DC induction cooktop

[marcham]

PS: instead of pasting a long AI response, it's possible to just post the link to the chat (share the chat):

Example:

‎Gemini - direct access to Google AI

Created with Gemini

share.gemini.google

Kind of like posting a link to a news article / sailing magazine post instead of copy / pasting all the content.

 

[CrispyCringle]

Practically speaking, it seems just going with an AC cooktop is the way to go. I have a Duxtop one that shows it uses 1800W. My West Marine inverter puts out a modified sine wave at 1500VA (4000VA surge max 15 seconds). Not sure how to convert the two, but the cooktop does not heat when powered by the inverter, so I assume output of the inverter is insufficient. Is there a cooktop that would work with my inverter? Any recommendations?

I think the problem may be that you are using a modified sine wave inverter and not a pure sine wave unit. I have that same Duxtop 1800 watt cook top and it works fine on a Victron pure sine wave inverter. Pure sine wave costs a little more, but its always the way to go.

 

[skunther]

It’s a 700w microwave, but I looked at the label and the draw is 1050w, so it seems 93A is in range and may be tripping the 100A breaker after running for 1 minute at that amperage. I traced the lines and the 100A breaker appears to be between the combiner and the house positive bus, which is what the inverter is cabled to. The battery bank positive has only one cable, which goes to that bus. Wiring for the inverter calls for a 200A terminal fuse between the inverter and battery though, within 18” of the battery.
Seems the breaker is undersized for the draw on the bus, though I’m not keen to modify it without understanding why it is there in the first place. Any thoughts here? Should I just wire the inverter + directly to the battery + with an 200A fuse at the battery end? Attached is a picture of the combiner and 100A breaker.

 

[dLj]

PS: instead of pasting a long AI response, it's possible to just post the link to the chat (share the chat):

Example:

‎Gemini - direct access to Google AI

Created with Gemini

share.gemini.google

Kind of like posting a link to a news article / sailing magazine post instead of copy / pasting all the content.

As a counter-position to this. Links tend to change over time. So if someone is reading this thread sometime in the future, the link may no longer work. Also when reading these discussions on my phone, I find it better to not have to jump around to different links.

There are pro's and con's to both...

dj

 

[dLj]

It’s a 700w microwave, but I looked at the label and the draw is 1050w, so it seems 93A is in range and may be tripping the 100A breaker after running for 1 minute at that amperage. I traced the lines and the 100A breaker appears to be between the combiner and the house positive bus, which is what the inverter is cabled to. The battery bank positive has only one cable, which goes to that bus. Wiring for the inverter calls for a 200A terminal fuse between the inverter and battery though, within 18” of the battery.
Seems the breaker is undersized for the draw on the bus, though I’m not keen to modify it without understanding why it is there in the first place. Any thoughts here? Should I just wire the inverter + directly to the battery + with an 200A fuse at the battery end? Attached is a picture of the combiner and 100A breaker.

Well first let me say - I don't fully understand what your wiring is exactly doing and how the different breakers/fuses are working as a system.

That said - fuses/breakers should trip when you exceed their rates capacity. If your 100A breaker is tripping at 93A it would seem to me it may be getting tired. Or, you are actually drawing more than you think - I like to measure and then know the answer to that question. I typically consider ratings on devices to be approximate. If I'm having a problem, I measure. Do you have an amp meter?

Fuses/breakers are used to protect wiring, not devices. If you do want to increase that 100 amp breaker to 200 amps, what is the wiring it protects and is that the correct breaker for that wiring.

dj

 

[marcham]

The inverter should NOT be connected to the house loads breaker (100A). It should be wired directly to the house battery, have it's own fuse and DC service disconnect. As it's a power source (inverter-charger), you may also need a fuse close to the inverter. Generelly, we use Class T fuses for inverters.

You wouldn't want tripping the inverter breaker/fuse to make the whole boat go dark

What you are seeing is a previous owner "improvement" ....

 

[skunther]

Previously, using the windlass would cause the same house breaker to trip. I replaced the breaker and it no longer tripped when using the windlass. It seems the wiring is off though, and that the windlass and inverter are downstream of the house 100A breaker when they shouldn’t be (could the house breaker somehow trip if they weren’t downstream of it?)

I currently have a 300A terminal fuse on the battery positive terminal. Should the wiring be modified for the windlass and inverter as follows?

House battery
│
300A MRBF terminal fuse
│
Battery disconnect switch
│
High-current bus
├── 200A Class T → inverter (rewire)
├── windlass breaker/fuse (rewire)
└── 100A breaker → house panel (existing)

 

[dLj]

It seems the wiring is off though, and that the windlass and inverter are downstream of the house 100A breaker when they shouldn’t be (could the house breaker somehow trip if they weren’t downstream of it?)

Downstream? That has nothing to do with location - it's if they are in the circuit.

Upstream, downstream has nothing to do with physical location of a component. The only question is if the component is in the circuit.

You don't have any wire sizes listed.

Not to be rude - you really should hire an electrician.

dj

 

[colemj]

I read downstream as being electrically connected after the house fuse. It doesn't matter at that point what circuit they are in, because that fuse is the common point for all of those circuits.

The proposed rewire is the correct sequence of fuses and devices, which was the specific question the OP asked. The wire sizes would be chosen accordingly.

Mark

 

[dLj]

I read downstream as being electrically connected after the house fuse. It doesn't matter at that point what circuit they are in, because that fuse is the common point for all of those circuits.

The proposed rewire is the correct sequence of fuses and devices, which was the specific question the OP asked. The wire sizes would be chosen accordingly.

Mark

Ah - I like your clarification.

