3.2kW wireless EV charger, uhhhhhhh

[Kjelt]

https://hypebeast.com/2018/5/bmw-wireless-charging-station

3.2kW ok
wireless uhhhhhhhhh

I was really wondering , does anyone have a decent guestimate about the efficiency of such a wireless charger?
Dangers ? Cats that crawl between the charger and the car ?

You're thoughts? Mine are, is it so much hassle to plug in a cord in a socket to gain 10% efficiency ?

[apis]

Google says: "an efficiency rate of around 85%". (3.2kW * 0.15 = 480W losses)
https://www.gizmodo.com.au/2018/05/bmw-launches-worlds-first-wireless-charging-for-electric-cars-groundpad-530e-iperformance/

85% sounds very optimistic though, that is probably under ideal conditions; if you are pressing the plate against the receiver in juuust the right spot... realistically, the car is never going to be aligned optimally. Seems incredibly wasteful.

Connecting a cable is easier and more flexible and almost 100% efficient. I don't understand why people want wireless charging plates for phones either. Is it so hard to plug in the cable? And we are moving/exercising too little, any tech that makes us lazier is going to be detrimental (yes Segway, I'm thinking of you).

The cat is probably going to love sleeping on that warm and cozy plate though.

[julianhigginson]

yeah... surely that's going to have foreign object detection as part of the design.
even Qi has that (well, for metal, at least)

[NiHaoMike]

I wonder if it's just a rebrand of Qualcomm Halo. One of the prototype cars is even a BMW.
https://www.qualcomm.com/products/halo

[Wolfram]

Inductive charging can be done at > 90 % efficiency with realistic geometries for EV charging: https://ieeexplore.ieee.org/abstract/document/6953459/ . Foreign object detection is one of the main challenges in this field, the actual power conversion is a solved problem.

[rfspezi]

If i owned an electric car, i would never accept losses that high especially if it only needs connecting a cable (doing sports is never bad, remember?).
And if it's not self aligning, it's simply crap.

Anyway... we all know it's not about another stupid contactless charger - it's about having seen the companies name again. 

[nctnico]

Google says: "an efficiency rate of around 85%". (3.2kW * 0.15 = 480W losses)
https://www.gizmodo.com.au/2018/05/bmw-launches-worlds-first-wireless-charging-for-electric-cars-groundpad-530e-iperformance/

Like a connected charger doesn't have losses 

[NiHaoMike]

Inductive charging can be done at > 90 % efficiency with realistic geometries for EV charging: https://ieeexplore.ieee.org/abstract/document/6953459/ . Foreign object detection is one of the main challenges in this field, the actual power conversion is a solved problem.

That seems like something that can be done by detecting an unexpected change in Q or resonant frequency, with thermal detection as a backup to sense an unexpected amount of heat being generated.

[james_s]

The wireless charger has those same losses, plus the losses of the wireless coupling. Any way you look at it, a wire is going to be more efficient and it's hard to justify wireless. I mean it's just so easy to plug in the cable and bypass the complex, expensive and lossy wireless coupling. I plug in my mobile phone every night when I go to bed, I wouldn't bother with a wireless charging pad for that either, I'm not that lazy.

[CopperCone]

I like it, I think its safer then having to plug in some crazy high current high voltage shit every time. And cleaner. And your garage will look nicer. And there is no high voltage shit to trip over or cut accidentally.

What I don't like is all the emissions.

I would like it so you can park the car right under it.

Those plugs will probobly EMP like a mother fucker if you unplug them while charging some how. It could be dangerous.

None of these are safe:
Charging time for 100 km of BEV range    Power supply    Power    Voltage    Max. current
6–8 hours    Single phase    3.3 kW    230 V AC    16 A
3–4 hours    Single phase    7.4 kW    230 V AC    32 A
2–3 hours    Three phase    11 kW    400 V AC    16 A
1–2 hours    Three phase    22 kW    400 V AC    32 A
20–30 minutes    Three phase    43 kW    400 V AC    63 A
20–30 minutes    Direct current    50 kW    400–500 V DC    100–125 A
10 minutes    Direct current    120 kW    300–500 V DC    300–350 A

The 10 minute one is just bananas. That can vaporize you.


