Deep dive into induction cooktops, magnetic coupling, power use.

[Denwood]

Six months back, I bought (what I now know is a crappy pan for use on induction), but labeled as induction compatible. I spent about three months testing, built a few dedicated test rigs, and got Home Assistant up and running to gather data for the tests. I was also pretty curious about how induction worked in the first place...so down the rabbit hole. Anyone who follows my garage thread here on the journal knows I have rabbit holeitis in the worst way.

As an experiment, I used ChatGPT to help script and design a shot list for the original video. It was the worst performing video I've ever published. I picked up my bruised ego and re-edited doing thing my way. If you're not into the video, here's a summary.

1. The fridge magnet test doesn't work if you're looking for what works well on induction.
2. Matching the hob size to the pot base can halve the time taken to boil a liter/quart of water. A 1.9L Tramontina Signature pot did the best (on the smallest induction hob!!), 2:56 to boil a quart.
3. Cast iron coupled the best and also pulled the highest wattage from the cooktop.
4. Using highest power on the induction cooktop does not equate to the same actual watts used on different pots. There are huge differences.

I hope you guys find this useful, interesting or even mildly entertaining

 

[rawen2]

That was interesting. Thanks for posting.

 

[nadogail]

We have been using a General Electric induction cooktop since 2017, if it ever fails it will be replaced by another Induction Cooktop.

We had to replace our 40 year old stainless Farberware pots with induction compatible modern stainless.

 

[Just_Steve]

Count me as an induction cooktop fan, been using one for the last five years since kitchen remodeling. I will never use anything else if at all possible. Thanks for the video.

 

[ChefRex]

Following, I really need a new stove but I want dumb, the problems I hear of make me want a stove dumber than the average 10YO.

I have considered an induction hot plate type deal on the side.

 

[nadogail]

Following, I really need a new stove but I want dumb, the problems I hear of make me want a stove dumber than the average 10YO.

I have considered an induction hot plate type deal on the side.

Wood and Coal stoves are very dumb.

 

[Just_Steve]

Following, I really need a new stove but I want dumb, the problems I hear of make me want a stove dumber than the average 10YO.

I have considered an induction hot plate type deal on the side.

There is nothing smart about an induction cooktop except it's ability to regulate the heat better than gas or electric.

 

[four.cycle]

My sister paid $1700 for one of those things. I absolutely hate it. Doesn't matter if I'm using Great-Grandma Potter's cast iron Dutch Oven, or a $3.99 second-hand "All Clad" from Goodwill, it does not maintain a consistent temperature. Absolute piece of garbage - burners can't seem to make up their minds if they want to be "on" or "off".
I would drag the thing out into the street and wait for a scrap metal guy to pick it up.

 

[gtae07]

We're quite happy with our induction unit; I wish I'd spent the money to get a double oven and 5th burner though...

 

[Denwood]

That was interesting. Thanks for posting.

Those are kindest words I've opened the browser to in the last few days..honestly. There was a lot about induction that had me curious when I started down the rabbit hole.

We have been using a General Electric induction cooktop since 2017, if it ever fails it will be replaced by another Induction Cooktop.

We had to replace our 40 year old stainless Farberware pots with induction compatible modern stainless.

Just be careful on those words "induction compatible"! There really should be a standard with cast iron at 10, and everything else measured as a standard against it. I think that's what got me going on this whole thing...compatible just means you'll get heat out of it, but it doesn't tell you how much.

Count me as an induction cooktop fan, been using one for the last five years since kitchen remodeling. I will never use anything else if at all possible. Thanks for the video.

I'm not a foody, but I do love making the Sunday Finn pancakes (super thin, like crepes) and for that the cast iron skillet (which I've sanded/polished) and induction at about power 6 for our cooktop is about perfect heat right across the pan face for these babies

Following, I really need a new stove but I want dumb, the problems I hear of make me want a stove dumber than the average 10YO.

I have considered an induction hot plate type deal on the side.