I haven't heard anything yet, however, about wire sizes and how the OP is addressing that. An earlier post suggested changing a 100 amp breaker to a 200 amp breaker also with no mention of wire sizes. None of us are present at the boat to actually see what is going on. Leading me still to the conclusion that the OP should get a professional on the boat to look at what's going on.

dj

 

[Johann]

House battery
│
300A MRBF terminal fuse
│
Battery disconnect switch
│
High-current bus
├── 200A Class T → inverter (rewire)
├── windlass breaker/fuse (rewire)
└── 100A breaker → house panel (existing)

This looks good but you will also need an additional disconnect switch specifically for the inverter as @marcham said.

 

[Hayden Watson]

Inte

Interesting. What inverter do you have?
I am able to use my 700w Emerson microwave for about 1 minute before it trips the 100A main house breaker at the battery combiner. Draw on the battery is 92A until it trips. Not sure if there’s an issue with my inverter or if this is behavior I should expect.

Warning, slightly off topic.
I have the same microwave and would like to be able to power it from an invertor. What size of invertor do you have. I am size limited and cannot find a 2000VA invertor that will fit anywhere that is close enough to the batteries. I have been looking at the Victron 1200VA VE Direct Inverter which has a 1200VA continuous power and lists peak power at 2200W.

I am curious if this inverter would power the 700W microwave.

 

[skunther]

My inverter is 1500w modified sine wave, but it can’t run at full 1500w because it is on a circuit downstream of a 100A breaker. The microwave ends up drawing I believe 1050w, resulting in ~94A draw on the circuit. Sustained it is too much and trips the 100A breaker.

 

[skunther]

I’m thinking I may as well just update my 30 year old inverter to a pure sine wave option. Any suggestions there? Looks like a rewrite as well. Any recommendations on a good inverter/charger? I plan to add solar, someday switch to lithium batteries, and change the gas range to a 2 burner induction.

 

[AaronD]

I’m thinking I may as well just update my 30 year old inverter to a pure sine wave option. Any suggestions there? Looks like a rewrite as well. Any recommendations on a good inverter/charger? I plan to add solar, someday switch to lithium batteries, and change the gas range to a 2 burner induction.

My experience thus far is very short, but I'm very happy with our Victron Multiplus 48/3000 (working great with our Duxtop burner).

You can buy cheaper systems, but Victron has become a solid standard, and you should get support from their dealer network. In 12v models, I think you can get anything from 500 - 3000 VA. Naturally, size and weight increase across the range.

 

[colemj]

I think your problem is the modified sinewave inverter combined with lead batteries. We have a 1100W microwave/convection oven running off a pure sinewave inverter connected to LFP batteries, and it draws ~85A.

Your 700W microwave should not be drawing 93A. Even if it is really a 1050W unit. Your inverter introduces a lot of inefficiency, and the voltage sag of lead batteries increases the current draw to maintain power.

Mark

 

[Johann]

I have been looking at the Victron 1200VA VE Direct Inverter which has a 1200VA continuous power and lists peak power at 2200W.

I am curious if this inverter would power the 700W microwave.

I think this would be marginal. The continuous power rating at 25C is 1000W but my 3kVA Multi will heat up pretty quickly so I use the 40C rating when planning. The 1200VA Multi is rated at 900W continuous at 40C. You can parallel Multis… do you have room for two 800VA Multis?

Also, did you look at the original Multiplus 2kVA and 3kVA? They have different forms than the Mulplus-II.

https://www.victronenergy.com/upload/documents/Datasheet-Multiplus-inverter-charger_2kVA-and-3kVA-120V-US-EN.pdf

 

[Stu Jackson]

A ddg search on "How to size an inverter" found this one, among dozens of others. I know your application is a boat, and why you are asking it here. However, your question is really one of electricity which doesn't much change between land & sea. Perhaps at this stage of your questioning, it might assist you in getting back to basics. It's what most of us do when faced with any [boating] issue. Good luck.

https://theinverterstore.com/portfolio-items/what-size-of-inverter-do-i-need/

 

[skunther]

So riddle me this: I purchased a 1000W resistance element cooktop, boiled water in it on the inverter for about 4 minutes, and the draw was ~93A (I saw over 101A draw at one point on the battery monitor (fridge was also on)). The breaker did not trip.

Why does the breaker trip when the microwave is drawing 94A for <1 minute, but didn’t trip with this cooktop drawing between 93A-100A for 4 minutes?

 

[capta]

I've been toying with the idea of 120vac cooking run from a portable power station of around 2500 continuous watts. The power station can be charged from multiple sources, some very quickly, and they come with all the safety circuits and monitoring included.
I've been trying out the new "pouch" meals and they seem to be the solution to tin cans rusting and/or losing their labels, and very quick, tasty, portioned food. One 8 ounce pouch of rice cooks in the microwave in 90 seconds. Another with some sauce with meat and/or veges may take from 60 to 120 seconds, and Bob's your uncle, in less time than it takes to toast a slice of bread, you have a piping hot meal, from a good curry to beans, rice, and roast beef in sauce.
I haven't figured out consumption, but @ less than 6 minutes for a hot meal in the microwave, a 2.5 kw portable power station should cover cooking for days, if not weeks. Also, the small Ninja Crispi would do rather well as a more healthy (and safer) frying or oven medium for fish, potatoes and meat.
I've run the gamut of cooking mediums; propane/butane, alcohol, kerosene, direct electric/Induction et all, and had settled on propane for simplicity, with a pressure cooker as the primary cooking vessel. However, were I to return to gallivanting about the world by boat, I think this would be my cooking choice.
I remember days, taking two parking places in the Ala Wai, and later in any major metropolitan area where food was less expensive, varnishing and marking literally a ton of cans, stowing them under the floorboards and/or bunks before our departure for the next adventure.