Street-legal electric go kart/car

[Joe_Oh]

I would like to make a street legal electric go kart with these parts:

Four 12volt 100AH GEL Deep-Cycle batteries - http://www.nationalsolarsupply.com/index.asp?PageAction=VIEWPROD&ProdID=178

1 E-Tek Motor - http://www.electricmotorsport.com/store/ems_ev_parts_motors_etek-r.php

1 CVT (Continuosly Variable Transmission) - Look on Wikipedea or HowStuffWorks.com

Hopefully a prebuilt frame I can buy cheap, or design. The frame has to have a very strong roll-cage.

1 Regen-braking systen would be choice to have.

LED Turn-Signals, ?Low-power Headlights, LED brake-lights, and proper BMV registration.

I'd like to hook this motor up to the CVT in a 48-volt configuration (Up to 4800 watts max). I seen some videos on youtube that give me hope to make a kart that will perform in terms of power and miles traveled before recharge. The idea is to keep this vehicle low-wieght, but not so low it can't hold to the road in a safe manner.

Thoughts? I'd think this will be kickass when completed.

[jr dragster Tyler]

Welcome to the forum. You dont need a CVT for a electric motor. And the mounting holes and shaft size's are not right for the torque a verter.

[Magice]

What would you register it as? You can't register it as a car (I don't think).. Or a moped.

[Joe_Oh]

I plan to design my own CVT from scratch that will be able to fit the shaft of the motor. It will basicly look like two cones pointed at each other kinda like this with the belt driving the two:

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[Joe_Oh]

What would you register it as? You can't register it as a car (I don't think).. Or a moped.

That's why I'd have to goto the BMV and ask them what to do.

[2or3wheels]

Dmv?

[Joe_Oh]

Dmv?

BMV, DMV, Whatever ;)

[Joe_Oh]

http://uk.youtube.com/watch?v=MhFK5gfAGpM

Goto 1:16 and see the demonstration. My design will be similar but without the grips on the cones. I see those wearing out fast so I wont do that. That's the kind of CVT I'd like to do.

[jr dragster Tyler]

Wow so much for a CVT. You have acces to a machine shop?

[JerryAssburger]

If AZ is any indicator, they generally regard electric bicycles as "appliances" , but woe to he or she that uses a lower-performance gas motor... go figure? Regardless, if a lawmaker views an idea as a potential revenue-generator, you'll be forced to licence/register a rubberband powered skateboard.

[Joe_Oh]

Uhm, how do the motor and the combined power from the batteries look? Will they move this thing or what? I seen a 350watt kiddy electric go-kart on YouTube.com and it seemed to get 15mph. The weight of the kid was probably 60lbs + kart/batteries = 140lbs total.

My rig will be 4800 watts max, that's 13.714 times more power than that kiddy kart. Dont get me wrong it was schweet watching that kid ride that thing. Wish I had that when I was that age.

I figure the combined weight of my SLEGK (Street Legal Electric Go-Kart):

4 batteries = 268lbs (I seen another site with the same battery, it gave me the weight of 67lbs)
Frame = ?50lbs
4 Tires/rims (I plan to use 16" [total diameter] tires) = 80 lbs
Turn signals, Lights, steering wheel, seats, Speedometer ect = 30 lbs
CVT Unit = 10 lbs
Brakes = 40 lbs with rotors and system. (unless there is something better and lighter)

...And finnally Me = 200lbs

Totalling : 458lbs

Seems kinda light. But if it's right, I think this thing will go-Go-GO!

[JerryAssburger]

Sorry I got off topic, Joe Oh.

With that motor you should more than fly. If you're familiar with Black & Decker rechargeable mowers, some of them have a 24v motor rated at a peak 5hp (4000w/165 amps). A friend built a tricycle with a pair of 150ahr batteries and no controller. When wired in parallel (12v) it'd go seemingly forever at about 14 mph and took hills,mud, sand, etc like it wasn't even there. On 24v, the thing flew. Never really did get to measure it, but it walked away from a scooter I had at the time that'd do 22mph topped out. In 12v mode, the motor was drawing about 25 amps on the level. I'm not sure if you're going to run yours as 48v or 24v, but the cool thing is, even if you have a monster motor (you do!) they only draw as much amps as they need, so your motor will be able to handle the extra amp-spikes of hills, acceleration, etc without burning up, but in cruise mode... it'll do pretty well.

If you're using a controller, I'd forgo the CVT. Most electrics make very close to the same torque at 1rpm as they do at full rpm; I think the cvt would add unnecessary complication. Just gear it for the top speed you need @ 3700 rpm.

As far as speed that you're looking for, it's hard to say what you can pull from an 8hp motor. I'd gear for 45mph and then closely monitor the motor's draw on level ground with an amp gauge. Why 45mph? Because electrics are more efficient than gas, and I've easily hit 45mph with a 6.5hp gas engine.

I think we were drawing about 30 amps on a 12v scooter thing I built at about 18mph, which would go through a 100amp deep cycle in about 2 hours of traveling.(35 miles.) You don't want to draw down a battery too far before it needs to be recharged.

