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Anybody know if you can run inverters in parallel?

Discussion in 'General Discussion' started by SB118, 22 Jan 2006.

  1. SB118

    Sgarrista

    Joined: 18 Oct 2002

    Posts: 7,581

    Location: "Sunny" Plymouth

    Been pricing up an inverter for a project, and it seems that "economy of scale" doesn't seem to apply here.

    600w units go for just over £30, but 1000w units are £70.

    If i could get the 600w units to run in parallel, i could save a few quid.

    So..... any clever begger out there want to enlighten me?

    cheers
     
  2. D.P.

    Caporegime

    Joined: 18 Oct 2002

    Posts: 30,932

    You would save £10, wow.
     
  3. saitrix

    Sgarrista

    Joined: 2 Jun 2003

    Posts: 8,944

    Location: Loughborough

    Yes you save £10 and you get an extra 200W free.
     
  4. SB118

    Sgarrista

    Joined: 18 Oct 2002

    Posts: 7,581

    Location: "Sunny" Plymouth

    Correct, 10 points, have a badge.

    I'd also have an additional 200w capacity to play with.

    And if i CAN run in parallel, i could run 3 600w units and have nearly the same capacity as a pair of 1000w units. 3 x 30 quid vs 2 x 70 quid, now does the query make sense?

    edit, and i might learn to type faster too! :D
     
  5. Tomsk

    Soldato

    Joined: 18 Oct 2002

    Posts: 5,198

    Location: Overground, underground..

    Probably won't work as the phases won't be synchronised.
     
  6. Jokester

    Don

    Joined: 7 Aug 2003

    Posts: 41,037

    Location: Aberdeenshire

    Yep, won't work without additional hardware.

    Jokester
     
  7. Adam_151

    Mobster

    Joined: 18 May 2004

    Posts: 2,703

    Location: Lincoln, Uk

    He's right you know, and OP, just clarify, are we talking about true sinewave inverters, modified sine, square, or what?
     
  8. Mickey_D

    Soldato

    Joined: 9 Dec 2003

    Posts: 6,204

    Location: Gone......

    Tomsk is correct. It would take an enormous amount of creative wiring between the two to get the phases to synchronise.

    Otherwise plugging two seperate inverters together to parallel them is going to amount to a terrific amount of smoke and two dead inverters.

    Sorry, SB. Not gonna work.

    The only thing you can do is divide up your loads so that you can put some on one inverter and the rest on the other. Then the two inverters CAN be hooked up to the same power source.

    Just remember that 1000W @ 12V = 831/3 amps. That'll draw a standard car battery down in a little over 21/2 hours (455CCA batery dropping below minimum voltage, not completely dead). And even if your car is running at the time, most cars only run a 35 - 55 Amp alternator. So all you've done is delayed the inevitable.

    As I found out the hard way. I was running my 1600W inverter off my truck, which was idling. Now, it has a GM 105A alternator, but with the truck idling the alternator couldn't put out full power. So after running my saw for a couple hours, my truck sputtered to a stop. I thought I'd run out of petrol. Come to find out the battery had gone so flat it didn't have enough power to fire the ignition coil. I had to take the battery out of the truck and carry it back to the garage to put it on the charger (for 24 hours it was so dead).

    So please be careful as to what you hook a 1000W inverter up to.
     
  9. Jonny69

    Man of Honour

    Joined: 3 May 2004

    Posts: 17,669

    Location: Kapitalist Republik of Surrey

    Can you not get one off an old junked generator? Probably be able to get a 3KW jobbie for not much
     
  10. Mickey_D

    Soldato

    Joined: 9 Dec 2003

    Posts: 6,204

    Location: Gone......


    That would work, but what are you going to spin it with? ;)
     
  11. SB118

    Sgarrista

    Joined: 18 Oct 2002

    Posts: 7,581

    Location: "Sunny" Plymouth

    This do ya? :) (just the green bit!)

    [​IMG]
     
  12. Jonny69

    Man of Honour

    Joined: 3 May 2004

    Posts: 17,669

    Location: Kapitalist Republik of Surrey

    Heheheh, Mickey you must have missed that bit last night :)
     
  13. SB118

    Sgarrista

    Joined: 18 Oct 2002

    Posts: 7,581

    Location: "Sunny" Plymouth

    Looks like i'll have to make do with a single 1000w unit then, going to have a half dozen or so batteries, so hopefully they shouldn't run flat overnight. :eek: Going to need a bigass charger to get juice into them during the day though, or i could even push a couple of car alternators into the loop, if i could find a way to stop them overcharging the batteries.
     
  14. PeterNem

    Sgarrista

    Joined: 15 Feb 2003

    Posts: 8,320

    Location: NJ/NY, USA

    I don't have any advise for you SB118, but am genuinely intrigued as to what it is you are trying to rig up!
     
  15. laiman

    Hitman

    Joined: 11 Mar 2005

    Posts: 964

    Location: Scotland

    I second that! What global domination scheme are you working on?
     
  16. SB118

    Sgarrista

    Joined: 18 Oct 2002

    Posts: 7,581

    Location: "Sunny" Plymouth

    I'm looking at going "off grid", 6hp Lister engine (got!), 5kw alternator (need), pile-o-batteries & a nice big inverter.
     
  17. NiCkNaMe

    Mobster

    Joined: 17 Jul 2005

    Posts: 3,188

    Your running your car off vegetable oil as well aint ya ?

    Next you'l be building an underground bunker ya self sufficient ******* :p ;)
     
  18. SB118

    Sgarrista

    Joined: 18 Oct 2002

    Posts: 7,581

    Location: "Sunny" Plymouth

    Yup, and the Lister engines love the veggie too = free leccy :D and depending on the heat output i can use the coolant circuit to heat a couple of rooms in the flat, doing away with our portable calor fire = more savings :)
     
  19. Adam_151

    Mobster

    Joined: 18 May 2004

    Posts: 2,703

    Location: Lincoln, Uk

    I hope you understand the implications of connecting stuff to something like this, if you are using more than just say a single appliance, you should tie the supply down to physical earth, then you have to make sure its adiquately protected against indirect contact, over current devices are unlikely to be sufficent as the fault current will be limited from such a set up, and you'll likely to need to protect against indirect contact via way of RCD.

    Anyway, what you thinking of doing, fitting a changeover switch before your CU, and having it switch between the supply from the grid and a ceeform inlet socket?
     
  20. LeperousDust

    Soldato

    Joined: 4 Nov 2003

    Posts: 5,729

    Location: Edinburgh

    This sounds like a huge project SB118! Off gird sounds kinda scary too, can't imagine a house "off grid"!