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electrical:inverter [2021/05/22 16:57]
frater_secessus [MSW and electronics]
electrical:inverter [2023/11/22 14:34] (current)
frater_secessus [Inverters]
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 AC-only items will require an inverter.  [[electrical:12v:wallwart|Devices that run off a "wall wart" adapter]] almost never require an inverter.   AC-only items will require an inverter.  [[electrical:12v:wallwart|Devices that run off a "wall wart" adapter]] almost never require an inverter.  
  
 +===== efficiency =====
  
-====== Modified Sine Wave ======+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 
 + 
 + 
 +===== 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. 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.
  
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   * widely available   * widely available
   * works for many/most AC items   * works for many/most AC items
-  * generally more efficient under no load (?)+
  
 Con:  Con: 
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   * some reports of damage to electronics;  see below   * some reports of damage to electronics;  see below
  
-===== MSW and electronics =====+==== MSW and electronics ====
  
-there is anecdotal evidence that MSW can damage some electronics.  The most commonly repeated stories are Dewalt cordless tool battery chargers and laptop chargers.+> In the end, probably 80% of the stuff you plug in will work fine [on MSW], 10% will fail pretty quickly, and the other 10% it will be difficult to tell.  -- BB((https://forum.solar-electric.com/discussion/comment/191612#Comment_191612))
  
-> Rule of thumb: Everything that has electronics and use a power supply or an integrated power supply to lower voltage will be fine [on MSW]. (Radio, charger, Screens etc.) Everything that uses a power motor (often without electronics) will not (hairdryer kitchen appliances etc.)  - WombatCombat2020((https://www.reddit.com/r/vandwellers/comments/i2fs18/power_inverter_wave_question/g04fz04/))+While MSW powers resistive loads like crockpots and coil heaters perfectly, there is anecdotal evidence that MSW can damage some electronics.  The most commonly repeated stories are Dewalt cordless tool battery chargers and [[electrical:12v:laptop|laptop chargers]].  Milwaukee battery chargers may also require PSW.((https://www.electriciantalk.com/threads/cordless-chargers-and-inverters.40405/post-754431)) 
 + 
 +Laptop chargers that work on MSW will usually run somewhat warmer and may buzz.  Laptop chargers that will not work on MSW tend to get hot, not power on at all (no light), or cycle on/off. Laptop chargers and other power supplies might be tested thusly: 
 + 
 +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)) 
 + 
 + 
 +------ 
 + 
 +Rule of thumb: 
 + 
 +Everything that has electronics and use a power supply or an integrated power supply to lower voltage will be fine [on MSW]. (Radio, charger, Screens etc.) Everything that uses a power motor (often without electronics) will not (hairdryer kitchen appliances etc.)  - WombatCombat2020((https://www.reddit.com/r/vandwellers/comments/i2fs18/power_inverter_wave_question/g04fz04/))
  
 Other devices which do not like MSW: Other devices which do not like MSW:
  
   * 433MHz remote radio controlled plugs((https://diysolarforum.com/threads/what-really-requires-a-pure-sine-inverter.22574/post-266515))   * 433MHz remote radio controlled plugs((https://diysolarforum.com/threads/what-really-requires-a-pure-sine-inverter.22574/post-266515))
-====== Pure Sine Wave ====== +  * asynchronous motors with a capacitor to build up the 90° phase do not run well on MSW((https://diysolarforum.com/threads/what-really-requires-a-pure-sine-inverter.22574/post-266767)) 
-PSW inverters are as good as (or better than) than AC mains power.  All AC items will run on a properly sized PSW inverter.+  * hair clippers 
 +  * In [[https://www.youtube.com/watch?v=wimTJw_Gpgk|an apples-to-apples comparison]] knurlgnar24 found a microwave to run 10% less efficiently and at 20% less power on MSW. 
 + 
 + 
 + 
 +===== Pure Sine Wave ===== 
 +[[https://amzn.to/2QPcfnt|PSW inverters]] are as good as (or better than) than AC mains power.  All AC items will run on a properly sized PSW inverter.
  
