An Idea for Inductive Cooking

[Statistical]

Originally Posted by Dockhead

I'm 24v and would love to have 48v, but I think you are fetishizing it a bit here. Voltage drop is exactly half, which is great, but it doesn't become a non-issue. It's an incremental improvement over 24v, not a revolution.

The nominal voltage drop is cut in half but the voltage is also doubled so as a percentage the metric we are looking to achieve the percentage drop is quartered.

If for a given conductor and amperage the voltage drop is 1V that is ~4% on a 24V system. If you have the amperage because the voltage doubled then it is 0.5V which on 48V system is ~1%.

Meeting the ABYC standard of 3% for critical loads becomes quite trivial at 48V for any amperage and lengths likely to be found on a sailing vessel. Even the 10% threshold is just a compromise for just how challenging it is to meet the 3% threshold. There is no good reason to be 10% drop instead of 3% drop beyond it may simply be impractical or cost prohibitive to even try to meet the 3% threshold.

There is no need for a 48v or any DC version of an induction top. Inverting DC power to 230v AC is very efficient, and distributing the power at 230v AC is a lot more efficient than at 48v. If inverter capacity is an issue, just add an inverter.

You could make the same argument for bow thrusters, windlass, AC, refrigeration, etc.

I do agree though that there is a huge chicken vs egg barrier and as such 48V may never take off. However the rise of 48V as the go to voltage for off grid applications combined with larger LFP banks, electric propulsion, and hybrid systems 'may' open a window.

[rslifkin]

What makes most sense to power induction cooking depends a bit on the AC electrical architecture of the boat in question and what else is onboard to be powered. In my case, I don't have a ring main setup and have a fairly large AC system (complete with a genset) that was originally designed with an electric stove in mind, so a separate inverter just for the stove doesn't make sense. It makes more sense to power most or all of the main AC system via the inverters and just size for the typical simultaneous loads that would be needed (knowing I can always stagger loads, start the genset, or go find shore power if I need more power than the inverters can supply on their own).

[CarlF]

My solution has been to leave the propane stove in place and place a single burner 2100 watt induction £50 cooker on top of one of the propane burners. It fits snugly in the stove rails and is held steady by a bit of stainless wire. My inverter handles it fine. The burner is more powerful than most boat induction stoves so it boils a large pot of pasta water in no time. And it has superior computer temperature sensing to simmer a stew perfectly. 90% of the time I use only the induction but the propane burners are always available for a more complex meal or if the batteries are a bit low.

The downside is I still have the gas bottle - but it's not storage space I particularly need and is safely isolated in its vented locker with the remote shutoff. I took out the 2nd bottle since it's not a problem if I run out of gas as I have induction. And the gas is used so little that I go a long, long time between fillings.

[Dockhead]

Originally Posted by Statistical

. . . You could make the same argument for bow thrusters, windlass, AC, refrigeration, etc.. . .

Indeed, and larger vessels often use AC for all of these systems. I'd love to have AC thruster and windlass.

Originally Posted by rslifkin

What makes most sense to power induction cooking depends a bit on the AC electrical architecture of the boat in question and what else is onboard to be powered. In my case, I don't have a ring main setup and have a fairly large AC system (complete with a genset) that was originally designed with an electric stove in mind, so a separate inverter just for the stove doesn't make sense. It makes more sense to power most or all of the main AC system via the inverters and just size for the typical simultaneous loads that would be needed (knowing I can always stagger loads, start the genset, or go find shore power if I need more power than the inverters can supply on their own).

Indeed, and which reminds me that I have a heavy duty AC generator which was designed for continuous duty, and my boat was designed -- like a large power boat -- to have the generator running all the time. My boat was built without any kind of inverter at all! I have made a number of mods -- combining battery banks, adding charger/inverter -- to make it possible to operate like a normal sailboat, off battery power, using the generator mostly to charge batts.



The easiest solution for this for me would be to forget all these additional mods and simply run the generator when I'm cooking on more than one burner. KISS.

[Dockhead]

Originally Posted by CarlF

My solution has been to leave the propane stove in place and place a single burner 2100 watt induction £50 cooker on top of one of the propane burners. It fits snugly in the stove rails and is held steady by a bit of stainless wire. My inverter handles it fine. The burner is more powerful than most boat induction stoves so it boils a large pot of pasta water in no time. And it has superior computer temperature sensing to simmer a stew perfectly. 90% of the time I use only the induction but the propane burners are always available for a more complex meal or if the batteries are a bit low.