What are your targets for range and speed?

[JerryAssburger]

Hmmm. With 16" wheels, a 4>1 ratio would get you to 42 mph @ 3700 rpm and you'd have 88.5 ft lbs of starting torque at the tread, or 188 ft. lbs at the tread during peak motor draw. That's pretty darned good, considering that you'll be generating all that from the get-go, whereas a trashy kart with a 6.5 hp hf engine, 16" wheels and a 4.5>1 ratio generates 65 ft. lbs MAX at the rear wheel. It's no acceleration monster, but it's quick enough to keep up across intersections, etc. You'll have even more power than that, even with the extra weight. (Me and kart 310 lbs, you and kart 458lbs.)

[Joe_Oh]

JerryAB, I would like to hit at least highway speeds. But I prolly wont be using this kart on the HW unless it'll hit 75mph max.

As for the range, I would like to get 70 miles total on one charge. If there is a way to get more, I'd be open to suggestions.

I may consider adding 1 more battery to the system making it a 60V setup. How would that change things? More speed? More Torque?

Thanx-

One more thing, I was wondering, are the batteries shown good for a setup like this? I read that they are deep-cycle and are made for such. Of course I wont run them dry everytime, but how many charges can I get out of these types of batteries if I only use 80% of the charge at a time?

[Joe_Oh]

Btw, I wont be using a controller. They are too expensive where I can find a fat potenteometer. I just hope I can find one that can handle the max amps.

The goal of the CVT is to get more speed without the motor having to run at max RPM to do so. I want to make this motor last for a long time.

[jr dragster Tyler]

Running it its desihned full RPM isnt bad at all! and actually a CVT allows your motor to rev up even more because when it first starts up its a very geared down ratio

[JerryAssburger]

Wow- 75 mph AND 70 mile range might prove to be a tall order. That's kind of what the major auto manufacturers are after, and they can't get it without resorting to expensive technologies. Please don't get me wrong- I'm not saying you can't do it, but it's not going to come easy. Hopefully Kibble can toss his 2 cents into the ring, because he's pretty dang sharp at this stuff. (Strapping lawn-motors onto bicycles is my speed limit!) JrDragsterTyler is right- that motor spinning 3700 rpm is nothing to worry about. You're biggest concern is keeping the constant and peak amp draw within limits, and making sure the motor gets the recommended cooling flow of air. (Both are factors of motor temperature, which is what we're really worried about.)

Kinda as an aside, is it 70 miles each way to work for you, or roundtrip? If roundtrip, plug it in while you're on shift- by the time you're off, it should be charged back up.

Either way, I hope this project is a success for you.

[kibble]

Btw, I wont be using a controller. They are too expensive where I can find a fat potenteometer. I just hope I can find one that can handle the max amps.

I hate to say this, but you're not gonna find a potentiometer that'll handle those kinds of amperages without burning up. Some sort of electronic controller would be the best thing. I've been wanting to make a relatively simple electronic controller for high amperage motors but haven't gotten around to it yet.

[Joe_Oh]

Well for now, my work is a 30 mile round trip and from what I'm hearing that'll be stretching it a bit.

Most likely I'll be using this kart just to goto the store, fast food joint, and other close-by places to give my truck a rest.

I know the importance of not draining batteries completely empty. But what I dont know is how much the batteries I shown in my first thread can take on a regular basis? Can I drain them 50, 60, 70% and they'll be ok before recharge? and how many cycles can I expect out of them.

Thanx-

[Joe_Oh]

I hate to say this, but you're not gonna find a potentiometer that'll handle those kinds of amperages without burning up. Some sort of electronic controller would be the best thing. I've been wanting to make a relatively simple electronic controller for high amperage motors but haven't gotten around to it yet.

how about the voltage? Surely I can find one that can do 60 volts and maybe 5 amps? If thats the case I can wire 20 of them togeather in parallel to protect them and get the desired effect. A lot of work, but a controller just isnt what I want to play with now-

[kibble]

60 volts and maybe 5 amps? If thats the case I can wire 20 of them togeather in parallel to protect them and get the desired effect.

Pot's are usually rated in watts, so you'd have to find high wattage pots, the voltage isn't so strict.

Remember, though, that with resistance, putting two resistors in parallel would be like dividing the value by the number of resistors you have, assuming they're identical values.

So if you have two 100k pots, putting two together would be like having a 50k pot. Three pots, divide by three, etc...

If you're gonna use 20, figure out the value that you'd need to have in the end and multiply it by 20 and that's the value you need to have each pot be.

I have never tried something like this myself, but it'd be interesting to see how it works out for you!

About the battery questions, I think it'd be best to get the specs about the particular battery you want to get. I don't know too much about batteries other than the higher the amperage the better! :arf:

[carbon]

60v x 5a = 300w...
i think you could do that though
im thinking of doing the same thing on my electric kart, which is only about 1400w, so i could use a bunch of switches

[Joe_Oh]

Actually, after reading this battery faq:

http://www.windsun.com/Batteries/Battery_FAQ.htm#Cycles%20vs%20Life

I've decided to go with a AGM battery. The battery I'm gonna use is at this link:

http://www.nationalsolarsupply.com/index.asp?PageAction=VIEWPROD&ProdID=175

Also, If I use larger drive tires, will I get more speed? The reason I would like to use a CVT is to get the higher speeds without having to run the motor at it's max rpm.