 Pro: Pro:
Line 44: Line 67:
  
 Con: Con:
-  * $$$. Many times more expensive than MSW.+  * $$$. Typically at least 2x more expensive than MSW for the same wattage rating.
   * Not as widely available as MSW; you may not find them at truck stops, big box stores, etc.   * Not as widely available as MSW; you may not find them at truck stops, big box stores, etc.
  
 +Not all PSW are prohibitively expensive.  Bestek makes [[https://amzn.to/3N4YE3S|a 300w PSW for about $50]].  See [[https://www.amazon.com/gp/customer-reviews/R3UKQ7A0GQ196N/ref=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B07KQ4Q2L5|the top-rated review]] for oscilloscope testing and limitations.
 +===== inverter chargers =====
  
-====== inverter chargers ====== 
 {{ https://m.media-amazon.com/images/I/61wb7PGYPNL._AC_UL320_.jpg?150}} \\ {{ https://m.media-amazon.com/images/I/61wb7PGYPNL._AC_UL320_.jpg?150}} \\
-An //inverter charger// performs several functions:+ 
 +//Inverter/chargers// are most often found on rigs that are on shore power much of the time and run heavy AC loads  
 + 
 + 
 +It provides several functions:
   - invert 12v battery power to 120vac   - invert 12v battery power to 120vac
-  - pass-through shore power when available+  - pass-through shore power when available, with auto-switching
   - some can bond shore and battery power to support heavy 120vac loads   - some can bond shore and battery power to support heavy 120vac loads
   - charge battery banks like a [[electrical:converter|converter]]   - charge battery banks like a [[electrical:converter|converter]]
 +  - some also handle solar charging
  
 They tend to be [[https://amzn.to/2KMcImw|expensive]], some over $1000. They tend to be [[https://amzn.to/2KMcImw|expensive]], some over $1000.
-====== Sizing your inverter ======+ 
 +Note:  the Victron Multiplus line has outputs for maintaining the starter battery: 
 + 
 + 
 +>> The main DC terminal can supply the full output current. The second output, intended for charging  starter battery, is limited to 4A and has a slightly lower output voltage.((https://www.victronenergy.com/upload/documents/Manual-MultiPlus-3k-120V-(firmware-xxxx4xx)-EN.pdf)) 
 +===== Sizing your inverter =====
  
 Once you have made your MSW vs. PSW decision the next step is **sizing the inverter** (picking the right capacity). Once you have made your MSW vs. PSW decision the next step is **sizing the inverter** (picking the right capacity).
  
-Note that to **actually power the inverter** you will need something like a 1:1 ratio of panel:inverter on flooded lead and 1:2 on AGM or lithium.((https://www.solarpaneltalk.com/forum/off-grid-solar/solar-living/15554-how-to-increase-solar-panel-output-amps?p=181738#post181738))  This would mean 400w of solar to run a 400w inverter (dipping into the battery as needed) or 400w of solar for 800w of inverter on AGM/Lithium, which have greater throughput.  
-===== estimating your needs ===== 
  
-You will need to know the largest draws you will need to meet **at the same time**.  If your TV is 10A, your refrigerator is 10A, and your corded drill is 20A then the most you would need is 30A, since you would not (I hope!) run the drill and watch TV at the same time.+==== estimating your needs ====
  
-Note that motorized equipment like the drill likely have **different current requirements for startup and for running**.  Getting that motor spinning takes more power than running it.    There are tricks you can use to minimize the start loadlike starting a sewing machine at a low-load position.((http://www.cheaprvliving.com/forums/Thread-Is-it-possible-to-Boondock-with-an-electric-sewing-machine?pid=165956#pid165956))+You will need to know the largest draws you will need to meet **at the same time**.  If your TV is 40wand your your laptop is 100w you would need (40w + 100w) * 1.10((inverter losses)), or an inverter that can power at least **154w**.
  
