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electrical:12v:intro [2023/02/06 12:30] frater_secessus [Table] |
electrical:12v:intro [2024/01/29 13:37] frater_secessus [Real-world(ish) examples] |
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====== Powering your vanlife ====== | ====== Powering your vanlife ====== | ||
- | Making, storing, and using power wisely is important for happy vandwelling. Power issues can seem overwhelming and confusing; | + | Making, storing, and using power wisely is important for happy vandwelling. Power issues can seem overwhelming and confusing; |
Before you spend money on making/ | Before you spend money on making/ | ||
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Only you will know that, because only you will know what kinds of electrical [[electrical: | Only you will know that, because only you will know what kinds of electrical [[electrical: | ||
- | ==== Daily power requirements | + | ==== Real-world(ish) examples |
- | + | ||
- | There is no way around it: you must come to grips with **how much power you need each day**. | + | |
- | + | ||
- | - be honest about what you want/need to run and how long you plan to run them | + | |
- | - [[https:// | + | |
Here are some very general ideas to get you thinking: | Here are some very general ideas to get you thinking: | ||
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* <=100w loads from [[https:// | * <=100w loads from [[https:// | ||
* very small loads (like a cellphone) might be run off the ciggy/USB port [[https:// | * very small loads (like a cellphone) might be run off the ciggy/USB port [[https:// | ||
- | * **Easy to run** off a [[lifestyle: | + | |
- | * fan | + | |
+ | * Phone/ | ||
+ | * Fan | ||
+ | * Small 12v LED lights | ||
* [[https:// | * [[https:// | ||
+ | * Note: there are power stations available in all the sizes described below. | ||
* **Average loads** - small ($) house power system: | * **Average loads** - small ($) house power system: | ||
- | * [[food: | + | * Small [[food: |
* laptop charging/ | * laptop charging/ | ||
* [[hvac: | * [[hvac: | ||
* swamp coolers (due to high power fan motors) | * swamp coolers (due to high power fan motors) | ||
* gaming laptops run off solar during the day | * gaming laptops run off solar during the day | ||
- | * 120v refrigerators off [[electrical: | ||
* charging e-bikes, etc [[electrical: | * charging e-bikes, etc [[electrical: | ||
* **Harder and more expensive to run** - substantial ($$$) house power system - 400w of solar, 200Ah+ of battery | * **Harder and more expensive to run** - substantial ($$$) house power system - 400w of solar, 200Ah+ of battery | ||
- | * charging/ussing | + | |
+ | * 120v refrigerators off [[electrical: | ||
+ | | ||
* gaming consoles|laptops|PCs | * gaming consoles|laptops|PCs | ||
* charging e-bikes, etc at night | * charging e-bikes, etc at night | ||
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* **Difficult and very expensive to run** - Massive ($$$$$) house power system - 600w+ of solar, 400ah of [[electrical: | * **Difficult and very expensive to run** - Massive ($$$$$) house power system - 600w+ of solar, 400ah of [[electrical: | ||
* Cooking with electricity, | * Cooking with electricity, | ||
- | * This includes things like insta-pots, electric stovetops, toaster ovens, larger microwaves, etc | + | * This includes things like insta-pots, electric stovetops |
* [[hvac: | * [[hvac: | ||
* electric [[food: | * electric [[food: | ||
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Note: devices that have [[electrical: | Note: devices that have [[electrical: | ||
+ | |||
+ | ===== Calculating power, battery, and solar requirements ===== | ||
+ | |||
+ | The following is a guide to calculate battery storage and solar needs. **Be honest** about what loads you want/need to run and how long you plan to run them. You can also check out [[https:// | ||
+ | |||
+ | A general guide is to have **200w of solar for every 100ah of 12v lithium battery**. No one has ever complained about have too much battery capacity or too many solar panels, so rounding up is always a good practice. | ||
+ | |||
+ | === Calculating your battery size === | ||
+ | (With credit to [[https:// | ||
+ | |||
+ | * **Make a list** of each and every electronic device you'll be using. | ||
+ | * Jot down the volts, amps, and run-time (in hours) of each device. When noting the run-times (one hour = 1, half an hour = .5, etc.), assume // | ||
+ | * If you're using any 120 volt devices, lookup the efficiency of your inverter. It should be easily found on the manufacturer' | ||
+ | * This is generally documented as a percentage. You'll want to convert that to decimal form (ie 93% = .93) Take note of this value -- it'll be used in the next step. | ||
