# building an EV conversion for a Spec Racer roadrace car. lots of questions!



## major (Apr 4, 2008)

Nice project. Have you ever done an EV? 

I like the idea of the Leaf motor, but I don't even know what type it is; ACIM or PMSM. If it is an induction motor, there may be some motor controllers available. If it is PM, then you'd likely have to have a controller developed (at least factory tuned) around it. And I am not sure how you'd handle the gearing. I don't think the Leaf does 110 mph and you have smaller wheels.

30 miles of racing will take maybe 20 to 25 kWh battery. Probably about the energy of the Leaf battery or my Think battery (which is 285kg fully packaged).


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## Duncan (Dec 8, 2008)

Hi Todd

How big is your budget?

Why are you going to use a Leaf motor?
If you have got one and can get it and its controller to work great!

If you haven't got one - then think about DC


AC is better and the way of the future

At the moment, 
DC is cheap and powerful
AC is either expensive or wimpy or both

That car with direct drive, a 9 inch motor and a Soliton controller would be great fun


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## d15b7 (Oct 15, 2013)

good morning gents! I'm thrilled to see responses already; please keep them coming! some info for your questions:

my research shows that a standard Leaf has a top speed of 94 mph. I'm not sure if that is drag limited, or an artificial limit imposed by the electronics. we were planning on upsizing from the standard 13" racer wheels to 15" wheels to improve the gearing if need be (race tire selection is also better in the 15" sizes. we'd probably be running a 205-50-15 sized tire). here's the info on the Leaf motor that I've found:

• The traction motor contains a compact, lightweight, high output, high efficiency “Interior Permanent Magnet Synchronous Motor (IPMSM)”.
• The traction motor inverter is a device which converts DC power from the Li-ion battery to AC power, and drives the traction motor. Because the AC power frequency and voltage can be varied when the DC power is
converted to AC power, it provides control performance with a high degree of freedom.
Specifications (Traction Motor) INFOID:
Max torque 280 Nm
Max output 80 kW
Max speed 10,390 rpm
Cooling system Water cooling type.

no, we don't have any of the EV parts yet; we just thought that the Leaf packaging, and robustness, and power/torque output looked very enticing. we like the idea of being able to lift the entire drivetrain out of a Leaf and drop it into the rear of our racer; we've got a chassis fabricator who is fantastic and the mechanical aspect of that doesn't phase him at all. what we don't have is an electrical engineer to handle the controller headaches/issues. we were really hoping that there would be an aftermarket type controller that could handle the Leaf AC motor and could be programmed with some ease/flexibility.

our budget as of right now is around $50k. we feel (we hope!) that that is 'doable'. those monies would be spent on the EV components, and also on an individual to really help us with the EV integration (programming, etc). we are trying to keep it simple in that regard; we aren't planning to try to integrate any regen braking to start with. no traction control, no abs. we just want a pure driving race car -- one which will respond linearly to the throttle, and which will give us the driving/racing goals that we want (0-60 time of 6-7 secs, top speed ~100 mph, 30 mile race range, able to recharge in ~3 hrs).

I guess I should have mentioned in my previous post our location -- we are located not too far from Philadelphia, PA. we will be running at most of the local tracks (Pocono, NJMP, Summit Point, Limerock, and others). please keep the responses coming -- and if you wish to talk to me directly, PM me and I'll shoot you my cell num too. We REALLY appreciate the help!!!! 

Todd


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## toddshotrods (Feb 10, 2009)

Welcome - the world can always use another Todd! 


I am gaga over AC these days (formerly gaga over DC) but I have to admit that DC probably makes more sense for what you're trying to accomplish. You could, as mentioned, purchase a Warp 9 and Soliton, plus an adapter for say a popular FWD conversion, and accomplish what you were thinking with the Leaf - without the headaches of trying to find a suitable inverter to drive the Leaf motor. I asked Rinehart about programming one of their drives to work with a Toyota IPM motor. It can be done, but requires a week or two on the dyno, on your dime. The WaveSculptor appears to have a self-learning feature, but less power - could be an option for the Leaf motor?

