# Ground up ultra light EV. Need some guidance.



## TriGlide (Feb 8, 2009)

The goal: 2 seater, 100 miles a charge, top speed 50+, budget important.

I plan to make a lightweight 2 seater much like the http://en.wikipedia.org/wiki/T-Rex_(automobile) . It will be lighter since the speed and torque will not be as demanding. I was going to make one with 600 cc bike motor but dicided that it would be a good chance to try electric.

Questions I need help with: 1. ac- dc? which of either better meet my needs? PM motor? good amps/ volts 
2 controller- reversable, variable speed, coast or use motor to slow and recharge?
3. Should I use some solar suppliments and should I separate power for drivetrain and lights, radio...
4. Battery options to suit the other components and goals.
5. Should I integrate a 6 spd motorcycle gearbox or simple belt drive?

I would like to stay as close to $2000 as I can for this project but that is flexable if worth it. Also wondering if there is a good source for used parts and EV clubs in the area.


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## RQDQ (Feb 9, 2009)

Well, your budget is making some of your choices for you... 

Batteries - Lead Acid is your cheapest bet. However, as you may have already guessed, any product with "Lead" in the title probably doesn't sound like an ultra light EV. If you want better power to weight ration, you'll need a more expensive battery system (e.g. Lithium based batteries are getting cheaper, but they're not there yet).

DC / AC - For the price, DC. From what I've read so far, AC is significantly more expensive.

Keep us posted on your progress!


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## TriGlide (Feb 8, 2009)

I am leaning to AC motor. I also think $2500 for just the drivetrain should do it for such a light EV.


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## RQDQ (Feb 9, 2009)

Cool - what are your numbers looking like for the prices of the main components so far:


Motor
Controller
Contactor
Batteries
Charger(s)
Gauges
Wiring


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## TriGlide (Feb 8, 2009)

To be honest I am just looking for a good direction so I can narrow down the options. There are so many choices so I have to know what I need to narrow it down. I am really just looking for motor controller and batteries right now. 

First thing I think is to figure out drive system... tranny or direct? Donno if a gearbox would provide more resistance then worth but with peak torques and efficancy around 1800-2400 rpms think I need it.

I would like AC for regen, reverse and lifespan but I don't know what my power requirments are. Once I figure that out then the controler and batteries will follow.

Once I get this figured I will worry about the rest. Oh yeah and I have to build the frame, lol. I have started drafting the plans and will post idea soon.


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## esoneson (Sep 1, 2008)

I don't know how light of a vehicle you are thinking about, but you might want to take a look at what the folks at the University of South Australia have done. They have created (using simple tools available to most everyone) a Monocoque tub (frame) and body that weighs in at 64kg, including an acrylic canopy.

http://www.autospeed.com/cms/search/index.html?keywords=ultra+light-weight&x=0&y=0

*Technologic*: Since you are also designing a light weight 3 wheeler, have you seen this too? What do you think?

Reminds me of the Graduate.............

*Mr. McGuire*: I want to say one word to you. Just one word. 
*Benjamin*: Yes, sir. 
*Mr. McGuire*: Are you listening? 
*Benjamin*: Yes, I am. 
*Mr. McGuire*: Plastics. 
*Benjamin*: Just how do you mean that, sir?


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## TriGlide (Feb 8, 2009)

I am going to use 2" tubing for frame with thin sheet welded for flors and housing components but it will be open ie sand rail ...


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## Jason Lattimer (Dec 27, 2008)

http://www.family-motorsports.com/SUNL_SPIDER_150cc_Motor_Trike_Moped_Scooter_p/sl-150t-27.htm

I found this. I am planning a reverse trike. This is 3000 dollars and is street legal in 49 states. Takes the work out of most of it. I plan on using the 13" hub motor on the Kelly website. It is the same size and power as the gas engine and tire it comes with..


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## TriGlide (Feb 8, 2009)

What I am planning is very similar in suspension and layout but with lower profile, slightly longer wheel base. Thinking of using motorcycle tires and use rear suspension from one too.


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## john818 (Aug 1, 2008)

TriGlide said:


> The goal: 2 seater, 100 miles a charge, top speed 50+, budget important.
> 
> I plan to make a lightweight 2 seater much like the http://en.wikipedia.org/wiki/T-Rex_(automobile) . It will be lighter since the speed and torque will not be as demanding. I was going to make one with 600 cc bike motor but dicided that it would be a good chance to try electric.
> 
> ...


I'm thinking of building a scratch-built reverse trike, too. I'm not the most knowledgeable guy around here, but here's my $0.02.

(4) I can't think of a way to get a 100 mile range on a budget of $2000, even if the whole budget went to batteries. Range isn't a priority for me, so I haven't really looked into it, but I'd bet range vs cost is where you'll have the most trouble making your build work.

(1) I agree with RQDQ. DC makes more sense for a budget build. If you can spring for AC, check these out...
http://www.electricmotorsport.com/store/ems_ev_parts_motors_ac-induction.php

(3) Solar panels on the vehicle is not worth it, especially on a budget build. Too much cost, weight, and complexity for too little gain.

(5) If a top speed of 50mph or so is your goal, I'd bet you can do without a transmission. Most EV motorcycles don't use them. Regarding belt drive, most people do chain. If you have to adjust ratios by changing sprockets, you can add or subtract links from the chain, but belt lengths are fixed, so you'd have to buy a whole new belt, and they're not cheap. Of course, they are much more quiet, which works great with a quiet EV!

Assuming you're not building a leaning trike, I'd recommend against motorcycle tires. They'll wear out much faster than car tires, so you'll have to replace them frequently ($). If you end up going with a motorcycle swingarm on the rear, I've heard of people mounting car tires on motorcycle rims. If you keep chassis roll to a minimum, the tilting of the tire vs the road won't be too much of a problem.

There are a few people building reverse trikes on the Locost site I visit. You might be able to get some ideas there. Here's a link to the part of the forum where much of the trike stuff is. They also have sections that cover building a frame, designing suspension, and all kinds of stuff.
http://www.locostusa.com/forums/viewforum.php?f=18&sid=0d792ab19d5b3aa3e0644c8b323d4015

Good luck with your build!


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## TriGlide (Feb 8, 2009)

I am thinking of one of these http://www.electricmotorsport.com/store/ems_ev_parts_motors_sepex.php

With http://www.electricmotorsport.com/store/ems_ev_parts_batteries_thunder_sky.php

but I don't know how many batteries I need and how to calculate amps needed.

I think this would really help too. 

Are there any components I am missing? Besides charger.


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