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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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