AC generator idea need help

I am trying to create an EV using an AC generator. my idea is to use the generator to power an AC motor connected to a manual car transmition in a 1989 Honda Civic Hatchback that has been gutted (as much weight as i could take out of it) only problem i face is that i don’t know what size AC motor i should horse power and torque wise. these cars with the standared Gas engine is 108hp 89fptq. i’m trying to achieve a max speed of 50 mph and travel distance of upwards of 300 miles to one tank of E85 in the generator. any input would be gratley appreciated and i will do my best to give any ideas i have

What size of generator are you planning to use?

Do you plan on having any batteries to help with acceleration?

I’ve heard that 1HP in electric is worth 3HP IC. This would suggest you use a 36 HP motor for equivalent performance… But I’ve never tested this theory…:slight_smile:

the generator i would be using is eather a honda EU3000is or the honda EU2000i they produce 3000, and 2000 watts of AC electricity. i didn’t think of putting batteries on board due to there weight and price, and with just the generator there should be plenty of power to run the motor and several electronics (ex: a radio) the EU3000is get’s 20 hours of run time on one tank with heavy load. now i know horse power is good for speed and torque is for acceloration (in gas engines anyway) i’m sortta new to the electric motor part :), so i guess another thing i’m trying to figure out is say a 3 HP electric motor going to be enough to push a 900 pound car?

I am new to the boards as well, and i too am wondering if what spyruem is suggesting is possible? Or are there other factors that need to be considered that would prevent this idea from working? And if so what are they?

btw love the forums, definitely learning alot!

I’m new to EVs too, so everything I say is just theory at this point. :slight_smile:

[I]Theoretically[/I] you could find the amount of power required to push your car down the road by the original highway gas mileage. Like this:

1 gallon of gasoline = 125,000 btu

Watt hours in a btu = 0.29307107

Horsepower in a kilowatt = 1.3


hp = required horsepower

eff = estimated engine efficiency (30% or 0.3)

spd = cruising speed of the car (55 mph)

mpg = original Gas mileage (30mpg)

gph = Gallons of fuel per hour

btu = BTUs per hour

gph = spd / mpg

btu = gph * 125,000

hp = [({[(spd / mpg) * 125,000] * eff} * 0.29307107) / 1000] * 1.3


hp = (((((55 / 30) * 125,000) * 0.3) * 0.29307107) / 1000) * 1.3

Which works out to 26.1 HP to cruise at 55 MPH (At the car’s original weight and drag). But again, this is all [I]theory[/I]! :smiley:

Those numbers are all fine, but they ARE theoretical. They are also assuming 100% thermal efficiency. With an internal combustion engine, most of that heat energy goes out the tailpipe and is diffused through the radiator. Using an internal combustion engine to power an electric motor you lose more energy in the process of coverting mechanical (kinetic) energy into electrical energy and then BACK into mechanical energy. There is no way this is going to work with a small Honda generator. The engine can only produce so much horsepower, and that little engine is the sole source of power to move the car. A 3K generator can probably barely run a 2 hp induction motor, which probably won’t move a car very well.

Another thing to consider is emissions. The small engines used in generators only have rudimentary emission controls, and produce much more carbon monoxide and unburned hydrocarbons per pound of fuel burned than a conventional car engine.

You could make a car powered by a small generator, but it would need batteries (basically a hybrid), and the generator would have to spend hours running while the car sits idle to keep the batteries charged.

[QUOTE=rjstractor;2126]Those numbers are all fine, but they ARE theoretical. They are also assuming 100% thermal efficiency.[/QUOTE]

Actually, the thermal efficiency is included in the general efficiency constant of 30%. I also just realized that I forgot to take into account the drive train loss. (Roughly 15-18%) Again, it’s all theoretical, but it gives you a ballpark idea.

Most electric motors can draw around 15000 watts ( 15kw ), so you generator would have to be the size of your current ICE motor or larger to meet your demands

in my EV hybrid concept project. It seems to me that it is not so much a matter of peak power but of average power and how to deliver that power as demand changes (or even reverses!).
(I am very new to this technology so please forgive my ignorance)
Seems that DC motors are currently the most available “engine” while AC motors are very limited in access and thus being a distant second choice. That seems to fly in the face of wide spread industrial use of ac motors in general being that 3 phase ac motors have similar hp / torque characteristics as dc motors. The additional bonus of ac motors seems to be that they are more easily integrated into regenerative braking.
Now given that most of what was just stated is true, then a hybrid consisting of a high efficiency ICE (maybe even a micro gas turbine generator) coupled to a bank of relatively small capacity batteries and a bank of ultra capacitors could create an optimum configuration of efficiency, average power, peak power, and power recovery if controlled and regulated by a small industrial grade computer such as a pc 104 with open source OS and application software.
Just as an experiment, it would be interesting to build a prototype conversion truck to fine tune the separate components to see what the optimum configuration would be. I like the idea of an off the shelf portable power plant as mentioned in the previous post but maybe the next level up in power rating because I doubt that a sustained speed of 65 mph in a head wind going up a 5% grade could be maintained with 3500 watts - Maybe an EM6500S would be a better starting choice to put in the bed of a truck to evaluate the package. Just my two cents worth… I certainly have a lot to learn and I am very happy to have found this forum.

I’d replace the pc 104 with a PIC32 from Microchip. :wink: No OS, just your code.:smiley:

Hello Everyone,
I just found and joined the forum. I am also considering a gen. powered vehicle. Have you all seen the Town Car by Robert Q. Riley? Here is the link
Check out the specs. It is based on a VW Beetle pan. I have a 5000 watt gen. I want to use. I’m thinking of building a tubular steel frame to keep weight down. I need to get the plans to find out more. Does anyone already have them?