Induction Cooktop issue on inverter

[Cbruson]

Hey! I'm new to the forum and saw the other thread about microwave issues on inverters. I am having my own issues with an induction cooktop on an inverter. The info in the microwave thread doesn't directly apply, so I figured I'd start a new thread to help me diagnose this problem.

I am trying to run an 1800w induction cooktop from my 2000w CNBOU pure sine inverter. I have 700ah of 12v AGM batteries.
The cooktop works well for 3 uses, but will not start on the 4th use. When the inverter is turned on, the cooktop "beeps" like it receives power, but no lights or power comes on to the unit. It is broken. I got a warranty replacement cooktop and this exact scenario happened again. I've never used the cooktop above 60% power, it is well ventilated, and it does not blow a fuse or anything - it just won't power on the 4th time. I do not want to break a third induction cooktop, so hopefully you can help me narrow down why this will not work with my setup.

Has anyone had success running an induction cooktop off a pure sine inverter? (If so, what brand)

Thanks for any info and troubleshooting help you all can provide.

- Connor

 

[gnubie]

Induction cookers are known for being fussy with their input power. There's many ways they work but the two common ways are zero point switching of the mains direct across the coil and a HF chopping of rectified mains into the coil. Its hard to say exactly what is going wrong with your setup without being able to do measurements but its entirely possible a resistor in the control circuit is being overheated and going open.

From a quick look at the inverter web site I'm going to guess your inverter is one of the oh-so-common direct HF designs. They are well known for having almost 0 surge capacity and will often output significantly lower voltage when a high current load is initially connected and then slowly ramp back up to fully voltage. In the case of a cheaper zero point switch of the mains direct style induction cooker it's entirely possible the inverter's output voltage is all over the place. This may account for high power dissipation in the control circuit causing it to fail.

That's just an educated guess but doesn't really help you. Can you connect the cooker to an actual mains supply rather than the inverter to see if it will actually start?

 

[HighTechLab]

From the spec sheet first glance, 60HZ+0.5HZ That is a pretty high frequency variation.

 

[Cbruson]

Induction cookers are known for being fussy with their input power. There's many ways they work but the two common ways are zero point switching of the mains direct across the coil and a HF chopping of rectified mains into the coil. Its hard to say exactly what is going wrong with your setup without being able to do measurements but its entirely possible a resistor in the control circuit is being overheated and going open.

From a quick look at the inverter web site I'm going to guess your inverter is one of the oh-so-common direct HF designs. They are well known for having almost 0 surge capacity and will often output significantly lower voltage when a high current load is initially connected and then slowly ramp back up to fully voltage. In the case of a cheaper zero point switch of the mains direct style induction cooker it's entirely possible the inverter's output voltage is all over the place. This may account for high power dissipation in the control circuit causing it to fail.

That's just an educated guess but doesn't really help you. Can you connect the cooker to an actual mains supply rather than the inverter to see if it will actually start?

Thanks for the insight gnubie. I have not had the chance to connect it to a mains power supply yet, since I am traveling, but I will try that with the "broken" unit that I have once I get home next week. I'll also try to ask the inverter supplier more about its design (direct HF or not).

 

[Cbruson]

From the spec sheet first glance, 60HZ+0.5HZ That is a pretty high frequency variation.

HighTechLab, can you elaborate more about what that might mean in my case? I'm not too familiar with hertz.

 

[HighTechLab]

HighTechLab, can you elaborate more about what that might mean in my case? I'm not too familiar with hertz.

It could mean the line frequency is too high for the cooker to function properly - if you turn it on and the frequency changes it could throw the microprocessor off - Have you tested this with utility power to see if it still has the issue?

 

[Cbruson]

It could mean the line frequency is too high for the cooker to function properly - if you turn it on and the frequency changes it could throw the microprocessor off - Have you tested this with utility power to see if it still has the issue?

I have not tested the cooktop with utility power. I'll get the chance to test it next week when I'm back at home. But I fear this broken unit won't work with any power regardless.

So, these responses are pointing to the outcome that I might just need a higher quality inverter to power any indication cooktop. Would that be accurate?

Can anyone suggest a higher quality ~2000 watt inverter that would work with an induction cooktop?

 

[Rider]

If the cooktop is 1800W, I'd be looking at a 3000-4000w inverter. Better to go higher than you need than try to run close to the line. A larger inverter doesn't use much more idle current than a smaller one.

 

[Cbruson]

If the cooktop is 1800W, I'd be looking at a 3000-4000w inverter. Better to go higher than you need than try to run close to the line. A larger inverter doesn't use much more idle current than a smaller one.

Will a 3000-4000w inverter still present me with the same issues pertaining to running an induction cooktop? The wattage doesn't seem to be the problem currently.

 

[Rider]

It's a good idea to give yourself a little headroom and not push the hardware right to the advertised limits. You asked for a recommendation for a unit that could work with an induction stovetop, so if/when you do find one, just upsize a bit. Not saying it will help the current problem, but may avoid a future inverter failure.

