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Can anyone help me with the calculations for an induction cook top?

Toddwmac

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Greetings

Are there any special considerations for an inductive cooktop?

I'm looking at a 24v 100Ah system in my van. My biggest draw is a 1500 watt induction cooktop for 15 minutes a couple times a day. It can be stepped up in 300 watt increments.

If I understand this stuff right, I have about 24Ah of 110v power. At a draw of 1500 watts (110v x 14 amps), I have about 1.7 hours of continuous 110 voltage that I could use to power my cooktop. In round numbers, is this about right or am I way off somewhere?

Thanks...and thanks to you Will for pulling all this together.
 
The power draw of the cooker won't be continuous, you are cooking your food not incinerating it. You might be looking at 1/4 of the rated power over time and the cooker maintains the set temperature in the pot. It all depends on what you are cooking and how. You could do 1500 watts continuous into a boiling pot of water and end up with a lot of steam.

Assuming a more realistic power use of 375 watts that's 6 hours. If you are using lead acid battery and only have 100ah of them you should halve this time as you shouldn't take a lead acid battery below 50% if you want it to last.

Your inverter will still need to be able to supply > 1500 watts. All factors considered you might be looking at an inverter > 2500 watts continuous in order to cope with the cycling or duty cycling of the cooker. As mentioned elsewhere these cheap HF inverters don't cope well with loads being turned on and off. They all usually drop their output voltage and then slowly rise back up again which isn't necessarily a good thing for your induction cooker.
 
It's hard to say, I don't think I've ever used mine above half power. Also the way I cook I don't think I've ever used them as long as fifteen minutes at a time.
 
I use a microwave, a convection toaster over, an induction cooktop, a rice cooker, an instant pot and a crock pot in my house exclusively. I rarely use my stove anymore. I just don't see why I want to draw 220v to heat up a burner to heat up a pot to heat up food. That 110v induction cooktop boils water SO FAST it's amazing. Same with the toaster oven. Heats faster, and has enough cooking room for me since I live alone. My electric bill went down $15-18 a month when I quit using the electric range. Very energy efficient cooking!
 
Are there any special considerations for an inductive cooktop?
Yes!

how-induction-works.png

To get the a workable magnetic field, you need pure sine-wave inverter. A modified wave inverter won't work efficiently.

1eb2db514a8ec5cf1c3557d3f1c9e561.jpeg

You'll also need ferric pots/pans of course.


I'm looking at a 24v 100Ah system in my van. My biggest draw is a 1500 watt induction cooktop for 15 minutes a couple times a day.
At a draw of 1500 watts (110v x 14 amps),

Question: [do] I have about 1.7 hours of continuous 110 voltage?
Not if they're lead acid!

Power Draw
: 1500W / 24V /.8 = 78 amps
Battery: 100 Ah@20hour rate, that means to get the full 100 Ah out of the battery, you can't draw more than 5 Amps. See this for more.
As you're pulling a lot more than that, it'll probably act more like a 65 Ah battery... so 50 minutes? Enough for two 15 minutes sessions at less than full power anyway.

110 or 120V?
Power in the US is typically 120 or 240V. You do see appliances marked 110V, and that's so consumers know it'll work in rural areas where due to voltagage drops, they might not see 120V.

To throws some gas on the fire, it's not uncommon to see 110V or 115V inverters. You'd think it makes sense, because lower voltage, lower current, lower power right? Nope. It's the opposite. Appliances draw watts and typically are tuned for 120V and less efficient if not at 120V. Even worse, some devices won't work at 110V. My advice, get a 120V inverter.
 
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Thanks svetz! We had a taste of this sensitivity with our boat. Some of the electronics were acting flakey and we chased ghosts for months until we finally replaced an almost brand new inverter. Poof...all good. I never considered that when thinking about a cook top....until now. Thanks!
 
I use a microwave, a convection toaster over, an induction cooktop, a rice cooker, an instant pot and a crock pot in my house exclusively. I rarely use my stove anymore. I just don't see why I want to draw 220v to heat up a burner to heat up a pot to heat up food. That 110v induction cooktop boils water SO FAST it's amazing. Same with the toaster oven. Heats faster, and has enough cooking room for me since I live alone. My electric bill went down $15-18 a month when I quit using the electric range. Very energy efficient cooking!
Just out of curiosity, what induction cook top do you have? I've been considering adding one.

Thanks,
Mike
 
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