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Siemens developing inductive charging system for plug-in vehicles with BMW; testing in Berlin in June 2011

At Hannover Messe 2011, Siemens presented a development project for inductive charging (“Contactless Charging of Battery-Electric Vehicles”), developed in cooperation with BMW. In June 2011, the capabilities of this non-contact charging system will be tested in a project funded by the German Environment Ministry and involving several vehicles in Berlin.

The charging station is connected to the public grid by a primary coil that is completely underground. A secondary coil is attached to the car, and the distance between the two coils is typically between eight and 15 centimeters.

When the driver starts the charging process, an electric current begins to flow through the primary coil. The resulting magnetic field induces an electric current in the secondary coil, which recharges the battery. Electricity is transmitted from the grid through all of the components to the battery at an efficiency of more than 90%.

The magnetic field is generated only in an exactly predetermined area between the two coils. The system therefore generates a magnetic field whose strength in and around the vehicle is far below the internationally recommended limit of 6.25 microteslas.

Starting in May, a prototype with a charging power of 3.6 kW will be tested in an electric vehicle. Beginning in June, the test will be followed by trials in Berlin to determine which improvements are needed to integrate the system into series-produced vehicles under real-life conditions and to obtain customer feedback for future customer-oriented charging solutions. The system also enables the smart use of energy, whereby the car also serves as a storage unit and most of the energy is surplus electricity from solar and wind power facilities.



"The system also enables the smart use of energy, whereby the car also serves as a storage unit and most of the energy is surplus electricity from solar and wind power facilities."

Apparently its bi-directional.. very smart of the Germans to specify that.


@Henrik, that only applies if the car is parked on the inductive coil at the time of renewable electricity.

Most likely, it will be used to charge with excess night electricity - which has nothing to do with renewables.

You would need an inductive charger for home and another at work (and you would have to park there) to soak up excess renewable power.

It sounds like a big ask.

It is typical of the renewables people - if everyone else does everything just right, we can use renewable electricity, else it goes to waste.

That is, without huge energy storage, which most countries don't have.

You end up running the grid for the benefit of the renewables suppliers, rather than the consumer.


Prototype 3.6 kW.

I hope this is scalable to a lot higher. We should hope that cars with 50 kWh battery packs chargeable in 10 minutes will exist eventually. (i.e. a car with enough battery energy to run 200-300 miles and recharge at a service station)

That would require a charging rate of 300 kW.

If inductive has any problem with that, you can always just go with old fashioned wires and contacts.


I don't agree with mahonj. To make sure that the renewable and/or intermittent e-energy is fully (100%) used it is just a matter of making it the primary power source and other other sources used for secondary or peak load sources.


I just curious what does it means 90% efficiency. Is it 10% power wasted in comparison with contact charging.


P.S. This development could be major breakthrough in customer acceptance of EV's and PHEV's and will make public charging system absolutely robust. Think about situation when you never care about charging - it simply instantly automaticaly turns on when you park you car at the parking place marked 'EV' according preprogramed charging pattern and price setup.


Darius: Another manufacturer recently claimed 96% efficiency with their wireless charging station. That claim may be high but 90% seems attainable. Wonder what will be the extra on-board weight? The ideal may be not to carry extra charger weight around. Some kind of auto-aligned charging plug or overhead power bar could do it. The heavy charger would stay in the garage and come on when an electrified vehicle is in contact with the power bar.


@harvey, you are agreeing with me.
Once you have a lot of renewables, the rest of the grid has to be used to balance them.
The purpose of the grid becomes to balance the renewables rather than just serve power to users. "The lunatics have taken over the asylum."

@Darius, I don't think the main problem of EVs is charging, it is batteries and cost.

Imagine you drive up to one of these chargers, but misplace your car, and come back and the end of the day to find your car - not charged - oops.

While (if used properly) these chargers would be very cool (assuming you have standards for interoperability),
it will cost a fortune to lay them out as you describe.

My suggestion would be to use small battery PHEVs, and increase the battery size as batteries get cheaper. Even a 5Kwh battery will greatly reduce fuel consumption, and won't cost so much.
+ if you forget to charge, it doesn't matter.

If you look at the "long drives" (say London - Edinburgh), you see that the charging times become a huge issue once you go beyond a single charge - for long range, you MUST have chemical fuels (at present) so you may as well optimize it for cost (small battery) and fuel efficiency (larger battery) as best you can.

I think the general acceptance of pure EVs is a long way off.
Nontheless, hybrids are here, now, and morphing into PHEVs - KWh by Kwh.


The article supports us with limited information. It is possible to know charging status after you complete parking. Also we don't know what shape of coil would be buried and how car will be sencitive to posotion. May be it is coil/wire sistem like Bombardir trams are using and so on. May be all parking will be charging place.


"for long range, you MUST have chemical fuels"

Not necessarily, we already have 50 kW chargers. Assuming 5 miles per kWh for a mid-size passenger car, that's 250 miles range for every 1 hour of recharging.

I think people would happily accept a 1 hour rest stop every 250 miles in return for very low fuel costs per-mile.


clett...the majority may not accept to stop one hour every 250 miles for a recharge. Swapping the battery pack, in about 5 minutes, may be more acceptable? That already exist.

Alternatively, a very small (15 to 20 Kwh) on board NG/Ethanol/gasoline generator could compensate battery depletion on long trips and extend range by 2x or 3x or equivalent to full day drive. The battery pack would be recharged over night at the road side motel/hotel. This is a basic PHEV.

Pure long range BEVs will have to wait until 400 Wh/Kg to 600 Wh/Kg quick charge batteries have arrived.


Let's be real, long range trips are rare events, most households have more than one vehicle, plus there are rental cars, genset trailers could be another option, so we are a long way off from actually having to worry about EV's doing long trips.


Expenditure barriers say that I want a car to do everything I want it to do whenever I want to do it, no limitations. PHEVs are a way to satisfy that without giving up anything but more money which you will get back with lower fuel cost over the longer run.


Rent a genset trailer for the occasional long trip is a cool idea. A one wheel very light weight model would do to house the ICE + generator + fuel.

Alternatively, a rental trailer with two extra battery packs (to extend e-range from 250 miles to 750 miles) would also do, but may be heavier and cost much more.


The trailer idea might fly, but maybe not. If it expands the cargo area, then maybe. People do not like hauling trailers unless they are for a house trailer or boat. Having to do it may not be popular. It sounds good, but public acceptance is another thing.

The Tzero trailer had wheels that steered making backing up easier and that might help. The rental cost is a factor. One hundred dollars per week might be acceptable, standards would have to be in place to make it more universal. Not saying it would not work, but some marketing needs to be done to see if it would fly.

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