Introduction: Off-Grid Tealight Slow Cooker
This idea is about as simple as they come, and a few people
will doubtless read this and think “duh… bit obvious”, but the idea for this came from a conversation about whether it was possible to power a slow cooker from an off grid 12V setup (the answer to that being “yes, but it needs a lot of batteries”). Which got me thinking of alternative off-grid ways of slow cooking, which in turn led me to the question “what would provide a low level of heat over a 6-8 hour period?”.
The answer is of course: Tea-lights – those pesky little things that clutter up a draw or cupboard for 99% of the time, until that one occasion you have a power cut. They burn steadily and reliably, and they come in all manner of burn duration times from 3 to 10 hours.
Anyone who’s done any hiking or camping in the UK will have come across the Trangia – it’s a brilliant all-in-one stove & pan setup that runs on meths; when cooking the pans nestle in a sort of container-cum-windbreak, and I thought that type of design would be a good place to start for building something that was solid, capable of handling a large stock-pot (with about 7 litres of capacity), and would provide sufficient shelter for what boils down to a candle-powered cooker.
I know this is by no means the only way of doing it, and I suspect this isn’t the best way of doing this, but the principle is sound and I’ve used it to make a slow cooked meal so I can claim it does genuinely work
So on with the guide….
What you’ll need:
· A stock pot to cook in
· Screws / nails / wood glue
Step 1: Size & Plan Your Build
What size stock pot you go for informs your build. My stock
pot had a 24cm diameter, so I settled with a design that would be about 30cm x 30cm and about 8” deep in total. I was also wanting to use materials I had lying about in the shed so decided to use some butchers block workstop offcuts, and a length of 6” wide dressed pine; though what you use is of course your own business.
Step 2: Build a Box
This can be as simple or as complicated as you want to make it. For me I used butchers block worktop as the top and bottom of the box, and used the 6” timber as the sides, and glues & screwed the whole thing together. From there I cut out a 24.5cm diameter (the diameter of the stockpot plus a little extra) circle in the top of the box, and screwed rubber feet to the bottom for reasons I’ll go into next. The height of the box was specifically set up to ensure that once the tealights were inside the box, the base of the stockpot would be about 2-3cm above the tealight where the flame was hottest (the stockpots handles rested on the top of the box to stop it dropping all the way through – see the pictures if you’re not sure what I mean) . Once the box was built, I sanded down the rough edges and gave it a coat of woodstain to pretty it up a bit
Step 3: Make It Candle Friendly
Remember the fire triangle from school? To function, a fire needs 3 things: Oxygen, Heat & Fuel; and the same is true of a candle-powered cooker. Setting aside the heat & fuel elements, the key thing we need to ensure this works is a good flow of oxygen, handily provided in every-day air.
To ensure good ventilation I pulled out the drill and put a series of 2cm holes in the underside of the box along 2 sides of the box, because the box would be off the ground due to the rubber feet I’d fitted, this meant air could be pulled into the box from the underside. I also got the holesaw out and put a 38mm hole in the side of the box, in the corner “opposite” the centre of the right angle of holes on the underside. Inside that hole I fitted a 40mm 12v pc ventilation fan, the logic being that once running that fan will draw old stale air out of the box and allow fresh air to be drawn in via the holes on the underside. The fan was then connected to a 12v power source and was good to go (and before anyone asks, I went for 12V as it would be easier to get off grid, also it would be a slow draw of air and less like to cause the candles to go out).
In fact on my first test cooking I had 6 tealights running and there was no need to run the fan, but possibly if you run a lot of candles it may become necessary
Step 4: How Many Tealights?
This is a little bit of trial and error – a slow cooker will normally cook at anything from 70 to 85 degrees C. so you need to have enough candles to get up to that temperature quickly, and then keep it at that temperature. For that reason I went – for my first slow-cooked meal – with a mixture of 3 hour and 10 hour tealights; all lit at the same time. The logic would be that the use of additional shorter burn tealights would help get the temperature up to 70-80, and then they die out and the remainder keep the stock-pot hot and slowly cooking. However how many you need will depend on what volume of water you’re using, so a little bit of trial and error may be needed (or you can just cheat and boil the water via some other quick method!)
Step 5: Cooking on Candles
With the box assembled, it’s time to get cooking.
For my first attempt I took the cowards way out and went for a vegetarian meal on the basis that if it didn’t work, and since it would be unattended, it wouldn’t cause me to be running to the toilet all night.
My recipe involved a litre of stock, and a lot of veg, so I peeled & chopped, put the whole lot into the stock pot, and settled on 3 x 3 hour tealights, plus 3 x 10 hour tealights, this just about worked as planned in terms of getting the temperature up quickly, and then maintaining it for 8 hours of cooking (I was at home so did the odd check on it during cooking) – at one point before the smaller tealights died out the temperature got up to just over 90 degrees C. so I can confirm that cooking meat should be fine (though I’ll not be held responsible for any undercooked meat and subsequent brown rain).
The tealights kept the whole thing at temperature until dinner time, and everything was fully cooked and tasted (as far as I was concerned) really nice. Next step will be some pulled pork.
So that’s about it – simple, effective and does the job. You could probably put some sort of cover over the box to help keep the heat in and keep the temperature up – more of a concern if you’re cooking with meat, but hopefully it’s given some food for thought.