Solar Powered Race Car for the ASC

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jonesw19
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Joined: Dec 04, 2015 7:20 am

Solar Powered Race Car for the ASC

Post by jonesw19 » Sep 20, 2017 6:19 pm

Hi all! My name is Will Jones and I go to Okemos High School. I have recently started a club to build a solar power racing car in the Formula Sun Grand Prix. What is the FSGP you might ask? Every year the American Solar Challenge hosts the FSGP (Watch the video on the bottom of the screen it’s worth it!). A three day event located at a TBD location where teams try and go around a race track as many times as possible for eight hours each day
A quick rule run down, there is no limit on solar cell efficiency, cars are able to use whatever battery chemistry they wish (typically Li-Ion or Li-PO), solar arrays must be less than four square meters, and teams must have less or equal to two kilowatt hours of batteries. For the entire rule book here is a link http://americansolarchallenge.org/ASC/w ... sion-A.pdf. In order to compete in the FSGP we would need to complete some extremely basic engineering documents by October 15th and have paid a registration fee.
Last year at the FSGP, over the period of the 24 hours, in order to be sixth place in the entire country and beat teams such as Northwestern, MSU, U of T, etc. you only had to drive 305 mileshttp://americansolarchallenge.org/fsgp- ... tus-board/. This calculates down to an average speed of fifteen miles an hour with a 6 minute break every 54 minutes. While highly efficient solar cells, advanced aerodynamics, carbon fiber bodes, exotic battery chemistries, etc. are nice they are not necessary to fielding a competitive team. The key is a reliable and durable car. Four square meters with twenty percent efficient solar cells nets us about 800 watts or one horsepower. This is no doubt easily enough power to propel a lightweight aerodynamic vehicle to well over 30 mph.
Where Endless Sphere comes in is helping us with our component selection. Four square meters comes down to about 800 watts of power we will receive through our panels. Here is our ever changing power system component list while we have learned a lot we still have lots to learn will these components meet our needs? (I have also included an image of a super basic layout to help clarify)
Key Power Component List
All prices reflect estimated shipping and if applicable tax!
Solar Cells
10 - 100 watt semi-flexible high efficiency panels (can only use 8 panels each cell is 125mm x 125 mm 256 = 4 square meters) 2 for backup? http://americansolarchallenge.org/fsgp- ... tus-board/
Cost $1600 (Includes spare)
Total $1600
MPPT charge controller (needs to work with LiPo) & have high refresh rate
5xMPPT 15 hertz 305 watts max Li** compatible (Still need BMS!)
http://americansolarchallenge.org/fsgp- ... tus-board/
Cost $850 (Includes spare)
Total $2450
BMS?
Est. cost $400?
Total $2850
Batteries
5 x 20ah LiPo 6s (22.2 nominal voltage) cells (Will make a 1.8KWh pack) http://americansolarchallenge.org/fsgp- ... tus-board/
Cost $800 (includes spare)
Total $3600
Speed Controller (Must have regen)
3x36-72v 40amp w/ regen http://www.ebikes.ca/shop/electric-bicy ... 40-gr.html
Cost $600 (includes spare)
Total $4200
Throttle, computer, etc?
Est. Cost $300?
Total $4500
Motor
3x48v 1000 watt motor est. 85% efficiency :( http://www.ebikes.ca/shop/electric-bicy ... 40-gr.html
Cost $540
Total $5040

Total estimated cost with spares $5040 est plus minus $1000

The two things that we are confused on are primarily the motor and BMS. We are unsure if there is an off the shelf BMS that might meet our needs and the leaf motor we have chosen is not too efficient. Please let us know if you see any problems in with any of our components. We have tried to choose the highest quality inexpensive parts we can, as obviously our budget is extremely slim. Do any of you have any recommendations on our component list or see anything that is incompatible?
Thank you very taking your time to help up!
OHS Solar

Link to basic electric diagram
https://drive.google.com/file/d/0B1HqnW ... sp=sharing

Link to Video (Watch it!)
https://www.youtube.com/watch?v=LTAK2XN ... e=youtu.be

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amberwolf
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Re: Solar Powered Race Car for the ASC

Post by amberwolf » Sep 21, 2017 1:20 am

Just a thought:

if you need it to be efficient, make sure the motor(s) you're going to use are at their efficient spot for the speed you're going for the highest percentage of the time. and the voltage you'll be running at. The one you've picked might be fine; I haven't checked it out.

This data might not be available for all motors, but you can use the http://ebikes.ca/simulator to play with combinations of system parameters and motors to see what those listed there are like.

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