An Idea for Inductive Cooking

[Dockhead]

One issue with inductive cooking for most cruising boats is the large amount of power which may be needed for relatively short periods of time.

A two burner hob may need 3000 watts; three or four burners even more. I read in another thread about an Ikea hob which you can configure with a maximum power setting (which will prevent using both burners at full power), which is nice. But you may still run into problems with overloading the circuit (my ring main is 16 amps * 230v but everything plugged into a socket in the whole boat, so including toasters, coffee makers, kettles, etc. is run off it.

Another problem is possible overloading of a shore power connection.

The second problem may be overcome if you have a charger/inverter like mine with power boost, which will supplement shore power with inverted power from the batteries when necessary.

But I have a completely different idea how to do this. How about wiring the induction hob to its own separate inverter, and only to this inverter? That will keep it off your AC sockets circuit and indeed off your AC panel altogether, solving the first problem.

And it solves the second problem because the load on the shore power circuit will be controlled by your main charger/inverter.

This can result in "deficit spending" on power, of course, and can flatten your batteries if you use full power on the hob for a long time without any power going into the batteries, but this can be managed.

[Ballsnall]

Originally Posted by Dockhead

A two burner hob may need 3000 watts; three or four burners even more
.

Then you problem is user error, electric hobd very rarely use full power and only for a very short duration, usually a few seconds or less. If you can run an electric kettle then 2 or 3 hops should not be an issue, just don't turn them all onto full at the same time.

You should also run a dedicated circuit for an electric oven/cooktop or any other hi draw appliance.

[Pete7]

Funny enough I was thinking about this yesterday, now that we only have an electric galley. We or at least I did once completely overload the inverter to galley circuit by switching on the kettle but forgetting the induction hob was running as was the toaster. Perhaps a 2.8kW load off a 2kW inverter. It did complain for a little while but still worked until the blue seas 120A breaker tripped.

At that point I realised what I had done, not bad and first time in 3 years of electric cooking.

However, we have a second spare 1600w inverter just in case. Also its a PSW Sterling combiS+ inverter with a built in charger and flow through if shore power is connected. So I could add it so we have one running the counter top sockets for kettle, toaster or Remoska and one for the induction hobs. The LFP batteries are good for a max of 300A.

Its quite a lot of work, the 12v DC cables would probably need changing up to 70mm2. A second RCBO (CGCI in the US) fitted and floors lited again to run 240v cables, so with other more pressing jobs this summer, it's on the back burner. We rarely use the existing ring main circuit.

Alternatively, we haven't found the 2kW galley limit to be a problem despite cooking and eating well on board. Careful selection of things like the kettle means being energy efficient. Therefore, whole system including solar panels, batteries and inverters can be smaller, really important on a smaller yacht if the installation is to be successful.

Originally Posted by Dockhead

A two burner hob may need 3000 watts; three or four burners even more. I read in another thread about an Ikea hob which you can configure with a maximum power setting (which will prevent using both burners at full power), which is nice.

I guess the question is do you need 3 or 4 burners? How about two plus a stand alone separate one for odd occasions and back up. Think you have this already. So this might total 3kW. If the third was plugged into the coffee maker socket, that reduces the risk and load.

Pete

[fxykty]

Put the induction hob on its own circuit to your AC distribution board. We only have a 2 ring hob so 16A (230V). Our AC distribution is on a 32A breaker. Then it’s just user beware if additional appliances on other circuits can blow the main circuit breaker.

A separate inverter just for the galley is another option, but starts adding complexity and cost.

[goeasy123]

We have the original 20 year old 420Ah LA set up with a 1500w inverter. We bought a LiFePO4 powerstation with a 3000W inverter in it. The powerstation is charged through a programmable VSR off the LA bus.


The LA bus is charged from the engine and 460W of solar. We run an induction hob, coffee machine and kettle plugged directly into the powerstaion. We also run a 230VAC 1500w hookah and can take the powerstaion with us in the dinghy if we want to use the hookah away from the mothership.


At anchor we don't use the mains sockets, but we can plug the powerstation into the shorepower socket of the boat and use the powerstation as a controller and power supply to heat water in the calorifier.



The yield from the solar is effectively doubled. LA and LiFepO4 are fully charged everyday in typical Med winter and summer conditions. Overload protection is supplied by the powerstation... which is an easy to access breaker button on the side of the unit.


We have an Allowers R3500. If I were buying again I'd go for the R2500. We have friends doing similar with Anker 767s and Ecoflows.

[Dockhead]

Originally Posted by fxykty

Put the induction hob on its own circuit to your AC distribution board. We only have a 2 ring hob so 16A (230V). Our AC distribution is on a 32A breaker. Then it’s just user beware if additional appliances on other circuits can blow the main circuit breaker.

A separate inverter just for the galley is another option, but starts adding complexity and cost.

It does add complexity and cost, but it neatly solves a couple of problems.


16A is the full capacity of the best case blue plug Euro shore power, so if you ever use that much power in your hob even for a moment you will have to have everything else on the boat shut down. That's a PITA. And then what do you do if you only have 12A or 10A, as is common in Northern Europe and other parts of the world?


With a separate inverter this would not be a problem. You would make up any deficit out of battery power, and "repay" it once that load is off. All without flipping any switches.

[Dockhead]

Originally Posted by Pete7

. . . I guess the question is do you need 3 or 4 burners? How about two plus a stand alone separate one for odd occasions and back up. Think you have this already. So this might total 3kW. If the third was plugged into the coffee maker socket, that reduces the risk and load.. . .

