# Top speed of your EV



## Greenflight (Sep 13, 2007)

Well, my truck tops out at about 55 mph. That's pedal to the floor, fifth gear. I rarely drive it at that speed due to the 300+ amp draw. My cruise speed is about 45 mph, generally in third gear at about 140A.

The limiting factor is power (yeah, I really take the cake for stating the obvious). My truck runs a 120V system. If I were to upgrade to a 144V system, I could probably run at 60+ no problem, but I'm a little worried about the 20 year old springs handling all the battery weight.

I'm hoping to get top speeds of over 80 in my Tercel, which will be running at least 156 volts, with acceleration better than with the ICE motor.

Hope that helps!


----------



## WCRiot (Nov 25, 2007)

Greenflight said:


> Well, my truck tops out at about 55 mph. That's pedal to the floor, fifth gear. I rarely drive it at that speed due to the 300+ amp draw. My cruise speed is about 45 mph, generally in third gear at about 140A.
> 
> The limiting factor is power (yeah, I really take the cake for stating the obvious). My truck runs a 120V system. If I were to upgrade to a 144V system, I could probably run at 60+ no problem, but I'm a little worried about the 20 year old springs handling all the battery weight.
> 
> ...


Is there anyone else out there that would care to post?
Greenflight: what kind of range do you get out of your current setup? and how many batteries are you using to achieve your 120V system?


----------



## Mr. Sharkey (Jul 26, 2007)

I hesitate to tell much about my car, because it's so out-of-the-ordinary as far as equipment goes, but here's the facts:

Car cruises comfortably at 50 MPH. It will willingly do 55, but you have to push it a little. If you want to run flat-out, it will do 65, but it takes a very long time to get there, and the motor temperature rises very quickly.

Best cruising on the freeway is done behind a semi truck. If I get in behind the trailer close enough, I can hold 55 while cutting my amperage in half (60 amps instead of 130).

Of course, with the Pusher, 75 MPH is easy, even uphill.


----------



## KiwiEV (Jul 26, 2007)

I will post my details as soon as I know them! Give me a few more weeks and I'll see what the car goes like on the open road.


----------



## Greenflight (Sep 13, 2007)

WCRiot said:


> Is there anyone else out there that would care to post?
> Greenflight: what kind of range do you get out of your current setup? and how many batteries are you using to achieve your 120V system?


I'm getting about 35-40 miles depending on speed. At 45-50 mph, I could probably get about 25-30 miles, but at 25 I could probably get 50 easy.


----------



## ohio (Jul 25, 2007)

i had mine at 85 mph and i know i would go faster i was in 4 gear


----------



## WCRiot (Nov 25, 2007)

KiwiEV said:


> I will post my details as soon as I know them! Give me a few more weeks and I'll see what the car goes like on the open road.


What are you expecting your top speed to be?
What are you expecting your range to be?



> ohio i had mine at 85 mph and i know i would go faster i was in 4 gear


What car? What are the specs on your EV?

After i get my reading done, Im sure Ill have more questions for everyone.
I trying to gather measured data not experimental data, to determine what setups are resulting in what performance.


----------



## houseoffubar (Nov 18, 2007)

Check out Austin EV, OHIO has a link in his post above. There are hundreds os EV's, with the specs for each. Eric


----------



## KiwiEV (Jul 26, 2007)

WCRiot said:


> What are you expecting your top speed to be?
> What are you expecting your range to be?


Top speed I'm estimating about 130km. I used an online top-speed calculator and ended up with 135km/h (83 mph) which feels about right when driving it.

Range? I'm really not sure yet. While my battery pack is 144V, it's actually quite small. I drove 10km (6 miles) around the neighbourhood last night just to keep things moving (and to get my "hit") and I used about 10% of my batteries capacity. I'm not sure if that's good or bad. In a few weeks once it's legal I'll take the pack from 165v right down to 144v (50% DOD) and see what I get from it.
It makes a BIG difference on your range if you put your foot down, that's for sure!

Edit: I had to make a return trip into the city so my wife could get to work. Our gas car was spluttering out of gas and we have 2 cents on our account so we had no choice but to use the uncertified EV. But man it felt GREAT! Illegal but GREAT! So that's now (unofficially) 16km (10 miles) of driving since it was fully charged 2 days ago. I checked the voltage after letting the batteries sit for an hour after driving and the pack has settled at 85% capacity remaining. Not bad for a little battery pack and hilly driving.

Double Edit: Total this weekend is now just on 31km (19 miles) with the pack going down to 60% full. That's a lot more than I thought I'd get so I'm really impressed!


----------



## WCRiot (Nov 25, 2007)

Something I can't grasp is. Why don't people run a very low gear ratio, let say 2.93:1? With the massive torque for the electric motor, the car should eb able to climb up to speed with ease, right?
If im wrong, why dont use a 6 speed manual transmission with a moderately low gear ratio?

If the amperage usage is based on rpm (for example), running a low gear ratio with a 6 speed transmission should allow you to cruis below 3k rpm at 80 m.p.h.

