On Fri, 20 May 2011 04:33:34 -0700, Smitty Two
wrote:

In article ,
Jeff Liebermann wrote:



[Q] What's the difference between a battery and an explosive?
[A] Energy density.
Batteries
Lead Acid 150,000 Joules/Kg
Li-Ion 460,000 Joules/Kg
Lithium Thionyl Chloride 2,000,000 Joules/Kg
Explosives
TNT 4,700,000 Joules/Kg
We're getting there with batteries.

Tesla should be working on a TNT powered automobile, then.

Sure. Black powder engines work:
http://www.youtube.com/watch?v=oE29MJOnTdE
However, I prefer reactor grade uranium fuel at 3.7*10^12 Joules/Kg to
power a UPS and vehicle.

The problem is that if you do find a way to rapidly discharge a
battery, it has enough energy to create an impressive explosion.
Power(watts) = Energy (Joules) / Time
The faster you extract the energy, the bigger the bang.

In the late 1960's, I successfully did that with a crow bar across a
55 gallon drum oil bath capacitor (fusible wire high voltage switch).
The crow bar didn't melt but the sound of the explosion shook the
building, set off alarms, deafend me for about an hour, and caused a
bulge in the can. With the latest Lithium-something battery
technologies, a major advantage is that one can extract large amounts
of current over a small interval. Most battery packs have circuits or
fuses to prevent this from happening, but if you're working with the
raw battery, the possibility of blowing something up is very real.
This might be one reason why UPS manufacturers are still using
lead-acid or AGM batteries, instead of going to Li-Ion mutations.

Of course, electric vehicle manufacturers have gone to some effort to
make their battery packs safe (SAE 2464, 2929). However, if you
bypass those safety features, you get a big bang.
http://www.teslamotors.com/roadster/technology/battery

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558