What do you need to run a 1800w oven?

[kllcbosmetris]

Need a little clarification from solar/energy experts. 

Trying to understand whether I can run a mini convection oven (AC, not DC) that is rated:

• Voltage:
  110 - 120 Volts
  
• Power:
  1800 Watts

What does that mean exactly? 

A) Uses up to 1800 watts depending on what you use? For example, less power needed if it is just a toast (vs. chicken rotisserie)?
B) Uses 1800 watts per unit (min or hr?) regardless of what you use it for?
C) You need a min. 1800 watts battery-to-AC inverter to even start the appliance?

 

[highdesertranger]

the 1800 watts is usually the heat output. it will use a little more on high plus the inefficiencies of the inverter(between 10-30%). look in the instruction or the name tag to get power usage. highdesertranger

 

[akrvbob]

The bottom line is it will take an enormous solar power system and battery bank to power it off solar. The problem is how long it needs to be on. You can run a microwave off of solar because it only works for 1-5 minutes. Convection ovens run a very long time.

 

[tx2sturgis]

An 1800 watt UL rating convection oven will pull 1800 watts whenever the heating elements are on. They cycle on and off to maintain cooking temperature, but the total power drain is significant.

A microwave oven is rated for 'cooking power', which is always less than the UL rating of wattage on the label.

Example: 1000 watt microwave cooking power might pull 1500 watts from the wall socket or inverter.

But since convection ovens operate much longer, maybe a half hour or an hour, you would have to have a VERY large solar array and a large battery bank to make that work.

Possible? Maybe.

Feasible? Practical? Affordable? Nope. Not unless you have a LARGE RV, and if you do, you probably already have a generator.​

A 2000 to 2500 watt (continuous rating)  generator would run it just fine however. I have done that and it works.​

There is no heavy 'starting' surge with electrical heating elements.​

Bottom line: a propane or solar oven would be much cheaper and lighter.​

 

[lenny flank]

In general, it's not practical to use solar power for anything that uses electricity to produce a lot of heat. You'd need a lot of panels and batteries.

 

[John61CT]

Any use of electricity for heating or A/C is a very large load, very expensive to set up.

Next down is refrigeration, most setups strain to handle that well along with other loads, needs to run 24x7.

Fans are pretty heavy, along with powerful computers, depending on hours per day used.

Smaller screen gadgets and LED lighting don't consume much

 

[kllcbosmetris]

The bottom line is it will take an enormous solar power system and battery bank to power it off solar. The problem is how long it needs to be on. You can run a microwave off of solar because it only works for 1-5 minutes. Convection ovens run a very long time.

This mini oven is a multi-function appliance (size of a microwave) that has toast, broil, pizza, bake, roast, cook, reheat options. So, I imagine using it for 1 to 10 minutes (depending on what is inside) at a time, on a daily basis. Similar to microwave usage, I guess. I recently got it as a gift and thought it could replace a propane stove (and I may not even need an induction cooktop, with this) and save a ton of space in my van conversion. I thought I could also use it as a drawer storage (store kitchen tools + cutlery + pan inside the oven) when it is not in use. However, it is an AC appliance and I am not sure if it can realistically work in a solar/battery set up. I'm still in the planning stages but I do plan to get a serious battery bank with as much solar as I can have on the roof -- but I am not sure if this multifunction oven set up is doable, technically speaking.

 

[John61CT]

Yes, if used like a microwave, that may be manageable.

Get a Killawatt, learn some basic units and you can do the math, create your own AH/day @12V energy budget.

As mentioned, using an inverter adds 10-30%, and of course extra costs.

Better to stick to native DC wherever possible

 

[Kia girl]

I was thinking of having mine also but I know solar will not work for mine and would need a generator to run it. I have also just looked at the propane ovens and the Coleman oven that just goes on top of you propane stove. I hear they work just as good. It seems to me it would just cost to much in the end to run that kind of oven for me to justify bringing it.


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[jimindenver]

You would need roughly twice as much solar as I have to provide enough output on a continuous basis. I CAN use mine for cooking but only the small burner on my electric cook top. At 470w I could run two off the solar output but not the 1070w large burner.

