AA`s,instead of mains

Discussion in 'General Electronics Chat' started by acebodge1, Jun 18, 2008.

  1. acebodge1

    Thread Starter Member

    Jun 18, 2008
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    Hiya folks,in the past i have managed to convert various mains operated equipment to battery power ,by following the mains input to the transformer,then locating the bridge rectifier,then sticking my avo meter onto the + - of the bridge rectifier and then supplying the measured voltage instead with batteries[6/12 volt motorcycle/car]or if a small device,rechargeable AA`s.
    Now for my question,hope someone can help.
    I have a satellite reciever i would like to convert to battery power,but it has a power supply that delivers several + and minus voltages.How can i set up a row of AA cells to power the satellite reciever?
    I have managed a plus/minus 9 volt supply by connecting two 9 volt batteries in series[the middle being 0volts,each end being plus or minus 9 volt].But can someone please suggest how i might connect up for something that requires say,+12,+6,+3,-4,-2,etc.
    thanks in advance for replies.
    regards acebodge1.
    ps,i love my solar AA recharger.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Well, how much current does each supply voltage require? And do these voltages really need to be isolated, or are they isolated due to the varying currents that are drawn?

    Ideally, you would want to balance out the current supply between the various supply voltages vs the capacities of the rechargeable batteries so that they all became discharged at roughly the same time.

    [eta]
    Anyway, if the voltages don't need to be isolated, and the current requirements diminish as the voltages get further from ground, the attached schematic may do it for you.
     
    Last edited: Jun 18, 2008
  3. Audioguru

    New Member

    Dec 20, 2007
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    896
    Are you using alkaline batteries?
    A circuit designed for a 9V adapter supply might still work when the mains sags and the 9V becomes 8V. But a 9V alkaline battery quickly drops to 7.2V then drops slower to zero.

    Do your circuits still work properly when the supply voltage is low?
     
  4. acebodge1

    Thread Starter Member

    Jun 18, 2008
    13
    0
    Hiya,thanks for the helpful reply @sgt,that was was the idea i had in my head,although without the diodes.
    @audio,thanks for reply,,,i use nimh AA`s,as they are supposed to lack the "memory effect" that nicads have.
    I measured output voltage of the bridge rectifier on my music center at 15 volts,and connected it up to my vehicles 12volt,it worked a treat.
    Also i made a pack of 5 nimh`s to power my 2.4ghz a/v sender,it is supposed to run with a 7.5 volt mains adapter.The pack of 5 runs it for about 4.5 hours.
    Recently i have bought a load of 2500ma/h cells,hopefully they should provide a little more use than the 1800`s/2000,i had been using previously.
    If those solar powered garden lights get any cheaper,lol,i will be using them for powering various devices,[i noted inside one of `em had a 800mah nicad].
    I can`t wait for those cheap "printed" solar panels to hit the market,if they ever do.I will cover the whole roof of my house with `em.The silicon ones are just too expensive.
    I also need some platinum wire so i can have a go at using some "solar juice" to power my idea of building a thermister controlled bank of electolysis tubes,then i might be able to have a go at cooking food with hydrogen.
    Thanks for having me on the site,i will visit regularly.
    bye for now.
    regards the bodger
     
  5. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The solar panel in a garden light is very weak. In bright sunlight its current is only 50mA. It will charge 2500mAh cells in about 1 week in the middle of summer.
    Behind the glass in a window the output current from a solar panel is much less.

    Ni-MH cells have an average discharging voltage of 1.25V each.
     
  6. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
    1,438
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    The obvious question is; Why do you convert mains equipment to run on batteries?
     
  7. acebodge1

    Thread Starter Member

    Jun 18, 2008
    13
    0
    Hiya folks,people here in ireland,do not like paying electricity bills.If there is a free source of power,it gets utilised,no matter how small,lol.I am just exploring ways of cutting out utility bills altogether.A lot of folk over here also experience power surges,that makes devices break down.I know a surge protector would prevent this,but that means more expense.
    What is needed is a completely free source of dc "juice"[roof full of cheap solar panels],and a electrolysis setup so free hydrogen could be obtained for cooking.
    Invertors could be used for converting 12v to mains,but it seems far better to have the devices run on 12volt/batteries in the first place.This would enable ones vehicle to be a source of power as well as transport.
    A couple of lorry batteries in the boot of the car ought to be getting charged every time the brakes are applied,or free wheeling downhill,then when returning home from a journey,the house could be plugged into the vehicle.
    At the end of the day,i just like using batteries to power my devices.Its a shame that dedicated 12v devices are so much more expensive than mains operated devices.
    regards bodger
     
    Last edited: Jun 19, 2008
  8. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
    1,438
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    I think a couple of lorry batteries in the boot of the car would consume more energy than they would store during braking/ freewheeling due the extra fuel required to lug them around.

    Large solar panels and salvage (recycled) batteries running an inverter would be no less efficient and far more convenient than converting stuff to run on AAs batteries.

    The problem is, there is very little free and clean energy available when you remove the rose-tinted glasses. And I have to say I love the idea of free electricity, solar panels, wind turbines etc.
     
  9. Gadget

    Distinguished Member

    Jan 10, 2006
    613
    0
    There are 12 volt sat receivers available. I am guessing they use various voltage conversion methods (buck regulators etc) to derive the + and -, as well as the 18v LNB supply.
     
  10. quicksilver

    Member

    Mar 6, 2008
    19
    0
    I lived in an area of the USA that utilized wind power to an extensive degree. It WAS workable! The stumbling block was the storage of the power. The most reliable method was not the most efficient, you always had to give up something to gain something. Many settled on using deep cycling marine batteries as that design was more reliable than other methods; but it was not as efficient as alternative designs.

    Many studies now exist on the cost vs maintenance of such things, as opposed to "buying" power from electric companies. Solar power (right now) does not appear viable. But many people are working on a whole NEW approach to solar energy & it may just revolutionize the world.
    But just as electric cars were fought against by the giant auto companies, there are many industries that do not want to see alternatives. That's just business.

    However if gas prices stay at the level they are; there just MAY be too much force exerted for change to stop it.
     
  11. acebodge1

    Thread Starter Member

    Jun 18, 2008
    13
    0
    hiya folks,i clearly remember the size of the flame,when my chemistry teacher lit the hydrogen from an electrolysis tube,after having it connected up to a 1.5v sulphuric acid cell for just a few seconds,i am gonna have somethin similar,only more tubes,and thermister control to stop the electrodes overheating.Its just a shame those 150watt silicon solar panels are about a grand each.I just wish those cheap printed circuit panels would hurry up and hit the market.Anyways,i am off to see how long my laptop will run on AA nimh`s,45 mins from the standard laptop battery pack just is not long enough.
    Huh,rose tinted glasses,,we will see,lol.
    regards the bodger
     
  12. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Someone saw you coming, Bodger! 5 USD per Watt is the going price on my side of the pond. Considering the current exchange rate, you should not consent to more than 380 Pounds for that panel! Tell 'em to sell it to an Englishman.:D
     
  13. acebodge1

    Thread Starter Member

    Jun 18, 2008
    13
    0
    hiya,thanks for the info`thingmaker,i won`t be paying 380 either,i heard about a new product on the news,where the panels are printed,they were supposedly gonna be very cheap,i haven`t seen them on the market yet though.
    regards bodger.
     
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