The other way (DC), you can purchase a complete FWD car - like a Honda Civic - transplant the FWD drivetrain into the race car, as planned, and bolt up the motor using a conversion kit. Since you don't need regen, it will deliver everything you need, and then some...

The best thing is you won't really need to hire someone to make that work, meaning you can spend the biggest chunk of your change on good batteries (and a charger) - which you're going to need to make your weight/power/range goals. If would be nice if you could afford two packs, and charge one while racing the other.

Finally, DC also keeps the voltage lower - meaning a larger off-the-shelf parts selection; and a host of people here with the knowledge and experience to get you going and winning.

I want AC in my bike, but just wired up an old series-DC forklift motor, so I can start having fun - now - while I sort out a decent AC system.


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## d15b7 (Oct 15, 2013)

hello guys. thanks for the advice; it's really helping us to make some decisions. we are really leaning towards the Warp9 DC motor and Soliton1 controller. have a few more questions:

1. we are wondering if we can just direct drive this motor/controller combo without a transmission? the spec racer is geared with a 4 speed trans; we typically only use 3rd and 4th gears while racing at any track we go to (we use 1st and 2nd only to get out of the pits). the gas motors redline at 6k rpms, and we typically shift them at 5500 rpms. the Warp9 motor falls right into that zone nicely, it seems. the big difference is that of course the electric motor has gobs of torque from 0 rpm, and the gas motor of course has almost none, thus needing the lower gears to start off in the paddock. we'd LOVE to do away with the complexity of the trans and just direct drive the warp9 to a differential in the back of the car. what's the opinion of doing this? would we be able to move away from a stop (there's never really any hills so to speak in the race paddock!) and then accelerate pretty decently from say 40mph on up?

2. need some help on batteries from you experts! we want the Lithium Ion type; for our needs what size pack would you recommend? (it's already been mentioned 20-25kwh battery pack). do you guys think that that is the size we should aim for? we need about a 30 mile race range, and we'd love to be able to charge up again in approx 3 hrs. eventually we plan on having 2 battery packs, and engineer some kind of 'quick change' battery pack, so that we can do a pit stop for longer races. that's in the future, of course! what vendors should I be looking at for the best quality battery packs?

thanks so much -- this resource is so very helpful to us!!! hope everyone is having a great weekend!

Todd


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## major (Apr 4, 2008)

d15b7 said:


> hello guys. thanks for the advice; it's really helping us to make some decisions. we are really leaning towards the Warp9 DC motor and Soliton1 controller. have a few more questions:
> 
> 1. we are wondering if we can just direct drive this motor/controller combo without a transmission? the spec racer is geared with a 4 speed trans; we typically only use 3rd and 4th gears while racing at any track we go to (we use 1st and 2nd only to get out of the pits). the gas motors redline at 6k rpms, and we typically shift them at 5500 rpms. the Warp9 motor falls right into that zone nicely, it seems. the big difference is that of course the electric motor has gobs of torque from 0 rpm, and the gas motor of course has almost none, thus needing the lower gears to start off in the paddock. we'd LOVE to do away with the complexity of the trans and just direct drive the warp9 to a differential in the back of the car. what's the opinion of doing this? would we be able to move away from a stop (there's never really any hills so to speak in the race paddock!) and then accelerate pretty decently from say 40mph on up?
> 
> 2. need some help on batteries from you experts! we want the Lithium Ion type; for our needs what size pack would you recommend? (it's already been mentioned 20-25kwh battery pack). do you guys think that that is the size we should aim for? we need about a 30 mile race range, and we'd love to be able to charge up again in approx 3 hrs. eventually we plan on having 2 battery packs, and engineer some kind of 'quick change' battery pack, so that we can do a pit stop for longer races. that's in the future, of course! what vendors should I be looking at for the best quality battery packs?


1) Probably don't need tranny, but need ability to adjust ratio to suit track.

2) Sample calc: 60 mph average. 30 mile race. 15 minute total run time. 20 kWh pack. 4C rate. 80 kW average at battery. Maybe 75 to 80 hp at wheels. That would be 100% DOD.

