Charlie99
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The statements above apply to 60Hz systems. If you drive the coils with high frequency, then inductive coupling at high power becomes feasible. For example, the SAE J1773 inductive coupling paddle for electric cars handles several kilowatts.cool_hardware52:There are a couple of practical impediments.
Some battery chemistries can offgas when recharged.
Inductive charging requires a coil in the battery case, inductive charging works by placing 1/2 of an "air coil" transformer in the charger and the other half in the battery case. Air coil transformers are not very efficient, requiring a fairly large coil if you want recharge times that are reasonably short. In addition some portion of the charge control electronics would need be in the battery canister. Adding a large, heavy copper coil, and charge control electronics to the canister poses obvious problems.
Inductive charging is practical when the batteries are small, and the duty cycle of the device is low, i.e. a shaver or toothbrush spends most of it's time in the charging cradle and not in use. If you had 2-3 days to recharge your light (or vest) and only wanted to use it for a few minutes per day inductive would work.
Power is transferred inductively. Control info comes back to the primary side either by RF or infrared. Most of the charge electronics are on the primary (the wall connected charger) side.
While the magnetics design are non-trivial, the electronics are pretty much the same as a regular isolated switchmode converter charger system. The only difference is that you took a bandsaw and cut the main transformer into two pieces and stuffed one inside the sealed battery case.
Doesn't solve any battery offgassing issues, though. It's a pity that simple real world issues like not blowing up the battery case interfere with dreams.