The downside is I still have the gas bottle - but it's not storage space I particularly need and is safely isolated in its vented locker with the remote shutoff. I took out the 2nd bottle since it's not a problem if I run out of gas as I have induction. And the gas is used so little that I go a long, long time between fillings.

That's identical to my solution. Works fine. But we lose the benefit of ripping out the gas system.

[rslifkin]

Originally Posted by Dockhead

Indeed, and which reminds me that I have a heavy duty AC generator which was designed for continuous duty, and my boat was designed -- like a large power boat -- to have the generator running all the time. My boat was built without any kind of inverter at all! I have made a number of mods -- combining battery banks, adding charger/inverter -- to make it possible to operate like a normal sailboat, off battery power, using the generator mostly to charge batts.



The easiest solution for this for me would be to forget all these additional mods and simply run the generator when I'm cooking on more than one burner. KISS.

That's exactly how mine was designed as well (although we *are* a powerboat), and we've made similar modifications. Proper house batteries, inverter, solar, etc. Currently we plan on a daily generator run to cook dinner and warm up the water heater, as the stove and water heater aren't on the inverter sub-panel. Our stove is electric, but I haven't swapped it out for an induction unit yet (realistically the resistive electric unit works fine for now).

Once I make some further battery upgrades and upgrade the inverter setup (and eventually add more solar) then cooking and hot water won't be generator dependent anymore and the generator can become just for heavy loads or battery charging (or if we need air conditioning, but we try to avoid that when away from shore power). As far as scale, I've ballparked our power use for everything except HVAC at around 6 - 7 kwh / day.

[Groathill]

Looks like many of us have an equal set up with a gas stow and a single plate 230VAC induction plate. I always use the induction when connected to shore power and only need a single hot plate.
I have so far limited 12VDC to 230VAC capacity, not enough for the induction unit and would have to get a converter with more AC output.

Question 1: Do I need a so called pure sine version or will a "modified" sine suffice?
Question 2: My induction is max 2000W (an IKEA unit), but has settings for several lower outputs, so what do I strictly need for AC power output from the DC to AC converter when I always quickly turn down the induction power? The inverters are normally specified for a higher short burst outputs than continuous output.
The inverter capacity is a mostly a size/volume issue more than cost

[Statistical]

Originally Posted by Groathill

Looks like many of us have an equal set up with a gas stow and a single plate 230VAC induction plate. I always use the induction when connected to shore power and only need a single hot plate.
I have so far limited 12VDC to 230VAC capacity, not enough for the induction unit and would have to get a converter with more AC output.

Question 1: Do I need a so called pure sine version or will a "modified" sine suffice?
Question 2: My induction is max 2000W (an IKEA unit), but has settings for several lower outputs, so what do I strictly need for AC power output from the DC to AC converter when I always quickly turn down the induction power? The inverters are normally specified for a higher short burst outputs than continuous output.
The inverter capacity is a mostly a size/volume issue more than cost

I would not get a modified sine wave inverter in 2024 given how cheap good sine wave inverters are. True sine wave will have better resale value if your plans change.

Many cheaper induction cooktops don't reduce heat by reducing power they do it by turning on and off the cooktop fast enough that the heat output is reduced but this only lowers the energy (Wh) not power (W). This means on high or low the cooktop may use the close to or the same as max power.

Inverters have a continual output rating and a surge rating. You would want an inverter whose continual output rating exceeds the expected peak power requirements of the cooktop and any other loads attached to it.

[FlyingScot]

We considered dual Multiplus 12/3000 in stand alone configuration, one being dedicated to the galley. We gave up on that idea as using them in parallel made life easier. The wife is much happier now that she no longer has to remember which things can be turned on simultaneously and where to plug them in.

Our induction is self limited to 1800W (2 burners). It has it's own AC circuit. The dishwasher has a separate AC breaker as well (950W max draw). We can use the electric kettle, induction cooktop, run water heaters, dishwasher and pretty much do anything we want all at the same time.
We do this with 12v battery and 120v inverters. Yes 48V has some advantages, but it's not perfect either as it will dictate your house battery configuration, solar panel configuration, wiring, etc. You also maintain multiple voltage banks or have more single point of failures to address.

We have a 3rd small inverter that we leave on continuously. It's a Victron Phoenix 800VA. The always on Gen 2 Starlink, countertop ice machine and all night mattress cooler are the typically connected loads.

The attached picture was nothing special for us now, just the wife brewing tea, cooking breakfast, and whatever else she does in the morning.

One complaint, Victron Cerbo/Touch will not properly display all 3 inverters on the home screen. So what you don't see in that picture is the load on the 800VA inverter. It only shows up on the home screen when we flip the dual parallel inverters off.

