Pushing the limits of electric cooking

[noelex 77]

Originally Posted by Dockhead

I think he is also not allergic to harbours, unlike you, so whenever he's in some kind of harbour, he will then be good for a few days whether the sun shines or not.

Yep, cruising for me means enjoying the world’s deserted areas. We tie up up to shore briefly only every two years or so, which I agree is not typical.

Not everybody feels the same. There is no correct answer. Fortunately there are many options. It is only important to aim for the lifestyle that makes you happy.

Unfortunately, a very large battery bank can only store enough energy for, as you suggest, a few days days of electric cooking. Even assuming there is some significant electrical input from solar this still means frequent access to shore power if there is a net deficit.

Regardless if frequent marina visits is your normal preferred style of cruising it is an unnecessary restriction to install systems that necessitate this requirement. This is easily avoided with sensible energy systems.

If you have enough electrical energy production moving to purely electrical cooking is a great solution, but it easy to underestimate the energy involved. 600w of solar is not enough at least in many areas of the world.

[Pete7]

Originally Posted by Na Mara

Alctel, maybe the marine environment is hard on them. In any case, they are hardly expensive.

So I have done a bit of surfing now and so far I haven't been able to find o combination microwave and oven that is under 45cm wide. What I have found is a mini oven that is 43cm wide and 26cm tall, 1300W, and a microwave that is 43cm wide and 23cm tall and 600W.

A problem with a lot of European yachts that were designed around a 450mm wide stove. We have the same issue and don't really want to do extensive wood work. There is a bulkhead one side and the built in fridge on the other. The narrowest dual induction stove I have found so far is the Vango Sizzle at 480mm, but the hobs are 2 x 800w.

https://www.amazon.co.uk/Vango-Sizzl.../dp/B08182Y3W1

The good news is whilst most induction hobs are rated between 1500 - 2000w for a single hob, you don't need that much power. Simmering pasta or rice is 200w, Omelette 400-600w, bacon 600w and steaks 600-800w. So even running a double hob shouldn't be a problem. The wattage I think is averaged as the battery monitor shows 50-60A draws when its running. They cycle on and off like a fridge to maintain temperature so the overall draw is also much less than first anticipated. Also during the daytime any solar power being generated reduces the load from the batteries first, which we can see on the battery monitor and BMS.

We spent Easter on board only to find the extension lead melted. No problem, we decided to do 2 full days of electric cooking off solar power. Weather was good, but April in southern UK doesn't have the long days of mid summer. Also the mast shadowed the solar at mid day That said we managed 2 full days of cooking including always boiling the kettle. Being English we drink a lot of tea, perhaps a 8 or 9 times a day. After 48 hours the result was that 300w of solar in sunny conditions wasn't quite enough. Whilst solar generated 1.4 Kwh each day we were short by 0.3Kwh each day. The LFP took the strain but clearly we need a bit more solar and plan to solve this during the winter.

Our other test last August involved more of a mix of gas and electric cooking. Perhaps 50/50%. We used the DC>DC charger just twice in poor weather to charge the house bank from the engine in 3 weeks, solar did the rest. This gave us the confidence to pursue the electric cooking further.

Like you we were worried about our old gas stove dating from 1988, so ditched it during the winter and replaced with a new gas/grill hob. We will probably keep this as a good back up and to use during the winter when we do like to get away, evening sailing on Christmas Day a couple of years ago, whilst the turkey was cooking. The gimballed gas hob also means we can cook when its rough and in a 31ft yacht that's F4 going to windward. Solar doesn't work for us mid winter. We have seen 10w from a 300w panel on a drab January late afternoon. Btw, the gimbal point for a hob is different from a hob/oven unit because there isn't 20kg of oven hanging below. That took a bit of metal work with bits of gimbals to sort out.

Some thoughts. If you plan on an electric oven, does it need to gimbal, why not just build it in? You're not going to be cooking roast dinners leaning over at 30 deg and a pizza in the oven should be fine.

