UM Solar - ASC - Day 6

Submitted by Bronco648 on July 20th, 2012 at 9:17 AM

UM Solar:

Today we began Stage 4 (Day 5) of the American Solar Challenge with about a 7 hour lead.  Quantum cruised through cornfields and into the Verona, WI stage stop in the mid afternoon (2:53 PM CDT - Ed.).  We will begin tomorrow near the Wisconsin Dells.  Check out the recap of Day 5 below and stay tuned on twitter tomorrow for another day of racing.

Iowa State paced Quantum with the intent of winning the Stage (I think). They stayed within spitting distance until just about the Illinois/Wisconsin border when they suddenly slowed dramtaically. There didn't seem to be anything wrong with their car other than consumming too many electrons too quickly (my speculation)? Quantum continuned on and turned an interesting day into another Victor's March.

UM Solar Tweet:

Set up camp and had a great team dinner! Getting ready for another day of ASC 2012 ...but first we need some sleep

UM Solar

CalSol: An electric vehicle plug in! At the University of Wisconsin Madison.


Hey Boys, that's cheating.

CalSol is charging with Iowa St. this morning at a park and ride. Great sun today!

CalSol and Hyperion

Other then CalSol and Iowa St. camping, together, at a park-and-ride, I have no information on Principia, Oregon St. or Minnesota. =( Sorry.

Updated results courtesy of the ASC

Team # and Name Ann Arbor Start 7/17 Kalamazoo Arrival 7/17 Normal Finish 7/18 Stage 3 Penalty Time Stage 3 Elapsed Time Total Race Elapsed Time
2 – Michigan 09:00:00 13:02:09 13:14:15 00:12:00 12:26:15 27:12:39
9 – Iowa State 09:03:00 13:29:33 14:57:33 00:10:00 14:02:33 34:28:32
32 – Principia 09:02:00 14:15:17 17:57:00 00:15:00 17:12:00 37:01:47
254 – CalSol 09:04:00 15:08:08 17:02:08 00:02:00 16:04:08 37:11:02
256 – Oregon State 09:05:00 14:30:12 17:18:44 00:12:00 16:30:44 39:34:15
35 – Minnesota 09:01:00 13:35:20 Trailer 04:01:03 22:01:03 39:58:28
5 – Illinois State 09:06:00   Trailer 11:33:27 29:33:27 59:43:08
20 – Western Michigan 09:06:00 14:26:34 Trailer 06:18:45 24:18:45 65:23:11
28 – New Paltz 09:07:00   Trailer 10:03:03 28:03:03 67:45:54
55 – Montreal 09:05:00   Trailer 10:46:39 28:46:39 68:33:09
4 – MIT 09:09:00 14:22:40 Trailer 21:49:33 39:49:33 92:26:44

The weather appears to have improved with clearing skies in central and western Wisconsin. The target today is La Crosse, WI and the end of Stage 4. As always you can visit the UM Solar web site: LINK and/or ASC: LINK. And, I'll do my best to provide updates as the ASC wraps up tomorrow. Go Blue!


MU Solar Tweet: Good Morning! One more day until we reach the finish line - Headed to La Crosse, WI today!

UM Solar


Timing board in La Crosse, WI, Quantum ~50 miles out.

La Crosse WI Timing Board


Almost there! Approaching La Crosse, WI for the end of Stage 4.

UM Solar


Quantum into La Crosse, WI at 12:43:47 PM CDT

UM Solar


Principia is in, Iowa State 25 miles out, then CalSol. MIT might be infront of Iowa St.

La Crosse Stage Board



July 20th, 2012 at 10:04 AM ^

Thanks for sharing this with us (and over the last few days).  I had always been mildly interested in the UM Solar, team, but you have made the whole thing seem much more "real" to me, so thanks for that, as well.

Good luck and Go Blue!


July 20th, 2012 at 10:09 AM ^

Couple questions I could probably answer myself if I google enough but;

Do these morning charging sessions last them the entire day or does it just "fill up" the tank and then the car constantly recharges throughout the day albeit at a much slower rate?

How long does it take to charge up a car?

