Touring - Light, Rechargeable, Compact -- Microwave Ovens for Touring?

Microwave ovens on tour.

Why?

They are

-energy efficient

-unusually quick

-silent

-odorless

-free from fuel (and refueling) requirements and restrictions

-clean

-light (potentially)

-versatile

-hackable

-fun to use


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At first, I didn't like them at all. My early experiences were rather skewed toward the bizarre (including sparking chestnuts, unusual smoke, bright internal electric arcs, and explosions). However, since then -- and as I have used them more, and learned how to use them more appropriately -- I find that I really like them more and more.

Also, I got over some microwave scare propaganda and rumours I had picked up along the way.

[Plus, I was overdosedly microwaved by a rogue chiropractor, and after that I got used to being around a few minor exposures without a lot of concern....]

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One idea is to find a microwave oven that is battery operable.

A compact, lightweight one.

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Another idea is to use a small, lightweight inverter.

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Batteries could be recharged using electrical outlets, whenever available (the oven could also be used directly from these outlets, when appropriate).

Solar chargers could also be used. And hub generators are an option.

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The microwave ovens I've seen do not use a lot of electricity. They cook many sorts of foods in a very short time -- unusually short -- the shortest time by far of the various available cooking techniques.

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Another idea is to hack an old microwave -- one that is sitting around, or one from a yard sale.

The outer hull could be removed, and the microwave generating unit could be isolated.
[...with appropriate precautions] [a custom, lightweight-compact, foldable or collapsible hood could be devised]

I wonder how compact one could make it?

Are you serious, or is this post a joke?

Anyway, all the microwaves I've seen run off of 600-1200 watts of electricity. This is a lot of juice and it's unlikely that you'll be able to power one with a battery for any length of time, unless you carry a staggeringly heavy array of batteries around with you.

You're kidding, right? A typical consumer microwave consumes on the order of 1,000 watts of power, ±40% of that needs to be dissipated as waste heat. While I'm sure you could find a smaller magnetron, the risk of stray microwave energy, stray high-voltage electricity needed to drive said magnetron, and the possibility of exposure to beryllium oxide in some magnetrons far outweighs any purported benefits.

If you're set on cooking food with electromagnetic energy, get a solar oven.

Undaunted by misunderstandings (;))and assorted 'impossibilities,' we will forge on.:)

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...An initial Google search revealed some patents for battery operated microwave ovens.

Some of them are very compact.

Even an oven that would only hold a two-quart microwavable container would be quite useful and versatile.

[Which reminds me: No metal cookware necessary. Some microwavable containers are extremely light.]

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Not a troll.

Not a joke.

That's what they all say at first -- many unfamiliar ideas are met with these sorts of reactions in the beginning.


[Okay, there may be some undercurrents of humour; but the main theme is quite transparent and above board.]

I have a hard time seeing this as viable without outlets. There are outlets at most campgrounds, but I don't see a lightweight means of doing it with batteries. Just a small microwave you could use at a campground sounds reasonable to me.

Rent a motel room with a microwave and there it is.

odorless and silent are two things a microwave is not while cooking. Ever cook popcorn on one???? You can always smell it and hear the fan running.

Just go into a gas store and just ask to borrow their microwave for a few minutes.

Another thing to consider is the **VOLUME** of a microwave to carry around and keeping it dry when it rains. Plus I don't think there is a microwave on the market that would withstand the bumping of a tour ride.

Something a lot better is to carry around a cat-can stove. Weighs almost nothing.

I'm sorry but I also have to throw a wrench at this one (really, if I had one, I WOULD THROW IT!)
I'm a long time commuter, solo tourist, hiker, camper. There is something un-pure about a microwave oven in the wilderness.
Now, the cat-can stove as mentioned above is an awesome idea! I have several! :D

Jerry H

Apparently there are some other microwave generating devices, in addition to the magnetrons.

I wonder if something extremely compact is possible.

Bakepacker

http://www.bakepacker.com/

:beer:
... There is something un-pure about a microwave oven in the wilderness.
Now, the cat-can stove as mentioned above is an awesome idea! I have several! :D

Jerry H

Yeah, I like those too. They are cool stoves.

