Jordy's UK EV Racer - Page 5 - DIY Electric Car Forums

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#41
07-05-2012, 05:08 PM
 MalcolmB Senior Member Join Date: Jun 2008 Location: Newcastle upon Tyne, UK Posts: 561
Re: Jordy's UK EV Racer

It would be nice if it was that simple Your calculations look good, but like you suspected, you won't get max torque all the way up to maximum rpm. The Kostov 9 may be able to take 1000 amps for seconds at lower volts, but I doubt it could cope with 1000A at 220V. Back EMF from the motor also means that torque starts dropping off before you get to maximum rpm. I'd suggest getting in touch with Kostov and asking what they recommend. One of their engineers is a member here and is very helpful. His user name is Plamenator.
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#42
07-05-2012, 05:21 PM
 major Senior Member Join Date: Apr 2008 Location: Ohio, USA Posts: 7,332
Re: Jordy's UK EV Racer

Quote:
 Originally Posted by Jordysport But with WOT at any rpm will the motor produce peak torque?
No, like I told you. You get peak torque (at current limit) only up to base speed (RPM). That base RPM is voltage dependent. And that voltage must include any sag and voltage drop. So just a guess.....at that point, your base RPM will be in the range of 2500/3000 RPM for the 220 volt curve.

What is your mph/RPM ratio? I typically use "XXXmph/1000RPM".

Also, what do your calcs say the voltage is at 1000A? And have you inquired as to the motor survivability at 1000A for 20 seconds?

major
#43
07-06-2012, 04:41 AM
 Jordysport Senior Member Join Date: Mar 2009 Location: East Devon, UK Posts: 386
Re: Jordy's UK EV Racer

Quote:
 Originally Posted by MalcolmB It would be nice if it was that simple Your calculations look good, but like you suspected, you won't get max torque all the way up to maximum rpm. The Kostov 9 may be able to take 1000 amps for seconds at lower volts, but I doubt it could cope with 1000A at 220V. Back EMF from the motor also means that torque starts dropping off before you get to maximum rpm. I'd suggest getting in touch with Kostov and asking what they recommend. One of their engineers is a member here and is very helpful. His user name is Plamenator.
Hi Malc, Yes as i expected, the best way probably to estimate it is to model the Motor graphs in excel that way i will get a much better value for top speed and Acc.

Thats a good idea, will contact him today.

Just an idea, with direct drive & long gearing requiring ideally higher rpm, would AC be a better option?

Quote:
 Originally Posted by major No, like I told you. You get peak torque (at current limit) only up to base speed (RPM). That base RPM is voltage dependent. And that voltage must include any sag and voltage drop. So just a guess.....at that point, your base RPM will be in the range of 2500/3000 RPM for the 220 volt curve. What is your mph/RPM ratio? I typically use "XXXmph/1000RPM". Also, what do your calcs say the voltage is at 1000A? And have you inquired as to the motor survivability at 1000A for 20 seconds? major
Hi Major,

Unfortunatly i did have trouble understanding at first, linguals and forums aren't ideal for expressing engineering topics. But I fully understand now, so thank you for your patience.

30mph/1000RPM , looking at the motor graph at 1000RPM it will be wanting the full 1000A at which point it begins to tail off. 0-30 mph will be done at full 1000A. Is my logic correct.

well at 1000A , V = I*R . internal resistance of the cells is 0.04 Ohms so 0.04 *1000 = 40V so 304-40 = 264V which would appear to be too high listening to most peoples estimations. but in my spreadsheet this has no affect on the calcs (only number of cells) as i take the torque value straight from the motor graph. (need to create a motor Map to get a proper estimation)

Many Thanks

Jordy

#44
07-06-2012, 04:18 PM
 Jordysport Senior Member Join Date: Mar 2009 Location: East Devon, UK Posts: 386
Re: Jordy's UK EV Racer

Anyone got any Ideas for a small compact 2 speed gearbox?? may have to make my own, will take a while lol.
#45
07-07-2012, 01:47 PM
 Jordysport Senior Member Join Date: Mar 2009 Location: East Devon, UK Posts: 386
Re: Jordy's UK EV Racer

Had a spare hour today, so one of the firs options for packaging. all the cells are in there, still leaving the sidepods (considering not having them on atm) and space under the seat (for the Pot)

#46
07-07-2012, 02:28 PM
 Tesseract Senior Member Join Date: Sep 2008 Location: Tampa, FL USA Posts: 3,199
Re: Jordy's UK EV Racer

Quote:
 Originally Posted by Jordysport Anyone got any Ideas for a small compact 2 speed gearbox?? may have to make my own, will take a while lol.
Lenco and Gear Vendors

But I'd seriously consider a modified PowerGlide as it is one tough mutha and is surprisingly small for the amount of power it can handle. Also, it gives you 2 forward and 1 reverse gear.

