SHOULD THE TECHNOLOGY LIMITATIONS FOR STOCK CLASS BE CHANGED?
In ASC2003, Stock Class teams were limited to commercially available lead acid batteries and commerically available solar cells (costing under $10/Watt).
Should either restriction be changed?
How to submit your response.
RESPONSES (Generally listed with newest response first.)
RESPONSE#6
I agree that this is an excellent idea for stock class [refers to Response#3].
I do not know if there is a manufactures suggested retail price for
these kinds of items, but such a price might be a usable comparison
value in the $/kWhr calculation.
FROM:
Carl,
Sunrayce 95 Participant
RESPONSE#5
Not a bad idea [refers to Response#3], but how do you figure cost: bare batteries or protection
circuitry included, or how you bought them (w/w/o protection circuitry)?
The reg would have to be worded so that good but costly protection
circuitry would not be "punished", but rather would be encouraged.
"Stock-class" batteries have not been limited only b/c of cost.
FROM:
Ruth
RESPONSE#4
I think this is an excellent idea [refers to Response#3], and lends itself to a list of
approved batteries that could be used for stock class entrants.
However, I do see a potential isssue with setting the price used, since
many of today's lithium batteries could be purchased from any different
sources. For example, Michigan's 01 team purchased Li-Ion cells
straight from LG-Chem and built our own pack at a considerably lower
cost than teams that purchased built up packs from Worley batteries.
Which $/Whr do you then use? Some specification and price would have to
be set to make this viable. Is the same problem present in solar cell
prices where the same cells are available from different distributors?
FROM:
Jason Kramb,
University of Michigan Solar Car Team Alumni,
Driver / Chief Aerodynamics and Body Design Engineer '99, '01
RESPONSE#3
When solar raycing started in America over a decade ago, Lead Acid batteries
were the most prominent, available, and "stock" battery in the world.
Today, Li-Ion batteries in cell phones, laptops, and PDAs probably outnumber
Lead Acid batteries. They are "stock" in today's world and the price is
only coming down. ASC regulations should be changed to reflect this
technological shift and make Li-Ion batteries available to the stock class.
Better yet, instead of regulating batteries by chemistry type, regulate
batteries by the same method used to determine "stock" solar cells ($/Watt).
A $/Whr regulation on batteries (available to every team) would not
exclude any specific battery technology, but it would help level the playing
field while keeping the "Thrifty" aspect of the stock class intact and
allowing "open class" teams to still push technology further with exotic or
more expensive energy storage.
FROM:
Nathan Rues,
42
RESPONSE#2
I'd like to put my support behind this proposal [refers to Response#1]. It seems to me that the
weight of the Lb-Acid batteries is preventing more and more teams from
using them. The one point I have to make is that stock arrays should
still be stock arrays. While many of the arrays on the cars on the
"stock" finishing order may have put out stock power levels, I'm not sure
that all of them were technically a legal stock array (and then again,
maybe they were). A new stock class should still have the same
limitations on arrays, and possibly also similar limitations on Li-Ion
batteries, ie. a list of approved batteries and associated protection
circuits that could be used in a variety of configurations. Additional
batteries not on the list could be submitted for prior approval as well.
FROM:
Jason Kramb,
University of Michigan Solar Car Team Alumni,
Driver / Chief Aerodynamics and Body Design Engineer '99, '01
RESPONSE#1
I would like to propose an idea for discussion on the listserv and at the
Debriefing meeting by fleshing out an idea that was suggested earlier on
this listserv and providing some supporting data. It was suggested
immediately following ASC '03 that the Stock Class should be redefined to
allow what are currently Open-Class batteries. As was noted in that earlier
email, the price of Lithium-technology batteries has come down substantially
since the initial ASC rules were defined in 2000, and charge-protection
systems are readily available off-the-shelf. In the '01 race, the cost and
safety concerns of Li-Ion batteries were enough that 9 of the 30 qualified
teams raced with Lead-acid batteries in the Stock class. As the experience
base with Lithium-type batteries has grown though, and the cost has come
down, only 3 of the qualified ASC '03 teams raced with Lead-acid batteries
in the Stock class, guaranteeing each of them a trophy and a spot on the
Stock-class podium. This to me is not an effective distribution of the
rules, when 7 other teams who could not afford more than stock-class cells
ran with Li-Ion or Ni-Mh batteries to push their technology experience
level, and their overall finishing position, up a notch while eliminating
them from contention for a Stock-Class trophy.
