magnetic/wireless charging

Hi all, I come bearing questions..
I've just taken an old 7x D cell incandescent torch that I acquired for £3 from a toot shop, ive ripped the innards out and will be putting back an aspheric lens, 4x 26650 li-MN cells and a cree LED unit with voltage regulator. I cant wait to get it functioning.
Thinking on charging though, would it be possible to come up with some form of magnetic/wireless charging system?
There's bags of room, im just far more mechanically minded than electrically.
I hsd a quick look online and it appears that most readily available charging modules are 5v whereas I would be looking more like 14-15v with 4x 26650's
If my understanding hasn't failed me?
Any pointers appreciated,
Cheers, Tony

I'm sure someone will come in and correct me but my thinking is this...
From what ive seen, wireless charging works on basically the same principal as a transformer; electrical windings so-far apart that allow a reduced level of current to travel between them from the line side to the service side. Id say youd need to figure out how big of a winding you would need for your light and properly size it to the windings on the charger side. Itd be neat idea if you can figure it out.

GasganoFJ60 said:

I'm sure someone will come in and correct me but my thinking is this...
From what ive seen, wireless charging works on basically the same principal as a transformer; electrical windings so-far apart that allow a reduced level of current to travel between them from the line side to the service side. Id say youd need to figure out how big of a winding you would need for your light and properly size it to the windings on the charger side. Itd be neat idea if you can figure it out.

Click to expand...

correct

Yes, that's how wireless charging works. Nikola Tesla never proved wireless power transfer by other means, though it is possible to transfer power using electromagnetic fields instead of magnetic ones. That's how radios work. Oh, and microwaves.They can transfer hundreds of watts into your food. I doubt that it's actually feasible, but wouldn't it be cool to quick-charge your light in the microwave?

If you were looking at one of the canned wireless charging modules, I wouldn't be at all surprised if the voltage on the receiver coils is actually higher than you need to charge, and is brought down to 5V by a regulator. It would be interesting to put an oscilloscope on one and see. I'm almost certain that it is on the transmitter, not so sure about the receiver.

You could also boost the 5V sufficiently to charge the batteries. If there's plenty of room, that's probably the simplest way, though certainly not the most efficient.

I wouldn't charge those cells in series in the flashlight. Bad idea with li-ion batteries. Just use an external charger if your safety is dear to you. Plus wireless charging would take FOREVER to charge 26650 cells.