Pushing the limits of electric cooking

[noelex 77]

Originally Posted by Na Mara

I’ll try that first as it’s (a lot!!!!) cheaper and see if I can cook within the 2.4kW restriction.

A wise move. I don’t think you will find keeping below 2.4 Kw any great hardship.

It is nearly always insufficient energy production that causes problems with electric cooking rather than limitations on the maximum power.

[Dockhead]

Originally Posted by noelex 77

A wise move. I don’t think you will find keeping below 2.4 Kw any great hardship.

It is nearly always insufficient energy production that causes problems with electric cooking rather than limitations on the maximum power.

I do electric cooking with the same inverter/charger as Na Mara has, and I find the inverter capacity to be a significant restriction for cooking without running the generator.



First of all, note that Victron's power ratings are quite ambitious. They call them "3000", implying 3kW. In the fine print you find out that that's VA, not watts, so with the power factor it's 2.4kW and only below a certain temperature. I find that even in cool weather I can't run a 2kW load continuously without the inverter complaining about high temp and eventually shutting down.


This is just enough for a single induction burner with no other heavy loads, so you can't use the kettle or microwave or blender or anything, if the induction burner is on full power.



I have a heavy duty, almost silent generator, and my batteries are lead-acid so don't like a lot of inverter duty anyway, so this is not a huge problem for me -- I just crank up the generator when I'm cooking anything serious. But a big lithium bank like Na Mara's cries out for a properly sized inverter, and he doesn't even have a generator. With the right inverter, he can live with complete autonomy -- as if he's on shore power. Shame to have the batteries but not the inverter to take advantage of them.

[Na Mara]

You’re making very valid points Dockhead.

I might just be able to run both hobs on half power on the inverter as is. I will have to be really careful about what I have on when I have the microwave, oven or kettle on.

Opposed to that, if I parallel another multiplus 3000 to the existing one all those restrictions go away and, as you say, I have the battery and distribution system to easily cope with that. The distribution system is rated up to 500A (6kW at 12V), the batteries can easily deliver that and more and there are free slots on the distribution system for another inverter even once the alternator is hooked up. I can get around the solar panel hookup issue by just fitting an extra bus bar for the renewable chargers and dc-dc charger.

The problem is where to put the second inverter. These things are big and heavy and need space around them to breathe. They also like to be cool and close to the distribution system. I have lots of space close to the distribution system in the engine bay but then it’s in a hot dirty environment even if I get the blower working. Perhaps I could get it into the rather useless cabinet under the deck saloon table above the engine bay?

Anyway, fitting that extra inverter and getting it all working with the other one is going to be the best part of 2500 euro which is what the Bluetti 2kW, 2kWh power station costs.

I installed the present inverter myself and according to the Victron guys my physical install was fine (apart from their recommendation of a buffer battery for the old bowthruster). The problems I had with getting everything working were to do with programming issues. This makes me confident that I can physically install a second inverter correctly but I would probably need professional help again with the programming. The Victron guys are great but expensive, so adding them onto the cost of the extra inverter makes that a more expensive option.

I am very confident I could “install” a power station myself.

So I’m back to where I started. I’ll live with the restriction on the output for a bit and see how that goes. If I find I can’t live like that, then I will take a decision about whether to go with a power station or a second inverter at that point.

[Pete7]

Something's missing, the gas We have used a mix of electric and gas cooking for two years, but finally took the big step and removed the gas hob.

The first step was to replace the inverter with a new 2000w pure sine wave Sterling, Victron Power In fuse box and a large MN master fuse in the event of the hybrid Lithium and lead acid has a major electrical short. Class T (£45) fuses are popular in the USA, but very expensive and difficult to find in Europe were the MH (£5) fuse is readily available at a tenth of the price. With the electrics upgraded, then on to the gas. However, the new inverter will also run the Remoska (580w) Ninja Air Fryer (1500w) and SWMBO's hair dryer (1800w) apparently very important happy wife, happy life.

Out came the two year old gas hob and grill and sold to a friend at mates rates as he re-fits his yacht for long distance cruising. The replacement double induction hob of choice is the Vango Sizzle with 2 x 800w hot plates. This is one of the few that will fit in the space of the popular European 450mm wide gas cookers. It is also one of the few induction hobs that throttles the current draw at lower heat settings rather than the cycle frequency to maintain a set temperature.

To be able to cook at sea we thought it important to have the Vango gimballed so kept the old gimbals that had previous been modified. The swing point needs to be higher for any hob compared to a full cooker as there isn't 14kg of oven below to stop the hob tipping with two full pots of food. The arrows on the photo below shows the old and higher new swing position.

To achieve all this I bought an off cut of 23mm English oak to make a base and then added a shelf underneath to store our original single induction hob, as we did using the grill on the gas hob. This adds to the weight lower down too. Several coats of hard clear varnish applied to protect the wood in the event of spills. Finally the Vango has a fan underneath to cool the hob down so a 60mm hole added to aid cool air in to the fan.

So does it work? Well a quick test with pans containing water showed just how quickly induction heats up, but a full test will have to wait until the end of May when we are away sailing for a week. Still with 2.7Kg (6 lbs) of Camping Gaz costing £45 for a refill in the UK, electric cooking with the Remoska and Vango Sizzle supplied with 600w of solar suddenly becomes attractive.

