Dave in AZ
Active member
I googled and watched 100 vids on this.
Very few ACTUALLY TEST CORRECTLY!
almost all are based on false labeling of wattage, and youtubers don't access microwave cables for amps, etc., they just trust the label and calculate time.
Or they take a snapshot of watts, then assume it stays same for whole cook. Worst, most of them just measure time to boil.
I did find a few that were better, and put together a decent picture. I also purchased a good quality kill-a-watt style meter that will measure total energy use over time, and have been testing at home.
Here is what I have found. My slant is "which of these will do the job with least drain on my battery". I concentrated on heating water, as it is the only thing you know EXACTLY how much joules it takes to raise temp, can measure precisely, and is key to camping.
Also of critical note, for drinks we actually target 190f for brewing coffee or tea, and 140f for actual drinking so instant coffee or hot chocolate-- you can save a lot of watts by not overheating then cooling it to drink!
Quantity-- standard size insulated travel mugs eveeyone uses hold 500ml, so large coffee for 2 people needs 1 L of water.
1. Actual device efficiency is NOT the only critical factor! Almost equally important is heat capture and insulation to prevent heat loss, critical for gas heat speed. Also, the thermal mass of the pan or pot, for induction and microwave where the vessel gets heates. So, the size and shape of the pan bottom for gas, the insulation of your pan sides and lid for gas and induction. And how long it stays hot while you cook for 5 or 10 minutes. Because very few pots have insulated sides, gas and induction lose heat thru those and water cools faster, which all has to be considered for how you cook.
2. Heating the actual correct amount of water, but not more, is key. A lot of in home studies showed microwave to use less energy because people didn't heat 2 or 3 times the water they needed. Immersion coil, kettle, and microwave all shine here because you easily measure out exactly 1 L for two 500ml large insulated coffee travel mugs. Microwave especially you tend to not heat more than needed.
3. Heating water. Immersion heater coil you stick into a cup is most efficient, if your cup is insulated and you put a lid on. Almost 100% electric to heat conversion.
4.. An electric kettle is almost as good. If you get one with insulated sides and bottom, it is about same, but hard to find with insulated sides!
5. Induction is supposedly next most effient at 78% measured, supposedly... in 50 videos, I never saw a single one showing an exact quantity of water and a meter. However, in actual use the wattage spike as induction cycles on and off means you need a larger inverter than the specified wattage. And you need to heat up a decently heavy metal pan or pot, not just the food or water, which can be a lot of watthours.
6. Microwave, you can get a small 700 or 800 w one. They are supposedly 65% efficient, according to the unsupported number everyone parrots, and despite high power use, you do short precisely targeted usage. With precise water measurements in an insulated plastic travel mug, it can be very efficient in actual use, and may be the most efficient to reheat meals, if you take cleanup etc into account. My tests showed 36 to 44% efficiency only, depending on your vessel.
7. Camping, gas is by far the best heat energy per weight, waaay more btus are in 1 lb of propane than 1 lb of battery. Zero comparison here. Only the need or desire to NOT use propane for some reason, makes electric cooking a contender.
Here are the measurements I have taken so far. I gathered all this to write a blog bit haven't finished testing yet so not organized.
1L water at room temp of 76f, 24.5c, heat to 212. Sm kettle, coleman standard double stove on hi propane. 136f rise, or 75.5c. 4min 20sec, 260sec.
Most peeps prefer to drink at 140f, just 47% of the boil rise. Best temp to brew coffee and tea is 190f, 88c, 76% of the rise or 57c. Assuming linear between 76 and 212f,
122sec for instant or cocoa, 199sec to brew.
It takes 4184 joules to raise 1kg or L water by 1 degree c.
Calculate the kilowatt-hours (kWh) required to heat the water using the following formula: Pt = (4.2 × L × T ) ÷ 3600. Pt is the power used to heat the water, in kWh. L is the number of liters of water that is being heated and T is the difference in temperature from what you started with, listed in degrees Celsius.
So, to boil 1L from 76f or 24.5c, 88watt hours, or 300btu.
To heat for brew, 67wh
To heat for instant or cocoa 42wh.
So, coleman burner transfers 88wh in 260sec
1 wh = 3.412 btu.
Popular mechanics measured 112wh to boil 1L water from 25c. With induction. So to get an actual 88wh input, 112wh was used, making it 78% efficient.
Watt meter was used to measure immersion heater boil 1L water.
I read several articles where the piwer was not actually tested, just parroted back from other sources, that listed this common quote, "microwaves are approx 65% efficient" , haven't seen actual measured test data. This is not at all supported for small 700w microwaves you might use camping. I got 36 to 44% efficiency only.
Conclusions:
1. Use propane if able, best weight tradeoff for camping.
2. For drinks, use immersion coil first if 500ml or so in mug. Use electric kettle next.
3. If you have a decently thick bottom ferrous kettle or pot for induction, and your inverter can handle, and you measure temps and don't overheat, induction is next.
