Hi all!
I'm trying to modify my car to get max MPG, and I've come to the conclusion that because of where I drive (mostly short, urban trips with lots of hills with occasional long highway trips a couple of times a year) some form of electric/petrol hybrid would be a good option for me.
I don't want to sell my car, and can't afford another. My car weighs around 1070kg, plus say around 200 for me and a couple of passengers.
My main target for this is creeping forward at very low speeds in traffic (5mph maybe a little more) and cruising at highway speeds around 56mph. I'll be working to improve aerodynamics on my car where possible, but according to a horsepower calculator I used that factors in drag and weight I need around 7-10hp to keep the car moving at this speed.
Basically, I want to make this as cheaply as possible. I haven't been able to source any motors out of a scrapped hybrid, and all the ones I see online are far too expensive for me.
Ideally I want to make it run from a seperate battery in the boot (I'm thinking start with 12v lead-acid because I have a couple of spares already) which I could charge from home and via solar panel, and also maybe regenerative breaking if I get that far.
Electronics are not a major concern for me but I am not the best at mechanics, so I will be getting help at installing anything that I need. My first thought was the starter motor. This is capable of providing around 20hp, and is already installed and ready to go in a sense. Could I use this to power the car?
As I understand it the problem with starter motors is they are designed to operate for very short periods of time before they overheat, which is understandable. If I added enough cooling to the starter motor would it be possible to make it drive the car? Also if I used one to turn the wheels directly rather than spinning the engine and gearbox, controlling the speed correctly would that be doable?
If that won't work, can anyone offer a suggestion as to where I should look next... I'm really interested in doing this. I'm going to be essentially making my own engine management and control combined with a computer monitoring speeds, gradients, fuel usage, temperatures and all sorts of other things to calculate what to do in order to optimize the engine and also switch between the two or maybe use both!
Any advice would be great here guys
Thanks!