+ | * Please also note that inverters are less efficient the lower your usage to max draw ratio is. In other words, if you get a larger inverter, but only use a small fraction of it's power generation, the efficiency will not be as good as advertised; get an inverter that properly fits your needs so that you're not wasting power for no reason. | ||
+ | * **Calculate the daily draw** of each device in watts: | ||
+ | * For all 12 volt devices use the equation: volts * amps * run-time | ||
+ | * For all 120 volt devices, use the equation: (volts * amps) / inverter efficiency * run-time | ||
+ | * The amp draw requirements for most 120v AC devices that you find printed on the label is usually the //peak// load, the maximum that the device could ever draw. Most electronic devices will in reality draw far less than this (although kitchen appliances will typically draw their full rated load). Getting an [[https:// | ||
+ | * **Calculate your //total// daily draw** in watts by adding the individual watts for each device together. | ||
+ | * Assuming you'll be utilizing a 12 volt LiFePo4 battery bank and wanting a 25% buffer to protect the longevity of your battery bank, use the following equation to get your minimum battery bank capacity in amp-hours: (total daily watts * 1.25) / 12. | ||
+ | * Jot the result down down -- **this is the minimum battery bank capacity in amp-hours** that you'll need to power your devices for a single day. | ||
+ | |||
+ | === Calculating Solar Size === | ||
+ | |||
+ | Solar panels only operate at " | ||
+ | |||
+ | As a general estimate, assuming ideal weather conditions, but worst-case charging time, **divide the result of your minimum battery bank capacity by four**. This result shows how many total watts of solar you'll require to fully charge your battery bank each day. | ||
+ | |||
+ | The chances of getting the full yield out of your panels are slim to none. In the North American winter, for example, you might only get up to 50% of your panel' | ||
+ | |||
+ | For a more exact estimate based on time/place, see [[electrical: | ||
+ | |||
+ | === Putting it all together === | ||
+ | |||
+ | An example with a 93% efficient inverter and a 12 volt battery bank (Results are rounded up): | ||
+ | * Electronic Devices: | ||
+ | * Laptop: 120 volts; .54 amps; 8 hours = (120 * .54) / .93 * 8 = 560 watts | ||
+ | * Light: 12 volts; 1.5 amps; 6 hours = 12 * 1.5 * 6 = 108 watts | ||
+ | * Phone Charger: 12 volts, .5 amps; 10 hours = 12 * .5 * 10 = 60 watts | ||
+ | * Total Daily Draw: 560 + 108 + 60 = **728 daily total draw** (in watts) | ||
+ | * Battery Capacity = (728 * 1.25) / 12 = **76** amp hours | ||
+ | * Battery bank capacity in watts = 76 * 12 = **912 watts** | ||
+ | |||
+ | " | ||
+ | |||
+ | The above calculations are for Lithium batteries; for lead chemistries, | ||
===== sources of house power ===== | ===== sources of house power ===== | ||
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Most campervans use [[electrical: | Most campervans use [[electrical: | ||
- | ^ ^ Pro | **Con** | + | ^ |
- | | [[electrical: | + | | [[electrical: |
- | | [[electrical: | + | | [[electrical: |
- | | [[electrical: | + | | [[electrical: |
- | | alternator (ciggy | + | | alternator ([[electrical: |
- | | [[electrical: | + | | [[electrical: |
[[electrical: | [[electrical: | ||
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* people who weekend camp can [[https:// | * people who weekend camp can [[https:// | ||
* people who drive hours each day (delivery, trucking, etc) may be fine with [[electrical: | * people who drive hours each day (delivery, trucking, etc) may be fine with [[electrical: | ||
- | * people who spend long periods off-grid will probably want a robust solar install | + | * people who spend long periods |
* people who want to run big loads off-grid can do it cheapest with a [[electrical: | * people who want to run big loads off-grid can do it cheapest with a [[electrical: | ||
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//Using// power is the simplest part. It's so simple the newbie may find themselves overdrawing from the available power. | //Using// power is the simplest part. It's so simple the newbie may find themselves overdrawing from the available power. | ||
+ | |||
+ | ===== higher bank voltages ===== | ||
+ | |||
+ | Although 12v house banks are most common there are use cases where higher bank voltages (24v, 48v, etc) may be desirable: | ||
+ | |||
+ | |||
+ | * when some big DC load demands it (DC minisplit aircon?) | ||
+ | * when 12v inverter size approaches 3000w((sometimes seen on propaneless "all electric" | ||
+ | * when someone stumbles into a great deal on a higher-voltage pack (Leaf battery fell off a truck) | ||
+ | * when the vehicle has a 24v alternator, as found in some commercial vehicles like buses or box trucks | ||
+ | |||
+ | |||
+ | Challenges: | ||
+ | |||
+ | * limited options charging from normal 12v alternators <-- even more niche than the inverter market | ||
+ | * requirement to buck back down for " | ||
+ | * requirement for higher solar array voltages. | ||
+ | |||
+ | |||
+ |