Another way to put it is 450w is roughly 35 amps on average using a clamp meter between the inverter and bank. Two I can run because my system tops out at 80 amps +/-. That is 70 amps so four would equal 140 amps. That's another 60 amps or roughly 800 watts more panel. So a bit over 2100w at peak should do it.

So I saw 300 watt panels on craigslist for $200 I think. (it was lower earlier this year) so $1400 for the panels. You will need a 150a MPPT charge controller. $600 You will need either a large bank or specialty batteries to take the output and not be fried by the C-rate, say $600. and then a buttload of wire, connectors, fuses, switches, etc. Maybe three grand and a lot of space on the roof.

Then again I personally feel a generator is part of a balanced system and for a lot less you can have a quiet little generator that will be useful for more that just the oven.

 

[RVtrek]

What does that mean exactly? 

A) Uses up to 1800 watts depending on what you use? For example, less power needed if it is just a toast (vs. chicken rotisserie)?
B) Uses 1800 watts per unit (min or hr?) regardless of what you use it for?
C) You need a min. 1800 watts battery-to-AC inverter to even start the appliance?

A) It may use slightly less for toasting versus full rotisserie.  But you're looking at probably 1500+ watts for the heating element and the balance for the rotisserie or whatever else it has going on.

B) It can pull up to 1800 watts when running.  As others have explained, the draw it takes will be variable based on when the heating element is on or off.  I've found with my toaster oven (1500 watt appliance) that if I run it for 25 minutes, it's on probably half that time, maybe less because the heating element cycles on and off.  (Note: I really should hook up a kill-a-watt and measure it's actual usage sometime.)

C) To run your device, I would recommend an absolute minimum of a 2,000 watt inverter.  I have a 2,000 watt inverter and it runs my 1500-watt toaster just fine, but it does suck down a lot of battery power.

 

[kllcbosmetris]

An 1800 watt UL rating convection oven will pull 1800 watts whenever the heating elements are on. They cycle on and off to maintain cooking temperature, but the total power drain is significant.

So, it will draw a constant 1800w per hour from the battery bank regardless of what I am cooking? 

Not unless you have a LARGE RV, and if you do, you probably already have a generator.

No, not a large RV. Just a van conversion. 

A 2000 to 2500 watt (continuous rating)  generator would run it just fine however. I have done that and it works.

There is no heavy 'starting' surge with electrical heating elements. 

I plan to have a van-installed battery bank that also features a movable unit (i.e. kodiak inergy type, where I can take with me and charge it at the office or starbucks during the day) so I can have enough power even in rainy/snowy days. 

Bottom line: a propane or solar oven would be much cheaper and lighter.

Propane is a bit dangerous for me to have in the van (and tank would take additional space in a small van), so I would want to go with an induction cooktop regardless (I believe they draw between 900w and 1300w?) So I figured, why not keep this mini oven (it's free) rather than buy a new propane cooktop set up. So, this actually would be cheaper for me. I just need to find out whether it is doable (energy/battery wise) and if so, what (i.e. 2000+ inverters?) I need when I convert the van.

 

[tx2sturgis]

Well, just for grins, lets run some numbers. I very rarely do math on this forum because it makes the reader's eyes glaze over, and if I get one decimal wrong or one formula wrong then it all falls apart, but here goes:

Lets say you preheat the oven for 5 minutes to cook something for 10 minutes.

Lets assume it runs for those 5 minutes then cycles on and off at 50% duty cycle for the next 10 minutes.

1800 x 10 minutes total heater ON time = 300 watt hours (wh) (1800 times 1/6th of one hour)

Suppose you did this 3 times a day.

3 x 300 = 900 wh total.

Add inverter loss: 20%

900 plus 180= 1080 wh per day.

Right away we know we need a LARGE solar array, roughly twice this value, rule of thumb.

So, 2000 watts of solar. (that's a BUNCH!) And you might need a trailer just to haul those panels.

Add in the cost of a LARGE solar controller to handle all of that power. They ain't cheap.

