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cooking with excess electrical power
Cooking and heating water with electricity off-grid is usually impractical but there are exceptions. In some cases the relatively large power loads can be used without affecting house battery1) state of charge:
Note there is a difference in how much power (W) a cooking appliance consumes and how much energy (Wh) it will consume over a cooking session. This will have real effects on system design, or how you can cook with an existing system.
gear
In general DC power3) is used for warming or very slow cooking. Part of this is due to the limits of cigarette lighter outputs, typically 120w (10A x 12v). The “catch-22” is that most people don't drive their vehicle sufficient hours to do real cooking off DC.
Higher power is common with AC devices but one must have the power to run it, and to recharge the battery bank afterwards.
DC
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heat only water with them; anything else baked on is extremely difficult to clean off the coils
carry extra fuses in case you blow the ciggy port fuse. Know where the fuses go.
babysit the heater while in use - if the container falls over or the heater otherwise slips out it can cause a fire.
unplug before removal from water to avoid overheating the element
have a safe place planned to set them down before heating; they will be very hot and can melt/burn surfaces after removal from the water
heated lunchboxes/warmers are large enough to hold hot lunches. They are typically better suited to warming precooked meals rather than cooking from scratch. They come in “lunchbox” and “suitcase” styles.
lunchbox - hard exterior, typically better insulated tops and higher power.
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there are several externally-ribbed RoadPro clones but they have less documentation:
Zento,
Vaygway,
ZonePro. Of these, only the ZonePro lists wattage (120w).
suitcase - soft exterior, often lightly-insulated tops and lower heating power.
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Sabotheat (12v/90w). Note: has heat levels and timer.
crockpot/slow cooker typically require many hours of cooking.
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heated mugs can be used to keep beverages hot, or heat small amounts of water for tea, coffee. Warm canned soup, etc. Example:
Wagan heated mug (12v/
24w).
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AC (inverter)
Analog cooking appliances (knobs, not electronics) run fine off inexpensive MSW inverters.
crock pots typically take 125w-200w on HI and half that value on LO.
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crockpot vs instant pot
There are some major ways the two differ:
also see this post
breaking the 10A barrier
techniques
Power/time saving
Preheating water on the dash or elsewhere
heating only the required amount of water
reducing power level after reaching a boils (ie, reduce power to simmer)
covering pots while heating
pre-soaking beans (overnight) rice (up to an hour), etc
Cleaning
use parchment paper, foil to line crocks
lightly oil crocks before cooking to reduce sticking
immersion heaters might best be used for heating plain water, as the loops can be difficult to clean
resources