I have a very nice wireless charger which can charge my smartwatch.

Smartwatch itself contains a neodymium magnet on its back (and there are chargers which also contain another neodymium magnet to align the charger and chargee).

This is how it looks like when a charger has the magnet:

enter image description here

And this is how mine looks like:

enter image description here

Mine has two coils because it can charge both watches and phones (not at the same time!)

The wires are glued onto a back plate (black one on the picture) which is kind of a metal plate (a magnet is pulling it aggressively) - to increase the coils effective (I think).

I hoped to improve my charger by adding a magnet to align my watch and keep it aligned during the charging phase.

Now, I bought some neodymium magnets and put it into the middle of the coil in my charger:

Pro: it can align my watch perfectly. Cons: it ruins the charging algorithm, feedback led blinks red (which normally means misaligned device).

I tried with several smaller magnets, but it is always ruining the charging.

Then I have created a metal "pot" to hold my magnet and force its field towards one direction to pull the watch but don't disturb the charger coils: kindof like this:

enter image description here

But this "pot" even without inserting the magnet ruins the charging algorithm.

I might have to create this pot from something else than iron, but I am out of ideas now.

Anyone has any idea I would appreciate it: how can I insert a magnet into the center of this coil without ruining the coil's effect?

Ps: I know these chargers are finetuned, and also doing protocol negotiation before and during the charging, but who knows, Community might always have some great ideas.

Update: I have some new images of that ferrite "bed" around the coil:

enter image description here

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1 Answer 1


Think about this: -

enter image description here

Ferrite material is non-conducting and therefore eddy current losses (due to induction) are very low. But, its main use is to divert the magnetic field away from the static magnet.

  • \$\begingroup\$ Would it be enough to have a ferrit "cup" (pot) around and underneath the magnet? \$\endgroup\$
    – Daniel
    Jul 7, 2022 at 20:17
  • \$\begingroup\$ It would help and you might get away with it with some tweaking of values on the tuning circuits and you might need to take a couple of turns off the coil @Daniel \$\endgroup\$
    – Andy aka
    Jul 7, 2022 at 20:31
  • \$\begingroup\$ I see thanks. Please check my update, with some new pictures of the magnetic charger's ferrite. It seems a massive one, with a massive magnet. I can only apply a much smaller one (smaller in height). Tuning circuits would be tricky, as we don't have the datasheet of all the ICs, and of course we also don't have the values of the current resistors, capacitors, coils. Thus, getting a ferrite "pot" seems extra hard, noone seems selling it even from China in small qty. \$\endgroup\$
    – Daniel
    Jul 7, 2022 at 20:39
  • 1
    \$\begingroup\$ You can buy pot cores that look very similar from the usual suppliers. You may need to sand it down to make it fit but that's a fairly easy exercise. The electrical problem of adding the pot core means that it will detune the coil by increasing the inductance by maybe double or triple @Daniel \$\endgroup\$
    – Andy aka
    Jul 7, 2022 at 21:08
  • \$\begingroup\$ Thx! Can you please link an actual pot which would worth to be tried out? \$\endgroup\$
    – Daniel
    Jul 8, 2022 at 12:40

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