American Solar Challenge

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oguitar
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Joined: Wednesday, December 8, 2010 - 19:31
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American Solar Challenge

Hello all. I am currently a student at UNM and for my senior design project we are building a solar car. We have about 12 team members (all EE's) and we are going up against so well funded well established teams.

Currently all my focus is on the mechanical side of the car but soon I will be looking into the electrical side. I was wondering if there are any people on this forum who would be willing to offer advice or give any tips to a rag tag team.

I can post pics later of the frame we are building. The goal of the race is to use solar energy to power our car around a track. If we can meet a certain amount of laps we can compete in a road race.

Has any one ever done this before?

colin9876
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Joined: Thursday, October 23, 2008 - 11:37
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Re: American Solar Challenge

Ive been experimenting with solar arrangements for a few years now, this is what I would suggest for ease and low cost.

If batteries are allowed in the rules, make some panel/battery units.
Each solar unit consists of a LIFEPO4 2.3 amphr A123 cell with its own 5v 250mA solar panel (This combo costs about $20).

Examples

http://cgi.ebay.co.uk/New-A123-systems-26650-Lifepo4-battery-cell-2300-x-8-/230564826267?pt=LH_DefaultDomain_3&hash=item35aebc0c9b

http://cgi.ebay.co.uk/5-5V-320mA-1-76W-solar-panel-power-led-lights-battery-/320512530812?pt=UK_Gadgets&hash=item4aa009197c

Aabout 15 of these units in series will give a 48v system

So for $300 you have a system that can store a whole days sun charge, doesnt need charge balancing (as each cell has its own panel), can supply (48v x 50amp= 2kw) no problem, and can charge while being used.

for a small car you could use say a 500w-800w hub motor as the back wheel (in a 3wheeler set up), this would give you about a 15 minute run time + whatever the sun tops up

....

If you are not allowed to use stored battery energy, use a 200w hub motor, and bigger solar panels, each unit being 2.5v 5amp coupled to a Maxwell 3000F supercapacitor (19 units=48v) - This would give unlimited while the suns shining, and around 15minutes too with no sun, I can supply more info if required?)

oguitar
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Last seen: 7 years 7 months ago
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Re: American Solar Challenge

Excellent links. Thanks for the help. I will post more details of our car soon. We will be running off of battery power, but if we could run directly off the sun then that would be even better. Currently we are planning to use the electric motor that is on the Vectrix scooter. We are using a Kelly KBL Brushless Motor Controller. Hopefully we can get the frame built within the next few weeks.

Do you know where I could find some of these flexible solar panels that allow the car body to be very aerodynamic?

Sort of like this.
//i141.photobucket.com/albums/r55/krystalMage/honda_solar_car.jpg)

colin9876
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Last seen: 7 years 1 month ago
Joined: Thursday, October 23, 2008 - 11:37
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Re: American Solar Challenge

I would definately NOT use a vectrix motor, just on safety grounds alone.
Anything up to 50v and you are unlikely to get a shock (body's resistance is too high), but the vectrix operates at over 100v, why take the danger risk?

Thin film solar panels are great, very light too, can be quite expensive but prices are dropping now more manufactures around, one is
www.powerfilmsolar.com

oguitar
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Last seen: 7 years 7 months ago
Joined: Wednesday, December 8, 2010 - 19:31
Points: 11
Re: American Solar Challenge

So after a lot of blood sweat and tears we finally got this car working good. I think we got the car up to about 45MPH. Total voltage was 108V and 33Ah. Our suspension and steering sucks but we will fix that. Next project is getting rid of the heavy lead acid batteries and gettng Li-Po batteries installed.

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