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Wikipedia and numerous other sources cite the following statement about Magne Charge high-power inductive charging system:

For example, the Magne Charge system employed high-frequency induction to deliver high power at an efficiency of 86% (6.6 kW power delivery from a 7.68 kW power draw).

The Wikipedia article on inductive charging has a citation near that statement, but it leads to a Magne Charge user manual that doesn't back the "power draw" part of the statement and doesn't give any details on where energy is lost.

Now a system like Magne Charge features two coils that are both rather large - the off-vehicle "coupler" used with Magne Charge is something like 100 millimeters in diameter and they are placed very close to each other and aligned in parallel during charging. There's no long-distance energy transfer. This looks almost like a plain old transformer (yet with an air core) and I've never heard of a 7 kilowatt transformer wasting as much as 14 percent energy in conversion - dissipating about one kilowatt of power would just melt the transformer.

How realistic is the "86% efficiency" claim? What would account for such huge losses?

sharptooth
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Some of the losses will be associated with processing the power to step it up to a higher frequency.

Other losses will occur from inductive heating of the surrounds and energy being lost as RF

Zac
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  • Also poor coupling between primary and secondary coils means more power is dissipated in the primary coil per the amount that gets transfered. – Robert Stiffler Oct 29 '15 at 10:27