I am not sure if the induction hob priced at 1400Kr is expensive, but if not, I would be tempted to buy two and keep one as a spare less that glass breaks whilst sailing in more remote areas. Are you going to gimbal the induction hob? There are 1mm silicone mats for induction hobs available on Amazon to make the glass surface less slippery. We bought a couple as they are very cheap so should be considered for cooking at sea.

Having a Ninja air fryer at home, we bought another for the yacht. It maxes out at 1500w but should use less over all. Fits nicely under the gas hob and the single induction hob in the grill slot when not in use.

Have you thought about a Remoska? The standard one draws 400w and will roast a small whole chicken. The photo on the website is genuine according to the Remoska FB group, who seem to produce some fabulous dishes btw. This would solve the double hob or one hob and oven at the same time. They will bake and do pizzas. We are tempted but running out of space on a 31ft yacht with the slow cooker and toasted sandwich maker, also brilliant at sea when you want something hot and quick.

https://www.lakeland.co.uk/brands/remoska-brand

Pete

[Dockhead]

Originally Posted by noelex 77

Yep, cruising for me means enjoying the world’s deserted areas. Marinas are more like caravan parks in my view . We tie up up to shore briefly only every two years or so, which I agree is not typical.

Not everybody feels the same. There is no correct answer. Fortunately there are many options. It is only important to aim for the lifestyle that makes you happy.

Unfortunately, even a very large battery bank can only store enough energy for, as you suggest, a few days days of electric cooking. Even assuming there is some significant electrical input from solar this still means frequent access to shore power if there is a net deficit.. . . .

Sure, but I don't think you're getting my point.

3 days of storage does not magically create power -- of course.

But it gives you greatly increased window to opportunistically harvest and store power. You don't need to find power every day, if the sun is not shining. You can wait until it does, or wait until you're motoring anyway for something, or wait until you are tied up somewhere. And it doesn't need to happen every day.

My alternator produces 2.5kW of power. I could put 3 days worth of his electric cooking into a lithium battery bank in maybe 90 minutes of motoring. He can fit the same alternator on his boat.

So if he's not producing solar, all he has to do is either be in a harbour or motor a little bit, to replenish the batteries and he's good for another 3 days.

I just don't think that's a big deal for someone who is moving around fairly often. I know you like to stay in one place for long periods of time -- that's a somewhat different use case. But even for that, even if you're not in a harbour and not moving somewhere so that you would be motoring anyway -- running the main engine for 90 minutes every three days, and at that just during those times when there's no sun, is just no big deal. Certainly a lot easier than what I do, which is run the generator for several hours every day, because I have (a) less battery capacity than he does; and (b) lead batteries with much lower charge acceptance rate, plus the need to be absorption charged. But even that I don't find burdensome, when I'm off the grid.


It's great if you have a huge solar array and always more power than you need. My father's boat was set up like that; it was great -- we just never thought about power. But when you have other sources of power a ton of storage, I don't think having a smaller solar array is really a problem. 600w is pretty decent, anyway.


FWIW I dislike marinas too. I love to be at anchor, but I rarely stay at anchor anywhere more than a few days. I like to move around (and there would be very rare times would I would motor less than 90 minutes in any given three day period, except maybe if I'm racing). I also like very much to stay in actual harbours, fishing harbours, harbours in the middle of cities -- this is not exactly the same as marinas.

But of course -- to each his own.

[noelex 77]

Originally Posted by Dockhead

My alternator produces 2.5kW of power. I could put 3 days worth of his electric cooking into a lithium battery bank in maybe 90 minutes of motoring. He can fit the same alternator on his boat.
So if he's not producing solar, all he has to do is either be in a harbour or motor a little bit, to replenish the batteries and he's good for another 3 days.

A common mistake when considering electrical power is to consider only a specific requirement such as electrical cooking. In practice the energy input has to exceed on average the total electrical output. Electrical cooking plus the normal house loads.

I think Na Mara has a similar view to engine run time as mine :

Originally Posted by Na Mara

noelex, you and I are thinking alike about the main engine as a primary source of electrons. I sail to sail not to motor. I have the attitude that using the engine to go somewhere other than through a narrow channel, or into or out of a harbour, is an admission of defeat

I agree that a high output alternator is a worthwhile improvement. I would also suggest Na Mara incorporates this upgrade, but I have my doubts that in this case it would solve his energy deficit.