And honestly, just fucking work out with weights. I don't count like, plugging something in, to be exercise. Its just a pain in the ass.

[rfspezi]

I like it, I think its safer then having to plug in some crazy high current high voltage shit every time. And cleaner. And your garage will look nicer. And there is no high voltage shit to trip over or cut accidentally.
I would like it so you can park the car right under it.

[CopperCone]

I like it, I think its safer then having to plug in some crazy high current high voltage shit every time. And cleaner. And your garage will look nicer. And there is no high voltage shit to trip over or cut accidentally.
I would like it so you can park the car right under it.

  idiot

[james_s]

The charger cords don't carry HV until they communicate with the car and determine that a connection has been made and what charging current the car can accept, only then is the high voltage switched on. If you unplug it during the cycle the power is cut off before you can get the plug all the way out. It's actually quite safe and works well, at this point I know numerous EV owners and being able to simply plug in when they get home at night rather than having to go to a gas station is something every one of them is always raving about.

It's not like plugging in a cord is exercise, it's just something so ridiculously easy that it's funny to hear people moan about it as if it's some big chore. It's like putting pants on in the morning or tying your shoes, do you need an expensive machine to do that for you?

[CopperCone]

Its quite safe if it works. The problem is still that you need to handle a high voltage conductor that can malfunction and it can be cut, insulation can go bad, control systems malfunction, etc.

If it was in a industrial setting they would probably check it with a fucking megger periodically. To do it right you probobly need to disable it with contactors (rather then relying on a software safety to depower a H-bridge or something). This means electromechanical parts, which means ware and tear, inspection requirements, etc.

I'd rather get a little bit of warmth from a 480 watt leakage

Pumping gasoline is not that great either.

I have yet to see a problem from my great electric toothbrush.

Personally if I controlled it I would make it so the car battery is removed and put into a hardened flameproof bunker. Preferably by a robot.

 I charge my power tools inside of a metal toolbox for this reason, and keep the batteries separated when not in use in different compartments.

A lighting bolt or bad transient can come up on the line and possibly damage the battery and cause a fire or explosion. Particularly as things get old, manufacturers cut corners, etc.

An RF bridge is going to have a intrinsically high isolation against bad transients, and since reactors are probably used, they provide current limiting (unlike a thick ass cable).

[CopperCone]

and seriously wtf is this all this laziness talk?? I lift heavy and walk. Why is some health conscious ompa loompas telling me I need even more exercise plugging in fucking cables?? What is that like 0.05 calories burned and minor hand eye coordination (maybe it prevents wasted people from sending shitty texts idk???)

If you are serious about your health you probably periodically go outside and go for walks, lift weights, run.. .wtf is plugging in a cable gonna do? Exercise is like, sweat coming off of you, sore muscles... if anything having to remember to plug in a cable is bad for you, you gotta occupy your mind with remembering to plug in a cable?? Why the unnecessary stress?

why you gonna try to make me touch something connected to mains? i don't go around trying to encourage people to beat alligators with broomsticks. wtf

[tszaboo]

It is not for EVs, but for PHEVs. I guess it makes sense. Hans Jürgen would be really lazy to plug in his 5 Series BMW twice a day to get 20km range, which is worth about a liter of benzin. I mean Hans is working in corporate middle management, has frameless glasses, wears light blue shirt for every day, and his time is very valuable.

[CJay]

and seriously wtf is this all this laziness talk?? I lift heavy and walk.

Yeah, I used to run 10-12 mile assault course races (see the profile pic) like Tough Mudder, Total Warrior etc and trained five days a week (broken rib, two broken toes and a lasting set of bad knees and Achilles tendon problems put paid to all that fun)

 I'd still rather plug in a cable, thanks.

