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Onboard Charger. What's the Big Deal?

Discussion in 'Model S: Battery & Charging' started by gavine, May 15, 2014.

  1. gavine

    gavine Petrol Head turned EV Enthusiast

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    Forgive my ignorance. I have never owned an EV and my 60 is due to arrive in about 3 weeks. Tesla brags about the charger being onboard. Can someone explain why that's great? They make is sound like this allows you to plug in to a standard outlet, but can't a Chevy Volt and Nissan Leaf do that too? You still need the UMC, right?
     
  2. scaesare

    scaesare Active Member

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    #2 scaesare, May 15, 2014
    Last edited: May 15, 2014
    When I was purchasing mine, I had not gotten impression they attempt to suggest other EV's can't... but rather simply tout the benefits an on-board charger brings.

    Is there somewhere they attempt to differentiate what they do from other EV's (other than the power handling capacity advantage the S enjoys)?
     
  3. mgboyes

    mgboyes Member

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    I don't think they're bragging about the fact it's an on board charger as such. They're just describing its capability clearly.

    The Model S has a 10kW or 20kW on-board charger, and can also use an off-board charger at up to 120kW (i.e. a Supercharger).
     
  4. hiroshiy

    hiroshiy Active Member

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    Standard charging stations, Tesla UMC, Tesla HPWC, Nissan Leaf EVSE are all connectors which supply AC power.
    Superchargers, CHAdeMO quick charging stations are connectors with "chargers" built-in, which supply DC power.
    Batteries need DC to charge.

    So if you connect your Tesla to AC power, you need at least an onboard charger. Of course, all plug-in vehicles have on-board chargers,
    because people connect those cars to AC power at home.

    Now how Tesla is different?
    Tesla Model S has 10kW or 20kW on-board chargers, which is WAY bigger than other plug-ins such as Leafs and Volts, allowing
    the car to charge more quickly. Well, Model S battery is WAY bigger so it's actually not much quicker, but at least charges more
    electricity into the car per one hour of charge.
     
  5. roblab

    roblab Active Member

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    Long ago, there were battery electric vehicles. The Toyota RAV4EV and the GM EV1 were a couple.

    Seems that the manufacturers really did not want electrics to be too convenient, because it was obvious that electric power was vastly superior to gas power. So they told everyone that batteries were horribly expensive and heavy, and so they could only give the car a hundred miles or so of range. Then, to make it even more inconvenient, they devised a way to make sure you could not just fill up anywhere, so they took the charger (the AC to DC inverter) out of the car and made people hard wire them to the grid. This way, you could charge at home, or charge at public chargers, but only a FEW places. These inverters were very heavy: Toyota's charger weighed 80 lb. And it is slow. You might pick up 20 miles per hour of charge, max.

    They thought they had made a car that few people would be willing to drive, but people loved them. After accidentally putting them up for sale, Toyota sold a "two year" inventory in 5 months, with virtually no advertising, at 21 dealerships, most of whom did not want to sell RAV4EVs. All other manufacturers kept control of inventory, and in the end, all other EVs were crushed except those sold.

    Tesla sort of pushed EV makers into putting the inverter (charger) on the vehicle so ANYone could charge at ANY outlet. The RAV4EV could only charge from a 220 volt outlet, only if someone had made the 80 lb. charger portable, so most RAV4EVs never went very far. Whereas, Tesla drivers have driven around the world with a very few adapters, able to plug into outlets anywhere.

    Some EV manufacturers still try to make driving an EV *just a little* inconvenient. They still offer batteries that would be equivalent of a four gallon gas tank on any of their other cars, claiming they are trying to hold down price, and then crying to Air Quality boards that no one wants their cars. They still make it difficult to get a charge anywhere, claiming you must use a several thousand dollar switch between that horrible electricity and your car. Tesla made it possible to use a safety connecting cord that plugs into about any outlet, and now, guess what? Chevy Spark and Leaf can plug into your wall.

    Believe me, it wouldn't have happened if somebody didn't have a rope around their neck telling them they had to do it.

    So, yeah, it's something to brag about. It's history. It's progress. Due to these little advances, I drove to Canada and back the first month I got my car, before there were any superchargers. With my RAV4EV, I drove 95 miles to Sacramento, charged for 4 hours, and came home.

    That's the difference.
     
  6. PhilBa

    PhilBa Active Member

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    @roblab, I never attribute to malice what can more easily be explained by stupidity. Those early engineers weren't EV owners so they didn't get how to "cross the chasm". True believers like Elon and his team understood what was needed to get to a mass market. It's funny that you see this same effect in the early charging networks - designed by people who really weren't EV owners. Like all those chargers at drug stores that nobody uses.
     
  7. gavine

    gavine Petrol Head turned EV Enthusiast

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    I understand now.....a 10kw external charger would be too big, heavy and inconvenient, let alone two of them! Thanks for the explanation. Very insightful and well-explained.
     
  8. tga

    tga Active Member

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    This isn't really correct. The EV1 and first gen Rav4EV did indeed have on-board chargers. They used a MagneCharge inductive coupling paddle (J1773) to provide high frequency AC (HFAC, 80-350kHz) to the car, which was converted to DC and controlled by the on-board charger.

    The MagneCharge paddle was the primary side of a HFAC transformer, with the secondary in the car. HFAC was used instead of 60Hz AC because it was made the inductive coupling system more efficient. DC couldn't be used, since DC wont inductively couple. You can't run DC through a transformer (well, not and expect it to work). That's the fundemental reason why AC beat DC in the "War of the Currents"
     

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