design of low cost electric vehicle

sivaramakh

we undergraduate students are plaaning to make a low cost economical tousrist vehicle partly powered by solar also.the specs of car is as folows

max weight of vehicle including ppl is 450kgs
max speed=20km/hr


we are having trouble finding the specs of battery solar panel etc .
can anyone provide us information on how to design a basic electric vehicle and how to decide on solar panel,battery ect

ChristianG

Well this forum does discuss certain Ideas around electric vehicles but it's not a very good place to ask how to build a electric car by yourself. You also don't tell a lot about your project, 450kg with passengers.. well how many of them?

It kinda sounds like an Idea you had over a beer or two and then bring it in here without any Idea... But well Google is your friend:

http://www.didik.com/ev_build.htm

And now your work starts. Find components, if they don't have specs, ask the manufacturer, compare them and then decide.

Remember there are many transportations outthere wich are already working and fun. for example segway. So you really have to do something right to compete. Especialy with 20 Km/h

sivaramakh

@christiang
actually we are trying to make a low cost electric car,replacing most of the mechanical devices in the car with its electric equivalent.


we have decided that the chesis will be made of iron and the abt the base is carbon fibre a good base compared to steel and aluminium??

Timo

Carbon fiber costs <b>a lot</b>. You wouldn't be doing low cost vehicle with that. There are other cheaper alternatives like hamp fibers. You probably also need steel frame to keep its structural rigidity high enough without increasing weight too much.

Aluminum is a good, light source, but AFAIK it is a bit tricky to work with. Aluminum that touches most other metals cause electric couple that causes heavy corrosion in there (usually that other metal is the one that corrodes).

Then there are plastics, which are cheap, but also look cheap, so desirability of the car weakens.

No matter how you look at it you will need to make some tough choices.

Because this is very low speed vehicle that doesn't really count as car, more like four-wheeled (it has four wheels, right?) golf cart for passenger transport, you could use something like fiberglass for body panels.

Actually you might have ready models for your project in golf carts. They can probably do 20km/h and some of them seat four. Maybe rip controls from electric wheelchairs? Those too can move pretty fast and have good and very precise controls.

Brian H

Good comment, Timo. Except it's "hemp", not "hamp". But don't let that hamp-er you!

Timo

Odd that my browser didn't warn me about that typo. Writing here in another computer it does. (hemp is "hamppu" in Finnish)

Kevin Sharpe

"Riversimple is a revolutionary transport company, based in the UK. We are aiming to produce highly energy-efficient vehicles for personal transport."

http://www.riversimple.com/

Lingil

Being one who really appreciates a clean environment and doing things for the good of the earth, I really don't for see the electric car making any major impact until the majority of car owners are in a financial position to own one. If car manufacturers would take into account, that by keeping prices obtainable for the common people, we would be able to make huge changes as far as emissions into the air far more quicker than we will if the cars are only made available to those who have unlimited funds. We need to ask ourselves what is it here we're really trying to accomplish? Clean air or the next best thing in a money-making car? Hmmm...

dsm363

Lingil: Even people who buy the Roadster don't have unlimited funds (most of them anyway).
Were the first cell phones or plasma TVs affordable? We're at the start of the adoption curve. Technology costs and more and more people adopting it will help drive the price down. Yes, you're right that a few EVs on the road won't cure global climate change but it's a start and it helps to reduce our dependence on foreign oil. Do you expect Tesla and the other car makers to sell cars at a loss?

Lingil

dsm363: absolutely not do I expect manufacturing at a loss. But I have experienced first hand, the positive results that are possible when dealing with people fairly from a financial point. By utilizing the best marketing tools available, having exceptional exposure, and by keeping manufacturing costs affordable for all, more product is sold in a shorter period of time. Whereas, if it is left to only those who are financially sound to drive the sales, what is being accomplished and how long will it last? I understand how things eventually come down in price when the newness wears off. But what I'm saying, is why should everyone have to wait that long to see positive results? Why not get it right, right out of the box? There are many intelligent people that have accomplished great things. But there aren't too many that I have seen that are doing it for the right reasons. When that one comes along, it will be evident to everyone. I hope it eventually comes to that. There's a lot at stake. Wouldn't you agree?

Lingil

Brian H. I'll consider being referred to as a true greenie, a compliment. Thank you. If there were, in reality, pixie dust, as you call it, the world wouldn't be in the condition that it is.

Brian H

dsm363;
Yep, true Greenies believe in pixie dust.
;p

dsm363

If people were clamoring for EVs, government or companies were fighting to place fast chargers ever 15 miles on the highways and batteries were dirt cheap the things would happen faster. All good manufacturers try to keep costs down to maximize profit. The batteries are a major cost at this point. Look at the Nissan Leaf. It's still in the low 30s which some people would consider too expensive.

