Electric shock from smps adapter

[nukie]

Hi all,
I have a multi chemistry AA-18650 charger and it is supplied with a universal voltage 12V 5A, 2-pin mains external adapter.

I get shocks from time to time whenever I touch the negative sping loaded pole whenever I try to load the battery.
I tried measuring the AC leakage by putting one probe on my finger and another touching the negative pole of the charger, the multimeter indicating ~100Vac. I am not sure if it's the rightway to measure the ac leakage but i did it anyway.

I tried measuring a USB port shield of my desktop PC it was ~6.6VAC.

I haven't tried breaking open the ultrasonic welded case of the smps adapter, is this worth fixing or should I just replace it. I have zero knowledge how these leakage works.
I have repaired plenty of smps so I know how to avoid fatal injuries when repairing them.

[Gyro]

That sounds like ordinary Y cap leakage current in the SMPS. You are maybe feeling it more because of the small contact area of the battery spring.

If you measure the leakage current to earth and it is about 160uA (for 240V 50Hz mains) then it is about right for a 2200pf Y cap. For safety it is probably best to measure the voltage drop across a highish value resistor rather than immediately using the current range on your meter (just in case there is an insulation fault).