[littlestymaar]

> One of the elecrodes of the battery (-) is generally connected to the metal body. You only need a cable touching your ring while your hand rests on the frame to cause a short

The current won't flow through your hand, 12V is too low to pass your skin with a significant current. The only way the ring can have raise to a significant heat is if the ring itself touches both sides of the circuit (anode -> car frame -> ring -> wire -> cathode). Anode -> car frame -> hand -> ring -> wire -> cathode won't cause any short, because your hand acts as a big resistance in that circuit.

[MayeulC]

> current won't flow through your hand

Of course not, I didn't mean to imply that.

> if the ring itself touches [the car frame]

That's what I meant.

> 12V is too low to pass your skin with a significant current

Now of course the human body has a complex impedance, with cell membranes acting as capacitors: higher frequencies let more current flow. And that also depends on how much skin there is (single finger vs arm to foot), if it is wet, etc. I remember trying a (discharged) 9 V battery on my tongue as a kid... that was literally quite a shock, even with continuous current.

In the end, I wouldn't bet that an electrocution is impossible using a mere 12V of electric potential.

[littlestymaar]

We weren't talking about electrocution here, but about heating a ring quickly enough to burn you, which requires a much higher amperage than what's needed to kill you.

Anyway, given that 12V is considered safety voltage for submerged swimming pool material in France, I'm pretty confident it is be extremely unlikely to kill anyone.