Inverter question

Discussion in 'The Beginner' started by lostinfrance, Aug 9, 2009.

  1. lostinfrance

    lostinfrance Read Only Funster

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    New to motorhoming.... I'd like to use my laptop in motorhome. If I buy an inverter, where does it plug in? Do I plug it into the cigarette lighter? Would that be running off the engine battery?

    Can it be run off the leisure battery? How would you connect it to leisure battery?

    I'd appreciate any advice, thanks.

    Cheers

    Louise and Roy
     
  2. Douglas

    Douglas Read Only Funster

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    Basically it depends on the size of the inverter, the small ones do come with the cigar type plugs fitted and that will be fine but the big ones, 1 or 2Kw need to be connected as close to the battery as possible.

    Unlike AC voltage DC looses voltage very quickly as it travels down the cable so the closer to the battery the better also the size of the power cables has a similar effect so the bigger the cable the better.

    And yes the cigar type plug is normaly run from the engine battery.
    Doug...
     
    Last edited: Aug 9, 2009
  3. sinbad1

    sinbad1 Deleted User

    My advice would be to get a 12v to ...19v converter from maplins why get an inverter 12v to 240v only then to be transformed back to 19v click here

    regards
     
  4. Snowbird

    Snowbird Funster Life Member

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    Hi,some laptops wont work from an inverter,My HP wont.If you just nead to charge your laptop it makes more sense to get a dedicated 12volt charger to plug into your cig, socket.Regards,Dave.
     
  5. lostinfrance

    lostinfrance Read Only Funster

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    Does that stay plugged in while you are driving, so it charges from the vehicle battery?
     
  6. pappajohn

    pappajohn Funster Life Member

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    i have a 600w inverter connected to the leisure batteries.
    the cable length is around 400mm and the size is the same as the engine starter motor wires....cross section of around 25mmsq.

    my lappy transformer has a power consumption of 1.5amps @230v
    but through the inverter it will be drawing 30amps+ @ 12v from the batteries and will soon drain a leisure battery.

    unless you have a very big battery bank (i have 3 batteries giving a total of 330ah)and solar panels, inverters should only be used sparingly.
     
  7. Snowbird

    Snowbird Funster Life Member

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    When you are driving or stationary,dont think it matters much.We use ours in car as well as RV.
     
  8. lostinfrance

    lostinfrance Read Only Funster

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    Thanks for all your replies. Very helpful.

    Appreciated

    Louise and Roy
     
  9. sinbad1

    sinbad1 Deleted User


    30Amps:Eeek::Eeek::Eeek:
     
  10. JeanLuc

    JeanLuc Funster

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    If you go to the downloads section (link on left hand side of the home page) there is a file I put there called "Install a small Inverter.pdf". It is in the Misc. section (also featured in the latest downloads list at present). That document discusses why I installed an inverter mainly for the purposes of running a laptop, and explains why I moved away from a simple cigar-lighter connection for the inverter, having suffered problems with voltage drop (in a Hymer). I can run the laptop (85W Apple power adapter) and run a set of powered speakers at the same time with very little current draw off the leisure batteries. Have a look.


    Philip
     
  11. pappajohn

    pappajohn Funster Life Member

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    yep!!!

    volts multiplied by amps = watts

    230v X 1.5amp = 345w

    therefore,

    watts divided by volts = amps

    345w / 12v = 28.75amps plus losses in the inverter.:thumb:

    unless i got it wrong:Doh:
     
  12. sinbad1

    sinbad1 Deleted User

    Hey you must have a big laptop to power mine it only requires 90w @ 18.5v you need a smaller lappy John:BigGrin:
     
  13. Tony Lee

    Tony Lee Read Only Funster

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    Pappajohn, you may be using the maximum rated power of the laptop power supply as the actual power. Normally laptops take less than 100Watts.

    This is still 7 to 10 amps out of the battery and must be monitored if you need to use the computer for long periods - otherwise it will run the battery flat.

    Makes sense to have it on charge while you are driving and run it off its own batteries when stationary
     
  14. pappajohn

    pappajohn Funster Life Member

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    agreed.....the output side of my lappy transformer is 5amps @ 15v which is only 75watts

    but the inverter will still draw 28.75amp (345w) @ 12v from the battery to give an input of 1.5a @ 230v to the transformer.

    it aint what power the lappy needs but what the transformer needs.
     
    Last edited: Aug 9, 2009
  15. pappajohn

    pappajohn Funster Life Member

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    very true Tony....but as its the only reference point we have (without metering equipment) i think that has to be the benchmark.........:thumb:
     
  16. sinbad1

    sinbad1 Deleted User

    Come on John that don't make any sense, any item that consumes energy is rated in watts and as you say divided by the voltage gives the current , admittedly there is some loss of energy transforming from 12 to 240v ;but its only providing the current to run the lappy which i guess is no more than 10A

    Where does the other 20A go then John?
     
  17. Douglas

    Douglas Read Only Funster

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    He often gets it wrong. don't worry about it. Its all flash and no substance.

    Doug...
     
  18. lostinfrance

    lostinfrance Read Only Funster

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    Thanks. I'll go and find the .pdf and have a read.

    So much to learn when you are new to motorhoming!

    Cheers, Louise and Roy
     
  19. barbt

    barbt Read Only Funster

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    We bought our inverter from NETPC for about £20 and plug it into the cigarette lighter, it runs the laptop perfectly and also of course is good to charge the phones and camcorder.
     
  20. GOREFISH64

    GOREFISH64 Deleted User

    HOW TO REGISTER A VEHICLE IN FRANCE
    :Wink::BigGrin::thumb:
     
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