[Kjelt]

Google says: "an efficiency rate of around 85%". (3.2kW * 0.15 = 480W losses)
https://www.gizmodo.com.au/2018/05/bmw-launches-worlds-first-wireless-charging-for-electric-cars-groundpad-530e-iperformance/

Like a connected charger doesn't have losses 

It won't surprise me if the 85% figure so -15% is only the additional efficiency  losses for the wireless part. Have to see about that, otherwise it would not differ that much from the 90% traditional converters would bring.

[IanB]

I have read that wireless charging of EV's is a standard thing. For example with electric buses in cities. When the bus parks at the stand it gets charged from a pad under the road. Therefore the bus can drive around all day and never needs to be plugged in. It's only a small stretch to install this in your home garage instead of the bus garage.

[Kjelt]

Yes but do the math, a real EV would have a 50-70kWh batterypack to allow a 300km radius.
With 3.2kW and 85% eff. It will take an entire day to charge from empty to full capacity.

The wired home chargers are at least 10kW upto 25kW making the wireless charger look like a gadget.

[IanB]

Right, but people rarely need a full charge every day. I have friends with EVs and they typically drive 10-20 km to work in the morning and 10-20 km home at night. So they only need a small top up charge each night, nowhere close to a full battery charge.

[IanB]

Also a standard home charger here in the USA might plug into an existing 240 V, 30 A residential circuit that many people already have in their garage, so it might be about 6 kW. It will only be more than that if people go to the trouble of having a special new circuit installed from their breaker panel, which is an unnecessary expense for most people.

[thm_w]

Its quite safe if it works. The problem is still that you need to handle a high voltage conductor that can malfunction and it can be cut, insulation can go bad, control systems malfunction, etc.

If it was in a industrial setting they would probably check it with a fucking megger periodically. To do it right you probobly need to disable it with contactors (rather then relying on a software safety to depower a H-bridge or something). This means electromechanical parts, which means ware and tear, inspection requirements, etc.

They do use contactors inside a level 2 charger.
The voltage is 120 or 240V, which you already have present in much weaker cabling all over your house.

[Mr. Scram]

I have read that wireless charging of EV's is a standard thing. For example with electric buses in cities. When the bus parks at the stand it gets charged from a pad under the road. Therefore the bus can drive around all day and never needs to be plugged in. It's only a small stretch to install this in your home garage instead of the bus garage.

It's not much harder to have the driver plug the vehicle in, or use something like a rail or automated arm. Across the fleet you're throwing away frightening amounts of energy when you go wireless.

Sure, wired chargers have losses too, but wireless has the same conversion losses plus the transmission losses. When you use a came those are almost negligible by comparison.

[james_s]

Its quite safe if it works. The problem is still that you need to handle a high voltage conductor that can malfunction and it can be cut, insulation can go bad, control systems malfunction, etc.

If it was in a industrial setting they would probably check it with a fucking megger periodically. To do it right you probobly need to disable it with contactors (rather then relying on a software safety to depower a H-bridge or something). This means electromechanical parts, which means ware and tear, inspection requirements, etc.

A bit hyperbolic don't you think? There are tens of thousands of EVs in the field, can you find me even one case of someone being electrocuted by the charging cord? I've never heard of it happening. People are occasionally killed by 120V straight out of an ordinary wall socket, rare but it happens and there are very few protective measures to protect it.

How many people have been injured by fires started while refueling conventional cars? I've seen videos of several of them and I'm sure there must be many more. I've personally witnessed 3 or 4 cars and on one occasion a big RV on the side of the road fully engulfed in fire as the owner stood helplessly nearby waiting for the fire department to arrive. Houses burn down on a regular basis due to careless storage of fuel, mostly gas cans used for lawn equipment and such. What is to prevent the fancy inductive charger from catching fire or developing an insulation fault that electrocutes someone? What if the battery pack bursts into flame as LiPo batteries occasionally do? That would concern me more than some hypothetical injury from the cord, although so far these are proving to be adequately safe.