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Old 13-12-2014, 12:59   #16
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Re: Induction cook-top and inverter compatibility

We have had a problem when the batteries were not fully charged. We think the inverter output voltage was not high enough to start the induction circuitry. It might have a safety low voltage cutout.
.
Perhaps you might try it with a full charge or even with the motor running.
Our first inverter was MSW. It cooked a couple of phone chargers. Pure sine is great.
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Old 13-12-2014, 13:02   #17
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Re: Induction cook-top and inverter compatibility

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Originally Posted by nimblemotors View Post
Is the cooktop actually set up to draw power from the inverter?

That would be the next thing to check.
It seems some inverters don't output power unless a draw is detected, and perhaps the cooktop doesn't work until iT sees power coming in, so there is a stalemate between the two.
I don't think sine-wave or not is an issue, the cooktop just converts it to DC. Sine wave is mostly an issue for motors that need the slower ramping up/down of the AC voltage.
I don't believe that's how it works. The cooktop induces current in the pan through building and collapsing magnetic fields - AC power.

The problem with MSW inverters, especially the cheap ones, is that their sine waves are so modified they don't look anything like a sine wave. They provide an almost square wave output, and this output is lacking the same power output as a sine wave. When you measure the current, it doesn't produce the same amperage due to the missing sections under the curve. The MSW waveform is an approximation of a sine wave, but it's missing all of the power under the curve.

Other devices - desktop PCs, laptops, cell phone chargers, LCD TVs, etc all have built in power supplies that filter out noise- and in the process fill in the missing portions of the MSW. However, induction cooktops and microwave ovens require all of their rated power, and they use it, an MSW does not provide the needed power under the curve.

I have installed a lot of inverters (mostly Xantrex) and none of them would allow a microwave to operate properly, even though they were rated to provide the necessary power.

There are a lot of cheap pure sine wave inverters on the market now, I'd try and find one of those that works.
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Old 13-12-2014, 14:56   #18
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Re: Induction cook-top and inverter compatibility

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Originally Posted by Erasmuss View Post
Hi,

Let me throw my two cents in here. First every Induction Cook Top I have tested from Pro Grade's like Cook Tek ( which I own ) to the infamous unit Sold on TV all cook in the same manner.

They don't have as Sophisticated Control Systems as One may think. Although they will hold a specified temperature they do so in an Old School manner with a Dead Band around that Set Point. This Means They Come On Full Power until they reach the Set Point and then Shut Off until the temperature falls off to the Low Side of the Dead Band. They do not regulate Inductive Power at a Specific Set Point.

I too had anticipated that these Induction Cook Tops would have a Sophisticated Control Circuit that would limit the amount of Inductive Power to the pan to Coequal that which was needed to hold a Specific Temperature. I was sadly disappointed to learn through use and testing that they do not. At least the units I have tested personally, which includes the American Designed and Made in the USA Cook Tek.

A simple test which you can do - without the aid of any test equipment - can be done by simply adding water (you don't need much, just enough to prevent burning the pan) to a pan or pot & set the temperature to say 150 degrees. Now wait for the heating cycle to bring the water up to temperature ... You will see bubbles begin to form on the bottom as it attempts to bring the mass of pot and water to the set temperature. Once the unit determines it has done so it will Shut Off the Inductive Power Unit ... at this point you will see the bubbles in the bottom of the pan disappear until the Low Side of the units Dead Band Range is reached at which point you will see the Bubbles reappear. Which only means one thing ... The Inductive Energy is Either On @ Full Power or Off with only enough draw to operate the Fan and Control Circuit. If these units utilized Truly sophisticated Control Circuits you would never see any Cycling once the Set Point was reached and thus you would have a Consistent Draw of Power from your system and it would be impossible to burn anything with an Induction Cook Top if it was set properly.

Because these units operate in the manner that they do I find that they are less than optimal ... considering what's possible with current state of the art Temperature Controllers !

What can help is the use of Heavy Cast Iron which will moderate the temperature better than most other containers.

The Point I'm trying to make here is that The Unit is going to Draw at It's Maximum Wattage (1.8 Kw in your case) when it's Ramping-Up to it's Set Temperature and will shut Down once it has reached that point - probably with some level of time delay. And the Cycling Begins. They do not reach that point and then Hold at some reduced power level to maintain that set point.

So when you say you set your Hob @ 800 Watts that is only a Temperature Set-Point Reference ... it is not what the unit is limited to at any moment in time. It will be @ full power until it reaches that Set-Point and then it will Shut-Off the Inductive Power to Zero.

Sorry for being Long Winded but I wanted to make the point clearly ... I hope I did so.

Sincerely,
Erasmuss


I'm sure those are the results you obtained, however, I only own one brand of induction cooktop and my results were different.