4. Microwave last.
Food: reheating thawed meals, vacuum packed, microwave is best, cleanest, least extra electricity for cleanup.
Combined All in One Concept: I want hot water for drinks, to heat prepacked meals sous vide style, and for cleanup! If you do one water heat, dump it into a 2 gallon wide mouth thermos, you can then make your drinks, stuff vac packed pouches in there to heat, and close lid. Now hot water doea triple duty-- drinks, cooking, and later cleanup.
Update. Just tested kettle and microwave.
Should take 88wh to bring 1 L of 76f to 212f.
Kettle did it at 87 wh, my input water was 78f in AZ today, so a little less. Basically 100% efficient, 1450w heater.
Microwave, a Sharp carousel. Ba kplate says 700w output, this is the small one you see at Walmart size. In actuality, on high power the microwave pulled 1166w while running. So, if it actually did output 700w from magnetron, that is in fact 65% efficiency on THAT conversion, but it is only 40% efficient in getting energy actually into the food. You can see where folks bite off on that 65% and then just assume it applies to the food too.
It took over 13 min, and used 0.236kwh or 236 wh! So it used 2.7 times as much electricity as kettle, and was in fact only 37% efficient!
Some of that is for sure due to using a pyrex 1L container, that is a lot of thermal mass to heat. However, the fact is that most folks will want to use a sturdy glass beaker to handle boiling water in a microwave. I also added a small ceramic piece in water to avoid superheated water that can happen in slow microwave boils, and to allow water vapor to nucleate on its surface for a true boil reading. I could retest usimg some thinner plastic, but I don't have anything that will fit and doesn't get floppy in hot water. So I will redo with 500ml, half, and double results. But I do think a glass pyrex measuring cup might be a true test for camping, that is what I will be using to make ramen etc.
Retest, 500ml in thin plastic cup. Couldn't really use it, too hot to hold, so it would need a handle. But a shallow plastic measure might be found. Anyways, it uses 0.099kwh, or 99wh, with 44 the theoretical 100% efficient energy needed. So 2.25 x energy as kettle, and only 44% efficiency. Additionally, it took 7 min to boil just 500ml, due to microwave cycling design.
So I am rethinking my microwave use. Maybe for prepacked vacsealed meals, but that will be it. And only because there is zero mess if I eat from the bag.
Very few ACTUALLY TEST CORRECTLY!
almost all are based on false labeling of wattage, and youtubers don't access microwave cables for amps, etc., they just trust the label and calculate time.
Or they take a snapshot of watts, then assume it stays same for whole cook. Worst, most of them just measure time to boil.
I did find a few that were better, and put together a decent picture. I also purchased a good quality kill-a-watt style meter that will measure total energy use over time, and have been testing at home.
Here is what I have found. My slant is "which of these will do the job with least drain on my battery". I concentrated on heating water, as it is the only thing you know EXACTLY how much joules it takes to raise temp, can measure precisely, and is key to camping.
Also of critical note, for drinks we actually target 190f for brewing coffee or tea, and 140f for actual drinking so instant coffee or hot chocolate-- you can save a lot of watts by not overheating then cooling it to drink!
Quantity-- standard size insulated travel mugs eveeyone uses hold 500ml, so large coffee for 2 people needs 1 L of water.
1. Actual device efficiency is NOT the only critical factor! Almost equally important is heat capture and insulation to prevent heat loss, critical for gas heat speed. Also, the thermal mass of the pan or pot, for induction and microwave where the vessel gets heates. So, the size and shape of the pan bottom for gas, the insulation of your pan sides and lid for gas and induction. And how long it stays hot while you cook for 5 or 10 minutes. Because very few pots have insulated sides, gas and induction lose heat thru those and water cools faster, which all has to be considered for how you cook.
2. Heating the actual correct amount of water, but not more, is key. A lot of in home studies showed microwave to use less energy because people didn't heat 2 or 3 times the water they needed. Immersion coil, kettle, and microwave all shine here because you easily measure out exactly 1 L for two 500ml large insulated coffee travel mugs. Microwave especially you tend to not heat more than needed.
3. Heating water. Immersion heater coil you stick into a cup is most efficient, if your cup is insulated and you put a lid on. Almost 100% electric to heat conversion.
4.. An electric kettle is almost as good. If you get one with insulated sides and bottom, it is about same, but hard to find with insulated sides!
5. Induction is supposedly next most effient at 78% measured, supposedly... in 50 videos, I never saw a single one showing an exact quantity of water and a meter. However, in actual use the wattage spike as induction cycles on and off means you need a larger inverter than the specified wattage. And you need to heat up a decently heavy metal pan or pot, not just the food or water, which can be a lot of watthours.