600w of solar is the only substantial energy source Na Mara has at present and this is not enough to support electric cooking plus normal house loads unless he confines his cruising to areas and seasons of high solar insolation.

Totally eliminating propane cooking is a substantial change, especially for a boat without a generator and only 600w of solar. While electric cooking is attractive and I am great fan of solar energy on a boat I think it is important to emphasise the limitations.

[fxykty]

Given our one year of full time live aboard with a dual induction hob 3.5KW and electric oven 1.8KW, supported by a 12V 700Ah LFP battery, 5KW Quattro (with power assist turned on), and 2.6KW of hard panel solar, I caution you against overly optimistic expectations for

1) peak current draws
2) overall daily usage
3) solar generation

We occasionally trip the Quattro. Induction hobs and resistive ovens average low wattages, but peak loads are right up at the rated wattages on startup when you want to boil water for example or preheat the oven. During operation at a simmer for example, after the initial boil at 1.8KW the wattage cycles between 0-800W. The average may be 200W but the actual usage is not.

Even if we don’t trip the inverter, we see 0.3V of voltage drop during 300+ A draws, particularly when the SOC is below 50%. So don’t expect same performance throughout the DOD range.

Power assist together with shore power works but can be flakey. Our Quattro does weird things with the shore power connection wattage and it certainly can’t be relied on to supply full shore power wattage plus full inverter wattage for continuous periods. There could be something wrong in our Quattro settings??

Your overall daily usage is your steady state power draw, which is made up of all the deliberate and parasitic loads when your boat is just sitting there: fridge/freezer, lights, radio, navigation equipment, mobile/wifi router, bilge pumps, inverter, BMS, Cerbo, and everything else that is turned on. The contribution of electric cooking to daily loads is significant but likely not the majority.

600W of solar may be sufficient in summer, but not at any other time of year or during cloudy periods. In winter our 2.6KW often generates less than 1 kWh, with some days up to 4 kWhs. No useful average can be counted on - it’s all just a bonus off season.

A petrol generator is cheap and cheerful, but is loud and won’t provide much more than 1.8-2KW of continuous power. We limit ours to 9A at 230V to avoid tripping its breaker during load surges (such as when cooking).

Upgrading your main engine alternator is your best bet, but it may mean that you run your engine occasionally just for power generation. If you haven’t already, extend the coolant circuit from your engine to your water heater for free hot water.

Commercial hydro generators are crazy expensive. And of course don’t do anything while anchored. Wind generators are also relatively expensive.

But to sum up, we love our electric galley and won’t ever go back to gas. We do have a charcoal bbq and a petrol camping stove as backups in case of lightning or other electrical system failure.

Hope this helps.

[zboss]

We have a dual induction stove top (total 1800 watts), an convection air fryer oven (1800 watts), electric coffee maker, electric bread maker, and a NuWave Instapot knockoff (1500 watts).

We use far less power than I expected but I think the numbers on the chart that was like 3 posts into this thread are pretty accurate as averages - we generally use less and occasionally use much more when we make bread or whatever. We have also learned the usefulness of the pressure cooker on the stove with the induction top and the instapot. Meals cook way faster, use far less power, and are usually tastier/juicier.

824Ah of LifePO4 with a Quattro 120/5000, 1125 watts of solar, two 60A dc-to-dc chargers, and a 5KW generator. We have zero difficulty maintaining bank in Northern Florida, in the summer with just the solar but we haven't had it long to say for sure what the impact will be. This is our first season with the electric galley and I think that we will end up having to run the generator in the winter. The Victron charger is 200A so I anticipate a maximum of one or two hour run with the gen every two or three days to make up for the solar deficit when we are actually cruising place to place with the help of our 120A dc to dc alternator chargers. The galley makes up only about 40% of our current consumption.

I would like to add another 400 watts of solar and add two more batteries bringing our total up to 1236Ah.