I tend to get bored with things after while though.

This is probably not good sometimes.

The various types of alcohol stoves were good for a fling, and for a while; but now I'm ready to try something else.

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Un-pure....

Yeah.

Very.

Practically radioactive.

...almost obscene.

*****

Interesting, though.

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I wonder if something small enough to fit inside a microwavable container could be devised.

They may have their drawbacks, but I've heard they are far more energy efficient than electric coils or gas at boiling water.

Niles, you know I'm just razzing you, right? :D I also got bored with all the alcohol stoves I made and bought. I actually went right back to my trusty Whisperlite.
I really do like invention, althought I'm not very good at it! It paves the way for new gagets. Keep those gears turning!! (no pun intended).

Jerry H

Just one of many reasons that this is a bad idea:
Any battery of sufficient capacity is would be too heavy to carry.

Just get one of these to power the microwave
http://bttf.wikia.com/wiki/Image:Mrfusion.png

How about a solar cooker (http://www.solarcookers.org/index.html)?

They do a camping (http://65.108.108.197/catalog/camperskit-p-66.html?osCsid=f13c9fdc4968c9790e32f0363ef70436)model

Hey Niles, maybe your miniature guard dog could serve double duty by powering the microwave using a small treadmill-dynamo.

Don't forget the 64" flat screen TV and the couch. Just as practical as bringing a microwave oven.

I would probably pass out if I was touring with someone and they produced a microwave at camp.

There's always the Felis Domesticus/Buttered Toast antigravity powered electrical generator....;)

Attach a piece of buttered toast to the back of a cat, butter side up. Drop the ca//toast combination, and since toast always falls buttered Side down and a cat always lands on their feet, the combined effect is to suspend the cat in midair, rotating. Harness the rotational energy and you can generate 410-15KW with a relatively light weight unit ;)

The Cat/Buttered Toast Paradox (http://en.wikipedia.org/wiki/Buttered_cat_paradox)

Why am I picturing this when I picture Niles on tour?.....
http://michaelbluejay.com/photos/images/bikejay.jpg

(Kidding ya, Niles ;) )

There's always the Felis Domesticus/Buttered Toast antigravity powered electrical generator....;)

Attach a piece of buttered toast to the back of a cat, butter side up. Drop the ca//toast combination, and since toast always falls buttered Side down and a cat always lands on their feet, the combined effect is to suspend the cat in midair, rotating. Harness the rotational energy and you can generate 410-15KW with a relatively light weight unit ;)

The Cat/Buttered Toast Paradox (http://en.wikipedia.org/wiki/Buttered_cat_paradox)

:roflmao::roflmao::roflmao:

I can't get the cat to hold still while I tape the toast to her. But the dog is generating 15 kw just watching.

While revolutionary, this bikerowave idea has been floating around Sheldon Brown's research labs for several decades. Here is a rarely seen photo smuggled out by messenger ferret.

http://michaelbluejay.com/photos/images/oven.jpg

Thanks for all the humour, guys.

What images are those?

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This morning I found some portable microwaves that are actually on the market.

Here is one of them:

http://thewavebox.com/power.htm

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It's too heavy and too large, but it could be stripped down.

A foldable hood, like the BakePacker, could be used instead of the ABS shell.

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Still wondering if it might be possible to put a microwave generating unit inside a container with the food. (If this has been done, please let me know....)

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If anyone knows of anything else on the web, please post (humorous or serious -- I'd like to see more of what others have done).

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Although many microwave ovens are rated at about 1000 watts, some are quite a bit lower.

200 watts for two minutes would not use up an excessive amount of battery power.

The larger ovens have to generate microwaves for a much larger compartment. If the compartment for a portable unit were much smaller, probably not as much power would be needed.

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Two-quart capacity is probably overkill for most people. One quart would do it. Even two cups would be adequate for one or two people.

It seems as if generating microwaves for such a small compartment would be a lot less demanding.

Maybe they exist -- if you 'image' guys know of something like this, please do post it/them.

