How To Figure Out Horse Power/ EV Car?

Question

Ok I Have 1990 Geo Metro That Lets Say Weights About 2000 Pounds. I Am Trying Come Up With The Minimal Amount Of Horse Power Electric Motor Will Be Need To Move It At 35 Miles An Hour With ½ Way Descent Acceleration. Town Is Pretty Flat But Let Think About A Small Grade All The Time?

Answer 1

If you don't want to do the sums drop these guys a line. they will recommend a system for you. I recommend that you do this as the calculations get pretty involved and these guys do it all the time.

http://www.metricmind.com/

If you like doing sums here is some info .

The power required to move a vehicle is made up of two sections rolling resistance and wind resistance.

The formula for wind resistance can be found on this link.(under power) ( I usually work in metric and use 1.22 kg/mmm for air density and if you don't know your drag coefficient 0.4 should give you somewhere to start.)

http://en.wikipedia.org/wiki/Wind_resist...

The formuls for rolling resistance will be found here. There is also some typical values for coefficients here

http://en.wikipedia.org/wiki/Rolling_res...

For acceleration (f=ma)

Force = mass x coefficient of rolling resistance x 9.81(gravity)

power = force x speed.

This is only a very basic guide and does not include calculations for going up hill. It does give you an idea as to what is involved though.

For the exercise

I come up with around 5.5 hp to maintain 35 mph On the flat. About 20 hp to do 35mph up a 7% slope (moderate hill)

The 20 hp is going to take about 8 seconds to get you to 35mph (pretty slow huh)

Picking a system usually mostly involves budget you just buy the most powerful system you can afford.(with the range that you need).

You should be aware that an electric vehicle that does not need to carry it's own energy is much more efficient. The technology already exists to transfer power to an electric vehicle. This is not available on our roads (yet)

Answer 2

A power level of 1 hp is approximately equivalent to 746 watts (W) or 0.746 kilowatts (kW). To convert from horsepower to watts, multiply by 746. To convert from watts to horsepower, multiply by 0.00134. To convert from horsepower to kilowatts, multiply by 0.746. To convert from kilowatts to horsepower, multiply by 1.34.

Answer 3

You can convert your Metro into an EV for little money.  Here is someone who has done it. http://www.forkenswift.com

Answer 4

Dont use a Geo Metro might blow up!!!!!!!!!!!!!!

Answer 5

Engine horsepower ratings are determined on special equipment .

Dynamometer

A machine that's used to measure the horsepower output of an engine.

Answer 6

That's an easy and straightforward build, since you're only trying to go 35 mph.  Shouldn't cost too much either.  I recommend getting on the EV list (mailing list) where you can get a lot of good advice.

http://www.madkatz.com/ev/evlist.html

Don't take motor horsepower too seriously.  Cars do a lot of temporary acceleration. Electric motors can be overloaded massively for short bursts. That's how the Maniac Mazda (with two 26hp motors) can beat a 400hp Dodge Viper.

Answer 7

try

http://www.amazon.com/Build-Your-Own-Ele... for all your answers

I don't know what a Geo metro is. but I have a Peugeot 205 conversion with a 62hp motor, does 60mph & 30 miles per charge on 10x12v deep cycle Trojan batteries.

In the UK there is the Battery Vehicle Society that can help; there must be local equivalents

Answer 8

It doesn't take much motor to make any car do 150mph and 0-60 in 2-4 seconds.

The standard in EV motors come from these 2 companies.

http://www.go-ev.com/

http://www.acpropulsion.com/

Both of these companies have motors that will out run even the fastest cars on the road today.

However, your speed and acceleration will depend mostly on your batteries. You can make a low voltage battery pack that lets you run a slow car for a long time or a high voltage battery pack that lets you run a fast car for a short time. If you can afford Lithium Batteries then you can have a fast car that goes 200 miles on a charge. Lithium battery packs start around $10k.

This page will start you on your way. You plug in all the details of your car then try different battery and motor combinations till you get something that'll fit your needs.

http://www.evconvert.com/tools/evcalc/

Beware the E-Tek Motors in the Calculations tho. It' says you can run 5000 miles on a charge but the E-Teks have a low RPM limit and won't actually do what the Calculator says it will.

The rest of the Calculations are fairly accurate and will give you a good starting point for your project.

I did a quick caculation with your car and you will need anywhere between 8-18 hp to do what you want on a 144v battery pack with most of the motors listed.

EDIT: NVM, they took the E-Tek off the caculator.