would actually work would be. I could just hook it up to a decent sized leisure battery, but even with the box in eco mode (at least as good as cool packs) I’m doubtful how long it would last. It doesn’t help that I can’t find much info on how much current the box will draw or what percent of the time it’s likely to run (the latter obviously depends on conditions).

Hooking the battery up to a solar panel seems a good plan (it’ll be generating when the box will be running most), but I know very little about the electronics needed to manage it. What would be a decent solution for this?

Obviously, on some sites we could just pay for an electric hookup, but I don’t think 240V electricity has any place in tent unless it’s all proper IP65(?) rated.

There are off the shelf “solar generator” systems designed for this sort of thing - but they’re rather expensive to take a punt on without being sure they’re up to the job, and they also all come with mains inverters (see above, unless they can be safely disabled).

I’m not expecting anyone to do my homework for me, but some pointers / relevant experience to get me going in the right direction would be appreciated!

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we manage to keep euroengels running from batteries for 72 hours for the MOD with medical supplies , if running from battery keeping it closed as much as possible is vital, I will look at the battery size tomorrow

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I have a split charge system in the 110 to a second leisure battery (At present a very small red top racing battery). With the current battery our Waeco (25ltr) will run all night and into the next day no problem. When we had a 110 ah battery in there it would run for a 3 day weekend no problem. 

Mike

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My Waeco CF40 (compressor type) will do a long weekend on the Numax battery which I think is the 70 or 80ah one from memory.

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Posted (edited)

We ran a Waeco coolbox for many years. Initially this was in a car off the engine battery and then from a dual battery system with a split charger, Without a doubt the current drain depends on the ambient temperature as the hotter it gets the more the unit has to work. In hot camping we could only keep running for 24hrs without risking flattening the car (which we did a couple of times). With the split charger we would run until the cut-off ( which was around 11volts I think). This can still be only two or three days in hot weather.

When the unit is fully running you might be drawing 4A. Ours had two fans, one to cool the Peltier junction and one in the cold space. Eventually I played around changing fans to try to reduce current and sound (they are quite noisy and in a tent this can be disturbing as they cut in and out).

It's obvious but you need to keep it in shade which isn't always easy. We carried a piece of silver bubble wrap to protect it from direct sunlight and that is really effective.

I would definitely run a power cable to it if you are staying for any length of time and not intending to move it back into the vehicle for a top-up charge. There nothing wrong with using a waterproof power socket but the issue then is that if there is wet weather you will want to put the unit in the tent. If it's hot as well then you have the problem of high ambient temperature. These units can only reduce the inside cold space to 20deg C below ambient and that's the theoretical best. 

If you do pay for camp electrical hook-up then take a small kettle too and make that €4 / £4 daily payment more useful by saving on gas.

Two batteries and spit charge is a better system but then you run the risk of damaging the second battery through under charging. A normal split system will connect the two batteries in parallel and they will never both fully charge. One of them will suffer and eventually will lose capacity due to this problem of never quite being charged-up. Lots of people will now say that they don't have this problem but I'm going on my own knowledge and reading around the subject as it has been an issue for me (compounded by a slightly low output from my alternator).

A solar panel would solve the problem and I would have thought that a fold-up 100W connected to your second battery will give you longer service at the camp site and the split charger can help to replenish once you get back on the move.

Without a doubt the single best thing I did was to buy a compressor fridge combined with a 100W solar panel and a little box of electronics that handles the panel and both batteries. On our recent trip around Spain we didn't even take a mains cable. That was the first time in many many years!

By the way, fit an rccd trip inline with the mains cable up near the plug. The same style as you get with garden equipment. Don't use a plug-in one as there often isn't room in the connection box. Also get a yellow or orange cable so you can see it and make it a long one. It doesn't have to be a big current size.

 

Edited by Peaklander
Added last paragraph

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The none compressor cool boxes I've had in the past were peltier type (the cheap ones). It's basically an electronic device which uses a current to create a heat difference across it. One side has a heatsink and fan to get the heat away and the other has the fridge. Mine didn't have thermostats they ran all the time and were capable of achieving a certain temperature below ambient. Due to this the current draw was fixed, it doesn't go on and off with demand, so if you measure it you can get an idea of how long it will last. There is another type of none compressor cool box with a gas in it but I don't know much about how they work.