I measured my Ford Ranger truck tires, and their total diameter is about 25 inches across. Will my motor of choice be able to move those within reason?

Thanx-

[2or3wheels]

its all relative, if you gear it a certian way you could turn 60 inch tractor tires. Find out what the max RPM of your motor is and gear it to go about 40 mid way through the RPM range.

[Joe_Oh]

That'd be great! With 60-inchers in the back, and 10 inchers in the front, that'd be a hoot!

I'd get pulled over for sure, either It's illegal, or the cop wanted to get a closer look at the rig :)

[carbon]

larger tires change your final drive ration, so smaller tires will give better acceleration but lower top speed, larger tires will be the opposite

[john818]

I've decided to go with a AGM battery.
...
Also, If I use larger drive tires, will I get more speed? The reason I would like to use a CVT is to get the higher speeds without having to run the motor at it's max rpm.


I'm no expert, but if my research is correct, you're probably better off with flooded batteries. Your original requirements seem to stress range and top speed over acceleration. AGMs are better for acceleration, but worse for range. Like others have said, freeway speeds for 70 miles is pretty tough to get, especially with bad aerodynamics. For my project, I'll probably go with AGMs, but my requirements are for better acceleration and lower range than yours.

As far as acceptable depth of discharge and number of cycles goes, that's going to vary with the type of battery. IIRC, flooded is more robust than AGM and will handle abuse better. If you can, get batts that are designed for EVs (eg golf carts) or make sure they're tough enough for EVs. Other types will not do well with the extreme demands of an EV.

Larger tires might get you better top speed, but it might not. Larger tires are heavier. Either way, you'll probably have to have some kind of gear reduction, whether it's sprockets and chain or a car-type differential.

Gearing an EV for direct drive (no transmission) and high top speed can be tough. CVT sounds interesting. One thing I think you might have wrong is you seem to not want your motor to run at high RPM. From what I understand, most EV motors run cooler at higher RPM than lower, because of internal cooling that's less effective at low RPM and the higher current needed during acceleration. What I've heard is that people use transmissions in EVs to minimize accelerating at low RPM. Accelerating obviously stresses the motor, and when it's at low RPM, it's worse.

If you haven't already, you might want to spend some time checking out EV sites. There's more than one DIY-type forum. You'll find a lot of info about what vehicles need to get freeway speeds and long range. Your original post asked about 48V and Etek. IIIRC, motorcycles with 48V and Eteks do about 45 mph and maybe 30 miles-no where near your target. For a lot of examples of EVs, check out the EV Photo Album. Watch out for predicted performance. Results don't always measure up.

It sounds like your goals are similar to mine. I hope your project works out for you!

[ZnsaneRyder]

Electric motors are not like gas engines. High RPM does not cause extra wear or things to break. There is no pistons or rods, just a spinning shaft with coils. It's the bogging down to a lower RPM that burns up the motor, and on top of that, a motor pulls MORE amps at lower RPM.

Look into RC cars and you'll see what I mean. Also, a potentiometer wastes power as heat. A controller uses PWM (pulse width modulation) to vary the amount of average power into the motor.

[KingCobra]

I have a couple nice 120 v. motors.. Wish I could do something like this.

[Hippie Mike]

take look http://www.evalbum.com/ you should look a t this

[DMMaine]

do a reverse trike, reg as a motorcycle

there is an etek with controller on ebay for about $600

http://cgi.ebay.com/Etek-Motor-Sevcon-Controller-for-electric-vehicle_W0QQitemZ300288790971QQcmdZViewItemQQptZLH _DefaultDomain_0?hash=item300288790971&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C 240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

you don't need the torque converter, motor characteristics are wrong for use with E motor, you will lose effciency and range!!!!

keep the weight down and use motorcycle wheels and brakes

you should see 15 peak HP and 17 ft/lbs of torque with a 48 volt etek and you want to be able to deliver 300 plus amps for short times to get the max out of that setup!!!

read up on JQ riley's website re the stability of reverse trikes... must keep the weight closer to the two front wheels and low, wider front is more stable.

I'm working on a similar setup

D&D sepEx motor model Es-32A-50 and 450 amp sevcon controller 30 plus peak HP and approx 65-70 foot lbs of torque

6 75 amp hr batteries, est 50 mile range. est finished weight 1000+ lbs (I'll add my 6, 21 amp gell cells as well for add'l range, see below)

I'm also setting up the same motor and controller on my Sodi DD2 chassis for autocross with 6, 21 amp hr gel cells....

UPS delivery scheduled for the motor/controiller... 1/26/09! YUP TODAY!!!!!!:cheers2:

Dan

[Hippie Mike]

U SHOULD LOOK AT THIS WEB http://www.evalbum.com/

[DMMaine]

already did... you posted this earlier in this thread... some interesting iron....