How do I use an inverter

Discussion in 'Tech/Mech General' started by Martin OSullivan, Jul 26, 2015.

  1. Martin OSullivan

    Martin OSullivan

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    So, Ive had an invertor in my 'van since I bought it but ive never used it as im not sure what can be run etc
    Cant find how to attach photo, think its 1500w max approx 4x2x9 inches. So when I plug it into my EHU outlet, I hear the fan kick in and a strange sort of buzzing noise, is this normal?

    What am I likely t be able to run and for how long?
    2 x brand new 110ah batts but only one connected at present

    would like to run TV, chargers etc, TV is 12v also but I dont have cigarette lighter in the back yet

    How long an you keep them plagged in??

    Any advice or tips appreciated, complete novice in inverters s dont hold bck

    regards
    Martin
     
  2. Jim

    Jim Ringleader

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    Hi Martin,

    If you are ever stuck about an aspect of the forum. In the blue menu up top.. Go to Resources>website help. Its packed with easy to follow instructions and videos etc. Click here to be taken there
     
  3. bubble63

    bubble63 Funster

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    Mmmmmm

    Hi Martin
    It will give you 240v when you are off EHU
    It will flatten one battery quickly
    It will only run appliances rated below 1500w
    Run everything on 12 v, only when you desperate revert to the inverter
    Connect your second battery!!
    You are unwittingly asking quite complex questions :)
    inverters are difficult beasts to tame, but keep asking
     
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  4. BwB

    BwB Funster Life Member

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    How long your batteries will last depends on the load being drawn by the inverter (plus anything else powered by the batteries at the same time) if, as your post suggests, you are running a connection from your inverter to your electric hook up, then you're likely to be running the motorhomes battery charger and possibly the fridge has flipped to mains power too (if it has an auto energy system). In my opinion, you're better off running a specific item off the inverter so you know what's going on and can estimate battery life.
     
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  5. CandC

    CandC Funster Life Member

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    Some basics first :) An inverter is a type of transformer which converts 12v dc to 230 or 240 is volts ac. Your 12v TV will then run through another transformer (the small box on the lead) to take it back down to 12v when you are using 240v. Similarly, your phone charger etc is a transformer giving out 5v.

    Transformers are all, to some extent inefficient and have some power loss as heat which is why your inverter and chargers get warm when in use.

    You would, as @bubble63 said, be better running your 12v TV on 12v to avoid this power loss. For charging phones etc, a lighter socket plug is also more efficient as you only change the voltage once so cut out one lot of power loss. You can also pick up 12v laptop chargers which convert 12v to the voltage you need... again more efficient.

    I know you haven't got a 12v socket in the back yet. Until you do, perhaps you could use an extension cable? If you do need to use 240v then I would suggest plugging into the inverter directly as plugging the ehu into it could cause conflict with the on board charger (another transformer!) and at the very least would be wasting energy as the charger draws from the inverter to charge the battery etc etc
     
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  6. pappajohn

    pappajohn Funster Life Member

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    Inverters are inefficient.

    Your tv may need 20watts of electric to run so to make it easier call it 24watts

    24watts on mains electric is 1/10 of an amp
    24watts on an inverter needs 2amps from your battery every hour so your tv will run for 25hours assuming a 100ah battery
    a 250watt heater, for example, will need a little over 20amps from your battery every hour which means a 100ah battery will last 2.5 hours before its flat.
    (A battery should never be discharged beyond 50% of its total capacity)

    To run your tv on an inverter means changing 12vdc to 230vac then the tv's transformer changes the 230vac back to 12vdc......extremely pointless and inefficient.
     
  7. Martin OSullivan

    Martin OSullivan

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    Well I did ask!
    Thanks all, a little clearer now.
    I have brought all the tools and cable to run a new 12v socket with me as I ran out of time before I left but with 4 young children finding the time here (1st day in france)is going to be difficult, I was just looking for a temporary fix of power to run TV this evening once kids are in bed so I can wind down and thought the inverter may do the trick
     
  8. pappajohn

    pappajohn Funster Life Member

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    The inverter will run it ok but turn off the battery charger and ensure the fridge is manually set to gas, as if it's an auto power select version it will revert to electric if it's available.

    The charger will use more power from the batteries, via the inverter, than it can put back in the batteries.
     
  9. Stealaway

    Stealaway Funster

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    It depends on how you use them.
    From my two 95A battery's I can watch TV ect for 3 hours a night without flattening the batter'y.
    I don't consider a 4W loss to be significant.
    I have 240V Smart TV and I am pretty sure you couldn't buy one on 12V. This TV also allows me to connect all kinds of USB devices with an HD picture and HD sound. A 100Gb hard drive full of films and TV series is a great bonus when you can't get a TV signal.
    Driving to our next stop over the next day always fully charges battery's again.
    We never use sites but have been known to run the engine at tick over for a couple hours if necessary and its still cheaper than a £20+ a night camp sites.
    I wouldn't be without one because it provides so many more power options.
     
