inverter

Discussion in 'General Discussions and Advice' started by Maddy, 10 Jan 2014.

  1. Maddy

    Maddy

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    Hi. Excuse my ignorance but how exactly does an inverter work? And what do you need and where do you get it and at what cost. Want to get my backups in place for power cuts.
     
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  3. dallasg

    dallasg Moderator MASA Contributor

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    an inverter takes a DC power source and makes a 220V AC power source

    have a look at builders warehouse at the renewable energy green stands and ask them to show you the FBIT1000
     
  4. Fred d

    Fred d

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    my question is how big an inverter do I need and then what size cells do I need to power it . I know the question sounds a bit like "how long is a piece of string" but there's gotta be a way to calculate this ...
     
  5. dallasg

    dallasg Moderator MASA Contributor

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    each inverter has a wattage rating, so 600w will run up to 600w of power for x time. the manual will give you a graph

    you can add more batteries in parallel to increase backup time
     
  6. mariusmeyer

    mariusmeyer

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    In general a 600W inverter is big enough as you only want to run the essential equipment like a return pump. But remember the difference between modified sine and pure sine inverters as some equipment have issues running off of modified sine.
     
  7. dallasg

    dallasg Moderator MASA Contributor

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    i use a modified sinewave and no issues with old or new pumps etc...
     
  8. mariusmeyer

    mariusmeyer

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    Many people use modified sine and have no issues but there have been some cases where some return pumps did not want to work.
     
  9. Fred d

    Fred d

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    if I add up all the wattage ratings of the consumers I want to run off the invertor , eg a 50w sunsun pump and a 200w heater and a 150w skimmer , totalling 400watts ... does that then require a 400 watt invertor
     
  10. HOT SAUCE

    HOT SAUCE

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    yes that's correct
     
  11. cknipe

    cknipe

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    Go slightly higher - you don't want to run a UPS or Inverter at maximum loads. It's bad for the batteries, and the device. Generally, you don't want more than 80% load.

    I would go for a 600W inverter, but yes, your calculations are correct. Just add the wattage of all the components together to get your max required rating, plus a little spare for future growth.
     
  12. mariusmeyer

    mariusmeyer

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    You want an inverter rated higher than the total draw of the equipment. But remember that running all of that off of a deep cycle battery will kill it quickly. It will dray about 39Amps from the battery per hour at an inverter efficiency of 86%. So a deep cycle battery of 102AH will be totally finished in just over 2,5 hours. And many people don't like draining the battery that much as it reduces its lifespan.
     
  13. HOT SAUCE

    HOT SAUCE

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    but also take into account that the inverter will be running at 100% ... personally not sure if that's a issue as i have no experience with invertes but as far as i know from selling UPSs you want to be sitting around 80% and not more... so if you are planning to run 400W of the inverter i think its best to get one rated for 450W or 500
     
  14. HOT SAUCE

    HOT SAUCE

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    i would like to ask a question...
    what is the difference between inverter and a UPS? will the inverter switch on to batery usage when there is no power and there is no one around to switch it manually?
     
  15. mariusmeyer

    mariusmeyer

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    The inverter will only act as an UPS if it has a built in transfer switch. Without the switch you will have to turn it on manually.
     
  16. HOT SAUCE

    HOT SAUCE

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    so why do people buy inverters instead of UPSs... if you add up the price of a deep cycle battery to a good inverter it works the same as buying a good ups.. or am i missing something
     
  17. dallasg

    dallasg Moderator MASA Contributor

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    a UPS contains an inverter.. so an inverter is just a component etc.
    a ups will run and charge and have a ATS built it, the ones at builders do it all with a built in voltage regulator
     
  18. cknipe

    cknipe

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    Inverters are generally not used long term. Think when you're camping and want to watch TV quickly from your car's battery. When used long term, they are mostly used in solar systems to power devices directly from solar. Personally, I have not seen inverters, generally, being hooked up to batteries long term. EDIT: PS - what is going to re-charge your batteries? Inverters can't do that

    The correct thing to do, would be to get a UPS, and not a inverter only. UPSes are specifically designed for what you want to use it application wise, and will make adding / expanding on batteries allot easier (and much safer) too.

    Please remember if you DO only go the inverter route, and you work with deep cycle batteries and DC cabling... DC is *FATAL*. Please be VERY careful with your cabling (you CANT use normal household wires, you CANT use thin wires, and if you short your battery (or battery bank) there is is going to be serious consequences). The current going through those cables from the batteries will kill you in a instant.

    If you don't have a VERY good understanding electrically what you are doing, I would strongly advise you go the UPS way, rather than a DIY based inverter. And I'm saying DIY because you will more than likely need to build up the battery bank yourself in the case of a inverter.
     
    Last edited: 10 Jan 2014
  19. Maddy

    Maddy Thread Starter

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    And cost-wise? What amounts more or less are you looking at? One guy at the petshop talked about between R2000 to R2500? Whats he talking about?
     
  20. dallasg

    dallasg Moderator MASA Contributor

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    a good UPS will be between R3000-R5000 complete, you might be able to get cheaper
     
  21. HOT SAUCE

    HOT SAUCE

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    it really depends how many watts is it rated for but 3 to 5 thousand is correct if you want to buy a 2Kva or bigger... for about 5000 rand you could get a 2 KVA UPS plus a external battery pack of two which will run the UPS at full load for 90 to 120 minutes

    i recently bought a 3.8Kva generator after a two day power black out where i almost lost my tank.. but now im starting to think that it was a waste of money because if the power goes off in the morning straight after i leave for work there will be no one to switch on the generator until 5-6 when i get back home... now im thinking of selling it and getting a proper UPS
     
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