And lead-acid batteries have a fairly low internal resistance, which allows them to produce high currents if the load is also low resistance (a required feature when cranking the engine).
The internal resistance of the body (and wet skin) is sufficient that it and the voltage are the relevant factors. Jimmy even went so far assume an ideal power source—as much current as 12v can get you. The resistance even without the benefit of dry skin is sufficient to keep the current that passes near the heart below the level that will result in fibrillation in healthy humans.
I would have to concur with Jimmy that death by car battery electrocution would qualify as ‘freak accident’. If you want to kill yourself with a battery you could perhaps try balancing it on top of a door and closing it while your head is
According to Wikipedia, the threshold for fibrillation is 60 mA for AC, 300-500 mA for DC. On reflection, it seems I’d previously cached the AC value as the value for all currents, so that was skewing my argument.
Given these figures, a 1k Ohm total resistance (internal plus skin plus body) would lead to a 12 mA current (painful but not fibrillation-inducing), whereas 200 Ohms / 40 Ohms total resistance would be required for 12 VAC / VDC to be potentially lethal. So, yeah, now that I think about it, a car battery probably couldn’t be lethal unless conductors were actually puncturing the skin and touching the bloodstream directly (or covering a HUGE amount of surface area). I retract my claim.
Edit: OH! Except that Wikipedia says the threshold for fibrillation is a mere 10 µA if the current is from electrodes that establish a circuit through the heart. THAT’s the figure I’d seen before and cached in my head. Still, that’s not a likely situation to arise when using jumper cables, so my claim remains retracted.
The internal resistance of the body (and wet skin) is sufficient that it and the voltage are the relevant factors. Jimmy even went so far assume an ideal power source—as much current as 12v can get you. The resistance even without the benefit of dry skin is sufficient to keep the current that passes near the heart below the level that will result in fibrillation in healthy humans.
I would have to concur with Jimmy that death by car battery electrocution would qualify as ‘freak accident’. If you want to kill yourself with a battery you could perhaps try balancing it on top of a door and closing it while your head is
According to Wikipedia, the threshold for fibrillation is 60 mA for AC, 300-500 mA for DC. On reflection, it seems I’d previously cached the AC value as the value for all currents, so that was skewing my argument.
Given these figures, a 1k Ohm total resistance (internal plus skin plus body) would lead to a 12 mA current (painful but not fibrillation-inducing), whereas 200 Ohms / 40 Ohms total resistance would be required for 12 VAC / VDC to be potentially lethal. So, yeah, now that I think about it, a car battery probably couldn’t be lethal unless conductors were actually puncturing the skin and touching the bloodstream directly (or covering a HUGE amount of surface area). I retract my claim.
Edit: OH! Except that Wikipedia says the threshold for fibrillation is a mere 10 µA if the current is from electrodes that establish a circuit through the heart. THAT’s the figure I’d seen before and cached in my head. Still, that’s not a likely situation to arise when using jumper cables, so my claim remains retracted.
I think we’re on agreement with all those figures. Embedding electrodes into your chest or using AC are definitely asking for trouble!