Help Finding a high wattage/temperature 12 volt Element for Warming Oven

[Keith Brown]

Until I saw a 12v lunch kit suggested by "wdlfbio" (thank you wdlfbio) earlier on this site, we have use either our BBQ or stove top in the cabin to heat our dinner once we're on anchor. Our BBQ sets up easy enough but its in the way when we're fishing and the stove top requires a baby sitter. With a 12v hot box we could heating up dinner on the water and have it ready when we setting anchor for the night. The store bought "lunch kit" would work great, however we would like an oven for 3 fisherman. I have installed a 150 amp 12 volt plug. I'm pretty handy and would like to build my own Hot Box however I have come up empty handed on the internet. I would like to have a high output heater/s capable of 300 F. Any suggestions would be appreciated.
Thank You
Keith

 

[macro]

Wind your own. .. nichrome wire and a temperature controller. Or if thats to hard.. a couple of old school headlight 100watt headlight bulbs.

 

[zurk]

no point trying to DIY it.

Amazon.ca

 

[Alex_c]

You can also just get one of those 12V “coolers” and reverse the polarity on the wires. Turns them into a heater. Ask me how I know

 

[Keith Brown]

Wind your own. .. nichrome wire and a temperature controller. Or if thats to hard.. a couple of old school headlight 100watt headlight bulbs.

I didn't know that nichrome wire existed. I'm going to give it a try. I just checked it out on Google and it looks like it will work. I just have to figure out how to facilitate the heat transfer to the box. I'm assuming it has to be mounted on a non-conducting surface. If it's used in toasters it won't have a problem maintaining 300°f.
Thank You for the suggestion.

 

[Keith Brown]

You can also just get one of those 12V “coolers” and reverse the polarity on the wires. Turns them into a heater. Ask me how I know

If I'm not mistaken the coolers are only capable of 30°f ∆t (temperature difference) so the would probably not be able to heat food beyond luke warm. Unless you know of one that can get hot. If so please let me know.
Thank You

 

[Keith Brown]

You can also just get one of those 12V “coolers” and reverse the polarity on the wires. Turns them into a heater. Ask me how I know

If I'm not mistaken the coolers are only capable of 30°f ∆t (temperature difference) so the would probably not be able to heat food beyond luke warm. Unless you know of one that can get hot. If so please let me know.
Thank

no point trying to DIY it.

Amazon.ca

That unit has everything I need except it's too small to heat dinner for three. I looked at one that size at Canadian Tire and it looks like it would work great for one person. Durability is also in question. I'm going to try a figure out something that could fit three small bread pans with homemade meals.

 

[Alex_c]

If I'm not mistaken the coolers are only capable of 30°f ∆t (temperature difference) so the would probably not be able to heat food beyond luke warm. Unless you know of one that can get hot. If so please let me know.
Thank You

Unfortunately I can’t provide any hard data on max temp. It was hot enough to melt all the butter and require throwing everything in the cooler out. It would say it was warm, but not hot and not lukewarm. This was in the summer, in an air conditioned car. I definitely wouldn’t rely on it to hold food at a foodsafe temperature for a long time, but I would toss my lunch in there for an hour or so if I wanted it warmed up. There’s probably much better options out there.

 

[zurk]

or you could buy 3 of the smaller units and carry them instead. $60 x 3 = $180. its not going to break the bank and is safer than wiring up a 150A(!) 12V circuit.
i use 4/0 AWG for my 275A 12 V circuits so idk how you wired a 150A circuit anyway lol.

 

[Keith Brown]

or you could buy 3 of the smaller units and carry them instead. $60 x 3 = $180. its not going to break the bank and is safer than wiring up a 150A(!) 12V circuit.
i use 4/0 AWG for my 275A 12 V circuits so idk how you wired a 150A circuit anyway lol.