A fellow user here by the name mizlplix appears to be our resident 'Glide expert.
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#47
07-07-2012, 02:54 PM
 Jordysport Senior Member Join Date: Mar 2009 Location: East Devon, UK Posts: 386
Re: Jordy's UK EV Racer

Quote:
 Originally Posted by Tesseract Lenco and Gear Vendors But I'd seriously consider a modified PowerGlide as it is one tough mutha and is surprisingly small for the amount of power it can handle. Also, it gives you 2 forward and 1 reverse gear. A fellow user here by the name mizlplix appears to be our resident 'Glide expert.
Hey, Unfortunatly both those companies are yank, I can get gears here in the UK, so shouldn't be a problem just time consuming and getting the right rated parts.

The Powerglide unit is unfortunatly Far far far far far too big, and i need chain drive to the rear axle, almost like a modifed transfer box. with gear ratio approx, 1.8:1 & second gear of 0.6:1 but without two output shafts just one.

PS. my model of the controller is just a visual representation, haven't taken anything lol.
Cheers
Jordy
#48
07-07-2012, 02:59 PM
 Batterypoweredtoad Senior Member Join Date: Feb 2008 Location: Gainesville, FL Posts: 457
Re: Jordy's UK EV Racer

You could use a Harley Davidson or Buel transmission but getting one to handle the 250-350 foot lbs of torque is going to be pricey. You could adapt a transverse transmission out of something like a Suzuki Swift but it probably doesn't have much in the way of an aftermarket (or torque capacity either). A powerglide is nice but it puts you back in the longitudinal mounting situation and stuck needing a diff. You could mount the Glide sideways with a chain drive input and output and stack the motor and trans. I still come back to a transaxle. You would lose the space in front of the motor you have currently designed for a pack, but you would gain space for a U shaped battery pack riding above and around the motor. The Air Cooled VW units are cheap, have a HUGE aftermarket, and cure my worries about you abusing that poor sprocket with torque.

You could just buy a Soliton Shiva and up the voltage to see how far you can stretch out the torque curve of a K9 220V. The motor is cheap compared to adding a transmission so you could afford to blow a few in experiment mode.
#49
07-07-2012, 03:05 PM
 Jordysport Senior Member Join Date: Mar 2009 Location: East Devon, UK Posts: 386
Re: Jordy's UK EV Racer

Quote:
 Originally Posted by Batterypoweredtoad You could use a Harley Davidson or Buel transmission but getting one to handle the 250-350 foot lbs of torque is going to be pricey. You could adapt a transverse transmission out of something like a Suzuki Swift but it probably doesn't have much in the way of an aftermarket (or torque capacity either). A powerglide is nice but it puts you back in the longitudinal mounting situation and stuck needing a diff. You could mount the Glide sideways with a chain drive input and output and stack the motor and trans. I still come back to a transaxle. You would lose the space in front of the motor you have currently designed for a pack, but you would gain space for a U shaped battery pack riding above and around the motor. The Air Cooled VW units are cheap, have a HUGE aftermarket, and cure my worries about you abusing that poor sprocket with torque. You could just buy a Soliton Shiva and up the voltage to see how far you can stretch out the torque curve of a K9 220V. The motor is cheap compared to adding a transmission so you could afford to blow a few in experiment mode.
The car's already got a diff on the rear end so no problem there, is just getting the drive to it (sprocket).

The Sprocket should be fine, i was planning on a dual chain setup, thats what the big boys use and there running same if not more torque.

Will look into some of those ideas, certainly worth a punt.

Pack voltage atm is 307V so i think i'm pushing the motor already. and still comes back with needing a box.
#50
07-07-2012, 03:11 PM
 Batterypoweredtoad Senior Member Join Date: Feb 2008 Location: Gainesville, FL Posts: 457
Re: Jordy's UK EV Racer

I think Planetmotor tentatively suggested something around 280 Volts in another thread. If that is under load then you will be far below that with sag. Going to straight Li-po like the turnigy or higher voltage would be a possible cure.

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