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"Honey we can't go I forgot to plug in the TESLA" -Tesla Motors OXYMORON #1

I don't want no plug in car. I'm ready for the grownup version. When are we going to get the unteathered version? Hopefully Tesla won't make this mistake again in future models.

Let dinosaurs like Chevy and Ford die with the cord....But Tesla-I'd expect more.

I expect once the wireless charging tech gets more stable you should be able to buy a version of a Tesla that forgoes the frunk space for a proprietary wireless solution.

Oh, and have you got that wireless solution for your phone yet?

Wireless feature of the future....
very similar to my dads wireless feature of the past,"SON! GO GET ME A BEER!"

Wireless Tesla, "SON, GO PLUG IN THE CAR!"

The payment for getting the beer was a few stolen sips of bear. I wonder what the payment for plugging in the car could be :-)

There is a fair amount of loss inherent when using inductive charging. There is also a limit on the rate of current. Eventually the current limitation will be overcome. I'm not hopeful that the loss though induction will get significantly better anytime soon.

I don't like paying more than necessary to the electric company. (However, I would rather pay less to the electric company than more to the oil companies).

Don't make perfect the enemy of good.

The patent for radial tires was taken out in 1908 (IIRC). The first commercial radial tire was sold in 1945. Patents don't mean "soon".

The the air suspension, the Tesla can be lowered to minimize the inductive losses, but the losses still won't be as low as "direct connect".

Oh look a patent dated almost 3 months ago. Where's my jetpack you slackers?!

Inductive charging of vehicles is nothing new. I read an article a few weeks ago that two different cities in Italy have had pure electric buses for the last TEN YEARS. The buses start out fully charged at the garage each morning, but then they charge inductively at each bus stop throughout the day. Those buses are able to go their full 125-mile daily run without having to plug in at all. Inductive efficiency of 95% was reported.

Charging rate was not disclosed. Since the system was installed 10 years ago, and the German company that made the inductive charging equipment is still around, then it is reasonable to assume that inductive charging for personal vehicles is viable now.

After that, the issues are cost, weight and space.

The EV1 also had inductive charging. It's not that it can't be done but it has a couple of problems:

- The amount of current (An inductive supercharger is a looong way off)

- The extra losses (So it's more expensive to use)

- Compatibility (You can't just buy an adapter and use an inductive public charging station like you can with the corded systems). So charges away from your home are going to be few and far between.

In fifty years, maybe they will solve these problems. I wouldn't look for anything before then--other than increased battery capacity so that you never have to charge away from home.

What if they use the same tech to get the SpaceX capsule to connect to the space station to also get the Model S to make a connection with your garage?

Space X has a bit larger budget than my garage does :-)

As I said, your garage is one place where inductive charging will work today, as long as you don't mind spending the extra money on wasted energy. It's when you need to recharge elsewhere that inductive charging becomes a problem.

Of course, a car can have both inductive charging and cord charging, but that adds extra cost and complexity. One of the beauties of EVs is that they are much simpler than ICE cars and so require less maintenance. Adding more bits to perform the same function isn't the way to go unless there is a real need to do so (like supercharging).

I was asking not for inductive charging, but a way to have the car make a connection with my garage physically so I don't have to remember to do it and since there is not air between the connections, avoid the loss that occurs with induction. I hope that wouldn't take a SpaceX budget to pull of? ;)

Assuming you get 300 mile version and normally drive just 40 miles / day, then you don't need to plug it in every day (even that it is really easy to do). About once a week overnight charge is enough.

But Timo, I heard that Tesla recommends a charge every evening regardless?

It's best for the battery to do a standard charge daily.

Originally Posted by hcsharp ( )

The cathode in Li ion batteries forms defects (microcracks) due to stress caused by expansion and contraction relative to neighboring materials. It is simply bigger or smaller depending on whether it's charged or discharged. The more you discharge it, the more it changes size. And the more it changes size, the more microcracks it gets. These microscopic cracks lower the battery's capacity. That's one reason why smaller cycles, more often, contribute to longer battery life. That's why you should plug it in every night.

