Crock Pot - Slow Cooker

[Pete7]

Originally Posted by belizesailor

Yeah, thats a lot of juice to cook a meal...a 10 hour cook = 80 amp hours...fine for dock side maybe, but for that I would just get an AC powered version.

By contrast, a WonderBag or similar uses zero amp hours and can be left unattended w no worries.

We have been using a small mains slow cooker this summer with great success. Its 120w and about 2L in size. In practice it takes about 30 minutes to come up to temperature drawing about 9A. From then on it cycles on and off so uses much less. The only thing we struggle with is how to secure it at sea, at the moment we only use it at anchor.

Pete

[belizesailor]

Originally Posted by Pete7

We have been using a small mains slow cooker this summer with great success. Its 120w and about 2L in size. In practice it takes about 30 minutes to come up to temperature drawing about 9A. From then on it cycles on and off so uses much less. The only thing we struggle with is how to secure it at sea, at the moment we only use it at anchor.

Pete

Yes, I just went with worst case. Would be interesting to track total usage for a typical meal/cook time. If a bit of insulation were added then total usage could be reduced further.

For more accurate temp control you can also use an external thermostat.

[Comix Bay]

I think you should talk to the "Long Haul Truckers" who use a lot of these 12V gadgets quite a bit.

They are also sold in most Flying J's that we have been in. In fact I bought my wife a 12V curling iron on one trip, she had no problems with it.

While under way they might be okay, we used our 120V home model slow cooker in the motor home, put it in the sink while running down the hwy and ran the genny, but then it was a lot smoother than the ocean.

Good luck.

Ted VA7YQQ
Comox, BC

[CaptTom]

Our pressure cooker runs easily off the inverter for the few minutes it takes to get up to pressure. Once there, you're essentially done.

I was a huge fan of slow cookers when I was younger. Now that I've seen what the InstantPot can do, slow cookers seem pointless. I can get the same results in minutes, as well as do all kinds of other things a slow cooker isn't good at. It has such a small impact on the overall energy budget that we don't really even think about it.

[odonnellryan]

Pressure cooker is the best item in my kitchen at the house. I intend to bring it on the boat next season.

Cooks basically anything quick - and for stuff like stews, chili, etc.. you get a "12 hour" chili taste (IMO) in 1-2 hours!

Also you don't boil off any water (or extremely little anyway), so saves on that but you need to remember to put less water into the mix

[zeehag]

found a lovely crack in the body of my pressure cooker so instead of tryina die, i use occasionally only a crock pot. have been using em since htey were invented but i wouldnot consider use of one at anchor. that is why bbq and other alternative fuel sourced cooking measures were invented.
ever try to out wait a pressure cooker in tropical summer??hahahahahahahahaha
low priority item in my book. outdoor flames and solar ovens are better ideas where i am.

[Mikado]

Originally Posted by CaptTom

Our pressure cooker runs easily off the inverter for the few minutes it takes to get up to pressure. Once there, you're essentially done.

I was a huge fan of slow cookers when I was younger. Now that I've seen what the InstantPot can do, slow cookers seem pointless. I can get the same results in minutes, as well as do all kinds of other things a slow cooker isn't good at. It has such a small impact on the overall energy budget that we don't really even think about it.

+1 InstantPot
We use it at least twice a week The meals from the recipe book are easy and delicious.

[thinwater]

Just so people understand the math.


2 quarts of liquid = 4 pounds. The reach boiling is under pressure is (220-80)x4=560 BTU, or with inefficiency and some minor continuous heating, about 1000 BTU for the whole cooking cycle. This is about 293 watts for an hour or 1000 watts for about 15-20 minutes.


Assuming some inverter inefficiency, about 25 Ah, which is not bad.

[CaptTom]

Originally Posted by thinwater

...The reach boiling is under pressure is (220-80)x4=560 BTU...

I'm totally lost. Is there another way to say that?

The IP is rated at 1KW. It takes about 10 minutes to bring an average meal up to pressure, at which point it either just maintains temp (minimal draw) or with many recipes, you're done cooking and you can unplug it.

1KW at 120VAC = 8.3A, and at 12VDC it would be 83.3A. Do that for 10 minutes (one sixth of an hour) and that's 83.3/6 = 14AH. Throw in some inefficiency and we're still a bit below your 25AH, although we're in the same general range.

I'm not convinced it really uses 1,000W for the whole 10-minute cycle, though.

[StuM]

Originally Posted by CaptTom

I'm totally lost. Is there another way to say that?

