4 ms·

Future is SAE J2954 (aka Witricity): you have a wireless charging pad under each parking spot. No screwing with power plugs, just park and go. This isn't ideal

by chipsa 4y ago

Future is SAE J2954 (aka Witricity): you have a wireless charging pad under each parking spot. No screwing with power plugs, just park and go. This isn't ideal for fast charging, but for the slower charging you'd get from being somewhere for 6-8 hours, it's perfectly fine. You still need to run power to every parking spot, but now it's embedded in the ground, and you don't have to worry about someone just coming around with cable cutters and stealing it.

adgjlsfhk1 4y ago
Losing 30-70% of the power and adding a bunch of cost doesn't seem like the way forward. Cables exist for a reason. They are the best way to move charge.
- ZeroGravitas 4y ago
  These can actually be cheaper than the alternative to install, and get greater use (assuming the standard gets widely implemented). Definately going to be a thing. Loading/waiting areas for taxis and delivery vehicles seem like an early adopter market.
  - adgjlsfhk1 4y ago
    A wireless charger is cheaper than a power outlet?
    - ZeroGravitas 4y ago
      Cheaper than an equivalent EV charger. Safety requires an isolating transformer in the charger, which adds costs and an efficiency loss. The wireless charger is the isolating transformer in their case, leading to surprisingly high efficiency and low costs in comparison.
      - adgjlsfhk1 4y ago
        have you ever looked at a level 2 charger? it's literally just a beefy extension cord.
        ZeroGravitas 4y ago
        The pitch isn't a 1 for 1 replacement, it's that the Witricity system (which is like a level 2.5) provides via convenience the extra charging that would otherwise require the speed and power of a level 3 charger. You're trading off speed of charge for time fiddling with the system. This trade-off may not work for someone with one car they plug in when they get home and unplug in the morning, just like they don't need a level 3 charger anyway, but might for an airport taxi firm, where they can charge their fleet while boarding passengers, or a loading bay for EV delivery vans. If that demand is enough to make it a standard item on the car side, then it'll likely displace plug in charging in a lot of places where both are possible for silly reasons like "nothing for drivers to crash into", feeling more "luxurious", "cheaper install" and so on.
- chipsa 4y ago
  They claim it's 10% total loss, not 30%. And yes, it's got a cost, but depending on how things shake out, it might not be much more if any. Cables are the best way to move charge, assuming you don't have to worry about the cables. But once you factor in damage from vandalism or theft or just accidents, how hefty the cables actually are, etc, compared to having the cable buried nice and safe. As for the difference in power loss between qi and this? Part of it is scale : they can fit a much larger diameter pad compared to a phone, which gets them much better coupling. You're essentially talking about an air core transformer, and there's plenty of transformers in the grid.
  - adgjlsfhk1 4y ago
    I'll believe 10% when I see it. you can definitely get that in a lab, but once you bury it under asphalt, and the driver parks 6 inches off center, does the efficiency still hold up? also, most cars are largely metal. how much energy do you lose from inducing current through the rest of the car?
    - chipsa 4y ago
      This includes have almost 10 inches between the plates, so including the asphalt. And probably will just not charge is you're really off center. Yes cars are mostly metal, but there's ways to focus the magnetic field so it doesn't go too far laterally. https://witricity.com/newsroom/blogs/what-is-efficiency-how-do-you-measure-it-and-why-should-you-care/ https://witricity.com/newsroom/blogs/what-is-efficiency-how-...

by chipsa 4y ago

adgjlsfhk1 4y ago

Losing 30-70% of the power and adding a bunch of cost doesn't seem like the way forward. Cables exist for a reason. They are the best way to move charge.

ZeroGravitas 4y ago
These can actually be cheaper than the alternative to install, and get greater use (assuming the standard gets widely implemented). Definately going to be a thing. Loading/waiting areas for taxis and delivery vehicles seem like an early adopter market.
- adgjlsfhk1 4y ago
  A wireless charger is cheaper than a power outlet?
  - ZeroGravitas 4y ago
    Cheaper than an equivalent EV charger. Safety requires an isolating transformer in the charger, which adds costs and an efficiency loss. The wireless charger is the isolating transformer in their case, leading to surprisingly high efficiency and low costs in comparison.
    - adgjlsfhk1 4y ago
      have you ever looked at a level 2 charger? it's literally just a beefy extension cord.
      - ZeroGravitas 4y ago
        The pitch isn't a 1 for 1 replacement, it's that the Witricity system (which is like a level 2.5) provides via convenience the extra charging that would otherwise require the speed and power of a level 3 charger. You're trading off speed of charge for time fiddling with the system. This trade-off may not work for someone with one car they plug in when they get home and unplug in the morning, just like they don't need a level 3 charger anyway, but might for an airport taxi firm, where they can charge their fleet while boarding passengers, or a loading bay for EV delivery vans. If that demand is enough to make it a standard item on the car side, then it'll likely displace plug in charging in a lot of places where both are possible for silly reasons like "nothing for drivers to crash into", feeling more "luxurious", "cheaper install" and so on.
chipsa 4y ago
They claim it's 10% total loss, not 30%. And yes, it's got a cost, but depending on how things shake out, it might not be much more if any. Cables are the best way to move charge, assuming you don't have to worry about the cables. But once you factor in damage from vandalism or theft or just accidents, how hefty the cables actually are, etc, compared to having the cable buried nice and safe. As for the difference in power loss between qi and this? Part of it is scale : they can fit a much larger diameter pad compared to a phone, which gets them much better coupling. You're essentially talking about an air core transformer, and there's plenty of transformers in the grid.
- adgjlsfhk1 4y ago
  I'll believe 10% when I see it. you can definitely get that in a lab, but once you bury it under asphalt, and the driver parks 6 inches off center, does the efficiency still hold up? also, most cars are largely metal. how much energy do you lose from inducing current through the rest of the car?
  - chipsa 4y ago
    This includes have almost 10 inches between the plates, so including the asphalt. And probably will just not charge is you're really off center. Yes cars are mostly metal, but there's ways to focus the magnetic field so it doesn't go too far laterally. https://witricity.com/newsroom/blogs/what-is-efficiency-how-do-you-measure-it-and-why-should-you-care/ https://witricity.com/newsroom/blogs/what-is-efficiency-how-...