It may be pointed out that those 7 teams were not eliminating themselves
from contention for an Open-class trophy, as University of Missouri-Rolla
demonstrated what a car with a stock-class array can do in ASC '01. With no
offense to Rolla, however, they are a very organized team with a long
history of solar car experience to build upon and committed faculty advisors
to carry on this knowlege to succeeding teams, something that not every team
enjoys. In my personal experience it is not realistic to expect this level
of performance from every team, as demonstrated in '03 where the top 7 teams
had full Ga-As Open-Class solar arrays. The only other teams with this
advantage were IA State and Stanford, both of whom suffered significant
electrical problems and were forced to trailer significant portions of the
race. Only Kansas State was able to finish close to those top 7 teams
without an Open-Class array, a commendable achievement.
These results point to the array as the major discriminator between Open and
Stock, and that running with Li-Ion batteries with a Stock-class array
likely puts you out of contention for honors. This is of course dependent
on race route and weather, but I believe this will hold true for a race as
sunny as the last two ASCs have been. Cloudly conditions will obviously
level the playing field, but this cannot be counted upon. Since the
configuration of Stock Array & Li-Ion batteries offers, I believe, the most
cost effective way to build a well-performing solar car, I find it
disheartening that this configuration makes it extremely difficult to
achieve any honors in a sunny race. I support my statement of
"cost-effective" by noting that the difference between Stock Class (16% Si)
and Open Class (20% dual-junction GaAS) cells for ASC '03 is at least $30K
today, while the difference between Lead-Acid and Li-Ion or Li-Poly
batteries (with charge management) is only $8K - $10K, though some teams
paid more and some claim to have paid significantly less than that. It is
significant that only 3 of the qualified teams with Stock-class arrays ended
up deciding not to upgrade to the Li-Ions, while 7 teams did. Allowing the
current Open-class batteries in the Stock-class does not prevent new teams
who do not yet have confidence to run anything but Lead-acids from doing so.
I hate to be divisive here, but frankly I believe that those teams who
finished in the top 10 with Stock-class arrays are more deserving of a
Stock-class trophy than those new teams who are still taking their first
steps. Or a less divisive idea (and one that was rejected from ASC '01) is
three classes as WSC has.
This proposal would make the Stock Class basically equivalent to the
"Production Class" in WSC, assuming the chosen batteries were generally
available on the open market. There is nothing stopping ASC from
coordinating with WSC for '05 though to coordinate and combine the
"Production" and "Stock" classes in WSC together to make for consistent
rules.
I believe this rule change would also generate more interest in ASC, since
teams would feel they could be more competitive, at least for class honors,
on a moderate budget. There has already been listserv grumbling about the
disadvantage the Stock class teams are placed at, which essentially
represents the opinion "we can never do well without an Open-class array".
I don't believe the cost difference between Lead-acid and Lithium-types
would be a significant hurdle for those few teams that chose Lead-acid in
'03, especially as prices continue to come down, and especially in
comparison to the higher cost hurdle for the Open-class arrays. This race
is at least partially about advancing technology, and the technology is now
such that Lithiums are the obvious choice (at least today). Electric cars
have already given up on Lead-acid entirely. Helping to generate more
interest would be the larger number of teams running for class honors. I
can speak personally for the motivation of racing for a class victory: it
was treated as nothing less than an overall victory by our team in '01. Of
course we're not all doing this just for finishing honors, this is only a
small part of the entire 2-year experience of the
team-building/designing/building/racing of the car, but I can also testify
as to the huge difference it can make to a team and that team's future after
dissapointing in '99 and shining in '01.
Also in support of this proposal, I would like to list the race finishing
order had this rule been implemented in '01. Arizona is a little weird here
since my former team may have ditched the 1/4 array of Ga-As cells had
Li-Ion been allowed in Stock. There may also have been impetus for the 3
Lead-acid teams to upgrade batteries and finish higher, but hey, history is
history:
Open Class: (10 teams)
1 University of Missouri - Rolla
2 University of Minnesota
3 University of Waterloo
4 Principia College
5 Western Michigan University
6 University of Missouri - Columbia
7 Queen's University
8 University of Arizona (1/4 Open-Class cells)
9 Stanford University
10 Iowa State University
Stock Class: (10 teams)
1 Kansas State University
2 McGill University
3 University of Toronto
4 Auburn University
5 Purdue University
6 North Dakota State University
7 CalSol
8 University of Pennsylvania
9 California Polytechnic State University - SLO
10Texas A&M University
Frankly, these results look more balanced and fair to me than the actual ASC
'03 results, not to take anything away from those teams involved. If
anything Arizona probably comes out looking worse here, so I'm not trying to
be biased, just more fair. I would like to see some discussion on this
topic. I would think that teams such as Kansas State, McGill and Toronto
would definately be in favor of this proposal, while the ND State, CalSol
and CalPoly teams could be against. What do those teams think of this
proposal?
Thank you and good luck,
FROM:
Colin O'Connor,
University of Arizona Solar Car,
SR '99 Mechanical Team Member,
ASC '01 Project Lead/Mechanical Team Lead,
ASC '03 Aero Design/Team Advisor,
ASC '05 ???
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