 

[HighTechLab]

Until you test on utility power it will be hard to say. If I'm understanding correctly it worked 3 times but the fourth time it didn't work, correct?

Based on your picture it looks like this is located in an RV / Trailer. This leads me to assume that you are running a 12 volt system. 3000 watt 12 volt inverters are starting to push the limit of what 12 volt is capable of - You would be at around 300 amps assuming you are at 12 volts and the inverter is 80% efficient. Your 700 AH battery bank likely could handle it, but why put the abuse on the batteries?

Do you have any generator options that you could persue? What is the budget you are looking at?

 

[Rider]

...starting to push the limit of what 12 volt is capable of...

Yes. I was thinking of re-arranging the batteries for 24-48VDC operation which makes the 3-4K inverter much easier, but not so easy to rewire the trailer if it's already wired for 12V.

 

[HighTechLab]

Yes. I was thinking of re-arranging the batteries for 24-48VDC operation which makes the 3-4K inverter much easier, but not so easy to rewire the trailer if it's already wired for 12V.

Do you have a generator that requires 12v to start?

You can't tap 12 volts off of a 24 or 48 volt bank, so any 12 volt loads would have to be ran through a dc-dc converter of sufficient capacity, and if you have a generator that wants a bunch of amps for a starter, then you start to run into some issues.

Definately some added challenges.

 

[Rider]

This poster appears to be doing it, maybe he can answer some questions...

Budget charge from alternator addition to solar

Hi dear community! Thanks administration for creating this forum. Hopefully it will be helpful. Currently my Ford Transit 2016 camper van conversion uses 350W solar only to charge 12V 200AH LiFePO4 battery bank. We have no propane, so it's all electric conversion with some massive loads like...

www.diysolarforum.com

 

[b.james]

Surely you can find a gas station toilet or shower somewhere to run a test on normal shore power?

 

[Cbruson]

Until you test on utility power it will be hard to say. If I'm understanding correctly it worked 3 times but the fourth time it didn't work, correct?

Based on your picture it looks like this is located in an RV / Trailer. This leads me to assume that you are running a 12 volt system. 3000 watt 12 volt inverters are starting to push the limit of what 12 volt is capable of - You would be at around 300 amps assuming you are at 12 volts and the inverter is 80% efficient. Your 700 AH battery bank likely could handle it, but why put the abuse on the batteries?

Do you have any generator options that you could persue? What is the budget you are looking at?

You are correct. The cooktop works great 3 times, then won't turn on the 4th time (this happened on the first and the replacement cooktops).

Yes, it is located in the van in my profile picture. The whole system is 12v, and I'd much rather solve this independent problem than re-do my entire system. I would even hate to have to buy a larger inverter (it should work on a 2000w inverter), since my inverter works for all of my purposes except this cooktop. I'd likely size up to something between 2000-2500 watts, not make the jump to 3000, for the reasons you specified. But even then, I'm not convinced that a bigger inverter will make this work.

I'm sorry, I'm in the mountains and still haven't had a chance to connect the broken cooktop to shore power. I will let you know what happens when I do (I assume nothing will happen).

Thanks for your thoughts, everybody. I'm also chatting with my inverter vendor (Matt @ Continuous Resources, who is great by the way), and he's never run into someone having this problem with a CNBOU inverter. I'm really grasping at straws here about how to get a working cooktop in my van. Surely other people use induction cooktops with inverters??

 

[Rider]

Surely other people use induction cooktops with inverters??

Check my post #14 above...

You haven't said what kind of wire you're using, or how far it is between components.

 

[Cbruson]

Check my post #14 above...

You haven't said what kind of wire you're using, or how far it is between components.

I made a 12awg extension cord that goes from the inverter to the cooktop. That run is approx. 10ft. The cooktop itself has a 4ft 14awg cord attached to it. I am plugging the cooktop into the extension cord.

This is the cooktop btw...

https://www.amazon.com/dp/B07FMTY8Q8?ref=ppx_pop_mob_ap_share

Could there be too significant of a voltage drop between the inverter and the cooktop?

As far as running the cooktop from the inverter versus from the batteries, it's a 120v cooktop...so it can't be run directly to the 12v batteries.

The inverter is connected to the batteries with 2/0 cables that span approx. 1 ft each. Batteries are connected together with 4/0 cables, 11" each.

 

[Rider]

Could there be too significant of a voltage drop between the inverter and the cooktop?

That's why I asked. For kicks and giggles, see if you can run a heavier gauge like 10, all the way to the cooktop, eliminate the 14.

As far as running the cooktop from the inverter versus from the batteries, it's a 120v cooktop...so it can't be run directly to the 12v batteries.

Yeah, I had just woken up from a nap when I posted that.... you'll notice I deleted it.

 

[Deleted member 783]

You can't tap 12 volts off of a 24 or 48 volt bank, so any 12 volt loads would have to be ran through a dc-dc converter of sufficient capacity, and if you have a generator that wants a bunch of amps for a starter, then you start to run into some issues.
Definately some added challenges.

Don't most charge controllers have a DC load output? I have mine connected to a small 12 fuse block.