Having done the Kitchen reno I wanted induction pretty much for the clean cooktop and efficiency. They are around 90%, so top of the heap that way. I also have the exhaust fan automated to the cooktop (it's an ECM fan, 0-10V control) so the fan ramps with the power use on the cooktop. The fact that the power delivery is pretty much constant (except at very low settings) makes the automation work smoothly too.

Wood and Coal stoves are very dumb.

Nice in power outages though...

There is nothing smart about an induction cooktop except it's ability to regulate the heat better than gas or electric.

I'm not an expert on the electronics of the hob, but I do think it cuts power depending on the coupling. Now if that's just inherent in the physics, or part of the control circuit...that I don't know.

My sister paid $1700 for one of those things. I absolutely hate it. Doesn't matter if I'm using Great-Grandma Potter's cast iron Dutch Oven, or a $3.99 second-hand "All Clad" from Goodwill, it does not maintain a consistent temperature. Absolute piece of garbage - burners can't seem to make up their minds if they want to be "on" or "off".
I would drag the thing out into the street and wait for a scrap metal guy to pick it up.

I am sure there are differences in control. The one I tested on is a pretty average IKEA 30" unit. Because I do have the 240V Aeotec switch in there, I can monitor power live. On 1 or 2 power level it may cycle a bit, but after that the power is pretty much steady and a function of which power level you're at, and what kind of pot is on the element. The max I saw on the large burner was 3700 watts with the cast iron, and that stayed very steady during the test.

We're quite happy with our induction unit; I wish I'd spent the money to get a double oven and 5th burner though...

I really was not happy about the Missus insisting on a wall oven and a cook top, but I'm quite glad we went that way. The only hassle really was running two 240V circuits instead of just using the existing feed for a range. We're not massive foodies by any stretch so I think the record for use has been 3 pots going at once. With a 30", you kind of run out of room anyway...

 

[loganb]

Hum....I've been considering a move to induction....this and my brother taunting on how fast he can boil water on his may push me farther towards it

 

[Denwood]

Hum....I've been considering a move to induction....this and my brother taunting on how fast he can boil water on his may push me farther towards it

Just pick the right pot!

We have a 120V single burner job out at camp and it takes forever to boil water. We use it to boil water for corn on the cob and my wife has questioned me every time on why it's taking so long. I used to blame the burner, but now I know that it's 100% the pot. It passed the fridge magnet test (on a few pieces of our old pre-induction cookware delegated for camp use) so I figured great...but as I learned in the video, that fridge magnet test doesn't really tell you much. I was buying a new set of cookware (I'm not), I'd like take a look at the Tramontina Signature stuff as you can get a 8 to 10 piece set without spending crazy $$$. I bought the 1.9 and 2.8L as one offs for the test, but going back I could have gotten a full set for not much more.

 

[four.cycle]

The max I saw on the large burner was 3700 watts with the cast iron, and that stayed very steady during the test.

^ I wouldn't know watts from my elbow. I don't really care about the "sciency" part of it, I just want a stove that does what I want it to, when I want it to. That range at my mom's fails on both counts: it does not maintain constant temperature - you can see the "element" going on/off/on/off/on/off while cooking. Ergo: NOT constant.

Appreciate the video. Maybe I'll take a pot magnet up to Mom's next time and check out the crappy pans my sister buys. Like her "Pyrex" cookware that she uses on that glass-top range. Could very well be that the problem is the pans, but that doesn't account for that on/off/on/off nonsense.

 

[Just_Steve]

I use a decently priced set of Cuisinart pots and pans, they work great. Bases are pretty thick.

 

[Just_Steve]

^ I wouldn't know watts from my elbow. I don't really care about the "sciency" part of it, I just want a stove that does what I want it to, when I want it to. That range at my mom's fails on both counts: it does not maintain constant temperature - you can see the "element" going on/off/on/off/on/off while cooking. Ergo: NOT constant.

