inverter question

redwoodredwood Registered Users Posts: 4

inverter available 24/7 .. does it have to be ON? ie: fan running and using power.. OR, can one Just start, ON Demand, ie; plug in coffee maker, and starts... in other words, have recepticles that are 'hot', but, not run the inverter constantly... thanks

Comments

  • BB.BB. Super Moderators, Administrators Posts: 28,768 admin

    For smaller systems, it is common to use the "search mode" of the inverter to reduce power usage.

    Basically, the inverter only puts out a couple sine waves of 120 VAC, and if it "sees" a load greater than ~8 Watts, the inverter will stay on.

    For some inverters, there is a significant power savings:

    https://www.solar-electric.com/lib/wind-sun/SureSine.pdf

    • Self Consumption Inverter
    • On (no load) 450mA Inverter
    • Off 25mA
    • Stand-by 55mA
    • 0.450 amps * 12 volts = 5.4 watts "on"
    • 0.055 amps * 12 volts = 0.66 watts "search mode"

    Others (less expensive/larger inverters) may use 40+ Watts "on" and 18 Watts "standby"... You really have to look at the specifications.

    And there are other issues... Modern LED lighting may be 4 Watts (won't turn on your 8 Watt search mode to on). Or if you have an appliance that needs constant power (many frost free refrigerators have a timer and it will disrupt the defrost timing--No AC, timer does not advance for 12 hour cycle--Or may have electronic timer and drop right into defrost mode when power is restored).

    On larger system (where you are using >~3.3 kWH or 3,300 WH per day, you probably leave the inverter running 24x7 -- The inverter self losses are not that big in the grand scheme of things.

    Other folks have gone the two inverter route. Use a small 300 Watt inverter for house lights, cell phone charging, running the laptop 24x7 and use a large inverter (X kWatt output), just during heavy loads (cooking, washing clothes, water pumping, shop tools) that is turned off at night/when larger loads are not used.

    As always, my/our first suggestion is to 1) choose EnergyStar rated/low energy loads, 2) turn loads off when not used (don't leave your desktop computer running 24x7 when not needed), and 3) measure your actual loads for each major appliance and add it all up into a peak watts and Watt*Hours per day.

    Then use that data to make paper designs of your system and configure your system. Before you purchase any hardware. Buying hardware without a plan usually ends up being expensive and probably will not meet your energy needs.

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • redwoodredwood Registered Users Posts: 4

    thanks Bill, I should have mentioned, in an RV, with LED 12V lights, and, low usage on 110 ac, BUT...

    "On larger system (where you are using >~3.3 kWH or 3,300 WH per day, you probably leave the inverter running 24x7 -- The inverter self losses are not that big in the grand scheme of things."

    I guess I mean, a couple things, , is it Harder, on the inverter, being Available anytime, also, I think most would have a noisy fan running always? so, Useage/power loss, and Noise, those two questions.. Thanks

  • redwoodredwood Registered Users Posts: 4

    ok, your link helped me... so this unit, NO fan.. nice, no Noise... and, is it Safe, to install, in an out of the way location? under bed or in a cabinet... so, Safe, and Quiet? nice, thanks so much!

  • BB.BB. Super Moderators, Administrators Posts: 28,768 admin

    Things that are hard on electronics:

    • Heat. For every 10C/18F increase in temperature you will see a 1/2 decrease in life (assuming ~25C/75F is standard)
    • Thermal Cycling. I used to test disk drives... I would run 2x cycles per day (from ~40F to 121F), and inside of 2 weeks, 1/2 to 3/4 of the drives would fail. Those that did not fail, passed the first stress tests and generally did not fail even if left thermal cycling longer.

    "Cheap" AC inverters--You may find models that whenever the DC power is on, the fans run.

    Higher end inverters--They may have thermally controlled fans.(DC fans typically have a ~8,000 to 50,000 hour life--Better fans, longer design life).

    And there are very nice AC inverters that use heat sinks and no fans. You can get 300 Watt inverters to 6+ kWatt inverters that do not have fans.

    Fans that draw dust and bugs inside the electronics (no filters, large hole screening)... That is another issue.

    Smaller/high density "power devices" tend to have fans and may have high speed fans (on solar charge controllers too). And those devices, you would not want to install in a bedroom or office as the fans can be pretty annoying).

    Switching stuff off vs leaving running 24x7... These days, I would not suggest turning off for longer life. The issues is generally turning off to save energy.

    We think if a microwave as being an energy hog at 1,200 Watts vs my desktop computer that draws only 300 Watts... As many people use them:

    • 1,200 Watt * 1/3rd hour (20 minutes per day) = 400 Watt*Hours (0.4 kWH) daily usage for microwave
    • 300 Watt tower computer * 24 hours per day (using as server or just not turning off) = 7,200 WH per day (7.2 kWH per day)

    That is why we use "general" derating factors and rules of thumbs when doing a paper design of the system (loads, battery, solar) so that you do not get "lost in the details". Once you have a paper "framework", then start looking for equipment that meets your needs (and perhaps start over when it is too expensive, too big to fit, or other issues).

    I could talk about the 12 volt TSW 300 Watt inverter (no fans, search mode, remote on/off) -- And you need a 6 kWatt inverter. Without the first paper framework, we really cannot give you better choices because we don't know what your needs are.

