From: russ@m-net.arbornet.org (Russ Cage)
Newsgroups: sci.energy
Subject: Re: EV's vs HEV's
Date: 27 Jan 1994 23:29:07 GMT
Message-ID: <2i9io3$odr@zip.eecs.umich.edu>

In article <8t33md@dixie.com>, John De Armond <jgd@dixie.com> wrote:
>But [NaS batteries] aren't practical and probably won't be.  They
>have to be kept hot and contain VERY reactive sodium.  After watching
>the hands-wringers scream about the alleged dire dangers of flammable
>refrigerants, I can just see what they'll do with hot sodium.  I've seen
>some wild DOE schemes that involve encapsulating the batteries
>in Dewars so that the internal losses will keep it hot but I have
>little faith in large, reliable Dewars ever being practical.

My former building-mates at Ford told me that the batteries as
currently implemented do not have any liquids free; everything is
inside an absorbtive material.  Breaking or piercing the battery
causes nothing terribly interesting to happen.

If you leave the batteries long enough, they will freeze and the
car won't move.  Of course, this isn't much different from many
people's ICE cars...  Idle time for the batteries to freeze is days.
I don't know what they're using for insulation, but it's not dewars
or even johnny walkers.

The biggest problem with EV's is charging time.  The second is
performance.  If you can fully charge the battery in 15 minutes
without stressing it due to its minuscule internal resistance,
and you can drain power out at 100-KW rates ditto, you have a
pretty reasonable competitor for a tank of gasoline from most
people's concept of convenience.

The killer problem with NaS batteries is corrosion of the insulators.
They become conductive after a couple of years and the battery
self-discharges.  If the insulator material which can last 20
years in that hellish environment gets found, watch out, things
will start to happen and *fast*.  Sodium and sulfur are VERY
cheap materials and manufacturing improvments could make NaS
batteries very common in a hurry, for utility load-levelling
if nothing else.
---
Russ Cage		| Forewarned is half an octopus
russ@m-net.ann-arbor.mi.us
(313) 662-9259		| Software engineer for hire, real-time a specialty.