Appreciate the video. Maybe I'll take a pot magnet up to Mom's next time and check out the crappy pans my sister buys. Like her "Pyrex" cookware that she uses on that glass-top range. Could very well be that the problem is the pans, but that doesn't account for that on/off/on/off nonsense.

That does not sound like an induction cooktop, sounds like a regular electric with a glass top , there are no elements to see on induction.

 

[Milton Shaw]

We are on our second induction hot plate now. First one was burned bad by turning the stove top on under it and cooking the bottom of it. Love them they are the fastest heating type for cooking and warming stuff. We did take the knobs off those two element controls under it. At $120 to $150 they are a super bargain. The pot we were using turned the element on while stiring the pot, which is why we took the off.

 

[BillK]

There is nothing smart about an induction cooktop except it's ability to regulate the heat better than gas or electric.

I dont understand how it could be better than gas as far as regulating the heat ? With gas you can actually see the flame and know what you are getting. And it doesnt require special cookware.

 

[Just_Steve]

I dont understand how it could be better than gas as far as regulating the heat ? With gas you can actually see the flame and know what you are getting. And it doesnt require special cookware.

i have used gas before, was never in the habit of stooping down to look at the flame, I know what "I'm getting" by the numbers. I'll admit there might be a small learning curve but it's quit intuitive.

 

[Dumber than lumber]

Six months back, I bought (what I now know is a crappy pan for use on induction), but labeled as induction compatible. I spent about three months testing, built a few dedicated test rigs, and got Home Assistant up and running to gather data for the tests. I was also pretty curious about how induction worked in the first place...so down the rabbit hole. Anyone who follows my garage thread here on the journal knows I have rabbit holeitis in the worst way.

As an experiment, I used ChatGPT to help script and design a shot list for the original video. It was the worst performing video I've ever published. I picked up my bruised ego and re-edited doing thing my way. If you're not into the video, here's a summary.

1. The fridge magnet test doesn't work if you're looking for what works well on induction.
2. Matching the hob size to the pot base can halve the time taken to boil a liter/quart of water. A 1.9L Tramontina Signature pot did the best (on the smallest induction hob!!), 2:56 to boil a quart.
3. Cast iron coupled the best and also pulled the highest wattage from the cooktop.
4. Using highest power on the induction cooktop does not equate to the same actual watts used on different pots. There are huge differences.

I hope you guys find this useful, interesting or even mildly entertaining

I bought an induction heater tool off of Amazon. It was not the cheapest one for what that is worth.
Anyway, it is fascinating what can be done with it. Not something that I use very often, but when needed there is no substitute.

 

[Denwood]

We are on our second induction hot plate now. First one was burned bad by turning the stove top on under it and cooking the bottom of it. Love them they are the fastest heating type for cooking and warming stuff. We did take the knobs off those two element controls under it. At $120 to $150 they are a super bargain. The pot we were using turned the element on while stiring the pot, which is why we took the off.

Now that is a new one I’ve yet to hear. Just glad all that burned was the appliance!

I dont understand how it could be better than gas as far as regulating the heat ? With gas you can actually see the flame and know what you are getting. And it doesnt require special cookware.

Gas is the least efficient (40% ish) but you’re right … it is easy to modulate visually. Induction is like that, but you need to spend some time researching a cook set, and then use them a few times to sort out heat etc. My wife and kids just started using the cooktop with near zero instruction. In my tests the induction power level was very consistent, so analogous to a flame in that way…but you can’t see it.

i have used gas before, was never in the habit of stooping down to look at the flame, I know what "I'm getting" by the numbers. I'll admit there might be a small learning curve but it's quit intuitive.

Induction is exactly like that. Power levels on ours go from 1 to 9 and then there is an extra “boost” setting that will send max power to the burner. So for my Finn pancake/crepe example, power level 6 on the cast pan is dead perfect.

 

[Denwood]

I bought an induction heater tool off of Amazon. It was not the cheapest one for what that is worth.
Anyway, it is fascinating what can be done with it. Not something that I use very often, but when needed there is no substitute.

