Modified sine wave and induction hob

andyjanet

andyjanet

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Hi all, after our disaster with a second hand dometic inverter tripping the whole stellplatz in Germany , I have bought the replacement and fitted it! My question is the new one doesn’t work my newly bought induction hob , can anyone recommend an induction hob that works with a 2000 w Dometic modified sine wave inverter
 
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andyjanet said:
Hi all, after our disaster with a second hand dometic inverter tripping the whole stellplatz in Germany , I have bought the replacement and fitted it! My question is the new one doesn’t work my newly bought induction hob , can anyone recommend an induction hob that works with a 2000 w Dometic modified sine wave inverter
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I think you need to do it the other way round - change the inverter for a Pure Sine Wave one :(
 
Yeah I am fairly sure it needs to be pure sine wave with induction hobs
 
David of Wildebus [Post #2] fitted our Victron pure sine wave inverter on 28th Sep and we bought a Vango Sizzle Induction Hob [Camping Version} a few days later. Only boiled water to see what demand the hob places on the battery, but hob and inverter play together nicely

Steve
 
Electric toothbrushes, which I believe get charged via induction.
Modified sine wave inverters "break" electric toothbrushes.
1 I am not surprised that an induction cooker will not work from a modified sine wave inverter.
2 It may also be that the induction cooker has been "fubared".
Check it on EHU
 
Definately need pure sine wave, as modified will not work the electronics, it would not work a microve either if it has a digital screen.
 
When you were at school, did you move bar magnets in and out of a coil of wire to "induce" an electric voltage?
If you do it quicker, the voltage gets higher.

Did you replace the permanent magnet with a powered coil of wire, to act as an electromagnet? Moving it has the same effect, but switching on and off also induces a voltage.
Did you convert it to a transformer, by using the coil as a primary circuit? It only works with alternating current, as that constantly changes the magnetic field.
That is the basis of an induction cooker/hob: your power supply creates an electromagnet which constantly changes in strength and the pan acts as the secondary coil, generating heat as the induced current flows through it.

In maths, did you draw a sine curve? It's a smoothly changing line, a bit like a gentle wave in the sea.
If you have a pure sine wave inverter then you get a smoothly changing current which induces a smoothly changing current it the pan.
But a modified sine wave is a series of straight lines: straight up then straight down (imagine at 45deg).
Where it changes from going up to going down there is a sudden change in current and that is like moving the magnet quickly: you induce a very large voltage (only for a brief moment, but enough to do damage).

You NEED a pure sine wave inverter!

Gordon (retired physics teacher)
 
andyjanet said:
You lost me when you mentioned school 😭
Click to expand...
My Physics Teacher, Roger Conibear, told me in 1969 not to take Physics at O Level 'because you'd be wasting the Examiner's time' ... Harsh, but true. I had dropped Biology after 2nd year, and was obliged to take a science subject, so had to sit Chemistry O Level, where I finished a 3 hour exam in 8 minutes; not because I am a genius, but because I didn't/don't have a bloody clue. I achieved a Grade 9 O Level fail, because the NUJMB Exam Board didn't offer a Grade 10 Fail.

On the positive side [the one with the plus on the battery terminal ...], I did get O Level passes in Latin and Ancient Greek, both of which have proven to be of immense benefit in my working life. I'm also an accomplished liar ... :rolleyes:

Steve
 
Norfolk NewBoy said:
When you were at school, did you move bar magnets in and out of a coil of wire to "induce" an electric voltage?
If you do it quicker, the voltage gets higher.

Did you replace the permanent magnet with a powered coil of wire, to act as an electromagnet? Moving it has the same effect, but switching on and off also induces a voltage.
Did you convert it to a transformer, by using the coil as a primary circuit? It only works with alternating current, as that constantly changes the magnetic field.
That is the basis of an induction cooker/hob: your power supply creates an electromagnet which constantly changes in strength and the pan acts as the secondary coil, generating heat as the induced current flows through it.

In maths, did you draw a sine curve? It's a smoothly changing line, a bit like a gentle wave in the sea.
If you have a pure sine wave inverter then you get a smoothly changing current which induces a smoothly changing current it the pan.
But a modified sine wave is a series of straight lines: straight up then straight down (imagine at 45deg).
Where it changes from going up to going down there is a sudden change in current and that is like moving the magnet quickly: you induce a very large voltage (only for a brief moment, but enough to do damage).

You NEED a pure sine wave inverter!