You are correct -- I use a single burner NuWave with another small cheap single burner stashed away to pull out if I really need two burners. This works for 90% of my cooking; for anything more elaborate I use my 4 burner gas stove.


Having both gas and induction solves different problems and gives you redundancy but I would get rid of the gas if I could, for the sake of safety and simplicity.

[Pete7]

Originally Posted by Dockhead

Having both gas and induction solves different problems and gives you redundancy but I would get rid of the gas if I could, for the sake of safety and simplicity.

I think you probably could, but would mean investing in a decent size LFP bank. Perhaps 48v. Use the genny or shore power to charge. this removes the problem of limited 16A supply in an instant as the batteries can take the additional short term demand without having to fire up the genny.

Pete

[goeasy123]

Originally Posted by Pete7

I think you probably could, but would mean investing in a decent size LFP bank. Perhaps 48v. Use the genny or shore power to charge. this removes the problem of limited 16A supply in an instant as the batteries can take the additional short term demand without having to fire up the genny.

Pete

As per my post #16.... we get 3200kWh of 48VDC LiFePO4 and a 3200W(7000W surge) inverter with a 4000w dual circuit mppt charger for $2000. Plus all the other usual DC outputs up to 10A.


And we still have the gas over and 2 burner hob.


Is that enough as a practical, low cost, easy to install and use solution?

[fxykty]

Originally Posted by Dockhead

It does add complexity and cost, but it neatly solves a couple of problems.


16A is the full capacity of the best case blue plug Euro shore power, so if you ever use that much power in your hob even for a moment you will have to have everything else on the boat shut down. That's a PITA. And then what do you do if you only have 12A or 10A, as is common in Northern Europe and other parts of the world?


With a separate inverter this would not be a problem. You would make up any deficit out of battery power, and "repay" it once that load is off. All without flipping any switches.

Shore power? What’s that got to do with it? We run our AC circuits from our Quattro inverter/charger because we’re a cruising boat and we don’t spend very much time in marinas. Our Quattro is sized for what we need it to do - 12/5000/220 provides up to 19A of 230V power. More than enough for our hob and other small AC consumers. If we want more simultaneous AC appliances then we need shore power, or as someone else pointed out a portable power bank. That makes more sense to me than a parallel second inverter.

And if we happen to be in a marina or on the hard, power assist by the Quattro makes up for weak shore power with power from the batteries if loads are high. No manual switches.

[fxykty]

Originally Posted by goeasy123

As per my post #16.... we get 3200kWh of 48VDC LiFePO4 and a 3200W(7000W surge) inverter with a 4000w dual circuit mppt charger for $2000. Plus all the other usual DC outputs up to 10A.


And we still have the gas over and 2 burner hob.


Is that enough as a practical, low cost, easy to install and use solution?

You mean you get 3200W of output power and have 3.168kWh of battery capacity for USD2,000. That’s darn expensive. But providing portable power such as for an hookah system, stand alone AC power, and being easy to integrate into an existing boat system using shore power plug are very useful use cases for some.

[fxykty]

[QUOTE=goeasy123;3907089]…
The yield from the solar is effectively doubled. LA and LiFepO4 are fully charged everyday in typical Med winter and summer conditions.
…/QUOTE]

What do you mean, how is the solar yield doubled?

[Statistical]

The ideal scenario would be boats run on 48VDC and the induction cooktop be 48VDC. Of course things like economies of scale and niche markets may mean that never happens.

It probably will never happen but as hybrid drives for larger boats and all electric for smaller daysailers become more common it would be really nice if boats transitioned to 48VDC. Voltage drop becomes a non-issue at any wiring that is short enough to fit on a boat. High current devices like inverters, windlasses, bow thrusters, induction cooktops, and marine AC units would be easier to manage at 48V vs 12/24V and avoid putting a load on the inverter all together.

[goeasy123]

[QUOTE=fxykty;3907123]

Originally Posted by goeasy123

…
The yield from the solar is effectively doubled. LA and LiFepO4 are fully charged everyday in typical Med winter and summer conditions.
…/QUOTE]

What do you mean, how is the solar yield doubled?

The LA takes charge until the battery resistance rises and chokes the LA's capaicity to take charge. If you only have the LA the rest of the sunny day is lost.

The solar panels are still capable of delivering charge at which point a programmable a VSR set to 'on' at 14.2V diverts the unused charge to the LiFePO4 powerstation. When the sun goes down and the LA buss' voltage drops to 12.7V the VSR switches of the supply to the powerstation so that the LA batteries are not drawn on. There's a 2 minute delay before switch on to stop the VSR from cycling when it is off loaded at 12.7V.

My VSR version is overkill, with a 200A relay inside a box controlled by an IV Controller (search Aliexpress). The allows me to run a buck booster between the VSR and the powerstation which causes my particular powerstation to switch to fast charge mode.

You could probably get away with just a 10A or 20A version of the IV Controller or a programmable VSR typically used by RV'ers. But you need the time delay.

[Dockhead]

Originally Posted by Statistical

The ideal scenario would be boats run on 48VDC and the induction cooktop be 48VDC. Of course things like economies of scale and niche markets may mean that never happens.

It probably will never happen but as hybrid drives for larger boats and all electric for smaller daysailers become more common it would be really nice if boats transitioned to 48VDC. Voltage drop becomes a non-issue at any wiring that is short enough to fit on a boat. High current devices like inverters, windlasses, bow thrusters, induction cooktops, and marine AC units would be easier to manage at 48V vs 12/24V and avoid putting a load on the inverter all together.

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.


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.