John Waters wrote:
> It is hard to imagine 8 D cells could kill someone, right?

Wrong.  It doesn't take long at much of a current accross the heart or thru
the brain to kill a human.  In other words, the total energy to kill a human
by electrocution isn't that high.  I'm sure 8 D cells contain way more than
that amount of energy.  Of course it has to be converted to the appropriate
voltage/current, but that's exactly what your inverter is doing.

Do the math.  I'm not up on the amp-hour rating of D cells, but 2 AH for a
primary AA cell is quite conservative.  Therefore 10 AH for a D cell must at
least be in the ball park.  10A x 3600 seconds x 1.5V = 54KJoules, so let's
say we've got about 50Kj to start with, and 40Kj after conversion to a
different form.  And that's just one D cell.

So let's look at some examples of 40Kj.  40Kj = 40000 N-m = 4082Kg-m at 1g.
That's about 1 ton (2000 pounds) lifted 4.5 meters or about 15 feet up.
Imagine that crashing down on you.  Or let's say you weigh 100Kg.  40Kj is
how much energy gets dissipated when you fall 41 meters.  In other words,
40Kj is about the splat you'd make after jumping out a 13th floor window.

But back to an electrical form of the energy.  40000 joules is 1000V and 1A
for 40 seconds.  A D cell couldn't release all its energy that fast, so this
is only meaningful if it were stored then quickly released.  But let's say
each cell can deliver 3A for long enough to kill a person.  3A x 1.5V x 8
cells = 36 watts.  That's 300mA at 120V.  Even if it's 200mA to account for
conversion losses, that means the D cells can sustain a 400 ohm load at
120V.  Without special electrodes that make good contact, you're body is
going to present a lot more than 400ohms, so the D cells will have no
problem maintaining the 120V.  And, this is using rather conservative
numbers.  In reality a 8x D cell to 120VAC converter should be able to
sustain a considerably lower resistance load for long enough to kill you.


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