    Electrical usage is a highly personal set of choices, The system needs to meet your needs and costs--Not mine.

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • redwoodredwood Registered Users Posts: 4

    thanks again Bill, ... yes, I DO have a CHEAP inverter... so, I know about fan/on/noise, thus, my questions...its my 'starting point' as in, I can NOT handle, a high fan in the background... you mention solar controlers also might have fans... I"ll be sure to keep this also in mind..

  • BB.BB. Super Moderators, Administrators Posts: 28,768 admin

    I should clarify that "search mode" is a short pulse of 60 Hz @ 120 VAC (like a 1/30th or 1/16th of second) every 1 second or so to detect the presence of an >~8 watt AC load as to when to turn on. After a period of time of no AC loads, goes back to search mode again.

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Ralph DayRalph Day Solar Expert Posts: 878 ✭✭✭✭

    Search mode...but don't leave your central vac plugged in! After all the loads shut down (fridge, freezer etc) the pulse would just be enough to "zip" the central vac, repeatedly until the elbow to the ribs wakes you up and you go unplug it. BTDT, more than once.

  • DaangeroussDanDaangeroussDan Registered Users Posts: 23 ✭✭

    I use two of these https://www.ebay.com/itm/EDECOA-Power-Inverter-1500W-3000-Watt-Pure-Sine-Wave-12V-dc-110V-120V-ac-LCD-RV/232635461270?epid=14031086292&hash=item362a276e96:g:71gAAOSwm8Na~A4h

    Amazing output, fan only comes on when I'm pulling close to a thousand watts constantly, and at idle (on but no load) it pulls about 8 watts. Its rated at 95% or greater efficiency and is made for a 12 volt battery bank. Amazing performance for over a year now on one of mine. Check out my 1000 watt powering 3 personal heaters. https://www.youtube.com/watch?v=Mqz0S8sn45Q

    I can't beat them for the price, here is a beginners complete setup, including pv, turbines, controller, batteries, inverter, and wire for under 1,500 bucks. https://www.youtube.com/watch?v=GO_d9Ek5nXg

    You can see more by simply clicking on my youtube name icon.

  • TecnodaveTecnodave Registered Users Posts: 205 ✭✭✭
    edited April 6 #10

    I have never seen any inverter that is 95% or better effenicy! Not even Outback or MagnaSine claim that for their 48 volt inverter! Another example of Madison ave Hawlkers selling krap. My MagnaSine claims 94% or so maximum efficiency........at 100 watts out its less than 50 % efficient.....that is on a 24 volt real inverter........absolutely no way in the real world that a 12 volt inverter is 95 % of better efficiency........only in admen' wildest imagination. Cotek states that on their SD-1500-112 inverter is 88% maximum efficiency. That does not imply that it is 88% efficient at any loading. That is one of the best if not the best offshore inverter manufacturers that exists! The SD-1500-112 is 12 volts in and 120 volts out. 24 volt and 48 volt inverters are more efficient than 12 volt ones! Period....go read the specs.

  • BB.BB. Super Moderators, Administrators Posts: 28,768 admin

    The specifications for that EBay inverter are not great either... In theory the operational DC voltage input range is somewhere around 11-14.5 volts or even 11-14.0 volts (depending one which line you read).

    Any good inverter should operate on 10.5 to 15.0 volts, and really, should be 10.5-16.0 or 16.5 volts on a deep cycle battery bank, and especially important for folks that run in subfreezing weather--FLA batteries require higher charging voltages when cold (and when equalizing). Many inverters will alarm/turn off at 15 volts (on a 12 volt battery bank)--And this is just a pain in the behind.

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • TecnodaveTecnodave Registered Users Posts: 205 ✭✭✭
    edited April 6 #12

    BB,

    Just curious....who did you test disk drives for....I did a stint at Slavegate in failure analysis analyzing pre-production prototype disk drives. I gathered failures from the production testing and looked for patterns of failure modes. We did root cause analysis there......Seagate in Scotts Valley......I did the 9XXXA and 3XXXA drives

    david

  • BB.BB. Super Moderators, Administrators Posts: 28,768 admin

    MDS Quantel in Hayward, about 3.5 decades ago. Back when there were a bunch of ST506 5 1/4 inch disk drive manufacturers (Maxtor, Micropolis, Atasi, Seagate, CDC, Hitachi, CMI, etc.) getting started... And were still using Fujitsu Eagle and 8" (?) disk drives in our larger systems.

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • TecnodaveTecnodave Registered Users Posts: 205 ✭✭✭

    I picked up a IBM "Winchester 30/30" disk drive a few years back 30 megabytes on a 12" or so platter, two in a stack, too heavy to keep, I donated it to a museum. The 9XXXA was a very early 2" notebook drive. 80 mb to 450-500 megabytes. Conner hit the market with a better drive with 1/4 the moving parts for less money......Seagate scrapped the 9XXXA drive and bought Conner. My efforts went in the grinder. 1990-93.......bailed, hated being locked in a hush-hush cage all day! Pre-Production is very taxing.....can't talk about anything! Locked inside! all day! I've worked outside every since.

  • CadenceCadence Registered Users Posts: 2

    If your batteries are draining quickly with no heavy loads on the inverter it is more likely that there is a wiring error somewhere that is short-circuiting your batteries, or your batteries have already been destroyed and are not able to take a charge.

    inverterreview.com

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