Gordon (retired physics teacher)
Click to expand...
And with an Inverter, you need a REAL Pure Sine Wave! (lots of "Pure Sine Wave" inverters are not really that "Pure", they are bit of a less choppy Modified Sine Wave Inverter, revealed when you put a 'scope on them. Interestingly, the Victron PSW Inverters actually have a cleaner Sine Wave than many grid supplies :) ).

PS. The Modified ones are not quite straight up and downs - they are more like playing qbert ... up, across, up, across, up, across, down, across, etc.🕹️
 
Norfolk NewBoy said:
When you were at school, did you move bar magnets in and out of a coil of wire to "induce" an electric voltage?
If you do it quicker, the voltage gets higher.

Did you replace the permanent magnet with a powered coil of wire, to act as an electromagnet? Moving it has the same effect, but switching on and off also induces a voltage.
Did you convert it to a transformer, by using the coil as a primary circuit? It only works with alternating current, as that constantly changes the magnetic field.
That is the basis of an induction cooker/hob: your power supply creates an electromagnet which constantly changes in strength and the pan acts as the secondary coil, generating heat as the induced current flows through it.

In maths, did you draw a sine curve? It's a smoothly changing line, a bit like a gentle wave in the sea.
If you have a pure sine wave inverter then you get a smoothly changing current which induces a smoothly changing current it the pan.
But a modified sine wave is a series of straight lines: straight up then straight down (imagine at 45deg).
Where it changes from going up to going down there is a sudden change in current and that is like moving the magnet quickly: you induce a very large voltage (only for a brief moment, but enough to do damage).

You NEED a pure sine wave inverter!

Gordon (retired physics teacher)
Click to expand...
Thank Gordon,
I studied Physics to A level (A grade!) But maths at Uni !
So your post makes perfect sense and useful to know precisely why modified sine wave inverters can "damage" things, or just not work
We have a low power inverter
(MSW) which I use only rarely as usb does most things these days.
 
Hi Barry , i have looked but no real luck.
Most induction hobs have various setting which should enable you to choose.. a low setting.
the one we have goes as low as 200watts and has 400 800 and higher as options.
i estimate 200watts would draw about 17 amps so ok as only using for a shortish time.
Efficiency leccy to actual heat is good.
300 ml of water will take 10 mins at 200 watts.
5 mins at 400 watts although the draw on your batteries is higher the time is halved in both cases about 17x 1/6th
so 3 amp-hours.
Many have a simmer setting and this is likely to mean the draw on the batteries varies as the heater will be kicking in and out.
I am not sure what the maximum power might be even if only very briefly.
The cost of a 2000watt psw. Inverter would seem to be totally OTT (for me)
 
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Norfolk NewBoy said:
When you were at school, did you move bar magnets in and out of a coil of wire to "induce" an electric voltage?
If you do it quicker, the voltage gets higher.

Did you replace the permanent magnet with a powered coil of wire, to act as an electromagnet? Moving it has the same effect, but switching on and off also induces a voltage.
Did you convert it to a transformer, by using the coil as a primary circuit? It only works with alternating current, as that constantly changes the magnetic field.
That is the basis of an induction cooker/hob: your power supply creates an electromagnet which constantly changes in strength and the pan acts as the secondary coil, generating heat as the induced current flows through it.

In maths, did you draw a sine curve? It's a smoothly changing line, a bit like a gentle wave in the sea.
If you have a pure sine wave inverter then you get a smoothly changing current which induces a smoothly changing current it the pan.
But a modified sine wave is a series of straight lines: straight up then straight down (imagine at 45deg).
Where it changes from going up to going down there is a sudden change in current and that is like moving the magnet quickly: you induce a very large voltage (only for a brief moment, but enough to do damage).

You NEED a pure sine wave inverter!

Gordon (retired physics teacher)
Click to expand...
Not strictly true Gordon, even a pure sinewave inverter has a digitally produced curve. School physics proved to be either wrong or misleading.
All the same a good crude explanation. ;)

Mark
 
Molly 3 said:
Are camping induction hobs low watts?.
Click to expand...
Yes, Barry. We bought the Vango Sizzler single hob which is set at 800W max and has 5 settings, including a 'pan warm/simmer' setting. Only used it to play since buying it 3 weeks ago to see how much it took out of the Battery via the inverter. Hope it'll get lots of work during our [yet to be booked] Winter Sun Trip!

EDIT https://www.vango.co.uk/gb/camping-equipment/335-sizzle.html shows the specification, weight, dimensions etc. 2.5m power lead should be great for outdoor cooking using the double socket in the 'Ski Cupboard' aka the Broom Cupboard!

Steve
 
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