[SGVLUG] Off-topic - for Tom - plug-in car that canpower yourhouse

[Emerson, Tom (*IC)]

> -----Original Message----- Of David Lawyer
> On Fri, Apr 13, 2007 at 09:46:00AM -0700, Jeremy Leader wrote:
> 
> > So for example, I commute 20 miles to work, and 20 miles 
> > back.  So I could
> > just about do my daily commute for only the cost to 
> > recharge the battery 
> > each night [...]
> 
> Note that [snipping several really good sounding stats...]

> So is electric power for automobiles more energy 
> efficient?  For using electricity the 30% efficiency is 
> reduced by: 

[snipping more equally-valid seeming arguments]

> increase in rolling resistance [...]

Whups -- gonna call you on that.

The batteries will only increase the "rolling resistance" if they are
actually touching the ground (and, umm, happened to be round and you
were using them as tires...)  If you are suggesting that the increased
*weight* will increase the rolling resistance -- yeah, probably true,
but this is offset by the fact that hybrids and electrics are typically
fitted with "LRR" tires -- Low Rolling Resistance -- which is
accomplished by filling them to a higher tire pressure (like a bicycle
tire -- something like 90 psi)

> [...] and aerodynamic drag due to the batteries.

<ding> number two: again, the batteries will only affect the aerodynamic
profile of a car if they are OUTSIDE of the car (i.e., the battery
compartment somehow disrupts the airflow)  Hybrids and electrics are
actually designed to have a lower CD than your average car (CD =
Coefficient of Drag), so in this case I believe you are mistaken.