6. Microwave, you can get a small 700 or 800 w one. They are supposedly 65% efficient, according to the unsupported number everyone parrots, and despite high power use, you do short precisely targeted usage. With precise water measurements in an insulated plastic travel mug, it can be very efficient in actual use, and may be the most efficient to reheat meals, if you take cleanup etc into account. My tests showed 36 to 44% efficiency only, depending on your vessel.
7. Camping, gas is by far the best heat energy per weight, waaay more btus are in 1 lb of propane than 1 lb of battery. Zero comparison here. Only the need or desire to NOT use propane for some reason, makes electric cooking a contender.
Here are the measurements I have taken so far. I gathered all this to write a blog bit haven't finished testing yet so not organized.
1L water at room temp of 76f, 24.5c, heat to 212. Sm kettle, coleman standard double stove on hi propane. 136f rise, or 75.5c. 4min 20sec, 260sec.
Most peeps prefer to drink at 140f, just 47% of the boil rise. Best temp to brew coffee and tea is 190f, 88c, 76% of the rise or 57c. Assuming linear between 76 and 212f,
122sec for instant or cocoa, 199sec to brew.
It takes 4184 joules to raise 1kg or L water by 1 degree c.
Calculate the kilowatt-hours (kWh) required to heat the water using the following formula: Pt = (4.2 × L × T ) ÷ 3600. Pt is the power used to heat the water, in kWh. L is the number of liters of water that is being heated and T is the difference in temperature from what you started with, listed in degrees Celsius.
So, to boil 1L from 76f or 24.5c, 88watt hours, or 300btu.
To heat for brew, 67wh
To heat for instant or cocoa 42wh.
So, coleman burner transfers 88wh in 260sec
1 wh = 3.412 btu.
Popular mechanics measured 112wh to boil 1L water from 25c. With induction. So to get an actual 88wh input, 112wh was used, making it 78% efficient.
Watt meter was used to measure immersion heater boil 1L water.
I read several articles where the piwer was not actually tested, just parroted back from other sources, that listed this common quote, "microwaves are approx 65% efficient" , haven't seen actual measured test data. This is not at all supported for small 700w microwaves you might use camping. I got 36 to 44% efficiency only.
Conclusions:
1. Use propane if able, best weight tradeoff for camping.
2. For drinks, use immersion coil first if 500ml or so in mug. Use electric kettle next.
3. If you have a decently thick bottom ferrous kettle or pot for induction, and your inverter can handle, and you measure temps and don't overheat, induction is next.
4. Microwave last.
Food: reheating thawed meals, vacuum packed, microwave is best, cleanest, least extra electricity for cleanup.
Combined All in One Concept: I want hot water for drinks, to heat prepacked meals sous vide style, and for cleanup! If you do one water heat, dump it into a 2 gallon wide mouth thermos, you can then make your drinks, stuff vac packed pouches in there to heat, and close lid. Now hot water doea triple duty-- drinks, cooking, and later cleanup.
Update. Just tested kettle and microwave.
Should take 88wh to bring 1 L of 76f to 212f.
Kettle did it at 87 wh, my input water was 78f in AZ today, so a little less. Basically 100% efficient, 1450w heater.
Microwave, a Sharp carousel. Ba kplate says 700w output, this is the small one you see at Walmart size. In actuality, on high power the microwave pulled 1166w while running. So, if it actually did output 700w from magnetron, that is in fact 65% efficiency on THAT conversion, but it is only 40% efficient in getting energy actually into the food. You can see where folks bite off on that 65% and then just assume it applies to the food too.
It took over 13 min, and used 0.236kwh or 236 wh! So it used 2.7 times as much electricity as kettle, and was in fact only 37% efficient!
Some of that is for sure due to using a pyrex 1L container, that is a lot of thermal mass to heat. However, the fact is that most folks will want to use a sturdy glass beaker to handle boiling water in a microwave. I also added a small ceramic piece in water to avoid superheated water that can happen in slow microwave boils, and to allow water vapor to nucleate on its surface for a true boil reading. I could retest usimg some thinner plastic, but I don't have anything that will fit and doesn't get floppy in hot water. So I will redo with 500ml, half, and double results. But I do think a glass pyrex measuring cup might be a true test for camping, that is what I will be using to make ramen etc.
Retest, 500ml in thin plastic cup. Couldn't really use it, too hot to hold, so it would need a handle. But a shallow plastic measure might be found. Anyways, it uses 0.099kwh, or 99wh, with 44 the theoretical 100% efficient energy needed. So 2.25 x energy as kettle, and only 44% efficiency. Additionally, it took 7 min to boil just 500ml, due to microwave cycling design.
So I am rethinking my microwave use. Maybe for prepacked vacsealed meals, but that will be it. And only because there is zero mess if I eat from the bag.
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