Of course there is, it's called "metrics"

2qt = 1.9 litres

Specific heat of water = 0.00116 kWh/l.K



Assume we need to raise water from an ambient 20°C to a pressurised boiling point of 105°C, that's an increase of 85K (°C).


So ideally it would require 0.00116 * 1.9 * 85 = 187W



(187W = 638 BTU/h - slightly more that Thinwater's figure but he use a smaller 220-80 = 140°F (78K) temperature rise.)


187 is approx 15Ah @ 12V nominal. Add say 20% additional power for heating losses and to maintain the temp/pressure for the required period plus another 10% for inverter inefficiency and you are up to about 20Ah.


That's again in the ballpark

[StuM]

Originally Posted by CaptTom

I'm not convinced it really uses 1,000W for the whole 10-minute cycle, though.

It will probably use full power while bringing the liquid contents up to temperature/pressure. A lot less while maintaining that for however long you cook.


Of course, the previous calculations assumed that we filled the 2qt container with water and raised the whole lot to over normal boiling point.



In reality, you only heat a small amount of water initially to that temperature and then continue to add heat at a lesser rate to maintain it as the heat enters and cooks the food (You don't raise the centres of the meat/vegetables etc to anywhere near the same temperature )


I'd still plan on 20-25Ah for a meal.

[thinwater]

Originally Posted by CaptTom

I'm totally lost. Is there another way to say that?

The IP is rated at 1KW. It takes about 10 minutes to bring an average meal up to pressure, at which point it either just maintains temp (minimal draw) or with many recipes, you're done cooking and you can unplug it.

1KW at 120VAC = 8.3A, and at 12VDC it would be 83.3A. Do that for 10 minutes (one sixth of an hour) and that's 83.3/6 = 14AH. Throw in some inefficiency and we're still a bit below your 25AH, although we're in the same general range.

I'm not convinced it really uses 1,000W for the whole 10-minute cycle, though.

High School Chemistry


(220F-80F) x (1 BTU/pounds*F) x 4 pounds =...


Inefficiency comes in many forms:
* inverter losses
* wire resistance
* heating to maintain pressure
* insulation losses

* charging hysteresis


Obviously, it depends on the vessel and the amount of food (you said "average meal," I said 4 pounds) and the type of food, but it is in the range we both discussed; 15-25 Ah. Not bad, really, for resistance heating. I was intentionally conservative (worst case) in my calculation, so that no one would say "it's more than that."

[Mike Banks]

Dunno about that one, it looks OK, but my wife bought a stainless cheap one with a ceramic insert from Big W for about twenty five dollars or so--uses 250 watts of power--and works like a charm. It would run from an inverter. All that excess solar could be used to cook something.

[longjonsilver]

Originally Posted by wrwakefield

You didn't ask, but related is the pressure cooker... On the boat I have always had a [modern] stove top pressure cooker. On land, I loved our electric pressure cooker, but find the stove top much more versatle on the boat- especially since it can easily achieve 15psi and therefore be used for canning...

Thanks all for the great responses. Makes my decision making easier. i guess a crock pot would be good if motoring.

i recently bot a pressure cooker (Presto) at a second hand store, and found out that it leaked, so i bot a new gasket. My wife and i use a crock pot all the time at home and so she asked about 12v crockpots for the boat. We have yet to use the pressure cooker. Anyone know any recipe books that you recommend for boats. The wonderbag (i always think wonderbra ) sounds like a good idea as well. The idea as you all know is to spend a few moments in the galley and then back to the helm (or wherever) and end up with a delicious meal, having spent only a tiny amount of time.

blessings
jon

[thinwater]

Originally Posted by longjonsilver

Thanks all for the great responses. Makes my decision making easier. i guess a crock pot would be good if motoring.

i recently bot a pressure cooker (Presto) at a second hand store, and found out that it leaked, so i bot a new gasket. My wife and i use a crock pot all the time at home and so she asked about 12v crockpots for the boat. We have yet to use the pressure cooker. Anyone know any recipe books that you recommend for boats. The wonderbag (i always think wonderbra ) sounds like a good idea as well. The idea as you all know is to spend a few moments in the galley and then back to the helm (or wherever) and end up with a delicious meal, having spent only a tiny amount of time.

blessings
jon

A thick fleece blanked folded 4x and wrapped around a pot is enough for many things that will only cook for an hour or two. Two blankets is better. Also great for rice (boil, bag, ready any time from 30 min to 3 hours). I commonly put dinner together when I anchor, go play for a while, and come back at dinner time. Often the only thing that goes in the pot is either rice or soup, but it can be some variation on stew or chilli.


Or rather try the heavy blankets to see if you like it, before buying something.