What do you think Tesla has done unfairly up to this point? You can't really consider the Roadster in this. It's a premium sports car and not representative of the general market. It was designed to prove the technology, attract attention, and build excitement for the brand. It was never made for mass consumption. The body is made out of carbon fiber after all which that alone probably costs more than most cars.

Timo

Currently cheap practical long range EV is an oxymoron. Can't be done...yet. Those that are cheap are either hybrids or city cars.

Also you can't build a startup company by producing a car that doesn't provide any profit. Look at Think City. Do you think that is practical? Or cheap even? You might be able to afford one, but would you buy one? Glorified plastic golf-cart.

That forces to go from top to bottom, not the other way around.

Kevin Sharpe

Lingil: it is possible for 'social enterprise' to have a role to play in the transition to electric transportation. For example, I run a UK charity that undertakes 'green' projects including the donation of EV charge points to public locations.

IMO however, it is unrealistic to think that a car can be produced by a social enterprise... the costs are simply beyond the reach of any such organisation and the best thing we can do is to allow companies like Tessa to take the financial risk and reward them for success by buying their products.

Sudre

I just finished a remodel project at a company called Paraquad here in St. Louis. They purchase used electric wheel chairs and refurbished them for re-sail. This might be the route to go for your electrical parts. They had one chair they rewired that would go 35MPH, if I recall correctly. It wasn't a real safe/useful thing it was a just for the fun of it wheelchair.

For a light weight frame maybe think along the lines of steel tubing. I built a go cart as a kid that way and it was pretty light. Rather fast too using a 3HP gas engine.

For some decent lithium ion battery packs and chargers, this site is a good one to start;
http://www.batteryspace.com/1-2cratepolymerli-ioncellspacks.aspx

Also gives you an idea why electric cars cost so much. Tesla is providing a very nice vehicle and dirt cheap prices at $50K.
$98.95 for a 3.7V 21Ah battery. Now think of the cost just to group enough to get to the voltage needed to run 400ish volt motor.

qwk

I still cannot believe people whine about the price of a roadster or model s. A roadster is comparable to a supercar, and a model s is comparable to a mercedes or bmw. I don't see any new supercars or luxury cars for sale that are cheap.

Tesla does not have the capital needed to build an affordable car, YET. They are working from the top down, which takes time.

As far as people not being able to afford the model s, it's all about how bad you want the car.
I run into way too many people that whine about being able to afford this and that, while spending $100+ on cigarettes, booze, junk food every week. With a little common sense, anyone who puts their mind to it can afford things that seem out of reach.

VolkerP

It is not the car makers job to change to "green" cars and produce them at a loss. It is the decision of the public society if they want to go green and at what cost. They should elect the politicians that can make the adequate policy.

One possibility is to adjust tax regulations. In Denmark, they tax 180% of purchasing price for ICE and 0% for EV. This will allow EV car makers to sell EVs even if production costs are higher than for comparable ICE car.

sivaramakh

why cant there be a low cost EV.
a car with speed 30km/hr is enough to travel in the traffic today .
talking about the battery capacity why cant we go for a low end li-polymor or or VRLA battery that can allow a person to travel max 6 hrs . it will be cheap for a two person drive isn't it.
more than that it will do a lot more good to the environment

Timo

5kW * 6 hours = 30kWh battery. Not so cheap or light considering that Roadster battery is 54kWh and weights about 450kg. Your battery would weight around 250kg and cost (assuming cheap li-ion) $6000 - $8000. Light weight costs. Heavy is cheap, but your range drops dramatically.

Kevin Sharpe

many people have tried this.... Going Green imported the G-Wiz NEV into the UK for many years but are about to stop because of limited demand...

http://www.goingreen.co.uk/

Ramon123

What do you mean "powered by solar ?"
Since solar panes on the car itself are practically useless, I
assume you mean a carport or something with solar panels on the roof. Knowing your latitude would help for a better estimate of
you expected irradiance, but more important would be exactly when are you planning on harvesting solar versus operating the vehicle?
If the vehicle is operating as the sun is shining, then you need stoarage batteries to store the harvest until the car shows up.
Lead acid would do, bu that's not particularly cheap and you'll lose 25% of the harvested solar energy because of storage. if net metering, then that's a different story. Currently I've been pricing multicrystal panels, with 25 to 30 year warranty. Costs of the panels themselves are $1.65 to $2.00 per watt. But if you need to store to the grid via net metering, you'll also need microinverters (or a central) and that'll run another 70 cents per watt or so. If going directly into car as DC, don't need the inverters. Assume irradiance of roughly 6.5 suns in June to a low of roughly 3.8 in December. Harvest averages suns times solar
panel array size (in kilowatts). A 5 kilowatt array will produce on average 6.5 times 5 or 32.5 kilowatthours a per day in June, etc. Without inverters, 5 kw array will run $8250 to $10,000.
Add about $3500 if inverters needed.