Heat aggravates the microcracking process, so keeping your battery cool contributes to longer battery life. And guess what? Your battery heats up more when used at a lower SOC because it requires more amps to keep your car going 65mph than it does at a higher SOC. That's why you should charge it every night.

Capacity fade also comes from the build-up of non-soluble deposits on the anode and cathode. This chemical process happens faster when the battery is warmer. It also happens faster when at a high SOC. But the process slows to a crawl when you drop the SOC to 80 or 90%, and slows only a tiny bit more at 50%. So if you are going to drive your car, keeping it charged in std mode has less impact on battery life (lower amps, less heat) than driving at a lower SOC. But if you're not going to drive your car for a few days, there are no amps or heat to worry about. That's when Tesla recommends putting it in storage mode, which keeps it at a lower SOC.

end of science lesson.

Yeah, what jerry3 said! :) Thanks Jerry!

How about a dock like my iroomba? Pull up and a robotic arm moves the plug over to the side or bottom of the car and does the rest.

@jerry3 Elaborate on this a little more would you?

"It also happens faster when at a high SOC. But the process slows to a crawl when you drop the SOC to 80 or 90%, and slows only a tiny bit more at 50%."

That almost implies that if the battery is close to full charge, it should be unplugged. Am I interpreting that correctly?

If the battery is close to full charge the car should be driven to drain the charge. About the worst thing you can do is to do a full (range) charge and then let it sit.

Note that if you do a range charge overnight before a trip and then start out in the morning (for that long trip) there is very little damage done. If you let it sit all day then a lot more damage is done.

The part that I don't know--and I'm not sure anyone does--is which of the following trips is less stressful on the battery:

Trip 1: Range charge, then drive 250 miles and supercharge.

Trip 2: Standard charge, then drive 200 miles and supercharge.

Of course, this assumes that there are enough superchargers to allow you to choose between the trips.

Personally, I'm not particularly worried as it appears there is little degradation in the Roadster batteries and they have a lot less temperature control then the Model S batteries.

I like the concept that Walla2 mentioned. But perhaps there's a simple dock method where we just drive over a general area in our garage, engage an electromagnet to draw (or pull close) a plate connector, latch the plate connector, release the electromagnet to save energy, then initiate charge. When charging is done, the latch can disengage and you're ready to drive.
The electromagnet would have to be strong enough to pull the charging plate to the proper location.

There would be issues with keeping the contacts clean while sitting on the floor of the garage, but that could be solvable by some type of mechanical cover. Anything's possible given enough money and ingenuity.

Like a modern-day bumper car, but getting electricity from the floor, not a pole attached to the roof...I like the idea.

Same, now your using that noodle between your ears! ;)

I would not worry too. much about the 5 percent loss. We deal with that running drop cords. 75 feet of extension cord like youd use in the yard has a 5 percentage voltage drop. When running an air compressor for air tools, they say, more hose, less cord.

What is "SOC"? Is there a glossary for all these terms people use but don't define?

Kind of ironic you ask this, being Nikola Tesla wanted to create a world where free wireless power would be available to anyone.

On the flip side, I have to charge my cell phone, iPad, laptop computer, and digital camera all the time. So having a car to remember to charge is just one more thing I will add to my list.

An air compressor or lawn mower is not drawing 50 to 100 amps for 3 to 5 hours a night at 240 volts. If you can run a tool on an extension cord it is probably drawing less than 10 amps at 120 volt.

At 5% per night it would be like adding one extra charge every 20 days.


Perhaps I was not clear. I mean to say a 5% loss via inductive charging is not excesive, as a 5% voltage drop is easily experienced with a plug (and a long cord).

I had a chance to look at the technology that Qualcomm is licensing earlier this year at the Vegas CES. It throws up to about 9 kW across an air gap of about 8-9 inches using an AC frequency of about 100-200 kHz. Very convenient for overnight in the garage, but I'm guessing that it would add at least $5k to the cost of the car and charger install.

Jack Bowers

SOC = State Of Charge.
The microcracking is the target of some of the nano-silicon anode developments; the tinier "pieces" don't stress and crack the same way. Something to do with v=r^3. :) Stress varies as the cube of the radial dimension(s).

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