Pete

[Pete7]

Interestingly it can be moved about like the cockpit, so cooking bacon outside on a Sunday morning whilst surrounded by other yachts very tempting

Photo taken whilst testing the Vango before removing the gas hob.

Pete

[Dockhead]

Super project, Pete!! I'm sure people would like to see more details of that -- lots of people are thinking about similar conversions.


Is the 2kW inverter proving adequate? And does it deliver its rated power?

[Pete7]

Originally Posted by Dockhead

Super project, Pete!! I'm sure people would like to see more details of that -- lots of people are thinking about similar conversions.

Is the 2kW inverter proving adequate? And does it deliver its rated power?

Thanks

The old 1600w PSW inverter wouldn't run the Ninja Air Fryer quoted at 1500w for more than a minute or two before shutting down. Tested the new PS 2000w model from Sterling and it runs the Ninja perfectly.

So our options are Remoska at 580w and one induction hot plate at full power with ease. Or Remoska and two hot plates at lower power. Ninja on its own, but it cooks so quickly that cooking one item like chips from frozen to cooked in 10 minutes isn't a problem. Kettle plus one hot plate or Remoska is also possible. So I think we will be fine, with lots of options.

As you know having been on board, space is at a premium on a 31ft yacht, so a large LFP installation and big Victron Multiplus difficult to find space for, never mind the budget. We have therefore chosen items that use less power. For example at home we use a 2kW electric kettle which is always over filled particularly by me. So by choosing a 0.8L kettle and only half filling it will still provide enough for two mugs of coffee, but using less electrical power. This approach across lots of mains electrical items means we can use a smaller house bank and can get away with a moderate solar installation of 600w to power it all.

Proof of the pudding will be a week away at the end of May. Only thing is I enjoy baking cakes, therefore I suspect our power demands are going to go up, we will see.

Pete

[Pete7]

Where possible we have tried to remove single points of failure. For example we carry a spare PSW 1600w inverter charger. Its not connected, but only a half hour task if needed. If the LFP shuts down, we have a pair of deep cycle Trojans to keep us going for a while. The original 1500w portable induction hob is also readily available.

For charging if 600w of solar isn't enough we have an additional 110w folding solar panel we can deploy in fair conditions. However, if its going to be heavy rain and windy for several days, not exactly an unknown occurrence in England, we are probably going into to a local harbour, boat yard or yacht club for a few days and most have shore power. Alternatively we can use the alternator through an Orion DC>DC charger for a couple of hours to top up the house bank if necessary.

Below is the latest wiring diagram. (Edited to take into account the extra LFP battery and consumer unit plus RCBO.

Pete

[GILow]

Great updates.

Our solution has been to gimbal the convection microwave and use three separate portable single burner induction plates. Freed up a huge amount of bench space in the process.

Backup is the Webber BabyQ on the aft rail.

[sv_isara]

Just finished my full induction setup. I was able to reuse the oven shell, and reinforced it. Had to add some weights in the front. Haven't cruised yet, so the real test will be this summer. 840ah 12v, 720w solar. Ninja air fryer, 20.5" width stove shell.

[sv_isara]

Also, I have a renogy 3500w inverter. My breakers break before the inverter gets overpowered. I can simmer 1 hob, boil another (crazy fast at 7/10 power), and have an electric heater on low simultaneously. A compromise...i suppose. At least i dont have to go outside to shut off a valve when im done cooking. I often turn off the water heater when cooking. I have lived aboard for a few months this way, shore power.
Haven't used a microwave in over 6 years so can't comment on that.

[Pete7]

Originally Posted by sv_sharky

Just finished my full induction setup. I was able to reuse the oven shell, and reinforced it. Had to add some weights in the front. Haven't cruised yet, so the real test will be this summer. 840ah 12v, 720w solar. Ninja air fryer, 20.5" width stove shell.

Looks neat, be interested to here how you get on using this for real

Pete

[GILow]

Originally Posted by sv_sharky

…. At least i dont have to go outside to shut off a valve when im done cooking.…

Well, that’s kinda old school. I turn the gas off on the current boat with a switch next to the stove.

Solenoid at the tank end.

But yeah, looking forward to no gas on the new boat.

[ChrisJHC]

Originally Posted by GILow

Well, that’s kinda old school. I turn the gas off on the current boat with a switch next to the stove.

Solenoid at the tank end.

But yeah, looking forward to no gas on the new boat.

It’s not uncommon for people to turn off the gas at the cylinder rather than just relying on the solenoid.

It is a pain, but so is a propane gas fire!
(And, yes, I know they occur very rarely but not never)

[Jdege]

Originally Posted by ChrisJHC

It’s not uncommon for people to turn off the gas at the cylinder rather than just relying on the solenoid.

It is a pain, but so is a propane gas fire!
(And, yes, I know they occur very rarely but not never)

What I've seen is people relying on the solenoid day-to-day and closing the valve when they leave the boat.

I have two solenoids on my boat, one uninstalled and the other not working.

I use neither.