Electric car questions

[Matt23]

Electric car from scratch!

hello everyone! I'm presently planning to build an electric car from scratch and need some help with a few factors. trying to get the best bang for my buck, i'm interested in getting the BLDC 5kw, 72v motor (with matching controller) and had a few questions (I have read around on the forum and had some some what answered).

1. the total mass of the car will be around 550kg to 600kg  (# was made after some calculation and is overestimated to conserve) with everything in it (motor, frame, person, wheels, batteries, etc.) and it will be quite     aerodynamic. using the 5kw and 6  88.3ah 12v batteries  is it possible to hit 50 mph (wheel size is 22'' and 15lbs of drag at that speed)?

2. How long with the setup above could the system go, distance wise?

3. can it climb a 10-20 degree hill for 3 miles with out going wicked slow or draining the batteries?

4. whats the best way to setup the six batteries above that can provide the most speed, acceleration, and distance?

5. what factors change if I were to step up to a 10kw motor (trying to conserve $$$ so if the 5kw works that's great!)?

6. with everything above what kind of gear ratio might be best or should I fabricate a custom transmission to suit all conditions (have considered this and the setup would be a chain drive system so the transmission would be more like a bicycle derailing setup)?

These are the only ones I have for now but i'm guessing more will come in the future  I really want to make this project a reality this summer so your help is much appreciated! I have done some calculations for total drag at 50 mph and some investigation on setting up the electronic system, the frame will be a breeze to build for me.

Oh also! if you know of other ways to save some money and I can still get the same outcomes i'm all ears! 

[naveen.rabelli]

Hi Matt,

I am doing something similar for last one year now, making a solar+electric tuk tuk www.facebook.com/projecttejas.  I want to share some of experience/results.

1) the total mass of the car will be around 550kg to 600kg  (# was made after some calculation and is overestimated to conserve) with everything in it (motor, frame, person, wheels, batteries, etc.) and it will be quite     aerodynamic. using the 5kw and 6  88.3ah 12v batteries  is it possible to hit 50 mph (wheel size is 22'' and 15lbs of drag at that speed)?
--> a) check on the weight again, go in to details of frame, battery weight etc. If you are still correct. 600Kgs is what my vehicle also weighs. And I use 48V 200AH batt, giving me a range of 80 Km, at a speed of 45 KMPH average on level road, and goes upto 15-20KMPH on 14 Deg Hill( this is what I could test for). so for 88.3 AH, Range will be around around 42-45 Km( my guess).
I don't have gear ratio with me right now as I am using 4 manual gears, I will get it to you soon. 
b) if you want to use 10KW next time, which is what I am too looking to change. Your setup , like adaptor plate, interconnecting shaft and mounting will change. Not so difficult, but the tricky part is ,Real estate.
c) It is very helpful to have some kind of diagonistic setup for speed of motor, temp of motor+ controller, speed of vehicle.
Only way I could have saved money was to do it right the first time. Sadly, with no prior experience, I spent more than my budget. No regrets though. And to do that, divide into small stages for example: 1) motor and transmission 2) battery setup 3) lectrical wiring harness 4) body. PLan and plan and plan before you do to save time and money..
cheers
naveen