"Place each on a charged, but one submerged, one not"

Unless the connector is waterproof ( i doubt it) , don't try this at home. Water is a good conductor.

DC plus water equals electrocorrosion[1] if the pins are in contact with water. USB 5 Volts is easily enough to corrode most electronics - certainly made a huge mess of one phone I owned that got dunked while charging.

[1] electrocorrosion isn’t used much as a word, but it should be. Google electrolytic corrosion, direct current corrosion, stray current corrosion.

[null] https://knowledge.electrochem.org/encycl/art-c06-cathodic.ht...

> electrocorrosion

Isn't that just galvanic corrosion?

Galvanic is two dissimilar metals, usually with an electrolyte like wet soil or water. One metal will corrode far faster than the other e.g. zinc sacrificial anode will corrode to protect iron.

Corrosion due to electric currents is different. A few Volts in reverse and you could make iron the anode to corrode and protect a zinc cathode (Cathode and Anode depend on current direction, e.g. they swap when charging a battery).

Two parts made of the same metal can be can be corroded with an electrolyte between them, with low AC or DC voltage driving differences.

Connector? This is about wireless charging.

If you're worried about the wire to the charger itself, I'm sure they've thought of that if the charger is submersible. (Do any of those exist? I'm only finding a splash-resistant one.) And if the charger isn't submersible it'll be outside the bucket and the cable will be fine.

I do see some wireless charging waterproof battery banks. No cable needed for that.

And make sure to plug it into your bathroom outlet for the fault protection!

Which only makes sense because how else would you test this beside sitting in the bath with a stopwatch?

Try sitting in tub with a toaster?