Posted by Neon John on June 11, 2008, 4:40 am
Yep. Always have been. Rule of thumb. It takes a thousand pounds of lead
acid batteries to go the same distance as a gallon of gas in the same vehicle.
Many EVs carry the equivalent of less than a gallon of gas's worth of energy.
We don't squander that on heat! In the motor or otherwise.
There are other strategies to supply heat in EVs. Phase change media, for
example. Fancy term for something that melts while absorbing heat and freezes
to release it. Phase change involves a LOT more energy than just heating and
cooling a substance.
Paraffin is a commonly used phase change storage material. It is available in
formulations with a wide range of melting points. It's also fairly light, an
important point in an EV.
The idea is that there is a container somewhere in the car that contains the
phase change substance and come mechanism to input and extract the heat. Say,
hot water. When the EV is plugged in, an electric heater melts the stuff.
Then when you're driving, the stuff slowly freezes, releasing its heat at a
constant temperature - the stuff's freezing temperature.
A 5 gallon container of paraffin will hold enough heat for a typical commute
in a small well insulated car. It is only fractionally as dense as water so
it's quite light, relatively speaking.
On the AC side, a good phase change media is water. Freeze a tank of water at
night using electrical refrigeration and use its melting to provide air
conditioning during the drive.
Phase change media may not be able to provide all the heating and cooling
needed (I don't know until I do the math) but it can sure augment whatever
other heat source and cooling sources that are available.
John De Armond
See my website for my current email address
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
There is room for all of God's creatures.... Right next to the mashed potatoes.
Posted by clare at snyder dot ontario do on June 12, 2008, 1:10 am
Boy, I'd hate to have your thumb!!!
GC2 battery weighs 64 lbs.
My EV had 8. That's 512 lbs of battery.
Car would go 50 miles at 30mph on those batteries. Best it EVER did on
gas was about 35 MPG in town.
Now, IF the electric motor is 80% efficient, and produces 6HP of
tractive force, it uses about 5.6KW of power and produces 1KW of
heat. Ig it is 90%, you get 500 watts of heat - and you are not always
pulling 6HP, so that drops further.
** Posted from http://www.teranews.com **
Posted by daestrom on June 13, 2008, 10:34 pm
Probably wouldn't work so well in some parts of the country. Around here in
winter it's typically 20F outside and you have to keep the defroster going
to avoid ice buildup on the windshield. With a modest defroster setting
that could be 0.5 ft^3 of air per second. To warm that air for a 30 minute
commute might require close to 7000 btu for a one way commute of 30 minutes.
With no place to plug in in the parking lot, you would need to store about
14000 btu for a simple round-trip commute. That's about 200 lbm of
Definitely would need some other heat source in some areas like 'snow belt'.
OOPs, what about the rear-window defroster??
P.S. That's about typical for two, two and half months here. Not to
mention 'white-out' driving :-)
Posted by Irregular on June 11, 2008, 6:19 pm
RW Salnick wrote:
New York Thruway, Winter of '77. Quarter inch thick in certain spots of
the less important windows.
Brrrrr. Why'd you have to remind me of that experience?
Posted by Eeyore on June 10, 2008, 12:39 am
nick hull wrote:
This is where PHEVs win hands down. The 'waste heat' from the ICE can be put
to good use. Indeed it's not wasted at all.