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Maybe the food container could double as the 'shell' of the oven; or the shell of the oven could be designed to be eaten from directly. --It could be designed like a nice bowl, with rounded corners -- rather than a typical rectangular oven space.

If anyone knows of anything along these lines, please post; I'd really like to see it....

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[It seems as if something like that could probably run on a Makita power tool battery, or any number of others, including those used for some of the bike light systems....]

Apparently this thing is popular,

http://thewavebox.com/buy/

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It claims to be the world's smallest; but I see no reason why one couldn't go quite a bit smaller and lighter.

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Especially if you're free from FDA and other regulations. :) ;)

OK, Niles,straight talk:


They've had 12V Microwaves out for years. There are durability issues though. As to the weight? That's primarily in the shielding, and there's a reason one needs FDA approval....

A Microwave enclosure needs to be an environment isolated by a Faraday Cage, since it's using High Energy RF Emissions to heat the H2O molecules contained in the food. It's a radiation source and can stop a pacemaker cold. If you use it with insufficient shielding, there is also secondary cascade radiation to contend with. That's the reason, other than the power requirements, that it's essentially, at the current level of emitter tech, power supply tech, and shielding materials available, it's fundamentally unworkable.

ATTACK THIS:


http://www.thewavebox.com/news/video.cfm

Good clips: the G4TV clip, and the EXTRA clip. ("One of the worst things about enjoying the outdoors is....")

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(No wonder some people hate the United States.) ;)

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This is just the ticket for someone making the transition from nature lover to mainstream.

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Just saw another product -- the Rocket Grill -- that started some wheels turning.

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The ultimate in portability might actually be along the lines of having a radiologist friend share some material.

There are reasons why the prime choice in portable battery packs on small spacecraft is along these lines. It makes sense.

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I still think that ultra-portable microwaves are a possibility.

That WaveBox thing is like the first portable/transportable computers (like the Osbornes).

It could probaly be shaved down to something more like a PDA.

I'm not saying it wouldn't be really nice, mind you, just that at current capability it's not practical. Give them some time though and I'm pretty certain that there isn't a single issue that we couldn't get past to make it workable, if the profit is there. :D

....They've had 12V Microwaves out for years. There are durability issues though. As to the weight? That's primarily in the shielding, and there's a reason one needs FDA approval....

A Microwave enclosure needs to be an environment isolated by a Faraday Cage, since it's using High Energy RF Emissions to heat the H2O molecules contained in the food. It's a radiation source and can stop a pacemaker cold. If you use it with insufficient shielding, there is also secondary cascade radiation to contend with. That's the reason, other than the power requirements, that it's essentially, at the current level of emitter tech, power supply tech, and shielding materials available, it's fundamentally unworkable.

Just saw this post. (I was busy with the videos.)

Yeah, I knew about the shielding.

But the ABS is not that kind of shielding, and it could be dispensed with.

That would lose a lot of weight and bulk.

And also, the Faraday Cage, for this application, does not need to be so heavy.

It could even be flexible, like the BakePacker hood.

Also, if you are DIYing the whole thing, and you do not have a pacemaker [or even if you do, come to think of it], and you are in circumstances (or on trips) that allow for distance protection, you might be able to get away with dispensing with it.

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Also, a Faraday Cage could be built into the bowl-shell-microwave container.

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Plus, there seem to be some options for the microwave generating units.

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Something tells me that the whole thing could be sized down far more than I have yet seen.

Well, why don't you build one and prove us all wrong?

Well, why don't you build one and prove us all wrong?

I'm working on it, but tend to take my time.

And sometimes to get distracted by other things.

(Especially when life seems to enjoy throwing delicious curve balls.)

Hey Niles, maybe your miniature guard dog could serve double duty by powering the microwave using a small treadmill-dynamo.

That would help keep the unwanted suitors off for sure.

Wavebox puts out 660 watts@12 volts connected directly to a car battery. Thats a minimum of 55 amps for as long as the unit is running. A fairly substantial battery would be required. Not small, not light, not easy to recharge on the road. At the 235 watts output from a car power jack, there is not enough power to pop popcorn.

