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I know nothing about electricity

Discussion in 'Model X: Battery & Charging' started by drewmcmanus, Jul 9, 2016.

  1. drewmcmanus

    drewmcmanus Member

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    Now that I own a Model X and just had SolarCity panels put on the roof, I wish I knew a little bit about electricity. It seems like black magic voodoo to me, frankly. Anyone have any links or resources I could use to learn the basics? I don't want to get a degree in physics, but I would love to know a volt from a kilowatt hour.

    Any help is welcome.
     
  2. HookBill

    HookBill Member

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    Then you've come to the right place. Find a thread that sounds like it might have answers to your questions and join right in. For the most part we're a friendly bunch.

    Welcome.
     
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  3. KJD

    KJD Member

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    Wikipedia is your friend :)
    Kilowatt hour - Wikipedia, the free encyclopedia

    The home charging FAQ also has a ton of good information.
    FAQ: Home Tesla charging infrastructure Q&A

    Congrats on the new X by the way.
     
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  4. FlatSix911

    FlatSix911 918 Hybrid

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  5. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Active Member

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  6. David99

    David99 Active Member

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    Electricity is has two attributes that are measured separately. Both are equally important. Volt and Ampere. If you think about electricity as being a river, Volt would be the speed at which the water travels and Ampere the width of the river. It's not a perfect analogy, but it helps understanding electricity a bit better.

    Power (Watt is power) is the product of both
    200 Volt * 10 Ampere = 2000 Watt.
    400 Volt * 5 Ampere = 2000 Watt.
    Think about the river. Volt is the speed of the water. A river that runs at twice the speed but only has half the width delivers the same amount of water. The same relationship exists with Volt and Ampere.

    Power over time is energy. So 2000 Watt over 2 hours = 4000 W/h = 4kWh. (k = kilo = 1000)

    Electricity comes in two times of flavours. AC and DC. AC = alternating current. DC = direct current. DC is like a river, it flows in one direction. AC changes direction all the time. It goes back and forth all the time. Like a swing set. Our grid is all AC current. Our car's battery is DC. AC current can very easily be transformed which is great, but batteries can only store DC. And then the motor of all EVs need a complicated patterns of AC current again that is adjusted depending on speed and power needs. So there is a lot of conversion going on.

    Fortunately you don't need to know anything about electricity to be happy with a Tesla. They got it all covered pretty well.
     
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  7. vandacca

    vandacca Active Member

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    If you're using a river analogy, AC is like a tidal river, with the flow changing directions. Tide comes in and goes out.
     
  8. weak_pig

    weak_pig Member

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    so can anyone explain which part of electricity kills you when you come in contact with it? Is it the ampere, voltage or wattage? And why do some people demonstrate currents running through their body without getting electrocuted?
     
  9. vandacca

    vandacca Active Member

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    Amps is the more significant rating when it comes to current. Amps is a measurement of the rate/volume of electrons. Wattage is the power, which is calculated by multiplying (Amp x Volts), so it will be proportional to both Amps and Volts, not typically considered when addressing this sort of question.
     
  10. Saghost

    Saghost Active Member

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    Not that simple, unfortunately. Amperage is what kills - but it doesn't take much of it, and you need a fairly high voltage to get it to flow through you.

    Thus you have both ends of the spectrum safely - Anything you do with twelve volts is generally safe, no matter how many amps a circuit could flow because it won't flow through you (holding a wrench that shorts 12 V can be very bad because the wrench heats up and throws bits of molten metal...)

    At the same time, a 30,000 volt stun gun is generally safe - the energy will certainly go through you, but it doesn't carry enough current to kill.

    How much voltage is dangerous varies with circumstances, too. Touching a thin wire to dry skin requires a lot of voltage to be dangerous - touching a ring or bracelet less, wet skin still less, and a pool of water that you're in can drop the requirement remarkably.

    This is why a charged 9 V battery stings when touched to the tongue, but not when touched to the arm.
     
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  11. David99

    David99 Active Member

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    #11 David99, Jul 11, 2016
    Last edited: Jul 11, 2016
    Great post @Saghost

    I would just like to add this to the 'what is dangerous' aspect. Is AC or DC current more dangerous?

    Direct current (DC), because it moves with continuous motion through a conductor, has the tendency to induce muscular tetanus quite readily. Alternating current (AC), because it alternately reverses direction of motion, provides brief moments of opportunity for an afflicted muscle to relax between alternations. Thus, from the concern of becoming "froze on the circuit," DC is more dangerous than AC.

    However, AC's alternating nature has a greater tendency to throw the heart's pacemaker neurons into a condition of fibrillation, whereas DC tends to just make the heart stand still. Once the shock current is halted, a "frozen" heart has a better chance of regaining a normal beat pattern than a fibrillating heart. This is why "defibrillating" equipment used by emergency medics works: the jolt of current supplied by the defibrillator unit is DC, which halts fibrillation and gives the heart a chance to recover.
     
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  12. CHG-ON

    CHG-ON Still in love after all these miles

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    Great explanations @David99 and @Saghost! I have always had an issue relating to electrons compared to fossil. The river analogy helped a lot. Hopefully I won't be one to complete the circuit that keeps my heart either going on not!
     
  13. wws

    wws Member

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    Voltage is often referred to as 'potential'. To use the river analogy, think about a dam. Drill a pipe into the dam high up, and another down low. The water pressure in the upper pipe will be lower than the pressure in the lower pipe. Amperage is analogous to the width of the pipes.
     
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