Now we might need about 1000 ah of batteries to power this thing at least once or twice during evening hours when we have zero sun.

So that's at least 4 large golfcart style batteries of average capacity. Maybe six or eight!

Then we also probably need a 3000 watt inverter.

AND all the fat cables and fuses to make all the electrons happily zig-zag along.

Getting very pricey here. And very heavy. On cloudy days you might not even be able to recharge the batteries to full. So that would mean several days of not being able to use that oven.

If you are able to make all of this happen, I want to see it in action!

Again, a propane oven or solar oven is the better and cheaper option.

Anyone else: I'd like your math help here, correcting or confirming as you see fit.

 

[highdesertranger]

we are just speculating on how much this convection oven uses. we need hard numbers. with electric heating appliances the advertised wattages are usually the power of the heating element. a blow dryer rated at 1200 watts uses more than 1200 watts on high. a small electric heater rated at 1500 watts draws more than 1500 watts on high. we need the bottom line on power usage before we can say what this oven needs. highdesertranger

 

[tx2sturgis]

Yes, we ARE speculating.

But the UL (or other standards) label rating of power consumed IS the maximum that the appliance will consume at the rated voltage. This is a US requirement for appliances sold in the USA.

A hair dryer, or space heater, or convection oven, or counter-top hotplate, always consume the power indicated on the label, (or less on LOW power) and never more than the label rating. This is a UL rating stipulation. 

Microwave ovens DO have a disparity between the UL rating and the 'cooking power'.

But these other simple electrical appliances are rated at the wattage that the unit consumes.

Example: This heater of mine will use 1500 watts on high, but can use either 600 or 900 watts on low and medium. But never more than 1500 watts.



This is an electrical standard for heating-type appliances in the US. It will be the same for that convection oven.

 

[kllcbosmetris]

Well, just for grins, lets run some numbers. I very rarely do math on this forum because it makes the reader's eyes glaze over, and if I get one decimal wrong or one formula wrong then it all falls apart, but here goes:

Lets say you preheat the oven for 5 minutes to cook something for 10 minutes.

Lets assume it runs for those 5 minutes then cycles on and off at 50% duty cycle for the next 10 minutes.

1800 x 10 minutes total heater ON time = 300 watt hours (wh) (1800 times 1/6th of one hour)

Suppose you did this 3 times a day.

3 x 300 = 900 wh total.

Add inverter loss: 20%

900 plus 180= 1080 wh per day.

Right away we know we need a LARGE solar array, roughly twice this value, rule of thumb.

So, 2000 watts of solar. (that's a BUNCH!) And you might need a trailer just to haul those panels.

Add in the cost of a LARGE solar controller to handle all of that power. They ain't cheap.

Now we might need about 1000 ah of batteries to power this thing at least once or twice during evening hours when we have zero sun.

So that's at least 4 large golfcart style batteries of average capacity. Maybe six or eight!

Then we also probably need a 3000 watt inverter.

AND all the fat cables and fuses to make all the electrons happily zig-zag along.

Getting very pricey here. And very heavy. On cloudy days you might not even be able to recharge the batteries to full. So that would mean several days of not being able to use that oven.

Thank you for explaining and giving me an idea how to calculate my watt needs. It does not look like it is doable, unless I am only cooking for 1-15 minutes a day. 

On your second point, I do understand there will be added expense for the solar set up but I figure that is part of doing business as you build your DIY campervan. If I go without the stationary set up (the solar + charge controller + inverter), then I might have to rely on GoalZero Yeti or Kodiak Inergy type of mobile battery packs and they are not cheap either (~$2,000). Either case, I see this as an investment as I plan to figure out a way to do full-time and keep the van for 10 years. 

P.S. Why do we need double the solar panels? Do they have 50% efficiency in charging or something?

 

[kllcbosmetris]

we are just speculating on how much this convection oven uses.  we need hard numbers.  with electric heating appliances the advertised wattages are usually the power of the heating element.   a blow dryer rated at 1200 watts uses more than 1200 watts on high.  a small electric heater rated at 1500 watts draws more than 1500 watts on high.  we need the bottom line on power usage before we can say what this oven needs.  highdesertranger

I read every page of the manual and there isn't a technical info on heating elements and how often they run. I guess my only option is to run it and buy a [font=Verdana, Arial, sans-serif]Killawatt to see how much it is drawing. [/font]

 

[kllcbosmetris]

Yes, if used like a microwave, that may be manageable.

