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electrical:inverter [2024/04/05 21:26]
frater_secessus [special case: tiny loads] 		electrical:inverter [2025/01/01 11:24] (current)
frater_secessus [differences from shore power 120vac]
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 It is **more efficient to use DC power directly** whenever possible. In particular it is more efficient than running a laptop of phone charger off an inverter.((http://www.cheaprvliving.com/forums/Thread-Here-s-one-for-you-inverter-lovers)) It is **more efficient to use DC power directly** whenever possible. In particular it is more efficient than running a laptop of phone charger off an inverter.((http://www.cheaprvliving.com/forums/Thread-Here-s-one-for-you-inverter-lovers))
  
-AC-only items will require an inverter.  [[electrical:12v:wallwart|Devices that run off a "wall wart" adapter]] almost never require an inverter.  +Note:  **only AC loads will require an inverter**.  [[electrical:12v:wallwart|Devices that run off a "wall wart" adapter]] that output DC almost never require an inverter.  Things that charge off USB (phones, fans, tablets, etc)  can use a [[https://amzn.to/3JmopvO|12v-to-USB port]]. Laptops often have car chargers that run off 12v ([[https://amzn.to/3Wax1Nw|example]]).  Search for "[specific make/model] car charger" 
 + 
  
 ===== efficiency ===== ===== efficiency =====
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 Inverting from DC to your local shore power spec will necessarily incur losses.  These might be 10-30%, depending on the inverter, the inverter's efficiency spec, etc.  In the absence of hard information you might use 20% losses as a rule of thumb.  This means it will require 20% more power to run your load than the rating spec. Inverting from DC to your local shore power spec will necessarily incur losses.  These might be 10-30%, depending on the inverter, the inverter's efficiency spec, etc.  In the absence of hard information you might use 20% losses as a rule of thumb.  This means it will require 20% more power to run your load than the rating spec.
  
-50w * 0.8 efficiency = 60w demanded from the system+50w / 0.8 efficiency = 60w demanded from the system
  
  
 ===== Modified Sine Wave ===== ===== Modified Sine Wave =====
-Originally called "square wave" inverters, MSW inverters are inexpensive and ubiquitous.  If your inverter doesn't say it is MSW or PSW then it is probably MSW.+ 
 +Note:  modified //square// wave is more accurate but relatively uncommon in marketing. 
 + 
 +MSW inverters are inexpensive and ubiquitous.  If your inverter doesn't say it is MSW or PSW then it is probably MSW.
  
 Pro:    Pro:   
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 > One way that I used to check computer/electronic power supplies... take a [[https://amzn.to/2XKSFfp|Kill-a-Watt meter]] and measure the power factor. If it was >0.9, it probably would work fine -- BB((https://forum.solar-electric.com/discussion/comment/191612#Comment_191612))((power factor is the PF button on the kill-a-watt)) > One way that I used to check computer/electronic power supplies... take a [[https://amzn.to/2XKSFfp|Kill-a-Watt meter]] and measure the power factor. If it was >0.9, it probably would work fine -- BB((https://forum.solar-electric.com/discussion/comment/191612#Comment_191612))((power factor is the PF button on the kill-a-watt))
 +
 +Appliances with motors tend to run poorly and hotter than usual. 
  
  
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-For ~120w loads you can use [[https://amzn.to/4cMWwdW|a small inverter]] intended to be powered by the [[electrical:12v:ports#the_cigarette_outlet|cigarette lighter port]].  They are typically fused at 10A, hence the wattage limit (12v x 10A = 120w).((technically you could use any size inverter as long as you remembered not to draw >10A))  +For ~120w loads you can use [[https://amzn.to/4cMWwdW|a small inverter]] intended to be powered by the [[electrical:12v:ports#the_cigarette_outlet|cigarette lighter port]].  The ports are typically fused at 10A, hence the ~120w wattage limit (12v x 10A = 120w).((technically you could use any size inverter as long as you remembered not to draw >10A))  
  
-Note:  Ciggy ports are already delicate so having an inverter that sticks out of the socket will cause poor connections and often failure of the inverter or socket.  To avoid stressing the socket you can use an inverter with a built in power cord (as pictured above).  If you already own [[https://amzn.to/4aLoUuT|one designed to hang out of the socket]] consider using [[https://amzn.to/3UgnTWF|a soft wire extension]] that will allow you to relocate the inverter. +Note:  Ciggy ports are already prone to failure and poor connections.  An inverter that hangs out of the socket will make matters worse.  To avoid stressing the socket you can use an inverter with a built in power cord (as pictured above).  If you already own [[https://amzn.to/4aLoUuT|one designed to live in the  socket]]((don't buy this!)) consider using [[https://amzn.to/3UgnTWF|a soft wire extension]] that will allow you to relocate the inverter. 
  
 In any case, find out what kind of fuse your ciggy port uses and have some on hand.  Mistakes are easy to make and easy to fix (if you have the spare fuse waiting). In any case, find out what kind of fuse your ciggy port uses and have some on hand.  Mistakes are easy to make and easy to fix (if you have the spare fuse waiting).
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 > In fact, the situation with an inverter is very similar to [a] 240 VAC circuit... which has 2 120 VAC lines driven 180 degrees out of phase, i.e., "push-pull."((http://thesurvivalpodcast.com/forum/index.php?topic=63891.msg758502#msg758502)) > In fact, the situation with an inverter is very similar to [a] 240 VAC circuit... which has 2 120 VAC lines driven 180 degrees out of phase, i.e., "push-pull."((http://thesurvivalpodcast.com/forum/index.php?topic=63891.msg758502#msg758502))
 +
 +
 +===== types of setups =====
 +
 +[for simplicity this section assumes 120vac and 12vdc and makes broad generalizations -- secessus]
 +
 +Most **campervans** have a simple setup:
 +
 +  * battery bank -> 12v loads
 +  * battery bank -> inverter -> 120vac outlet[s]
 +  * [other forms of charging/power ignored for the purpose of this section]
 +
 +Vintage **"conversion" vans** might have
 +
 +  * battery bank -> 12v loads
 +  * shore power -> 120vac distribution (120vac loads only run when plugged into shore power)
 + 
 +Since **Class A and Class C RVs** are expected to be on pedestal power at RV parks much of the time and run huge loads like air conditioning, water heaters, and clothes washers they often have robust 120vac setups that can pass through shore power when available and use the inverter when it is not:
 +
 +  * shore power((or [[electrical:generator|generator]])) -> **transfer switch**((automatic or manual)) -> 120vac loads
 +  * battery bank -> inverter -> **transfer switch** -> 120vac loads
 +
 +Very **small RVs** like popups, A-frames, truck campers, etc, with modest loads might have
 +
 +
 +  * shore power -> converter/charger -> battery bank 
 +  * battery bank -> inverter -> 120vac outlets 
 +
 +There are losses inherent in 120vac -> 12vdc -> 120vac but 1) we're on shore power; and 2) the loads concerned are usually quite light.  This setup might also have a dedicated 120vac outlet that only works when shore power is connected. 
 +
 +
 +
 +
  
electrical/inverter.1712366801.txt.gz · Last modified: 2024/04/05 21:26 by frater_secessus

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