# Electric single seater



## irmis01 (Nov 26, 2011)

hi guys,

i'm new to this forum and i'm hopping i could get some advice here.

i am doing a project which is essentially an electric race car design. I am still in the early stages of research. I am currently looking for a suitable motor

the performance figures should be as follows:
top speed: 160mph
accelaration: 0-60 mph in 3s
decceleration: 130-50mph in 2.8 seconds
the chassis weight is 420kg with driver but no motor or battery

so here goes some general questions
1) twin motors vs single?
2) whats important when looking into motors? kW/kg ?

more questions to come along the way

help would be much appreciated

thanks


----------



## Guest (Dec 7, 2011)

What kind of race car design and are you going to race it at the 1/4 mile or are you going to race ilke an indy 500 race where you need distance as well as performance? There are lots of variables that we would need to know to help you. For some applications a single motor would be just fine but for all out grunt power twin motors that are large would do the job. Then there is the battery issue. Are you thinking of lead acid? If so forget it. You looking at lithium? You looking a LiPo Pouch cells? LiFePO4 pouch Cells or LiFePO4 Prismatic cells? Voltage of the system and space in the vehicle for the cells? There is lots to figure first. If you just want an electric car to experience a fun vehicle then you might think of just buying an older abandoned conversion and put in lithium cells and go have some fun driving around. Then come back to the table to design an all out race car. You'd have a better understanding and idea of what you can and can't do. Also you will understand the cost involved. Designing and building from the ground up will require a huge investment. HUGE. 

Pete


----------



## irmis01 (Nov 26, 2011)

I am not going to build the car itself it is only a case study.

it has to be Formula 3 like single seater and run for 15 minutes. I haven't looked at the batteries yet, but from what I've researched the types used in single seaters:
Formulec EF01: SAFT lithium cells
Fondetch E-11: lithium-ion cells
Toyota EV P001: lithium ceramic

So i guess it is what i would consider later on.

I am currently looking into motors and from my calculations it would need 150-170kW motor to reach a top speed of 160mph. 

So far am thinking out of these 5:









it seems like evo electric would be best choice


----------



## Rational (Nov 26, 2011)

Point taken. I didn't factor in how long it takes to travel 1 ft at 160 mph.

correction:

0.30	>enter Cd
3.00	>Enter A, cross sectional area, m^2
1.30	>Enter p, air density in kg/m^3
72.00	>enter v, velocity, m/s
236.88	=calc'd ft/sec
0.31	enter D, distance traveled, meters
1.00	= calc'd D, distance traveled, ft
E=0.5(Cd)pAD(v^2)
924.96	=calc'd E, energy, in joules
682.12	=calc ft-lbs
0.00422	=calc'd time elapsed in seconds
161580.6695	=calc'd ft-lbs/sec
294	=calc'd hp

When I wake up tomorrow I'll find something else wrong with this calc


----------



## frodus (Apr 12, 2008)

try adding a couple zeros..... 1.2 won't get it above 30mph. More like 120hp.

Check your calculations.


----------



## major (Apr 4, 2008)

Rational said:


> irmis01 said:
> 
> 
> > top speed: 160mph
> ...


Do you even look at what you type before hitting the submit button


----------



## Rational (Nov 26, 2011)

major said:


> Do you even look at what you type before hitting the submit button


Apparently not. 
I have to log off before I do any more damage. 
The problem is I don't know what are reasonable values, yet, not to mention logical and arithmetic errors and one of the first things I learned was to ask the question, Does this look reasonable?
Sorry, folks. . .


BTW, the drag and cross section I used are default values. Assuming my Excel sheet works now, the OP should plug in his own values.


----------



## tomofreno (Mar 3, 2009)

First calculate the overall gear ratio you require for the car to move at 160 mph without driving the motor past its max rpm, and ensuring the motor has enough torque at the required rpm to supply the required wheel torque and tractive effort to move the vehicle at that constant speed. The tractive effort is equal the force on the vehicle due to rolling resistance force and air drag force, accounting for drive train losses. 

You can also calculate the required motor shaft power, but the main constraint on this will be the acceleration you require. So knowing the required gear ratio, then calculate the motor torque required to supply the wheel torque and tractive effort to accelerate the car from 0 to 60 mph in 3 seconds, assuming you have tires up to the task. You need acceleration of 20 mph/sec. That, the vehicle mass, and drive train inertia, determine the required tractive effort and motor torque. Have fun!


----------



## epyon (Mar 20, 2008)

You could easily build this car with two direct drive motors and Li-ion battery's with off the shielf parts but ...... money would kick your butt . It's stopping me for now. If I had $20,000.00 I could build a 210 mph car with out a dougt in my mind .But then again , just to get the 10 battery's I have , I had scrape money together and wheel and deal just to get them . I'm only saying that we don't like to be teased .


----------