  10. pappajohn

    pappajohn Funster Life Member

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    I wasn't referring to the 4watts as a conversion loss but merely rounding up to make the calculation easier to understand..... 24w@12v=2amps
    20w@12v = 1.66amps
     
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  11. bubble63

    bubble63 Funster

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    martin

    I have just re read you OP
    not sure why you are plugging the inverter into the EHU outlet

    an inverter connects one end to 12v, the other end gives you 240v out

    As a guide, I almost never use my inverter
    the family are at the coast now for 4 weeks and off grid
    solar [180w] gives a charge every day [2x110 batt] and almost everything runs 12v [yes it is a large list with two teenagers]
    the inverter is used only for one laptop
    ipad,s iphones, tv, pumps, fridge spark, fans, lights et al, all 12v

    some on here are inverter Gods [note the cap. G]:coffee:

    me, I worship at the solar 12v Alter(y)

    happy holiday:)
     
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  12. IanS

    IanS

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    Don't plug your inverter output into your EHU ! This is trying to make a perpetual motion machine, the battery is running the inverter, which is running the battery charger to charge the battery, all the power is going round in a loop, generating waste heat and will just flatten your battery.

    I have an inverter, but run all my phone chargers etc. off 12v usb. The only thing I can't get a 12v charger for is my toothbrush, so that gets run off the inverter which I only have on when I'm driving.
    Also handy for running a hair dryer, but not for too long, as this pulls quite a lot of power from your battery. A battery monitor like
    http://www.nasamarine.com/proddetail.php?prod=BM2
    is brilliant for well, monitoring your batteries
     
  13. peterc10

    peterc10 Funster

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    If you are on a EHU you do not need an inverter. It is only useful when you are not on a EHU!
     
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  14. motorhomer

    motorhomer Read Only Funster

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    I guess we are all different!

    Like the post from Stealaway, I also use a TV with all sorts of USB connections, and I carry a 1tb hard drive for films. But unlike stealaway its all 12v. I do possess an inverter and always carry it "just in case" but despite many many nights wildcamping I never feel any need to use it. I have 12v to usb connectors which work for charging most things. I have a 12v to 19v transformer to charge a laptop. Much better than an inverter which would change from DC to AC just for the normal computer power supply to change it back again! The only thing in my van that doesn't work on either gas or 12v is the microwave, which we live without as it would take more current than the inverter could deliver anyway.

    Clearly some people like inverters, but for me they are not really necessary as there are workable and far more efficient alternatives that do not flatten your battery so quickly!

    PS I'm sure Stealaway wouldn't run his engine for a couple of hours anywhere near other parked vans!
     
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  15. peterc10

    peterc10 Funster

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    I agree with that generally, and we use 12V for almost everything in the motorhome. But the one thing we do use the inverter for is my wife's hairdryer. We also occasionally use it to charge our electric bikes' batteries. They are the only two things we have found that needs 240V. And we can certainly live without a microwave.

    As for charging the batteries solar is the way to go. I have 2 x 100W solar panels and 2 x 110Ah leisure batteries, and that meets all of our needs with power to spare.
     
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  16. motorhomer

    motorhomer Read Only Funster

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    Agreed. The hairdryer, or lack of, did give us (well actually my wife!) a bit of an issue. So we bought a 12v hair drier. Its not brilliant if we are honest, but it does produce a little warm air - just enough to keep my wife reasonable happy at the lack of mains!

    The other issue we have in really cold weather is that my van has underslung tanks with tank heaters, 12v. We learned the hard way that these are capable of flattening a 110ah battery in a few hours - less than a full overnight. Mains hook up solves this but obviously its nothing to do with inverters. So we have now had much more insulation put round the tanks so we should be able to cope better next winter.
     
  17. peterc10

    peterc10 Funster

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    Was not impressed by the 12V variety and I knew I was never going to get away with that! The hairdryer does not need pure sine wave so the inverter I bought was a cheaper modified sine wave one from Germany - in fact this one. Only cost me £85 but gone up in price now - I guess because of the weakening Euro.

    Our water tank is inboard but the waste is underslung with a 12V heater. But we don't use the motorhome in really cold weather without a hook up .
     
  18. Puddleduck

    Puddleduck Funster

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    I thought the inverter was for using the slo-cooker on the move :rofl:
     
  19. Martin OSullivan

    Martin OSullivan

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    Thanks all, a few people picked up my questions wrong but too long to go into as I'm on the phone with poor connectivity.

    Yes solar is the way we are going but we are changing the ' van when we get back so it was a false economy to fit solar but it will be on the next 'van for sure.

    The 3 pin house plug outlet on the inverter is currently coupled with a short fly lead, 3 pin house plug to 3 pin round 16amp blue plug which I had assumed was located next to the ehu inlet (sorry said outlet before which may have confused some people, I knew what meant) so rightly or wrongly someone has set it up to plug into inlet to liven all sockets in habitation area, can't see a problem with this myself but I'm n9 expert. Yes I understand the visions circle situation but it's only for a couple of hours of TV use a night and charging laptop etc ( which is not 12v it's 19v I think)
     
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