I have no doubts that the size/weight issues could be overcome, but the power consumtion issues would remain a major problem. For a group of people who can obsess over whether an extra pair of bike shorts might be too much weight, a microwave of any size seems a bit , dare I say, frivolous

What about infrared cookers? They aren't great for cooking dishes that require the boiling of water, which is where microwaves excel, but they do cook things like meat quite fast. Commercially available infrared cookers are rather bulky, but you could easily remove the light and use some kind of light, flexible container to cook inside. I'm guessing the power consumption would be minimal compared to a microwave, so you could get away with a much smaller battery.

I think an easier and lighter system would be to get a time machine and travel back to earlier in the day when you weren't hungry and then you don't need to cook anything. The only thing you need for your bike touring time machine is a Flux Capacitor, they are available here:

http://kalecoauto.com/index.php?main_page=product_info&cPath=6&products_id=28

I'm working on it, but I'm slow.
If you were capable of solving the battery issues there are about a million other applications where the battery technology would be better used.

Wavebox puts out 660 watts@12 volts connected directly to a car battery. Thats a minimum of 55 amps for as long as the unit is running. A fairly substantial battery would be required. Not small, not light, not easy to recharge on the road. At the 235 watts output from a car power jack, there is not enough power to pop popcorn.

I have no doubts that the size/weight issues could be overcome, but the power consumtion issues would remain a major problem. For a group of people who can obsess over whether an extra pair of bike shorts might be too much weight, a microwave of any size seems a bit , dare I say, frivolous

Good points.

However, some microwaves only require 500 watts.

These have relatively large cooking chambers.

A (much) smaller chamber, with more focused waves, would probably require less power.

Even if it were a three- or four-hundred watt microwave, I don't think it would be so bad. I haven't done the calculations yet, but I would guess that a rechargeable battery (made for power tools, or for bike lights -- or those high-capacity, fast-discharge, fast-recharge battery packs that kids who race RC cars use and cycle frequently) has enough amp hours to do the job, especially in light of the fact that microwaves are so quick. They can cook things in a couple of minutes that take many times longer on stoves (that are burning fuel all the while).

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The same people who obsess over the bike shorts often carry stoves, pots, fuel and fuel canisters.

They end up going out of their way to refuel.

Over time they can spend quite a bit of money and time on these things (if they ever bothered to total it all up), and quite a bit of time cooking and cleaning....

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There are a few other things about microwaves that are to like: No fumes and smoke to breathe is one of them. Winter morning tent cooking is another.

No carbon monoxide. No fossil fuels. No flames. Less risk of fires and mishaps.

*****
They may be able to get down around one or two pounds (possibly less), and be at least as compact as most conventional cooking systems.

I would love to take one apart and actually see that (little) unit that generates the microwaves. It may happen soon....

The ionizing-radiation thing may be an urban legend. Initial research indicates that it is. Will check into it some more.

The media have caused some semi-hysteria over microwaves and these sorts of things.

Microwaves were used for years by chiropractors to relax people's muscles.

The devices were called 'diathermy machines.'

When you lie down, they put something that looks like a heating pad under your back. That heating pad is not an ordinary heating pad, though (they don't always tell you this). It is a microwave heating pad designed to help relax the muscles.

Great fun.

http://www.youtube.com/watch?v=_lNfBZTz2xQ&NR=1

I love to calculate things.

Let's take 8 oz of water, that's 227 grams. Heat it from room temperature to the boiling point that's a diffrence of 77.8 deg C. So it will take 17700 calories, which is the same as 73900 joules, which is the same as 20.5 Ah. I found a dive light site where you can get a 9 Ah battery that weighs 3.25 kg. So scaling that up you would need 7.4 kg or 16.3 lbs of battery to heat up 8 ounces of water.

That would be for a 100 percent efficient system.

Double check my numbers, but I think I'll leave the microwave at home.

Speedo

I love to calculate things.

