Tuesday, 21 October 2014
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The Engineer Q&A: wireless electric vehicle charging

Send us your questions about wireless electric vehicle charging technology and our panel of experts will answer them.

The hassle of recharging electric vehicles – either by trailing a cable out to the car or driving around looking for one of the few publicly charging points yet available ­– is one of the factors preventing them from becoming more popular.

So what if EVs automatically began to top up their batteries when parked using wireless inductive charging technology buried in the ground? And, even better, what if the technology could be placed underneath roads to charge the vehicles as they drove? This might even eliminate another public fear surrounding EVs: running out of power.

Several car manufacturers including BMW, Nissan and Renault are experimenting with inductive charging while US electronics firm Qualcomm is currently running a trial of its Halo wireless system in London and has partnerships with Delta Motorsport and Drayson Racing.

The technology works in a similar way to electrical transformers by creating a localised electromagnetic field around a charging pad, which induces a current in a counterpart pad on the vehicle parked above it.

The Engineer has lined up a panel of experts to answer your questions about wireless charging technology, how it might be used for mainstream cars and motor racing and what the challenges might be in rolling it out.

Thanks to all those who sent in questions. You can read the answers from our panel here.


Readers' comments (16)

  • The idea on the surface is very appealing, but I'd like to understand more about the efficiency of the system in comparison with direct connection. With the potential of so many vehicles and the transfer of huge amounts of energy, then every fraction of a percentage lost is critical.

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  • What precautions will be employed to mitigate conducted and radiated interference? Do the proposed systems meet the essential requirements of the EMC directive?

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  • What are the health implications of having this strong electromagnetic field near humans? A 'one-off' OK perhaps, but hundreds in a car park or in the roads...?

    How fast can it charge currently and potentially in the future?

    Is the industry working to standardise any aspect of the chargers? Similar to the socket of electric cars

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  • What batteries would suit this most? Li-ion, Li-polymer, Lead Acid-VRLA,SMF ?

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  • Agree with point raised above. As the whole point of electric cars is to offer greater efficiency, what percentage is lost by this induction charging method? Do we actually need improved convenience at the cost of effieciency at a time when vehicle manufacturers are going to great expense in order to realise even marginal efficiency gains?

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  • It's clearly not practical or cost effective for all roads to have underfloor charging, so what's the plan? Will the M25* have charging coils and everyone who wants to charge up will go for a joyride around the loop? Or will it be concentrated in central London where the slowest (ie. mostly stationary) traffic gives the longest time over the charging coils?

    Perhaps bus lanes could be converted into charging lanes with ANPR used to charge the users for charging their cars.

    * for M25 and London read any other town with a ring road.

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  • I agree with EV technology but don’t see how it is a viable solution financially or environmentally using batteries, battery life is a problem especially when using quick charge options the life of the battery is reduced greatly, so if the battery has to be replaced at huge cost every 5 to 10 years is it worth it? Also batteries are a dirty process to produce using 3000 for example on every car; I can’t see how this out weighs the benefits of zero emissions. We also have the dilemma that the electrical power needed to charge these batteries needs to be produced, so isn’t it a case for just substituting 1 form of pollution for another, maybe a different direction is needed away from these technologies altogether…. The best I can see is hydrogen but this again has its own explosive problems.

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  • And your question is?

  • at what cost?

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  • The idea of an inductive e-highway is very appealing (if we omit health safety), but does anyone really consider that idea feasible in the short term (let`s say 2025)?

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  • 1. Since the replacement rate of city infrastructure is (I'm guessing) rather slow and given the immature nature of this sort of technology can we really invest in this sort of solution any time soon?
    2. How do these charging plates affect road maintenance?
    3. Is this the sort of thing that could be implemented into formula E?

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  • Inductive charging is !. inefficient energy transfer mechanism 2. dangerous for humans, animals and birds and if underground insects and bacterias too 3. no way justifiable for the sake of convinience of non contact mode as it is waste of energy in stand by mode. We keep TV computers and many other gadgets in standby mode for the sake of remote control conv. push button on off. and pay for costly electricity for the sake of lithargy to just walk few steps to plug in or operate on off mech switch. EV tech is far off from so called green label.

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  • Would you like to ask a question?

  • When comparing the achievable efficiencies and less carbon producing technologies. Combustion engine to electrical propulsion systems I see greater potential for efficiency improvements in electrical infrastructure. Of course the first argument that comes to mind is how in the world we will be independent from burning fossils to make electricity. There has been a very rapid movement toward reduction in use of fossil fuels, be that research in making better batteries, more efficient windmills, building a fusion reactor or even harnessing the power of the sun with huge laser beams (this one doesn’t exist but you never know) Those are all new innovations that are far progressive than those of a combustion engine. I believe combustion engine has reached its time and it needs to retire. Pollution and health safety are everyone’s biggest concerns I believe. Question 1). Would it possible to have cars that do not depend on batteries but rather use electricity on demand to power the propulsion? Just like the maglev train but with the wheels. Eliminating batteries from the cars would eliminate the overbearing demand for battery manufacturing as well as their toxic disposal. Health safety is another concern as mentioned above. Question 2). What if a person is vulnerable to electromagnetic fields, such as pacemakers, hearing aids and other gadgets that are now being implanted in human bodies, would there be a way to shield the electromagnetic waves?
    Thank reading my comments and perhaps answering my questions!

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  • Can you guys give me an idea of the costs of the recharging system to be embedded under the roadways for EVs. On the move per linear foot or meter? Labour included?

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  • If inductive loop charging on roads becomes the norm and the number of electric vehicles substantially increases, what consideration is being given to the considerable additional burden on to the power supply grid? We are already heading towards power poverty with power stations shutting down and we are likely to be so for a quite a number of years.
    As to the installation of road charging loops, once again, the motorist will be faced with years of roadworks disruption. Also, on to which roads will loops be added? Not everyone uses motorways and surely the infrastructure will be impossible on minor roads?
    I can understand static charging point loops, but once again where is the power to come from if they become substantially used?

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  • - How fast can you drive while charging?
    - How many miles will you have to drive to get a full or half charge?
    - How close to the road does the bottom of the vehicle have to be?

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  • I would wait for instant charge graphene wound capacitors to appear. This way, a toll booth system can be set up on a road not unlike the M6 toll road. Drive up, credit card in, instant re-charge, go......This way, the massive induction load would be controlled and localised to the car. An elecromagnetic shield could lift up to the stationary car to minimise radiation of discharge....

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