Hello! Advise (Electric Motor) on EV build!

[CarlosP]

Excellent build.. More or less what I'm looking to build..

Ironically I was looking at some 72v motors a couple of days ago, but they were golf cart engines.. But I'm not sure if they would be powerful enough for a build like this. They were rated about 4-5hp and around 4,200rpm.

What specs would be the best to look for in a 72v motor, as in torque, hp rpm?

[Oval_Overload]

20 HP, 40 hp peak seems to be a common number. Don't worry much about torque. Any electric motor you find will have fistfulls more torque than the three pot engine that you pulled out. Besides, you have 5 gear ratios to choose from. Before you go out buying ****, think about the future. 72 volts is a very low system voltage... Solectria's are 144 volts, Tesla is like 320 volts. I worked on a gel lead-acid/WarP car that ran at 177 volts...
You may want to upgrade at some point!

The lowest voltage component in your system is what will hold you back. You are building a 72 volt car, but you may want to spend a wee bit more for a 96 volt charger (Delta Q makes a nice one), 96 volt contractors, 96 volt shunt, 96 volt fuses, etc...

Going overkill on the component rated voltage will make voltage upgrades easier. Say you are not satisfied with the car's performance, if your components are appropriately sized, you just pop another battery in and away you go! Also, using a higher system voltage will yield the same performance from smaller, lighter wiring, while drawing fewer amps and getting more range.

Just something for you to chew on

~Jimbo

P.S. Could the mods move this to the FFF forum?

[CarlosP]

Yes, I would be a good idea to spend a little more on better chargers, etc.. in case of a future upgrades. Although, a setup of 144volts or more is going to be too costly. It would definitely be a a far better choice.

If I could over volt to 96v, I think it might be enough for daily commute. I don't think a car this small is going to handle so many batteries as to accommodate a 144v system, and a 320v is even further off.

Yes, this thread went from introduction, to technical.. should be moved.

[CarlosP]

I found some pretty good books online, with conversion charts, formulas etc.. I think they might help a lot of beginners like me, and probably some experienced people too.

I'll see if I can post them on the forum..

[Oval_Overload]

For your needs, I think you'll be more than happy at 96 volts. You probably want to connect with other electric Geo owners to discuss suspension and weight distribution.

I probably should read those books :P

May I ask you what we are dealing with financially? What components would you like to buy new and what would you prefer used? This way I can give you a heads up if I happen across a suitable part.

Carlos, are you going to build Paul's controller?

[Oval_Overload]

Carlos, come out come out wherever you are