Assuming your vehicle has a relatively low coefficent of drag, why couldn't this be acheived? 

I am not asking for my personal project or anything of this sort. I would just like to consider the disadvanategs of owning an EV and try to address these issues with feedback from others.


----------



## Brendonbosy (Dec 13, 2007)

EVs are only limited if the driver chooses to limit themselves to 1 gear. That's the drawback of trying to drive "automatic" on an EV; having only 1 gear to work with makes you have to compromise acceleration vs top speed. Too low a ratio and your 0-60 time suffers; to high a ratio and your stuck going 55 mph on the highways to avoid overheating your motor. I assume that since most people drive in city traffic, they prefer a higher gear. I say, just suck it up and drive manual. Besides, with manual you can always just skip gears and work with only 2 or 3 gears. That's what the Tesla Roadster does. Since EVs are torque monsters, you don't really have to worry about gear hunting like you do with IC engines. Plus, an EV doesn't really need a clutch to shift so no worries about driving with a 3rd pedal.

I haven't converted my 99' Celica GT 5-spd yet. I'm trying to make a high performance EV, not some slow-poke goofy Prius. Right now I'm gathering the money up for a lightweight battery pack out of either lithium polymer or NiMH cells to deliver sufficient voltage. I already got a motor and controller set to put out a peak of 134 HP (100 kW) and an estimated 200+ ft-lbs of torque. Currently my Celica has a factory top speed of 120 kph (194 kph). I estimate after the EV conversion, I'll be able to do 0-60 in under 7 second and max my Celica out at about 145 mph (234 kph). Of course, if I want to go that fast, I'll need some higher rated tires. Right now, I only got H-rated ones. In any rate, my EV definately isn't going to be limited; I want it to be as fast as it looks.


----------



## BHall (Aug 1, 2007)

Not to jack the thread but what motor/controller did you decide upon Brendonbosy? 

Brian


----------



## WCRiot (Nov 25, 2007)

it seems like one membe had posted something but it is not being displayed. I saw his\her post in ym email notifications of a reply to my thread, i want to address his comments.

When i discussed using the lower final drive ratio (rear differential) i mentioned that because the lower ratio would allow for higher speed with a lo rpm.

I was concerned about having a low rpm because, from what i was told a hig rpm means a larger drain on the battery which would even take the battery into DOD faster or limit your range.

I then mentioned the electric motors being torqey because i wanted to know if this high torque value would get the car moving faster because of the low gear ratio.

_Brendonbosy: I have no problem driving manual. i do it everyday in my m3, on top of that, i drive the manual in Los Angeles traffic. I prefer manual because it keeps me alert, off the phone and not picking up bad habits like smoking or picking my nose._

_Reread my post where i was discussing the gear ratio and read this post more carefully. I am not trying to build a single speed EV, Im not trying to build an EV with an auto trans._

_The tesla roadster is using advanced componets and a different setup than i would like run. their AC vs the typical diyever's DC. The ac motors can twist to high rpms without putting a high load on the power source. Good luck with your project but i think u should add a clutch pedal..._


----------



## Brendonbosy (Dec 13, 2007)

My motor is a 3-phase AC industrial one from Siemens, if its not the same, its similar to what the Ford Ranger EV used. I'm running a higher voltage than the 250 rated in order to get more power. It's factory operating voltage goes up to 380, so there shouldn't be any problems. I got it from my friend who runs a machine shop. I'm building the controller with another friend's assistence (he's an electrician).

As for the clutch, its not really neccessary. Unlike an IC engine which is running all the time, when you let off the gas on an EV, the motor stops completely and it "freewheels" on its own. The only advantage keeping the clutch is in the rare event the motor doesn't shut off, that way you can disengage it.


----------



## mattW (Sep 14, 2007)

I'm pretty sure you use less amps at higher rpm. When the motor is stationary there is no induced voltages so the motor gets the full voltage of the pack, lets say 120V. When the motor is spinning at high rpm, conservation of energy means that the spinning coils induce a voltage in the opposite direction to the battery pack (i.e. the motor sort of acts like a generator at the same time it is moving, but giving out less voltage than it puts in). So while you have 120V at the battery pack you have a negative voltage of say 50V which opposes the pack voltage and the motor only sees 70V. And since V=IR lower voltage means less amps and much less power (P=VI). This is why DC motors tend to burn out when they are forced to stop suddenly; you have max amps at 0 rpm.
_
Disclaimer: I know this is how it works for permanent magnet motors and I am assuming it is the same for series motors but I could be wrong. Any motor experts out there? _


----------



## rbgrn (Jul 24, 2007)

WCRiot said:


> Something I can't grasp is. Why don't people run a very low gear ratio, let say 2.93:1? With the massive torque for the electric motor, the car should eb able to climb up to speed with ease, right?
> If im wrong, why dont use a 6 speed manual transmission with a moderately low gear ratio?
> 
> If the amperage usage is based on rpm (for example), running a low gear ratio with a 6 speed transmission should allow you to cruis below 3k rpm at 80 m.p.h.
> ...


One word for this: Amperage.


----------