I really want one of those in my shop for the rusty salt belt fasteners on the cars…they are far more targeted than the usual torch go-to.

 

[four.cycle]

That does not sound like an induction cooktop, sounds like a regular electric with a glass top , there are no elements to see on induction.

OH?
it's got "elements" that heat up and turn red under the black glass.
so... that's not an induction range?
that would make sense, because she uses those glass pyrex pans!

 

[Overboost44]

Thanks for that video.

We replaced a perfectly good 20 year old GE Profile electric range with an Electrolux Induction about 5 months ago. It took a bit to get used to the precision it is capable of to cook on it, but I am sold. We have a variety of cast iron and it is my go to for many things but we also purchased a set of Made In pots and pans. No need for non-stick pans if you have some properly seasoned cast iron and heat it properly before plopping your eggs in there for frying. Boiling a pot of water for pasta takes me 3.5 min vs. the 11 minutes it used to take.

 

[mm08822]

Back in the early 90's I had a project to install a large induction coil (water cooled) to add extra curing capacity to an 8' wide industrial oven. The conveyor was all steel perforated slats.
As long as it was moving there was no concern about damaging the slats. If it stopped it could turn those slats cherry red and eventually melt them.

Not sure why anyone would market a pan as induction ready without it being all iron.

 

[WisJim]

I've considered an induction cooktop but we do a lot of canning and our big kettles are non-magnetic stainless steel and our pressure cookers are aluminum. When I have asked over the years about using them on an induction stove, I've been told to use a compatible metal plate on the burner of the stove--but I've never got an actual answer from anyone who has actually done it and who has any kind of believable results comparing the induction to gas.

 

[Denwood]

OH?
it's got "elements" that heat up and turn red under the black glass.
so... that's not an induction range?
that would make sense, because she uses those glass pyrex pans!

That is the same essentially as an electric resistance element...it's just under glass to make cleaning easier. The whole thermostatic control nature of electric elements is what makes them so hard to use if you want constant temp. What you have there is not an induction cooktop!

Thanks for that video.

We replaced a perfectly good 20 year old GE Profile electric range with an Electrolux Induction about 5 months ago. It took a bit to get used to the precision it is capable of to cook on it, but I am sold. We have a variety of cast iron and it is my go to for many things but we also purchased a set of Made In pots and pans. No need for non-stick pans if you have some properly seasoned cast iron and heat it properly before plopping your eggs in there for frying. Boiling a pot of water for pasta takes me 3.5 min vs. the 11 minutes it used to take.

I've heard Made In referenced often and they do sound like a good choice.

Back in the early 90's I had a project to install a large induction coil (water cooled) to add extra curing capacity to an 8' wide industrial oven. The conveyor was all steel perforated slats.
As long as it was moving there was no concern about damaging the slats. If it stopped it could turn those slats cherry red and eventually melt them.

Not sure why anyone would market a pan as induction ready without it being all iron.

I think an "Induction Ready" label that adds a magnetic coupling rating from 1 to 10 would make sense so you could at least predict how well it would work. Either that or go shopping with 3 sticky notes and the same magnet I used..ha.

I've considered an induction cooktop but we do a lot of canning and our big kettles are non-magnetic stainless steel and our pressure cookers are aluminum. When I have asked over the years about using them on an induction stove, I've been told to use a compatible metal plate on the burner of the stove--but I've never got an actual answer from anyone who has actually done it and who has any kind of believable results comparing the induction to gas.

There are induction adapter plates that do exactly what you're describing. I don't see how they would be different than the pan with the same thing embedded into the base, other then less efficienct heat conduction with the hob completely outside the pot base. If you look at reviews though, folks don't seem to like them much. My gut on this one is stick with what you're using until you're ready to replace the pots etc.

 

[Denwood]

I use a decently priced set of Cuisinart pots and pans, they work great. Bases are pretty thick.

