I live in a van and have only a certain amount of energy I can use each day but can never tell what appliances are efficient or not. HELP
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You can’t, really? How many watts an appliance uses doesn’t tell you how efficiently it’s using it. Something like an electric heater is near enough 100% efficient because every watt it consumes is converted to heat, which is obviously the whole point of such a thing, but it will use a lot of power doing so.
Volts should be the same for all the items in your van: probably 12 or 24V. The exception would be anything run off an inverter which will be at 230V.
Watt is the unit of power, and power multiplied by time is energy. So something that consumes 50W for 2.4 hours is using the same energy as something that draws 5W for 24 hours.
Efficiency is rather harder to determine, but I suspect that isn’t really what you care about?
For most appliances efficiency will be relative to other appliances in the same class.
To take a lightbulb as an example. Imagine a light bulb uses 10 watts of electricity and produces 1 watt of heat. That’s a lot less efficient than a heater that uses 100 watts of electricity and produces 100 watts of heat! But obviously you can’t ditch your light bulbs for heaters because they don’t do the same thing.
What you need to do is compare the a light bulb with another bulb. If the next best bulb you can find uses 15 watts for the same light, you can say your bulb is as efficient as you can get.
As another commenter said, though, that might not actually be what you’re interested in – you might be more interested in the power consumption of different things so you know how much you can/should use them, and that’s wattage x time used.
You need to compare X to Y and take the thing that uses less watts for the same result.
Heating is always going to use lots of energy. For instance, you want to make a cup of tea.
You need to take 200g of water from 27C to 100C.
+1C per 1 gram of water = 4.18 Joules. 4.18 * 200g * +73C = 61028 Joules.
1 Joule is 1 Watt for 1 Second, so 61k Joules to heat your water would take a 1kw Electric kettle, 61 seconds to boil and use 1kw for 61 seconds of time. 1kw @ 230v pulls 4.3 amps.
Now lets put that into perspective, what does 1kw for 61 seconds (61kJ) look like for a cup of tea.
1, 100 w incandescent bulb could be lit for 10 minutes with the same energy.
1, 13w LED bulb (100W incandescent equiv) could be lit for 1 hr 15 mins with the same energy.
1, 21 inch box fan could run for 12 minutes with the same energy.
For heating things, charcoal briquette come in at around 8kJ/g, meaning burning 10 grams of charcoal, which is less than 1 single briquette, would produce more energy than needed to boil your 200g of water. You may want to find some kind of mini-fire stove to heat shit and not use your power for heating. Save it for light and motors which require it.
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