-The best way to understand how much your 110v equipment needs during startup/running is to use a **power monitor** like the [[http://amzn.to/2fdgIrs|Kill A Watt]]You may find that even non-motorized 110v items run at much lower power than their labeling would suggest.  Kill A Watts may be available for loan from your public library.((http://www.cheaprvliving.com/forums/showthread.php?tid=26835&pid=337451#pid337451))+Motorized equipment like drills likely have **greater current requirements for startup and for running**.  Be sure to measure both startup and running (see below)   There are tricks you can use to minimize the start load, like starting a sewing machine at a low-load position((http://www.cheaprvliving.com/forums/Thread-Is-it-possible-to-Boondock-with-an-electric-sewing-machine?pid=165956#pid165956)), or //easing// into the trigger of a variable-speed power tool.
  
-===== understanding the specs =====+Note that to **actually power the inverter** without voltage sag or dipping so much into battery capacity you may want need something like a 1:1 ratio of panel:inverter on flooded lead and 1:2 on AGM or lithium.((https://www.solarpaneltalk.com/forum/off-grid-solar/solar-living/15554-how-to-increase-solar-panel-output-amps?p=181738#post181738))  This would mean 400w of solar to run a 400w inverter (dipping into the battery as needed) or 400w of solar for 800w of inverter on AGM/Lithium, which have greater throughput. 
  
-Inverters are generally **rated in watts**.+ 
 +=== reading the label === 
 + 
 +If you are lucky the device will **show power consumption in watts**;  this is useful because watts are watts here you are talking about [[electrical:shore_power|120vac wall power]] or [[electrical:12v:intro|12vdc automotive power]]. 
 + 
 +Some devices will only show Volts and Amps.  Since Watts = Volts * Amps we can do the math to get watts: 
 + 
 +  * 110v x 1A = 110W 
 +  * 110v x 0.5A = 55W 
 +  * 110v x 10A = 1,100W (possibly more than your camper's power system can provide) 
 + 
 +A standard wall plug in the US is 110v x 15A, or 1,650w. 
 + 
 + 
 + 
 +=== kill-a-watt === 
 + 
 + 
 +[[https://amzn.to/3ptHIbX|{{ https://m.media-amazon.com/images/I/61FOAk4UA5L._AC_UL320_.jpg?75}}]] 
 +The best way to understand how much your 120vac equipment needs during startup/running is to use a **power monitor** like the [[https://amzn.to/3ptHIbX|Kill A Watt]]. You may be pleased to find that some appliances run at much lower power than their labeling would suggest.((the label likely has to list the highest-possible wattage draw under any conditions))  It is rare to find a device that pulls more than the label states. 
 + 
 + 
 +Kill A Watts may be available for loan from your public library((http://www.cheaprvliving.com/forums/showthread.php?tid=26835&pid=337451#pid337451)), and sometimes used at thrift stores.   
 + 
 +The buttons on the traditional Kill-a-Watt have two functions each.  You press the button repeatedly to see the information: 
 + 
 +  * Volt - Not directly useful for load testing, Later when you have an inverter and plug the meter into the outlet you will be able to see your inverter's output voltage.  It is generally quite close to your grid power voltage. 
 +  * Amp - Amps at 110vac.  Not particularly useful for load testing. 
 +  * **Watt / VA**   
 +    * **Watt** - this reading is the most important thing for load assessment. Add 10%-20%((depending on your inverter's efficiency)) to tell how much power the appliance will actually consume.  
 +    * Volt-Amperes is //apparent power//, normally not directly useful. If you have a device that is unexpectedly tripping an inverter (200w load tripping 300w inverter when powering on) you might watch VA to see if apparent power is >300w;  this can happen with some loads.  For this reason some inverters are rated in VA rather than W.  See Power Factor below.  
 +  * **Hz / PF** 
 +    * Hertz - as with Volts, you can check your inverters AC frequency with this. In the US it is 60Hz. 
 +    * **Power Factor**  - this reading can be indirectly useful.  It is a relationship between Watts and VA (see above).  One rule of thumb is that [[https://forum.solar-electric.com/discussion/comment/191612#Comment_191612|devices with a PF of >=.90 are good candidates for MSW inverters]].  A resistance heater may have a perfect 1.0 power factor and works great on MSW.  A laptop charger or other wall wart might have a PF of .040 - .60, which suggests it might overheat on MSW.  Also see [[https://www.youtube.com/watch?v=Tv_7XWf96gg|this video]] about power factor. 
 +  * **kWh / Hours** 
 +    * **kWh** are 1,000w-hours.  This is the actual amount of power used over time 
 +    * **Hours** are clock hours.  Dividing kWh by Hours will give you your hourly consumption.  Multiply by 24hrs for daily consumption.  Run over multiple days to get better averages.  
 + 
 + 
 + 
 + 
 +==== understanding the specs ==== 
 + 
 +Inverters are generally **rated in watts** in terms of continuous resistive loads (heatihg elements, etc).  Inductive loads (things with motors, some electric blankets, etc) can draw more than their rated wattage and overpower the inverter.  Plan accordingly
  
