Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM. Today I’m discussing the power usage of cooking appliances, particularly slow cookers.
We’re planning on boondocking this summer because finding a campground with available spots is a nightmare. I love the idea of boondocking without using a generator, but I wonder if this would be practical for my wife’s cooking style?
She loves her slow cooker (not an Instant Pot), and so we would like to know just how much battery power one would need to do this. Can I power it from one of those portable battery boxes? How about adding more solar panels to my RV? Hey, I’m serious about good food while boondocking. Any ideas on how to make this work? —Sam and Edna
Dear Sam and Edna,
You’re in luck because I just finished a quick study of how much power my wife’s Hamilton Beach slow cooker used to make pork and sauerkraut for Thanksgiving. This is part of my year-long study on how much electric energy you need for an all-electric kitchen in an RV.
Now, I’m just as serious about food as you two obviously are, so in the interest of science I plugged in a Kill A Watt meter before she got started on the 8-hour slow-cooking process of her Pork and Sauerkraut. BTW – It’s delicious…
How much power does a slow cooker use?
These are electrically very simple devices – basically, just a heating element with two or three wattage levels. There’s no thermostat that I can find, except for an over-temp fuse that will shut off the power if it gets way too hot.
This is an old-school slow cooker without a thermostat or timer. You just plug it in and occasionally turn the heater up to high or down to low. It’s that simple.
So when you put it on the Low setting, I found that it draws around 123 watts of power.
And when you put it on the High setting, I found that it draws around 189 watts of power.
But the real question is: How much energy will it use over 8 hours of slow cooking? For some reason I couldn’t convince my wife to fill out a time sheet of when she switched between High and Low power. She said something about having too many other things to worry about when cooking a Thanksgiving meal to fill in a time sheet.
But I did get the cumulative energy usage after 8 hours of slow cooking, which was 1.17kWh, or 1170 watt-hrs. That’s equivalent to powering a 60-watt tungsten light bulb for around 19 hours.
If you were plugged into an outlet at your house, that’s not a lot of energy. Consider that if you’re paying 15 cents per kWh to the power company, then that only amounts to around 17.5 cents for those 8 hours of slow cooking. Pretty good deal…
But what about a Jackery 1500 and 400 watts of solar panels?
Well, I have two examples of battery power to consider. If you compare this to the amount of energy available in a Jackery 1500, you’ll note that 1,170 watt-hrs / 1,500 watt-hrs = 78%. So this will use around 3/4 of the available stored energy in your Jackery 1500.
However, if you have the 400 watts of solar panels sitting in the sun while doing this, it would be nearly a break-even energy usage situation. That is, the solar panels should be able to recover those lost 1,170 watts as long as the sun is shining, plus have a few hundred watt-hrs of extra energy stored in the battery.
What about a Rockwood Geo Pro with a 400 amp-hr MasterVolt battery and 580 watts of solar panels?
In this case, we have a lot of stored energy in the 400 amp-hr MasterVolt Lithium Battery, plus more solar panels. To find watt-hrs from the 400 amp-hrs at 12 volts we just multiply amp-hrs times volts and find that it equals 4,800 watt-hrs of energy.
Even without any solar panels we can calculate that the 1,170 watt-hrs of energy needed by the slow cooker is 1,170 / 4,800 = 23% of available battery storage. So, you would need less than one quarter of your available battery power for this slow cooker heating cycle. And the 580 watts of solar panels on the roof of the Geo Pro would easily recover that energy in just a few hours of sunshine. So, your wife could be making Pork and Sauerkraut every day on solar power alone. Of course, you can make chili or pot roast or pulled pork, or anything else you like!
Yes, these are just SWAGs
I know I haven’t considered inverter overhead or battery charge/discharge efficiencies, so the actual numbers I’m showing could vary by plus or minus 10%. So, I have to gather some more empirical data to fine-tune my usage model. But don’t worry, I’ll get there.
We can probably all see that the day of the all-electric RV kitchen is fast approaching. I’m now a firm believer in the 12-volt DC compressor refrigerator, and who can argue with the convenience of a microwave oven. But there’s a lot of new appliances, such as the induction cooktop, that are good candidates for replacing the propane cooktop. Good thing I have a high enough metabolism to try out all the great test food! So let the RV kitchen testing begin.
Stand by for taste tests on solar/battery power
In the interest of science, I already have some all-electric cooking and baking experiments lined up this winter and spring. My wife is a fantastic cook with years of experience as a catering manager. And my son Kevin is a Culinary Institute graduate who teaches baking and pastry making in a tech school. I’m pretty decent on the grill, and it does appear that Santa is bringing me a pellet smoker for Christmas. So, we’ve all volunteered to help measure energy usage with electric kitchen appliances such as induction burners, air fryers, sous vide cookers, and electric convection ovens. Yummy!
OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.
Let’s eat safe out there….
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Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
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The HotLogic portable ovens/food warmers are another possibility worth looking at for slow cooking. They are available in 12 volt or 120 volt models, and heat up the Pyrex casserole containers the food is cooked in to 165*F, which is high enough to kill harmful germs, but only use 45-100 watts/hour, depending on the size of oven used. Most of their recipes call for about 6-8 hours cooking time, depending on whether or not the meals are frozen to start. They’re also pretty inexpensive. (https://hotlogic.com/)
Yes, Mike, I also want to know the recipe for your wife’s pork and sauerkraut in the slow cooker! We’re new to RVing and plan to use our cooker a lot, and pork and sauerkraut is one of our favorites. Could you ask her, “Pretty Please”, to share it with us? Thanks, and Merry Christmas!
This question might not be relevant, but in order to use a slow cooker, I have to turn on the inverter. Doesn’t that also draw power that is not in your calculation? Thanks for all of your helpful articles.
Yes it does. But I’ll next be doing a test on these cooking methods using a Jackery 1500 Power Station with its own 1,800 watt inverter. I also have a 100 amp-hr Lithium battery with a 1kw Pure-Sine inverter for testing…
So how much is the Gym membership costing you to work all of this “testing” off?
Lucky for me I have a very high metabolism and self-caffeinate, so I can pretty much eat as much of anything I want. It’s my one superpower which means I never step into a gym. But I have slowed down a little, and my doctor recommended I cut back on the sugar a bit. But she didn’t say I have to cut back on the BBQ though!
Thank you for breaking it down for us!
Hey Mike great information about the slow cooker! What I want to know is what is the recipe for the pork and sauerkraut????
Let me ask my wife. She has literally thousands of recipes at her fingertips. Yes, I’m quite spoiled!