[rslifkin]

Originally Posted by FlyingScot

We considered dual Multiplus 12/3000 in stand alone configuration, one being dedicated to the galley. We gave up on that idea as using them in parallel made life easier. The wife is much happier now that she no longer has to remember which things can be turned on simultaneously and where to plug them in.

Our induction is self limited to 1800W (2 burners). It has it's own AC circuit. The dishwasher has a separate AC breaker as well (950W max draw). We can use the electric kettle, induction cooktop, run water heaters, dishwasher and pretty much do anything we want all at the same time.
We do this with 12v battery and 120v inverters. Yes 48V has some advantages, but it's not perfect either as it will dictate your house battery configuration, solar panel configuration, wiring, etc. You also maintain multiple voltage banks or have more single point of failures to address.

We have a 3rd small inverter that we leave on continuously. It's a Victron Phoenix 800VA. The always on Gen 2 Starlink, countertop ice machine and all night mattress cooler are the typically connected loads.

The attached picture was nothing special for us now, just the wife brewing tea, cooking breakfast, and whatever else she does in the morning.

One complaint, Victron Cerbo/Touch will not properly display all 3 inverters on the home screen. So what you don't see in that picture is the load on the 800VA inverter. It only shows up on the home screen when we flip the dual parallel inverters off.

It looks like you went for paralled 3kva inverters on a 12v system. How has that been as far as managing the huge current involved? I've been debating between doing that vs converting to 24v.

[Groathill]

Thanks Statistical, I guess your right about choosing Pure Sine converters.
I know the induction plates will run at full high 230VAC and 2000W (for my unit), but with a variable duty cycle, pulse width on/off in accordance to the selected power setting.


My thinking is that the converters are specified with a much higher, often the double of the continuous max power and that I could get away with a slightly smaller version than 2000W continuous power versions.

[Statistical]

Originally Posted by Groathill

Thanks Statistical, I guess your right about choosing Pure Sine converters.
I know the induction plates will run at full high 230VAC and 2000W (for my unit), but with a variable duty cycle, pulse width on/off in accordance to the selected power setting.


My thinking is that the converters are specified with a much higher, often the double of the continuous max power and that I could get away with a slightly smaller version than 2000W continuous power versions.

It could work but it probably won't. Surge capacity is for brief one time events. If you are "surging" to 2000W once every couple seconds it is effectively a continuous load.

Given the length of time induction cooktops are used I would consider a 2000W cooktop to be a 2000W continuous load even on a lower setting.

[K_V_B]

An induction how already has an inverter build in. It is what drives the coils. It gets fed with DC from a rectifier...

So from batteries to coil you convert three times: DC - AC - DC - AC

So the best solution would be a DC powered induction cooker. Maybe even with a local battery as a buffer.

[FlyingScot]

Originally Posted by rslifkin

It looks like you went for paralled 3kva inverters on a 12v system. How has that been as far as managing the huge current involved? I've been debating between doing that vs converting to 24v.

Nothing that lots of fat high quality wires, large buss bars, proper lugs and crimps can't solve.

We used a lot of Ancor brand 4/0 awg (120mm2 equivalent). The parallel inverters are each fed from dual 2/0. Meaning two black and two red 2/0 to each inverter. All battery wires are 4/0 with one class T per battery. All wires equal length from batteries to Lynx train and to each inverter. Everything is hooked to a Victron Lynx Input, Lynx BMS500, 2 x Lynx Distributors. Blue sea 1000A buss bars, FTZ power lugs, MRBF fuses, etc. Price of wiring & components was near nose bleed territory. Especially when you consider spares like BMS500, spare MPPT, spare Smart Battery Connect, etc.

I tell people that we basically traded lead (AGM) weight for copper weight. It's not that far from the truth but now the system is much more powerful and much more efficient.

This might not be the right solution for everyone, but so far we love our system. I wanted to run one large Solar Panel per MPPT. I wanted to maintain one battery bank location and voltage. We have 2895Wp of solar making 10-15kWh per day. Hard to achieve those goals with 24v or 48v.

[bill good]

AC power may require licensed electrician to sign off the installation.
Most drop in LIFEPO4 batteries won't take the high current draw due to their internal control circuits if working on house batteries without generator/shore power. Currently using DIY LIFEPO4 280A/H installation for single plate induction top, microwave oven, 800W kettle & airfryer which leaves gas only for larger back up jobs. The 280A/H replaced 700A/H lead with a big saving in weight & space. Just watch the load is below the C rating of the batteries/inverter & all is good.
Cook on. Bill