Get a Killawatt, learn some basic units and you can do the math, create your own AH/day @12V energy budget.

As mentioned, using an inverter adds 10-30%, and of course extra costs.

Better to stick to native DC wherever possible

If I use a Goal Zero Yeti or Kodiak Inergy type of compact lithium battery pack (instead of a full stationary solar set up w/ inverters) there won't be any (10-30%) loss, correct? Though I am not sure if they would power 1800w appliance. Probably not.

 

[johnny b]

Without knowing the specific draw of each appliance we still know that the OP wants to use an induction cooktop and electric oven.
And we know that there is a desire to carry the battery pack into the office or Starbucks for recharging.
So looking at ~800 aH of lead batteries, we got about 468 pounds for 765 amp hours (three Lifeline 8D AGM).
That gives about 340 usable amp hours (50% drawdown + 10% inverter loss).
A 1000 watt load at 12 volts is about 85 amps. (83.333)
340 / 85 = 4
So best case scenario with the system at top operating condition would be 4 hours at that load before required recharge.
800 watts of solar (4 x 200w)...5 foot x 3 foot each + 45 pounds each. So that's a 10 foot by 6 foot flat space on the roof needed and also adds another 180 pounds of weight. Figure another 100 pounds of wire, inverter, fuses, etc.
So....468 + 180 + 100 = 748 pounds.
Still need to factor in a good charger for plugging in to shore power when necessary...and the fact that this would be a fairly 'advanced' system, perhaps not suited to a novice...mistakes can be quite costly.
Weight could be cut by half using LiFePo4 lithium batteries (~240 pounds vs 468 of lead), but the price would increase by 4 times.
Not looking good for use in a "small" van that doesn't have room for a propane tank.

Hope that helps.

If you want to cook with electric, get a generator; it just makes more sense.

 

[kllcbosmetris]

Without knowing the specific draw of each appliance we still know that the OP wants to use an induction cooktop and electric oven.
And we know that there is a desire to carry the battery pack into the office or Starbucks for recharging.

Yes, I thought just running everything with electric (w/o propane, butane, sealed propane container, drilling ventilation for propane, etc.) would be simpler. And since I need to work, I'll most likely be in an urban area (vs. boondocking in national parks) where I can easily charge devices, if I buy a mobile battery pack (i.e. goal zero or kodiak inergy type, where I can plug it in while I do work). 

So looking at ~800 aH of lead batteries, we got about 468 pounds for 765 amp hours (three Lifeline 8D AGM).
That gives about 340 usable amp hours (50% drawdown + 10% inverter loss).
A 1000 watt load at 12 volts is about 85 amps. (83.333)
340 / 85 = 4
So best case scenario with the system at top operating condition would be 4 hours at that load before required recharge.
800 watts of solar (4 x 200w)...5 foot x 3 foot each + 45 pounds each. So that's a 10 foot by 6 foot flat space on the roof needed and also adds another 180 pounds of weight. Figure another 100 pounds of wire, inverter, fuses, etc.
So....468 + 180 + 100 = 748 pounds.
Still need to factor in a good charger for plugging in to shore power when necessary...and the fact that this would be a fairly 'advanced' system, perhaps not suited to a novice...mistakes can be quite costly.
Weight could be cut by half using LiFePo4 lithium batteries (~240 pounds vs 468 of lead), but the price would increase by 4 times.
Not looking good for use in a "small" van that doesn't have room for a propane tank.

Hope that helps.

If you want to cook with electric, get a generator; it just makes more sense.

As I am reading and learning more, I was thinking about lithium batteries ... not because they are lighter and smaller but they apparently can be discharged more than 50%.  As for the solar panels, I hear that there are lighter/flexible models (although less realiable, I read) which would also be more stealthy I think.