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electrical:12v:dailypowerrequirements [2023/09/29 10:19]
frater_secessus [add them all up] |
electrical:12v:dailypowerrequirements [2024/07/29 12:40] (current)
frater_secessus [also consider your highest-current loads] |
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| Aside: if you haven't made or used a spreadsheet before, here is [[https://www.youtube.com/watch?v=7Q2C9MB-YH4|a beginner's intro]] on youtube. Many computers come with a spreadsheet program (like Excel) and there are free ones like [[https://www.libreoffice.org/discover/calc/|LibreOffice Calc]] and free online ones like [[https://docs.google.com/spreadsheets/u/0/|Google Sheets]], etc. Google Sheets was used for the screenshots in this article. | Aside: if you haven't made or used a spreadsheet before, here is [[https://www.youtube.com/watch?v=7Q2C9MB-YH4|a beginner's intro]] on youtube. Many computers come with a spreadsheet program (like Excel) and there are free ones like [[https://www.libreoffice.org/discover/calc/|LibreOffice Calc]] and free online ones like [[https://docs.google.com/spreadsheets/u/0/|Google Sheets]], etc. Google Sheets was used for the screenshots in this article. |
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| ==== and note your highest-current loads ==== | |
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| Sometimes a load doesn't use much energy (Wh) because runtimes are short, but still consumes a lot of power (W). An example might be an electric coffeemaker. | |
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| It might run for only 5 minutes a day (1200w / 60 minutes in an hour * 5 minutes) = **100Wh**. But during that run it is pulling ~118A (1200w / 0.85 inverter losses / 12v). **So the entire system (batteries, wiring, inverter) has to be sized to that 118A load** thar runs only 5 minutes a day. Do you love that Keurig enough to buy extra batteries, fatter wire, and a bigger inverter to run it? | |
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| * this is a giant PITA for only two loads. But when you get to ten or twenty (or more) loads the spreadsheet starts to shine. It also allows you to easily see the increase/decrease from using, say, a 45w or 90w fridge instead of a 60w one. | * this is a giant PITA for only two loads. But when you get to ten or twenty (or more) loads the spreadsheet starts to shine. It also allows you to easily see the increase/decrease from using, say, a 45w or 90w fridge instead of a 60w one. |
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| | ===== also consider your highest-current loads ===== |
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| | Sometimes a load doesn't use much energy (Wh) because runtimes are short, but still consumes a lot of power (W). An example might be an electric coffeemaker. |
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| | It might run for only 5 minutes a day (1200w / 60 minutes in an hour * 5 minutes) = **100Wh**. But during that run it is pulling ~118A (1200w / 0.85 inverter losses / 12v). **So the entire system (batteries, wiring, inverter) has to be sized to that 118A load** thar runs only 5 minutes a day. Do you love that Keurig enough to buy extra batteries, fatter wire, and a bigger inverter to run it? |
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| | also see [[opinion:frater_secessus:run_this_load|How Do I Run This Load?]] |
| ===== now what? ===== | ===== now what? ===== |
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| Now that we assessed our daily power requirements we can think about | Now that we assessed our daily power and max current requirements we can think about |
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| * assessing our [[12v:bank-sizing|power storage needs]] | * assessing our [[12v:bank-sizing|power storage needs]] |
| * and power generation options ([[electrical:solar:sizing|solar]], [[electrical:12v:alternator|alternator]], [[electrical:generator|generator]], [[electrical:shore_power|shore power]], etc) | * and [[electrical:12v:power_mix|power generation options]] ([[electrical:solar:sizing|solar]], [[electrical:12v:alternator|alternator]], [[electrical:generator|generator]], [[electrical:shore_power|shore power]], etc) |
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| | ===== resources ===== |
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| | * [[https://faroutride.com/van-electrical-calculator/|FarOutRide's calculator]] |
| | * [[https://www.vanlifeoutfitters.com/sizing-your-electrical-system-load-calculations/|VanlifeOutfitters article and calculator]] |
| | * [[https://www.parkedinparadise.com/calculate-electricity/|Parked in Paradise calculator]] |