Mine is a Nuwave Precision Induction Cooktop, and here are the results of current draw vs temp. setting.

Low = 100* drew about 650 watts.
Med. low = 175* drew about 650 watts
Medium = 275* drew about 1030 watts
Med. High. = 375* drew about 1300 watts
High = 425* drew about 1580 watts
Max/Sear = 650* drew about 1680 watts.

This is the only brand I've tested, but those results are different from other brands. I have not yet tried this model on a Xantrex inverter, but I have a Freedom 458 and an HF 1800 that I can test it on. I'll report back when I do.
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Old 13-12-2014, 16:11   #19
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Re: Induction cook-top and inverter compatibility

Quote:
Originally Posted by Erasmuss View Post

They don't have as Sophisticated Control Systems as One may think. Although they will hold a specified temperature they do so in an Old School manner with a Dead Band around that Set Point. This Means They Come On Full Power until they reach the Set Point and then Shut Off until the temperature falls off to the Low Side of the Dead Band. They do not regulate Inductive Power at a Specific Set Point.

I too had anticipated that these Induction Cook Tops would have a Sophisticated Control Circuit that would limit the amount of Inductive Power to the pan to Coequal that which was needed to hold a Specific Temperature. I was sadly disappointed to learn through use and testing that they do not. At least the units I have tested personally, which includes the American Designed and Made in the USA Cook Tek.

A simple test which you can do - without the aid of any test equipment - can be done by simply adding water (you don't need much, just enough to prevent burning the pan) to a pan or pot & set the temperature to say 150 degrees. Now wait for the heating cycle to bring the water up to temperature ... You will see bubbles begin to form on the bottom as it attempts to bring the mass of pot and water to the set temperature. Once the unit determines it has done so it will Shut Off the Inductive Power Unit ... at this point you will see the bubbles in the bottom of the pan disappear until the Low Side of the units Dead Band Range is reached at which point you will see the Bubbles reappear. Which only means one thing ... The Inductive Energy is Either On @ Full Power or Off with only enough draw to operate the Fan and Control Circuit. If these units utilized Truly sophisticated Control Circuits you would never see any Cycling once the Set Point was reached and thus you would have a Consistent Draw of Power from your system and it would be impossible to burn anything with an Induction Cook Top if it was set properly.

Because these units operate in the manner that they do I find that they are less than optimal ... considering what's possible with current state of the art Temperature Controllers !

What can help is the use of Heavy Cast Iron which will moderate the temperature better than most other containers.

The Point I'm trying to make here is that The Unit is going to Draw at It's Maximum Wattage (1.8 Kw in your case) when it's Ramping-Up to it's Set Temperature and will shut Down once it has reached that point - probably with some level of time delay. And the Cycling Begins. They do not reach that point and then Hold at some reduced power level to maintain that set point.

So when you say you set your Hob @ 800 Watts that is only a Temperature Set-Point Reference ... it is not what the unit is limited to at any moment in time. It will be @ full power until it reaches that Set-Point and then it will Shut-Off the Inductive Power to Zero.

Sorry for being Long Winded but I wanted to make the point clearly ... I hope I did so.

Sincerely,
Erasmuss
That's not how mine works. I don't use bbuilt in temperature control at all. It has 8 LEDs and +/- buttons. The legend below the LEDs is "120,300,800,1000,1300,1600,1800,2100W".

I set the power initially depending on what I am doing and how long I want to wait for it to come up to the desired temperature. Once up to temperature, I adjust the power as required to maintain the heat input I need (a slow simmer and a rolling boil are both at 100C, but require different power settings to maintain).
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Old 13-12-2014, 19:29   #20
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Re: Induction cook-top and inverter compatibility

Some "smart" inverters do not output full voltage unless there is something drawing power. Some "smart" appliances don't draw power unless the voltage is above a certain level. This can be a catch 22 situation. If your inverter has this feature turn it off.

But my guess is that the "hob" draws too much power at startup and the inverter folds back so the hob shuts down. Most of these induction stoves don't really have variable power control. They just run full throttle and turn on and off to control temperature. Microwave ovens are the same way. If the inverter can't deliver full power to the stove it may never work.
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Old 14-12-2014, 01:13   #21
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Re: Induction cook-top and inverter compatibility

Induction stoves need pure sign to operate. and most of them if not all have different wattage ratings for the different settings but they also cycle on and off relative to temperature( I spent a few months reading reviews mostly from Amazon before I purchased mine)
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Old 14-12-2014, 06:02   #22
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Re: Induction cook-top and inverter compatibility

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Originally Posted by rwidman View Post
You were doing fine until that last sentence. Perhaps you meant to say "shorepower"?
Umm, yep, good catch, thanks

-Chris
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