I would be curious to pull out the thermal camera and see what's happening at the logo area. Some of the pots/pans I've tested with that setup have a dead zone in the middle. That is not a huge deal as the hob has a dead zone at the middle as well. I suspect if the pan has a fairly thick coppper or aluminum core to distribute heat (or is solid/heavy/thick like cast) this is not so much of an issue. That said, other than viewing the heat pattern right after start up, I found thermal imaging pretty much a waste of time when testing out the pots/pans.

 

[ALinCarolina]

Excellent video, you're my kinda guy. I have an induction in one of my houses and gas in the other. Really love the induction. What I didn't know and learned from the video is matching the hob to the size pan. I have been mostly using the largest hob for everything.

 

[Denwood]

Excellent video, you're my kinda guy. I have an induction in one of my houses and gas in the other. Really love the induction. What I didn't know and learned from the video is matching the hob to the size pan. I have been mostly using the largest hob for everything.

Thanks for the kind words The hob vs pot sizing was a complete surprise to me. However, after learning that the pan base becomes part of the circuit when in use, it does make sense that a small pot on a large hob likely requires the control circuitry to limit current. This tidbit explains it:

"Think of the hob coil and pan as a very loosely coupled transformer. The pan acts roughly like a shorted secondary winding. When the pan couples well, it presents a substantial real load back to the induction coil, so energy leaves the resonant circuit and becomes heat in the pan. The hob does not normally just apply a fixed AC voltage and let physics determine the current. Its inverter monitors things such as coil current, voltage/phase and the apparent impedance of the coil/pan system. It then changes switching frequency, duty/pulse pattern, or delivered power to keep the inverter within safe operating limits."

 

[snickers muncher]

I have considered an induction hot plate type deal on the side.

I bought one for my mother a few years ago and she loved it so much that she uses it almost exclusively.

 

[gtae07]

I dont understand how it could be better than gas as far as regulating the heat ? With gas you can actually see the flame and know what you are getting. And it doesnt require special cookware.

I last had gas in college, and then we had electric resistance glass-top for 20 years. When we moved, the rental and then the house we bought had gas, and I remembered why I hated it. It smells, makes the room humid, the rising heat messes with your hands if they're near the pot/pan, it's a ***** to clean. I have bad memories of college roommates leaving the gas going without a flame, and I have a 10 year old (and younger nephews who visit) who might well do the same.

So we pulled the gas stove out and replaced it with induction. Found pans that work well (sorry, I'm lazy, trying to season and maintain cast iron for cooking eggs is too much trouble) and we've been happy since. And it's super easy to clean; stuff doesn't burn onto the surface if it spills over.

 

[Old tool guy]

Interesting video.
At about 6:00 why does the graph go down from left to right?

 

[ChefRex]

There is nothing smart about an induction cooktop except it's ability to regulate the heat better than gas or electric.

Does it have a motherboard?

 

[ChefRex]

Those are kindest words I've opened the browser to in the last few days..honestly. There was a lot about induction that had me curious when I started down the rabbit hole.



Just be careful on those words "induction compatible"! There really should be a standard with cast iron at 10, and everything else measured as a standard against it. I think that's what got me going on this whole thing...compatible just means you'll get heat out of it, but it doesn't tell you how much.



I'm not a foody, but I do love making the Sunday Finn pancakes (super thin, like crepes) and for that the cast iron skillet (which I've sanded/polished) and induction at about power 6 for our cooktop is about perfect heat right across the pan face for these babies



Having done the Kitchen reno I wanted induction pretty much for the clean cooktop and efficiency. They are around 90%, so top of the heap that way. I also have the exhaust fan automated to the cooktop (it's an ECM fan, 0-10V control) so the fan ramps with the power use on the cooktop. The fact that the power delivery is pretty much constant (except at very low settings) makes the automation work smoothly too.



Nice in power outages though...



I'm not an expert on the electronics of the hob, but I do think it cuts power depending on the coupling. Now if that's just inherent in the physics, or part of the control circuit...that I don't know.