How far can a car travel on just 1 recharge?

Thanks for the input!


July 20th, 2012 at 10:41 AM ^

The car constantly receives significant powere from the array while driving (assuming it's sunny). However, it usually burns more energy than it brings in while driving at highway speeds. So the morning and evening charges are essential for maintaing speed during the day.

The battery packs have enough juice to go a couple hundred miles. The packs can be charged in full sun in about 3 hours, depending on solar cell efficiency.


July 20th, 2012 at 11:19 AM ^

Let me see if I can address a couple of your questions but I'll pose them all to some former Team members.

A charging session usually begins in the afternoon after the car stops for the day. Usually the Team will stop racing mid-afternoon and charge for a few hours. The race won't resume until 9 AM the following morning, so they get up and chage for a few hours first thing in the morning. The solar array provides electricity to the motor as does the battery. So, on a sunny day, you're pulling electricity from the array as well as the battery but the array is doing most of the work. On cloudy days, the battery does most of the work and the car must run at a reduced rate to ensure the charge lasts.

I would guess a full charge can take four hours or so (??). I'll find out.

I do not know how far the car can go on just one battery recharge alone.

I'll return with more info, provided I get it. Stay tuned.

EDIT: former Team member 'gbdub' replied with answers ^^. Here's some replies I gathered from other former members (this is several people responding):

All teams will try to get as much energy out of morning and evening charges as possible. Whether those charges can replenish the battery pack depends on how drained the pack was at the end of the day.
Cars continue to receive energy from the solar panels as they drive. Each car has a "break even" speed based on how much sunlight there is - driving below this speed means that some of the solar energy will be put into the battery pack as a charge, driving above this speed means that all solar energy plus some battery energy is required.

Charging a car depends on how sunny it is, how big your pack is, and how good your solar array is. An example using Minnesota's old published numbers: For Centaurus II, they listed a peak array output of 1.2kW and a battery capacity of 2.8kWh. That gives a charge time of 2.3 hours. However, that 1.2kW output on the array had to have been from strong sunlight (intensity of ~1000W/m^2)

Alright, let's do math for the charging time. Battery regs may have changed, but I seem to recall 5 kWh being a reasonable battery pack size. Let's say the silicon array is 20% efficient at 6 m2 and solar radiation is 1000 W/m2. That's about 1200 W array output, so 4-ish hours to refill the pack.
Sounds like batteries are smaller now than they were in the past. But yeah, 1000 W/m2 is only plausible around noon. So if you're looking at morning or evening charging multiply the time by like 2.

If you were to drive at night, you could drive 4 hours perhaps. If you wanted to go highway speeds, perhaps only 2 hours.

It depends a lot on speed and terrain. If it's perfectly flat and you're going slow, (you can go) a long way.

You will also sometimes hear teams talk about a "break-even speed" at which they are neither discharging nor charging their pack while driving. Of course, this break-even speed is dependent on how much solar radiation you are getting. On a sunny day in Australia, you might be looking at a 55 mph break even speed.

Anyways, assume a constant solar radiation: Go your break-even speed, and you can travel forever, even without a battery. Go faster than this, and you discharge your pack. Go slower and you charge your pack, even while driving.

Here is a better summary of your battery only driving question: Cruising around the suburbs/town on surface streets - 4 hours perhaps (with not a lot of stop/go)

Cruising on a US route (maybe 55mph) - 2 hours.

We can probably run about 250 miles on just the battery at a decent pace (45-55 or so).




July 20th, 2012 at 10:26 AM ^

I heard some pretty interesting tips. First, I guess the rule of thumb for solar is every square meter of sunlight has about 1kW of power, but then you have to figure in the efficiency of the solar panel to realize how much you'll get. The solar panels out there get ~15% of efficiency, so 150W for every square meter of panel. Now, as for the charge time, that just depends on your battery size. I'm not sure what size motor they use in the vehicle, but I would guess the battery is sized to supply just about enough power to run that motor long enough for one leg. If I had some values of the battery size and the dimensions of the vehicle I could probably give you a more accurate answer. I hope this helps you understand it a bit better.


