Newbee Competition help

[slackcat69]

What an awesome website! I am a mentor for a high school where we are building a fuel efficient vehicle for a competition. The vehicle must have four(4) wheels (16" x 3"), 46v nominal and 60v max.(I like to keep it 36v for the ease of obtaining parts), 2 electric motor max., maximum weight 408#s (our build weight will be @ 125#s +/- with a driver of @ 120#s...we are attempting to keep the weight as low as possible), the average speed must be 15mph for a max distance run of 6 miles where the teams are allowed to "coast and burn", and LiPo batteries are mandatory with a BMS. I am completely overwhelmed with the options out there. I would like to use a dual propulsion system (one being internal combustion engine and the other battery / electric motor). I've got the "smelly polluter" worked out. I am not sure what is the most efficient method of propelling the vehicle using battery / electric (ac/dc - brushed/brushless motors?, voltage?, controllers?). They will have a joulemeter installed to determine the consumption. Can anyone be so nice to get me pointed into the correct direction?

Thanks,
Mike

 

[Ypedal]

welcome to the forum...

I deleted the other posts, please do not spam the forum, one post per topic is all you need !

cheers.

 

[Pure]

Is 15MPH max as fast as it can go?

 

[Drunkskunk]

BLDC motor is the way to go. A very small Lipo battery could power a 300lbs total vehicle 6 miles at 15mph, without any need for a gas motor. but if you insist...
If you use a Direct drive brushless motor either as a hub motor, or driving through a gear setup with no freewheel, you could have electric power and regenerative braking too.

 

[slackcat69]

Hello Pure!
15 mph is the average we must maintain and verified with a transponder by the organizer. Last year we brought the vehicle up to about 20+/- and let it coast down to 10mph, while checking the lap times with a stop watch.

Mike

 

[slackcat69]

Hello Drunkskunk!
I'm using the ICE to turn a motor (which will serve A's a starter and when running a generator). The vehicle will compete in two(2) separate divisions at the competition. What is the best brand of scooter hub motors and controllers? The secret is to have the wheel to spin A's freely A's possible to maximize the coasting distance.

Mike

 

[Pure]

OK, was curious because a 15 mph limit seems kind hohum to me and most others on this site. Not to mention incredibly below standard of what can be achieved with today's motors and batteries.

Ditch the ICE as it's not needed for just a 6 mile commute. Your 2 motor limit would be much better spent with 2 hub motors in the rear wheels. Slap on 18-20S (74-83 volts) of LiPo and you will have a vehicle that should be able to smoke those 6 miles at about 40+ MPH..

 

[Ypedal]

this is not a commuter machine, this is for competition and the goal is least amount of energy used to cover the distance, first to the finish line does not = win.. It's all about using the least possible amount of energy measured on the provided joulemeter.

I helped a team last year win the challenge :
http://www.shell.com/home/content/ecomarathon/americas/media/event_highlights/2011/04172011_final.html

And this year i have a team from pakistan trying to get me to help them but i'm not overly willing to ship stuff that far away.

 

[Pure]

Ok so then you go with 2 RC geared setups and use coroplast to make some sort of velomobile type of shell. Still get rid of the ICE. I'm pretty sure that it's been proven that, wile ICEs will get you good distance for the amount of fuel burned but that they are actually horribly inefficient when compared to electric motors.

 

[Kirk]

For something off the shelf, get a Pterovelo Velomobile. Install a 250W hub motor, glue a RC motor to the floor. You should be able to get about 5 Wh or less at 30 mph with the hub motor and you have the ICE motor in it glued to the floor. As long as the rules don't specify that the gas motor be hooked to anything, you should do OK.

 

[theRealFury]

If you absolutely have to go with an ICE then so be it, but it sounds like you have a choice and you are wanting to choose to run an ICE and an electric motor. If this is the case then as soon as you start the ICE motor then you have effectively lost the competition to an all electric motor vehicle. Electric motors are over twice as efficient as an ICE motor.

6 miles at average 15mph is going to take somewher in the region of 100watts of battery power with a single motor, if you do not have to use 2 motors then 1 will be more efficient, basically becase you will noly have 1 lot of losses rather than 2. 100watts of lipo is about 1KG or less , same as a large bag of flour! so very light indeed. Another thing against ICE motors is that they tend to weigh alot more than an electric motor capable of the same power output.

short answer, a single electric motor powered with lipo will be the most efficient way to travel the 6 miles at average of 15mph or so. either direct drive or geared drive motors will do the trick (geared being slightly more efficient at those speeds) and transmission should not be needed unless you have large hills to climb?