[Na Mara]

As far as energy consumption from electric cooking goes, there really are two sides to that story. One can increase generating capacity to meet the extra load but one can also cook smarter to reduce it. If you haven't tried thermal cooking I can highly recommend it. I did a test yesterday with making mash potato. I did it the standard way on one of my induction hobs at home (skin and cut up potatoes, raise to boil, simmer for 15 min, mash, season, serve) and I did the same amount of mash using thermal cooking (skin and cut up potatoes, raise to boil, transfer to preheated thermos flasks, leave for 30 mins, mash, season, serve). The end results tasted and looked identical but the thermally cooked spuds saved 15 minutes of simmering at about 600W and so about 0.15kWh of energy. Its also dead easy to do. Just leave whatever it is in a thermos for twice as long as you would have it simmering for. Some things, like pasta, need some shaking from time to time, but basically its all good. Particularly stuff, like bolognese sauce, that require hours of simmering to be really good, benefit from thermal cooking (as will your energy usage). You just need to carry enough good quality thermos flasks and be a little patient.

[Pete7]

Originally Posted by Na Mara

Particularly stuff, like bolognese sauce, that require hours of simmering to be really good, benefit from thermal cooking (as will your energy usage). You just need to carry enough good quality thermos flasks and be a little patient.

Already on it with a slow cooker Curries as well. 110w but again cycles on and off at a medium setting.

Like the mash solution, a wide mouthed vacuum flask would be useful for us.

I am just looking at some of the numbers people are giving. Boy are we on the thin end with solar and batteries. As Noelex says, its the overall consumption, so fridge, freezer and diesel heating Oct to Mar also needs to be considered. Though he did suggest a while ago we don't bother with the fridge, just put the milk outside in winter

But the good news is it can be made to work even on a small yacht and for us, end of March to early October solar will meet most of the demand most of the time. If it all goes pear shaped with a summer gale with heavy rain and clouds, well chances are we will be safely tied up in a marina or traditional harbour. Therefore as Dockhead says, just plug in, or for us, just use a bit of gas or engine time.

[jimellifritt]

Originally Posted by Na Mara

The gas system on my boat is not up to code and needs changed. The costs of upgrading including a new oven and stove is about 1200 euros give or take. I love cooking with gas but I am not a fan of the space it takes up in my cockpit lockers, the sourcing of the gas, and the (albeit minimal) ever present danger of blowing oneself up.

As it happens I am presently upgrading my electrical system and in that upgrade is included 600Ah of lithium batteries, a 2400W inverter, and 600W of solar. Roughly the inverter is big enough to run a single hob on full power, 2 hobs on two thirds power, a minioven at full power, a minioven and a hob at two thirds power, and so on.

So here is my thinking. What if, instead of upgrading the gas system, I put a combi electric microwave oven and dual induction hob onboard and ditch the gas completely. On shore power cooking would be totally unrestricted but away from a plug we would have to restrict ourselves in how we cook. Basically, the rule would have to be no more than one cooking appliance on at any one time. One hob, or the other, or the oven, but no combination of the above.

This would require some getting used to and some planing but it should be eminently possible to do without too much sacrifice on the cuisine front.

So I have two very different questions, one is an electrical question while the other is cuisine question.

1. Using a standard rule of thumb the solar panels should deliver about 2.4kWh of energy a day on average. Will that meet the needs of an electric galley plus domestic loads on a typical cruiser? How long do we really cook for anyway? What is the average power used on a hob when cooking? Is it about 1 kW and do we use that for about an hour each day or is that guess way off?

2. Could you live with serial cooking, where only one hob/oven can be used at any given moment, when away from shore power? What would cooking be like then? Are there meals you couldn't make or make as well? Would you miss them?

If the answer to 2 is no, then there is a fairly easy solution, which is to buy another similar inverter and to parallel couple it with the existing one. But that is money and complexity I would rather do without (also it was hard enough finding space for the first monster inverter, finding space for a second would be challenging).