Sorry, still can't keyboard with cast on hand. Take a look at EnerDel batteries. disclaimer... I have some for sale


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## dtbaker (Jan 5, 2008)

d15b7 said:


> ... leaning towards the Warp9 DC motor and Soliton1 controller. have a few more questions:
> 
> 1. we are wondering if we can just direct drive this motor/controller combo without a transmission?... the gas motors redline at 6k rpms, and we typically shift them at 5500 rpms. the Warp9 motor falls right into that zone nicely, it seems.


you have to change your thinking a little since torque drops off above about 4k rather than building to peak hp at redline like a gas motor. If you have a fixed gear enabling top speed at 5000 rpm, you'll still want a couple gears below that for best torque coming out of tight corners/lower speeds. You may well need to have a taller gear in rear to achieve most likely max speed at a LOWER rpm than 'max'. I can start my Miata in 5th, but don't hit max output till 1000 or 1500 rpm, so need at least 3rd and 5th for keeping things in the power band.... which seems to be about 1500-4000rpm





d15b7 said:


> 2. need some help on batteries from you experts! we want the Lithium Ion type; for our needs what size pack would you recommend? (it's already been mentioned 20-25kwh battery pack). do you guys think that that is the size we should aim for? we need about a 30 mile race range,


the 30 mile race range will determine the capacity of the pack. going DC means you won't get any regen from braking.... and hard driving will impact your consumption significantly more than standard formulas might predict. i.e. a car that might consume 250whr/mile under normal driving, may well double that under race conditions. With heavy accelleration, you'll have to plan thermal management to COOL the batteries, and may have to consider pricey batteries rated for high output and low weight. For instance, going with pouch cells rather than moderately priced prismatics like the CALBs. for minimum weight, extended periods of high output and best thermal management you are going to have to consider things like Kokams or some other pouch cells.



d15b7 said:


> and we'd love to be able to charge up again in approx 3 hrs. eventually we plan on having 2 battery packs, and engineer some kind of 'quick change' battery pack, so that we can do a pit stop for longer races.


certainly possible..... batteries in a tray underneath with spring-loaded contacts, or big anderson plug, etc., jack up and swap just like tires. quick charge is just a function of how big a charger you have, and access to lots of juice. typical pits may not have 50 amps of 220vAC available, so you may need a standalone generator!


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## tylerwatts (Feb 9, 2012)

Check out endlesssphere and search 2 speed. The guy used automotive dog engagement gears to drive 2 chains for a simple 2 speed trans. Light, cheap, strong and easy quick gearing changes! 
DC setup is advised, but have good air cooling.


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## Duncan (Dec 8, 2008)

d15b7 said:


> 1. we are wondering if we can just direct drive this motor/controller combo without a transmission?
> 
> Todd


Hi Todd

You need to do some sums
Max speed
Weight on driven wheel

Use the maximum expected speed - 100mph??
Calculate maximum wheel rpm -
Motor max rpm - say 7,000rpm for a 9 inch DC
See what type of setdown ratio you need

On my car with a standard subaru diff (4.1: 1)- 4000rpm = 110Kph, 7,000rpm = 192Kph (my motor won't go that high)

http://www.diyelectriccar.com/forum...ns-dubious-device-44370.html?highlight=duncan

If your car ends up at 400Kg - with 55% on the rear that is 220Kg - 484lbs

So if you tires have a coefficient of friction of 90% - you can apply 
90% of 484 lbs accelerative force

At about 1 ft radius = 484 ftlbs
4.1 : 1 diff = 118 ftlbs at the motor - that is not very much probably 500amps worth!
My car weighs 700Kg - 500amps will not spin my tires - I think 700 amps would
and in a lighter car 500 amps would

As a first approximation a Warp 9 with a Soliton (1000amps capability) and a 4:1 final drive would be able to spin the tires at any speed up to 100mph

A multiple speed transmission would probably add weight without adding any performance
(once you can spin the tires.....)

This is only half the battle - now you need batteries capable of feeding the monster


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