Out of curiosity I contacted CTEK re the buzzing or tingleling when touching the car with the charger attached. Worth posting their reply should anybody have concerns.
"This is specially the case when:
• The air and vehicle tires are dry, typically indoor a warm garage or in a dry season of the year with a very low humidity. The vehicle is then well electrically insulated from ground potential.
• Electrical equipment as for example a battery charger is connected to the vehicle.
• A person touching an electrically conductive part of the vehicle and at the same time touches a part that is well connected to the ground potential as for example an electric lift device in a workshop.
This small leakage current is normal and derived from the EMI filters inside the battery charger. These filters are necessary to keep the radio interferences from the unit to a minimum.
Normally the leakage current will drain down to ground through the dirt and moisture on tire or other surfaces and the residual current is not detectable by touch.
The leakage current of all our mains connected chargers are certified by a third party safety institute to verify that the leakage current is below limits and harmless to human body.
How to avoid this?
To minimize the discomfort in these situations you may add an electrical connection between the vehicle chassis and ground by using a single jumper start cable. Alternatively use semi conductive lift pads between vehicle and lift/jack support. "
