Electric Pressure Cooker vs LPG Set-up

[tyleroday]

Hey all,
I got an Instant Pot IP-DUO60 7-in-1 Programmable Pressure Cooker (6Qt/1000W, Stainless Steel Cooking Pot and Exterior) as a gift. I was just about to return it and get an old fashioned non-electric one but began to wonder if this could be a good idea. It is stainless steel and generates 0 steam and is also safe. No gas leaks/explosions, mildew, mold, or rust.

I have a 34ft O'Day moored boat with absolutely no cooking instrument. I was going to buy a LPG stove top, canister, solenoid, pipes, etc. and do the whole "propane set-up", although I have to admit I am nervous of the explosion horror stories. I have 2 100w solar panels in sunny FL with a dual battery controller going to my two batteries. I only use electricity for lights and the radio at the moment. I know I will need an inverter (which I don't have yet) and maybe another battery, these two combined would be cheaper, safer, and cleaner than that the LPG set-up I was planning on.

Do you think this pressure cooker could work on my boat electricity-wise? The specs for it say 120V~ 60Hz, 1000w. I am clueless when it comes to electrics so I thought maybe someone on here could help me out...

[roverhi]

What happens when you don't have AC electricity?? Inverters fail, you may be anchored out, the sun don't shine, etc. Would want a back up way to cook. If you are going to have to have a back up, why not make it your primary.

Wouldn't be overly worried about propane if you do the installation according to specs. and maintain the system properly. If you can't handle propane's risk, kerosene works great without the explosion issue. There is also non pressure alcohol but alcohol is low in BTU output. Makes boiling water for lobster a yawning affair.

[hellosailor]

Tyler-
I would guess that cooker takes 1000W when it is heating up, maybe 5-10 minutes, and then it cuts back to maybe 200W to maintain the heat. So the true average that it pulls will not be anywhere near 1000W.
You can buy a $25 gadget called a "Kill-o-watt" that plugs into the AC cord and actually measures and records the wattage it pulls (instant and total) and try it out at home to see what the real numbers are. Pressure cooking also usually isn't a very long process, 15-30 minutes, often 15-20, so you're not pulling that power for a long time.
It does take some getting used to, because you can't open the pot to see if it is cooked--that loses all the pressure and defeats the whole purpose, takes WAY more time.
So run the numbers, see if it will work for you.


A surprising number of boats use a $25 "Korean bbq" single-burner butane stove for occasional cooking or boiling a kettle. Any explosive gas below deck is an issue, but that's a personal consideration. A lot of us haven't been blown up by one. (Again, occasional and careful use.)

[socaldmax]

While I understand people being cautious about propane and that it settles into low areas like bilges, it does have an odor to it that should alert you to it's presence.

My local gas & electric company sends their employees out to test your gas connections, all of the joints, valves, etc and your furnace whenever you call them after new construction or you want to prepare for the winter.

They use a long BBQ lighter to test for leaks. I was kind of alarmed when I first saw the female employee casually moving the lighter all around the pipe joints, but she reassured me, they're professionals and they've never blown anyone up yet.

[Paul54]

A quick rough guess is that the cooker will draw close to 85 amps of DC current on the input side of your inverter. That is a lot of power draw.

[tyleroday]

Thanks for all the input. roverhi, I have a back-up single burner stove )the $25 "Korean bbq") that I can use incase of no power, but it does make sense to use a primary as a back up if there is a lack of storage.

hellosailor, I will have to get the Kill-o-watt, although is there is device that measures the power in your batteries? I can try to cook something and see how much it drains. I feel like I need something like this anyway. Is there a meter I can use? There is a meter that goes with my solar panel controller but I think it just measures how much energy is coming in.

socaldmax, I guess I am not too worried of the installation of the LPG (I am thorough when working on my boat), but some other factors are nice about the pressure cooker like easy cleaning, setting a time to cook, no lugging gas tanks or buying fuel, etc. I would hate to have the job of sticking a flame to a potential gas leak haha.

Paul54, that is what I was trying to figure out. I have watched multiple videos on Youtube but can't entirely grasp the concept enough to make a logical judgement. I guess I need to read more about electricity still. I basically am just wondering if it is even feasible, would cooking rice for 20 minutes completely drain my 2 batteries, would it leave barely enough for cabin lights, or would it only suck 15% of them so they can recharge the next day?

[GordMay]

Greetings and welcome aboard the CF, Tyler.