As for solar I put a 10w panel on our van as it doesn't get used much and the tracker was flattening the battery. It's enough to keep up with the tracker in the summer but does struggle in the winter. You have to make sure it's parked facing the right way. I went for this as it was the biggest I could find without needing the expense of a charge controller at the time. There are calculations online to help you size your solar panel once you know your demand, if it's just for camping I would assume it's going to be used on long summer days only :lol:

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Yes I am referring to a Peltier coolbox too but mine has two "cycles". There's a "coldness" setting but usually we had it set to coldest. Only on cool days did we reduce this setting. It was / is a lot more costly than others but far more effective than the first ones we tried. It sits on a low fan setting and depending on heat load / temperature measured in the cold space, it then switches to a much faster fan speed periodically and then that draws the bigger current. This duty cycle gets more and more demanding on the battery with increasing ambient temperature The second fan only runs when the lid is closed and I assume that runs constantly.

I'd still recommend an electric compressor type though (not the big gas ones unless you don't mind carrying gas too), if you can justify the spend. The difference is night and day. You don't need a big one. We have a 35l Waeco chest type and it's amazing what you can get in.

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I think the key is to keep a look out for a second hand compressor type. You should get one for not a lot more than the cost of the extras to run the peltier type off grid for any period of time.

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Or you can get one of the 3-way (inc gas) powered boxes, like this:

https://www.leisureshopdirect.com/caravan-accessories/cool-boxes/electric-cool-boxes/dometic-combicool-rc1200-silver-grey#ppSales[iframes]/0/

Gas can be much more efficient, I can run a much larger fridge/freezer and cook from a 4.5Kg butane bottle for around 10 days.

You'll always be fighting a losing battle trying to run a fridge from 12V, when not getting topped up by an alternator regularly, if the box you have is anything like this, it is suggesting you just run it on 12V when in the vehicle:

https://www.leisureshopdirect.com/outdoor/cool-boxes/electric-cool-boxes/outwell-ecocool-slate-grey-24l

Most of these things run around 8 amps, which is pretty juicy, getting a solar set up to cope with that, in light cloud, will be tricky, and rather large.

Compressor fridges are great, run around a quarter the current, so much easier to keep going, but are four times the price.

 

 

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A. How many amps does the thing draw on average?

B. How long do you want it to run for?

A x B = Size of battery in Ah that you'll need.

If you want a solar panel you need to go for one which is ~10x the power (in watts) required. Non-compressor coolers/fridges are very thirsty, it may pay (in convenience) to buy an expensive compressor fridge which can run from a standard battery for days rather than cart a huge solar panel + big battery around.

TBH though, IP rated mains hookups for tents are cheap and plentiful, might be the path of least resistance and will be guaranteed to keep the beers as cool as possible.

 

We have an Waeco CRX50 in the ambulance, 100Ah battery and 100W solar panel and that is fairly self-sustaining, but the CRX50 draws just 1.2A/h average which is a fraction of a non-compressor type. I've not done a proper write-up of it yet though...

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2 hours ago, FridgeFreezer said:

TBH though, IP rated mains hookups for tents are cheap and plentiful, might be the path of least resistance and will be guaranteed to keep the beers as cool as possible.

IP rated hookup is cheap - but the cool box itself is not remotely water resistant...

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20 minutes ago, geoffbeaumont said:

IP rated hookup is cheap - but the cool box itself is not remotely water resistant...

Do you not have somewhere in the tent to have the fridge? (Ideally not inside the closed living area as these can get toasty warm in the sun....)

Why are you so far away.... You could borrow our Dometic CFX50W fridge if you moved closer !!

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24 minutes ago, geoffbeaumont said:

IP rated hookup is cheap - but the cool box itself is not remotely water resistant...

Is your tent not waterproof :unsure: 

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9 minutes ago, landroversforever said:

Is your tent not waterproof :unsure: 

Usually - we have had water driving in the vents at the top in a storm. It was some of the worst conditions I’ve ever camped in though... :blink:

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3 hours ago, Bowie69 said:

That’s the one - yes, just a relatively (as these things go) cheap peltier type.

Sounds like I need to rig something up and see what it actually draws in eco mode. Shouldn’t be hard to find out the current draw - how much of the time it’s running is going to be a bit of a drag, I’ll probably have to sit there with a stopwatch. Don’t think I have anything that’d log that for me.

Then I can decide whether it’s worth rigging something up to power it or whether I should can the idea and start saving for a proper fridge :)

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For logging, a Raspberry Pi Automation HAT has 3x ADC's, you could measure the drop cross a low-ohm resistor to get a rough idea of current, plus straight voltage.

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So that Model
States an energy use of 73kWh/Year (it's in the picture of the standard energy efficiency label)

Some calculation so this is 0.2kWh a day or 200Wh a day (* there are some gross assumptions here but about voltage conversions but Wh sort of removes that)

So https://www.campingandcaravanningclub.co.uk/helpandadvice/technicalhelp/solar-power/

States that a 50W panel generate 300-350Wh  a Day in summer (less in winter, but then less cooling would be needed in winter)

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