July 20th, 2012 at 10:46 AM ^

Current silicon cells are more like 20-25% efficient. Gallium arsenide triple junction cells are over 30% effiicient, but have been more or less banned from the major solar car races to make the competition tighter (those cells are incredibly expensive and shut out the less wealthy teams).

The size of the packs is set by regulations to a certain weight, depending on battery chemistry (e.g. you can carry more lead-acid cells by weight than lithium ion, but lithium ion cells are more power dense). The net result is that a good pack holds about 5 kilowatt-hours of energy (i.e. you can use 1000 watts, basically a microwave, for 5 hours).


July 20th, 2012 at 10:41 AM ^

Was wanting to get out to see you guys in Verona yesterday, but work got in the way - being in madison and badger country, seeing the maize and blue would have been awesome!

Naked Bootlegger

July 20th, 2012 at 10:52 AM ^

As promised, I cheered on the Quantum crew at their mid-afternoon control stop near Madison, WI. This crew is a well-oiled machine.

The most annoying aspect of the control stop today was construction immediately preceding the parking lot. The crew ably hand-carried Quantum for maybe 100-200 yards over a section of chewed up road laden with rocks.

My favorite image was of UM Solar Car uber-supporter Chuck Hutchins surveying the landscape:



July 20th, 2012 at 11:22 AM ^

Awesome, thanks for the pictures. Former Team member, Ethan Lardner, posted images from the same parking lot. There was talk of penalities for carrying the car over the gravel. Since it was after the control stop, there should be no penalty. Chuck is very cool.

Naked Bootlegger

July 20th, 2012 at 11:32 AM ^

I was wondering this myself yesterday, but Chuck convinced me that the official timing tent was located before the road work and the crew was able to carry the car to the parking lot for 1 hour break without penalty.    I hope this scenario still holds true today.   I think it's completely ludicrous to make the car navigate rocks, gravel, and deep potholes just to park in the ASC designated parking lot.    Oh well.   This scenario allowed us to watch the team in action with on-the-fly problem solving, so that was cool to see!  


I offer one additional picture of a mini-Denard in complete awe of the UM Solar Car trailer: 




July 20th, 2012 at 11:16 AM ^

I got stuck behind Minnesota's car on the drive into work today.  They were at the corner of County Road PD and County Highway M in Verona at approximately 9:20 am central time, FYI.


July 20th, 2012 at 12:08 PM ^

I spotted one of the Competitors cars on my way home from work in Kazoo the other day.  It must have been one of the one's listed a "Trailer" above, because they were putting it on a flatbed.  Go Blue! 

Feat of Clay

July 20th, 2012 at 2:50 PM ^

I didn't know for sure who anyone was, although Rachel looked familiar from the documentary I saw on WSC.  I would be reluctant to tag anyone while they were on the road and unable to un-tag  if they preferred anonymity.  

I didn't get a shot of this, but I also enjoyed eavesdropping while someone (might have been Jeff Cwagenberg?) provided an animated account of how they shipped the car to Australia for rapt Iowa State team members.

I just missed getting a photo of MSC chatting up the team.  I stopped to greet someone else from the Fleming building and when I got done with that President Coleman was headed out.

Blue since 82

July 20th, 2012 at 4:30 PM ^

I have been swamped at work and not able to watch this race too closely today.  Do we know if they have improved their lead today?  I tried to get on the ASC website but not only is it slow, for me it isn't even loading.


July 20th, 2012 at 4:39 PM ^

The ASC site is mastered by a former Team member, ironically. However, he has no control over the hardware which must suck.

Anyway, Quantum cruised in at 12:43 PM with Principia following 2.5 hours later. Iowa State is approaching La Crosse but not in yet. No idea where CalSol is. The speculation is that Quantum's lead will be so big that they can pretty much push the car into St. Paul and still win. Ha.


July 20th, 2012 at 5:40 PM ^

Michigan's lead over the pack at the Stage stop in La Crosse, WI is currently 11 hours 1 minute. This is more than the 9 hours I predicted 2 days ago. I suck.