Let's take 8 oz of water, that's 227 grams. Heat it from room temperature to the boiling point that's a diffrence of 77.8 deg C. So it will take 17700 calories, which is the same as 73900 joules, which is the same as 20.5 Ah. I found a dive light site where you can get a 9 Ah battery that weighs 3.25 kg. So scaling that up you would need 7.4 kg or 16.3 lbs of battery to heat up 8 ounces of water.

That would be for a 100 percent efficient system.

Double check my numbers, but I think I'll leave the microwave at home.

Speedo

You may be correct. But there may be an error somewhere along the way. I don't know. It does sound excessive and counter-intuitive; but I'm certainly open to the facts.


How did you arrive at 17700 calories, 73900 joules, and how did you equate that with 20.5Ah ?

Also, I have seen lighter batteries with more capacity than that. Aren't there AA batteries with well over 2500mAh capacities? They don't weigh anywhere near that much.

http://www.nimhbattery.com/sanyo-2700-aa-rechargeable-batteries.htm

30 grams per cell....

Niles,

When I point out shortcomings in an idea, so you know, it's not because I want to discourage you, or that I'm making fun of you......you'll know when I'm teasing you, as you know. It's because I see the idea as interesting enough to critique and hopefully get you thinking about how to overcome the issue in the critique ;)

Frankly, the idea is interesting and I'd LOVE to see you make it workable, because if you do, a unit light enough and power skimpy enough for bike touring will make you filthy rich......

Alternative applications: Space Program, think about it, lifting to orbit is bloody expensive. That makes a true lightweight microwave of extreme interest to NASA or the ESA, for one example. ;)

Thanks, Tom -- it's easy to see things in various ways (and people often do); and it rarely hurts to check in and clarify, even if there are sometimes no misunderstandings going on. So thanks for doing so.

I don't know where this might go; even if it is just playing around (safely) with some magnetron tubes and variable power supplies, it will be interesting.

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How's this for entertainment on a long winter's night:


http://www.youtube.com/watch?v=vCNNqgKqnaQ

You may be correct. But there may be an error somewhere along the way. I don't know. It does sound excessive and counter-intuitive; but I'm certainly open to the facts.


How did you arrive at 17700 calories, 73900 joules, and how did you equate that with 20.5Ah ?

Also, I have seen lighter batteries with more capacity than that. Aren't there AA batteries with well over 2500mAh capacities? They don't weigh anywhere near that much.

I did screw up along the way. I forgot about the battery voltage.

Trying again

Warming 227 grams of water to 77.8 degrees C is 17700 calories. (just multiply them)
Coverting calories to joules multiply by 4.19 joules/calorie to get 73900 joules.

Battery is NiMH. 14.4 volts 9 Ah and weighs 3.35 kg. I'll scale to get the battery we need.

9 Ah is 9*3600 coulombs = 32400 coulombs. Where I screwed up is I didn't use the battery voltage to get the amount of energy per coulomb. 14.4 V= 14.4 J/C, so the battery can deliver 14.4*32400=467 kJ.

Scaling the battery weight for what we need 3.35 kg * 73.9 kJ/467 kJ = 0.53 kg or 1.17 lbs of battery. Accounting for the 14.4 Volts scaled my original result down by 14.4. Sorry.

I think I'll take the cat can stove still.

Speedo

The Army spent a million bucks developing the Bakepacker. It weighs a couple ounces. It works. It doesn't need a zillion watts and it isn't dangerous. You put the thing in the bottom of the pot and it channels steam up around the item being cooked.

I used one for years. Made pizza, cranberry bread, you name it.

Wavebox puts out 660 watts@12 volts connected directly to a car battery. Thats a minimum of 55 amps for as long as the unit is running. A fairly substantial battery would be required. Not small, not light, not easy to recharge on the road. At the 235 watts output from a car power jack, there is not enough power to pop popcorn.

I have no doubts that the size/weight issues could be overcome, but the power consumtion issues would remain a major problem. For a group of people who can obsess over whether an extra pair of bike shorts might be too much weight, a microwave of any size seems a bit , dare I say, frivolous

Good points.

However, some microwaves only require 500 watts.

These have relatively large cooking chambers.

A (much) smaller chamber, with more focused waves, would probably require less power.