We moved from AC oven to propane and would not go back. We have 4 600 watt panels. We have a portable induction burner we use when we are at dock or batteries are fully up. We also have a convection Microwave that we can electric bake in, along with an air dryer. Both the hairdryer and Induction burner us under 1500 watts. They will drop our percent of charge 5% for a meal on the hook. It takes all day with solar in Costa Rica to top up. Clouds are not your friend. We have some days that the clouds just will not let you top up. Bottom line for us is I wanted to have redundant ways to cook and it has worked well for us.

[Na Mara]

5% drop in charge from what if I may ask? Also I’m very surprised that you can’t keep up with domestic loads with 2.4kW of solar panels (surely you are a catamaran?). Even in midwinter in Europe you should be averaging about 2kWh of charge a day. In the summer you should be averaging 10kWh. That latter figure is 4 times my daily consumption.

[SV Jabberwock]

Just adding a data point for induction cooking.

32ft boat in the Baltic, April - October.
400Ah / 12V LFP
Victron MultiPlus 3000
Kenyon SilKEN2 two-burner induction cooktop, gimballed
2x120Wp Solar

Cooking a meal (once a day) usually takes between 30 and 50 Ah. As it's only me, reheating on the second day is 20 - 30 Ah.

After three weeks last summer batteries were still somewhere between 70 and 80% full. Just from that little bit of solar (and occasionally using the engine for 10 minutes to set the anchor). In addition to the cooktop of course there's navigation electronics, fridge, occasional laptop use, smartphone for weather and music, breadmaker once a week (don't have an oven), blender for smoothies daily, cameras...

The cooktop is internally limited to I think 1800W, so if you try to run both burners at full it will limit them to like two thirds. But even for boiling water there's no need to go full power, I rarely go over half power.

I get 60 - 70Ah easily from Solar on somewhat sunny days. Over 100Ah on really sunny days with good exposure on the panels.


With 600Wp Solar, at least during the regular sailing season you should not have any problems with induction cooking in the Baltic.
And even if you do run out of power there's always and outlet no more than a two-hour sail from wherever you are.

[Andypids]

While induction hobs etc can work very well on boats, my point would be that you are putting all your eggs in one basket. If your electrical system goes down you even loose the ability to make a cup of tea!
There are plenty of more deserving uses for your limited electrical supply on board than turning it into heat although I do support the use of a good coffeemaker!

[Adelie]

Originally Posted by Ballsnall

Your upgrade was never designed to include an adequate cooking solution which you now want to "tack on".



You will have less capacity and functionality and will need to make serious comprises. You seem to be looking for affirmation that all will be fine but you system is seriously undersized.



Spend an additional 1200 euro on sizing your system correctly or replacing your propane system.

How big do you think a system needs to be to support electric cooking?

[sailcrazy]

Following. We took a little different approach-21 years ago. The admiral does not like/trust propane, so we converted to a Force 10 electric stove and oven. We've lived aboard full- time, but now, over the past 11 years, we've sailed seasonally...4 yrs in the Medd, and now 7 yrs in the Caribb. We use our (installed) Onan Diesel 6/5kva genset, and have built our boat around it. The refer sys, watermaker, batt recharging (although we do have approx 400w of solar+windgen), aircons (but rarely use them), and cooking are all centered around it. We typically run it 2x per day. It's failed us only twice since 2001...when we sucked up some jellyfish in the cooling water intake(the Philippines), and several years later when the cooling water pump failed(in Sicily). As commented on earlier, we do carry a portable cooking stove-never used it yet, and a rail-mounted BBQ-that we use all the time. Electric cooking is doable! We've rarely used more than 1 burner on the stove at a time, have used the oven only twice that I recall, and use our m/w alot. The mentioned idea of a gimbaled box- with a cooktop on top and a m/w below is a great idea!

[Rohan]

Originally Posted by Na Mara

2. Could you live with serial cooking, where only one hob/oven can be used at any given moment, when away from shore power? What would cooking be like then? Are there meals you couldn't make or make as well? Would you miss them?

Here's a partial solution, although it's not as high-tech as many of these suggestions, but it should work. If you go with an electric stove, nothing is stopping you from buying a small BBQ grill you can attach to the stern, either charcoal or propane (with those very small camping propane tanks) and use that for the occasions when you don't have enough battery power for cooking.