Okay, this is odd...

[Difdi]

I have a pretty standard US-style 3-prong GFCI outlet in my bathroom. I know the outlet has power, because I can plug in anything from a battery charger to my electric shaver and it works.

I've got this rechargeable flashlight, it has a built-in nightlight function and switches itself on automatically when it senses a power outage. It charges by magnetic induction. The charger has the standard 3 prongs.

Here's the weird thing: When I plug that charger into the outlet, the flashlight immediately reports no power and switches itself on in power outage mode. But there is power to the outlet, and any other device I plug in works normally. If I plug the flashlight charger into any other outlet in my apartment it works normally.

It just will not work with that outlet. My circuit tester reports no problems whatsoever with the outlet. Any ideas why this might be?

[BeeMused]

All I can think of is a wiring error. The flashlight charger has some elctronic inside for detection of power outages that might be more sensitive to faulty wiring.

[Ironclad Alibi]

Do you have a second GFCI outlet you can try the flashlight on? The GFCI function may somehow be interfering with the induction feature.

[It's me]

My circuit tester reports no problems whatsoever with the outlet.

What kind of circuit tester do you have? Is it the sort that shows correct/incorrect hot, neutral and ground?

+1 On the interference suggestion. A GFCI works by detecting an imbalance between in the current flowing in the hot and neutral wires, using a small transformer. It is very likely the transformers magnetic field is the culprit. Try using an extension cord to test.....

[Difdi]

Do you have a second GFCI outlet you can try the flashlight on? The GFCI function may somehow be interfering with the induction feature.

Good thought. I tried it and it does NOT work in either GFCI outlet.

But I have a microwave oven plugged into another outlet on that second GFCI outlet's circuit and the microwave has an alert that goes off if it registers a power surge. When I unplugged the nightlight/flashlight after testing as you suggested, the microwave sounded its alert.

What kind of circuit tester do you have? Is it the sort that shows correct/incorrect hot, neutral and ground?

+1 On the interference suggestion. A GFCI works by detecting an imbalance between in the current flowing in the hot and neutral wires, using a small transformer. It is very likely the transformers magnetic field is the culprit. Try using an extension cord to test.....

Yes, I have that type of tester.

Your idea about the magnetic field seems to be spot on. I tried your suggestion of an extension cord using a power strip and the night light came on. Sortof. The power strip's surge protector breaker didn't trip, but the nightlight came on very dimly and flickers.