I am sure there are differences in control. The one I tested on is a pretty average IKEA 30" unit. Because I do have the 240V Aeotec switch in there, I can monitor power live. On 1 or 2 power level it may cycle a bit, but after that the power is pretty much steady and a function of which power level you're at, and what kind of pot is on the element. The max I saw on the large burner was 3700 watts with the cast iron, and that stayed very steady during the test.



I really was not happy about the Missus insisting on a wall oven and a cook top, but I'm quite glad we went that way. The only hassle really was running two 240V circuits instead of just using the existing feed for a range. We're not massive foodies by any stretch so I think the record for use has been 3 pots going at once. With a 30", you kind of run out of room anyway...

Are you cast iron flat bottomed or with a fire ring? I would imagine the flat bottom would be better.

 

[ChefRex]

I bought an induction heater tool off of Amazon. It was not the cheapest one for what that is worth.
Anyway, it is fascinating what can be done with it. Not something that I use very often, but when needed there is no substitute.

Which one did you get?

Correction, I read hot plate, I bought Mini-Ductor Venom HP not cheap buts makes me happy when I get to use it.

 

[Just_Steve]

Does it have a motherboard?

Most likely but I was referring to basic cooking functionality.

 

[Dumber than lumber]

Which one did you get?

Correction, I read hot plate, I bought Mini-Ductor Venom HP not cheap buts makes me happy when I get to use it.

Bought this one three years ago

EMAGIH 110V 1100W Auto Use Bolts Nuts Remover Car Garage Repairing PDR Tool Flameless Portable Magnetic Induction Heater… - Amazon.com

EMAGIH 110V 1100W Auto Use Bolts Nuts Remover Car Garage Repairing PDR Tool Flameless Portable Magnetic Induction Heater… - Amazon.com

www.amazon.com

Amazon says it is not currently available.

 

[Denwood]

Interesting video.
At about 6:00 why does the graph go down from left to right?

Good eye!! The screen grabs used in the video were generally taken after each test was complete. The calcs for power use and cost start when the water passes 60F, but then the data capture stops when it hits 212F. The graph on the other hand is realtime and reflects the last 6 minutes or so of data. I could have just sped up the entire screen video taken during each test so you would have seen the graph real-time. I'll remember this for next time.

Are you cast iron flat bottomed or with a fire ring? I would imagine the flat bottom would be better.

Pretty much flat bottom. I took some time to sand and polish the cooking surface and I'd say that is my next best tip for any cast iron user! That's why the cast iron thermal image looks a bit funky as parts of the polished surface are bit more reflective than others as the pan comes into itself with curing/use.

 

[Overboost44]

Good eye!! The screen grabs used in the video were generally taken after each test was complete. The calcs for power use and cost start when the water passes 60F, but then the data capture stops when it hits 212F. The graph on the other hand is realtime and reflects the last 6 minutes or so of data. I could have just sped up the entire screen video taken during each test so you would have seen the graph real-time. I'll remember this for next time.



Pretty much flat bottom. I took some time to sand and polish the cooking surface and I'd say that is my next best tip for any cast iron user! That's why the cast iron thermal image looks a bit funky as parts of the polished surface are bit more reflective than others as the pan comes into itself with curing/use.

Do you have a video for your polishing process? I have seen some and it looks like more work than I want to tackle. I am hoping it is easier than I think. Once I season a pan, I only clean it with a chain mail and follow with a hard bristle brush if necessary. I rarely ever use soap in it. I find it easy to maintain.

 

[ChefRex]

Do you have a video for your polishing process? I have seen some and it looks like more work than I want to tackle. I am hoping it is easier than I think. Once I season a pan, I only clean it with a chain mail and follow with a hard bristle brush if necessary. I rarely ever use soap in it. I find it easy to maintain.

The ones I have are old and slick, should I acquire and old rusty one I would consider making one smooth from the start but I'm pretty happy with mine.