[Russ]

Think you are going to be unpleasantly surprised at power draw of the cooker and what an invertor can do irrespective of the size of your battery bank. I find I cook only on my propane stove and most power boat people with electric stove tops start their generators. I'd ask the Invertor company but I think the invertor won't deal with the electric pressure cooker very effectively or for very long . Average electric stove burner is 1200 Watts and I don;t think an invertor will do the job despite the specs. Any electrical engineers to set me straight???? Russ

[Paul54]

You can design a battery/inverter system to power most anything. But trying to power an AC load of 1200 watts from a 12 volt DC system will require approximately 100 amps of DC for as long as you are running the electric stove burner. To deliver that kind of power at 12 volts will require a large battery bank, very big wire to the inverter, some way to recharge the battery bank, and a inverter that you won't easily find at walmart or an auto parts store. Propane will give you lots of cooking energy with low cost and small space requirements.

[richardhenshaw]

The benefit of Butane for cooking is that it is lighter than air. Any leak will leave your boat rather than sinking into it like Propane.

[socaldmax]

Originally Posted by Paul54

You can design a battery/inverter system to power most anything. But trying to power an AC load of 1200 watts from a 12 volt DC system will require approximately 100 amps of DC for as long as you are running the electric stove burner. To deliver that kind of power at 12 volts will require a large battery bank, very big wire to the inverter, some way to recharge the battery bank, and a inverter that you won't easily find at walmart or an auto parts store. Propane will give you lots of cooking energy with low cost and small space requirements.

Paul is absolutely right. As easy as it would be to just plug in an electric cooker, it's simply going to draw too much power. Propane is a much more fuel efficient way to cook, after you get it installed (unfortunately.)

[Bill Seal]

Originally Posted by richardhenshaw

The benefit of Butane for cooking is that it is lighter than air. Any leak will leave your boat rather than sinking into it like Propane.

Ummm no, that's CNG. Propane and butane are both heavier than air.

[Stu Jackson]

Originally Posted by tyleroday

I am clueless when it comes to electrics so I thought maybe someone on here could help me out...

None of us, NONE, were born electricians.

We learned.

DIY Selecting an Inverter or Inverter Charger | West Marine

The West Advisors have tons of electrical material.

Here's some more:

Electrical Systems 101 Electrical Systems 101

[TrentePieds]

1000 watts at 120 volts = (1000/120) amps = 85 amps, or so. Just like in information technology ("garbage in -> garbage out"), so in electrics: "Amp/hours out" must be replaced with an equal number of "amp/hours in" to maintain battery state of charge.

So 85 Amps out for 20 minutes must be replaced by putting 85 amps back in for 20 minutes. Or (which is the equivalent) 30 amps for a little over 20 x (85/30) minutes, say, an hour.

Lotsa small boat engines are fitted with alternators that produce no more than 30 amps. So if you are going to burn an hour's worth of diesel fuel to run your pressure cooker for 20 minutes, you are infinitely better off just burning propane for 20 minutes. Smaller "carbon footprint" among other things. Cheaper too! Remember also that running at idle for prolonged periods is something small diesels HATE! And if you do the idle for the sake of your ear drums, the alternator is unlikely to even produce measurable output.

If you are on the hook and you run the diesel at "charging RPM" for the love of electric pressure cookers, your anchorage mates are going to take s STRONG dislike to you.

All in all, MINIMIZE the number of electical devices you have in your boat. Be ever conscious of the difference twixt "wanting" and "needing" :-)

TrentePieds

[hellosailor]

Tyler-
There are many posts and many opinions on how accurate different ways and devices measure battery capacity, or not. If they are new, you have to decide how far down you are willing to cycle them. If they aren't new, you have to start by figuring out how much capacity they have at best.
The kilowatt device has an easy job, since it is just measuring AC and intended for use on land. (With an inverter and non-sine-wave output, I wouldn't know what imaginative stories it would tell.)


Let's say a pressure cooker takes 1000 watts for five minutes, then 300 watts for ten more minutes, and in theory your meal is done in 15 minutes. (Things also continue to cook very nicely after you SHUT the power.)


So you've pulled 5000 watt-minutes plus 3000 watt-minutes for 8000 watt-minutes total. 8000 watt minutes divided by 12 volts gives you 666 amp-minutes or more conventionally, 11 amp hours of current drawn. If you have a 100AH deep cycle battery, like a single new Group 31, you've just consumed over 10% of the battery charge cooking dinner. If you want great battery life and you only cycle the battery to the 50% point...Well, you might cook dinner for four days on that one battery, if you used no other power and then promptly recharged it.
If you've got a 200AH bank, or a 400AH bank, or you have shore power every second or third night...it becomes more tolerable. If you have older batteries and also plan to cook breakfast on AC...that butane burner can seem way simpler.(G)