Even if it were three or four hundred watts, I don't think it would be so bad. I haven't done the calculations yet, but I would guess that a rechargeable battery (made for power tools, or for bike lights -- or those high-capacity, fast-discharge, fast-recharge battery packs that kids who race RC cars use and cycle frequently) has enough amp hours to do the job, especially in light of the fact that microwaves are so quick. They can cook things in a couple of minutes that take many times longer on stoves (that are burning fuel all the while).

*****
The same people who obsess over the bike shorts often carry stoves, pots, fuel and fuel canisters.

They end up going out of their way to refuel.

Over time they can spend quite a bit of money and time on these things (if they ever bothered to total it all up), and quite a bit of time cooking and cleaning....

*****
There are a few other things about microwaves that are to like: No fumes and smoke to breathe is one of them. Winter morning tent cooking is another.

No carbon monoxide. No fossil fuels. No flames. Less risk of fires and mishaps.

*****
I would love to take one apart and actually see that (little) unit that generates the microwaves. It may happen soon....

The ionizing-radiation thing may be an urban legend. Initial research indicates that it is. Will check into it some more.

The media have caused some semi-hysteria over microwaves and these sorts of things.

Microwaves were used for years by chiropractors to relax people's muscles.

The devices were called 'diathermy machines.'

When you lie down, they put something that looks like a heating pad under your back. That heating pad is not an ordinary heating pad, though (they don't always tell you this). It is a microwave heating pad that is designed to help relax the muscles.

Great fun.

I'm happy using the microwaves at 7-Eleven :)

In Asia, they even dispense free hot water for your coffee, instant noodles, etc.

But, well, if we're just dreaming, I'd like to have a tiny generator that attaches to my wheel so that after I climbed a big hill, I could coast down, converting that descent energy into electricity that would boil enough water for a cup of coffee. A cup of boiling water to brew a cup of coffee. That's all I ask. On tour, it's all I need to make me happy.

I have a basta sidewall generator that I won't be using anymore. You could easily create a water heating element by just placing a resistor of some type inside the airspace inside an insulated mug and running a lead wire to the generator. Do you want the generator?

but I would guess that a rechargeable battery (made for power tools, or for bike lights -- or those high-capacity, fast-discharge, fast-recharge battery packs that kids who race RC cars use and cycle frequently) has enough amp hours to do the job, especially in light of the fact that microwaves are so quick. They can cook things in a couple of minutes that take many times longer on stoves (that are burning fuel all the while).


Their "quickness" is related to their power. My 1300 W microwave can heat up my cup of coffee in 50 seconds. 240 W available from 12 V through a 20 A fuse would take over four and a half minutes.



The same people who obsess over the bike shorts often carry stoves, pots, fuel and fuel canisters.

They end up going out of their way to refuel.

Over time they can spend quite a bit of money and time on these things (if they ever bothered to total it all up), and quite a bit of time cooking and cleaning....


The energy density of that bottle of fuel is pretty high. A much better way of carrying energy around than a big battery.



No carbon monoxide. No fossil fuels. No flames. Less risk of fires and mishaps.


Well, no carbon monoxide and fossil fuels at the microwave itself. But something provides the energy to run it. I suppose you can imagine that your particular battery was charged by energy from a wind farm!

Have fun!

Speedo

The energy density story tells it all.

The energy density of Naptha (http://astro.berkeley.edu/~wright/fuel_energy.html) (white gas) per unit volume is 31.4 MJ/L. The density of Naptha (http://www.simetric.co.uk/si_liquids.htm) is 0.665 kg/L. So the energy density of Naptha per unit mass is 47.2 MJ/kg.

The Battery University (http://batteryuniversity.com/partone-3.htm) has a nice comparison of battery technologies. Ignoring everything else except energy density, we see that the highest energy density they have listed is 190 Wh/kg for Litium-Ion (cobalt). A Wh is 3600 J, so the top battery energy density is 0.684 MJ/kg.

47.2 MJ/kg vs 0.684 MJ/kg pays for a lot of inefficiency in the white gas stove.

Speedo