 While there are both **peak** and **continuous duty** ratings it is common for marketers to advertize only the peak rating.((http://www.cheaprvliving.com/forums/Thread-PROBLEM-Dorm-fridge-won-t-run-on-1000-watt-inverter?pid=86851#pid86851))  The peak rating is only for short bursts of heavy draw. While there are both **peak** and **continuous duty** ratings it is common for marketers to advertize only the peak rating.((http://www.cheaprvliving.com/forums/Thread-PROBLEM-Dorm-fridge-won-t-run-on-1000-watt-inverter?pid=86851#pid86851))  The peak rating is only for short bursts of heavy draw.
  
 +Stand-by power ((parasitic draw when no loads are present)) may be a factor when an inverter is run for many hours.  The inverter drops to a power-saving mode then checks regularly to see if any load has been added.    
  
 +  * [[https://diysolarforum.com/threads/victron-power-save-modes-a-short-explanation.33621/|an explanation]] of Victron inverter power save modes
 +  * Renogy inverters >700w appear to have a power saving mode
  
-===== why not buy the biggest one available? =====+ 
 +==== why not buy the biggest one available? ====
  
 The immediate temptation might be to **buy a massive inverter and call it good**.  There are factors arguing against this approach: The immediate temptation might be to **buy a massive inverter and call it good**.  There are factors arguing against this approach:
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-====== the case for multiple inverters ======+===== the case for inverters ===== 
 + 
 +Even though inverters cost money directly((purchase price)) and indirectly((~10% inefficiencies increase charging and battery costs)) there are cases where an inverter may be more useful than 12v: 
 + 
 +  * with devices which only exist in grid power((110vac, etc)) models 
 +  * with devices which are much cheaper in grid power configuration.  This includes items which are rare in 12vdc but commonplace on the used market((thrift stores)):  coffee grinders, [[food:cooking:excess_power|small cooking appliances]] like rice cookers, crock pots, etc. 
 +  * with devices that have strange DC input voltages provided by [[electrical:12v:wallwart|wall-warts]]:  3v, 7v, 9v, etc. 
 +  * when you need long wiring runs.  This can be useful for donating power to another vehicle:  inverter -> extension cord -> other camper 
 + 
 + 
 + 
 + 
 +===== the case for multiple inverters =====
  
-SternWake says: //"One can get a small PSW for the delicates and get a Beast of a MSW for those less delicate electronics..."//((http://www.cheaprvliving.com/forums/Thread-Inverter-Size?pid=89481#pid89481))+"One can get a small PSW for the delicates and get a Beast of a MSW for those less delicate electronics..." - Sternwake((http://www.cheaprvliving.com/forums/Thread-Inverter-Size?pid=89481#pid89481))
  