I thought of buying 3 ready made lunch box ovens. They are on sale at Canadian Tire right now, I even went and had a look at them. They're just to small. I have ordered the Nichrome wire in three different gauges and some flat strips as well. I'm going to see how it works on 12 volts. I have a 100 amp fusible link which has a high rupture current on my 2/0 plug. The unfortunate reality of 12volts is the current draw has to be high to produce any substantial heat. E.g.. 12Volts X 50Amps = 600watts X 3.42 = 2052 Btu's. It seems unlikely that even a 50 amp load can be sustained for an extended period without depleted the house battery even with a large outboard running at 700 RPM. I enjoy the challenge and the upside would be awesome to have a durable Stainless oven that works on the boat. Its a 50/50 bet at this point. I'm not going to bother building the oven till I can come up with an element that can heat a well insulated box/oven for at least two hours. When I got this brain wave to build an oven I thought I would be able to buy the element. That was my first mistake not my last. If I get the element figured out and working, welding up a insulated box with a tight lid wont be a problem. I always have the BBQ in the meantime. The wire and strips are coming from Asia so I have a while to dream up a plan of attack. LMAO
A couple of things I'm thinking about.
Question 1) What is the maximum permitted charging load on a 200 Mercury DTS running at 700 rpm.
2) If I do build a heating element that is satisfactory how and what non-combustible, durable surface could it be mounted on and how would I protect it from incidental damage.

 

[macro]

Refractory brick. Also. If its drawing to many amps.. make it longer its resistance will go up with length. There are online calculators. Also look into pwm. Then you have more than on off control.

 

[macro]

Also. Rockwoll between your layers of stainless sheet. Better you insulate between the stainless, the less the oven needs to draw power for.

 

[jim morrow]

I wonder what the boat surveyor and the insurance agent will think of these ideas?

 

[Keith Brown]

Refractory brick. Also. If its drawing to many amps.. make it longer its resistance will go up with length. There are online calculators. Also look into pwm. Then you have more than on off control.

Thank You for your awesome idea's. I was thinking of building a inner and outer stainless cabinet and separating them with small pieces of high density Styrofoam, then injecting 2 pound foam between the inner and outer boxes. I would do the same for the lid albeit a lot easier than the box's. But come to think of it just about every oven has a Rockwoll looking material for insulation. I would just have to figure out a method of separation for the boxes.

 

[Rain City]

Thank You for your awesome idea's. I was thinking of building a inner and outer stainless cabinet and separating them with small pieces of high density Styrofoam, then injecting 2 pound foam between the inner and outer boxes. I would do the same for the lid albeit a lot easier than the box's. But come to think of it just about every oven has a Rockwoll looking material for insulation. I would just have to figure out a method of separation for the boxes.

Why don't you just buy a used toaster oven and modify it?

 

[Alex_c]

Or strap a panini to the power head and call it a day.

 

[Keith Brown]

I wonder what the boat surveyor and the insurance agent will think of these ideas?

Like I said I have a 2/0 cable protected by a 100 amp fusible link which is part of the boat. Not so sure the appliance/stove would be part of any survey. Aside from the Survey and the insurance, I simply will not have an unsafe devise or appliance on my boat. If, pie in the sky this idea to build a 12V oven actually becomes a successful, operational appliance, I could always have it inspected and approved locally. Hey maybe I'll get ULC approval and sell them or better yet I'll buy a 649 ticket. LMAO

 

[Keith Brown]

Or strap a panini to the power head and call it a day.

Maybe your on to something. A lot of riders cook lunch on there Snowmobiles exhaust.

 

[Rain City]

Or strap a panini to the power head and call it a day.

Now you've got me thinking about strapping a warming box onto my Espar outlet. That thing cooks!

Mind you, I do have four burners, an oven and a bbq on board.

 

[Keith Brown]

Why don't you just buy a used toaster oven and modify it?

Can I get a toaster oven big enough to take 3 small bread pans? Plus toaster ovens get hot on the surface. I envision a stove that did not get hot on the exterior.