  
-Coultergeist says:  //"I use two for redundancy and efficiency.  Large loads need big inverters to power them.  Most inverters will scale down their power use to the load that is being placed on them, but they all have a minimum amount of power that they use just when they are powered on.  Generally, the larger the inverter, the larger this parasitic power draw is.  Most items that need large inverters are not used constantly.  You will only use a microwave a few minutes per day probably.  There is no need to waste all the extra power required to keep the big inverter on constantly for that few minutes of big power draw each day.  I use a much smaller inverter for the majority of things that get powered in the van.  The television, dvd player, and antenna amplifier all draw less than 200 watts combined.  The refrigerator runs at about 150 watts intermittently.  My 1000 watt inverter will easily handle all of that and have enough surge capacity to handle the refrigerator compressor when it turns on.  Because its smaller, it is more efficient and doesn't waste as much power just by being on."//  ((http://www.cheaprvliving.com/forums/Thread-What-type-inverter-do-you-use?pid=48427#pid48427))+"I use two for redundancy and efficiency.  Large loads need big inverters to power them.  Most inverters will scale down their power use to the load that is being placed on them, but they all have a minimum amount of power that they use just when they are powered on.  Generally, the larger the inverter, the larger this parasitic power draw is.  Most items that need large inverters are not used constantly.  You will only use a microwave a few minutes per day probably.  There is no need to waste all the extra power required to keep the big inverter on constantly for that few minutes of big power draw each day.  I use a much smaller inverter for the majority of things that get powered in the van.  The television, dvd player, and antenna amplifier all draw less than 200 watts combined.  The refrigerator runs at about 150 watts intermittently.  My 1000 watt inverter will easily handle all of that and have enough surge capacity to handle the refrigerator compressor when it turns on.  Because its smaller, it is more efficient and doesn't waste as much power just by being on." - Coultergeist((http://www.cheaprvliving.com/forums/Thread-What-type-inverter-do-you-use?pid=48427#pid48427))
  
-====== overvoltage and undervoltage ======+===== overvoltage and undervoltage =====
  
 Most inverters will shut off if they get too hot, or if the input voltage is beyond certain points. Most inverters will shut off if they get too hot, or if the input voltage is beyond certain points.
  
-The low voltage cutoff is to protect your batteries from [[electrical:depth of discharge|over-discharge]].  The high voltage cutoff is to protect the inverter itself.  +The low voltage cutoff is to protect your batteries from [[electrical:depth of discharge|over-discharge]].  The high voltage cutoff is to protect the inverter itself.  In addition, [[https://forum.solar-electric.com/discussion/comment/419096#Comment_419096|the current consumed by the inverter may increase]] as bank voltage drops.
  
 HandyBob((https://handybobsolar.wordpress.com/)) reminds us that //"Properly adjusted solar systems with temperature compensation will regularly exceed the 15 volts many inverters use as a high voltage shut down."//((https://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/)) HandyBob((https://handybobsolar.wordpress.com/)) reminds us that //"Properly adjusted solar systems with temperature compensation will regularly exceed the 15 volts many inverters use as a high voltage shut down."//((https://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/))
  
  
-====== sharing power ======+===== sharing power =====
  
 Because higher voltage power has less losses over long wires, it may be most efficient to share power between RVs as 120v.  The donor vehicle would invert to 120v, plug in an extension cord to their inverter and run it to the recipient.  The recipient could plug it cord into their [[electrical:shore_power|shore power]] inlet or use it as 120v. Because higher voltage power has less losses over long wires, it may be most efficient to share power between RVs as 120v.  The donor vehicle would invert to 120v, plug in an extension cord to their inverter and run it to the recipient.  The recipient could plug it cord into their [[electrical:shore_power|shore power]] inlet or use it as 120v.
  
-====== differences from shore power 120vac ======+===== differences from shore power 120vac =====
  
 Inverters make 120vac in different way than [[electrical:shore_power|shore power]] does.  [[http://thesurvivalpodcast.com/forum/index.php?action=profile;u=13518|Alan Georges]] explains: Inverters make 120vac in different way than [[electrical:shore_power|shore power]] does.  [[http://thesurvivalpodcast.com/forum/index.php?action=profile;u=13518|Alan Georges]] explains:
electrical/inverter.1621717074.txt.gz · Last modified: 2021/05/22 16:57 by frater_secessus