# Re: [EVDL] Newbie, Hot Rod truck AWD EV project



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

Great links guys! I'll join NEDRA as well.

Right on! That seems a bit more simple. It would actually fit a truck 
chassis better (man they had to hacked up that car!) and drop a few pounds 
of transfer case as well as inertial weight and rotating mass of the drive 
line. I'm a little more comfortable with mechanical rather than electrical 
things though so it brought up another question I had a while back during my 
preliminary headscratching.

I had considered a similar design with 2 smaller 8 inch DC motors but was 
concerned about keeping both excelerating at the same rate. How could I 
match the controller, motor tolerances, electrical resistance of the wire 
etc that close? I figured without a mechanical link, one would always 
either have more torque or speed at any given load or RPM causing it to drag 
the other a bit. It seems it would have the same effect as a 4WD truck with 
spools and suck in the handling dept at highway speed on concrete. Depending 
on which one is end lagging, I'd expect over or under steer and terrible 
tire wear. Thus the thought of a center differential either planetary gear 
or viscous coupling style AWD set up and open differentials front and 
rear... like an ICE AWD basically.

I looked and didn't get much info in Proev's build section of the Subaru. 
How do they clock both motors electrically? They have a speed sensor or 
something that feeds back to the controller? Am I missing something basic 
about EV? I get the no engine drag/braking thing but we are talking the 
differential of 4 tires going around a corner at 4 different points on the 
ground with a center turning point without rear steer.

Chris




> Bradley Lindberg wrote:
> > Hi Chris,
> > I am far from being a seasoned veteran on this list. Your project
> > sounds great and you have the tools and background to make it happen.
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

Hi Chris,

Our Siemens controllers see the same potentiometer throttle signal. This is 
all we have found necessary to keep the motors balanced.

According to the data from the inverters, the motors use just about the same 
amount of power.

We have also found the handling very consistent. We control balance with 
springs, anti-roll bar, rake. We can dial in oversteer or understeer.

Cliff
www.ProEV.com



----- Original Message ----- 
From: "Chris Stephens" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Sunday, September 14, 2008 8:00 PM
Subject: Re: [EVDL] Newbie, Hot Rod truck AWD EV project


> Great links guys! I'll join NEDRA as well.
>
> Right on! That seems a bit more simple. It would actually fit a truck
> chassis better (man they had to hacked up that car!) and drop a few pounds
> of transfer case as well as inertial weight and rotating mass of the drive 
> ,
> line. I'm a little more comfortable with mechanical rather than electrical
> things though so it brought up another question I had a while back during 
> my
> preliminary headscratching.
>
> I had considered a similar design with 2 smaller 8 inch DC motors but was
> concerned about keeping both excelerating at the same rate. How could I
> match the controller, motor tolerances, electrical resistance of the wire
> etc that close? I figured without a mechanical link, one would always
> either have more torque or speed at any given load or RPM causing it to 
> drag
> the other a bit. It seems it would have the same effect as a 4WD truck 
> with
> spools and suck in the handling dept at highway speed on concrete. 
> Depending
> on which one is end lagging, I'd expect over or under steer and terrible
> tire wear. Thus the thought of a center differential either planetary 
> gear
> or viscous coupling style AWD set up and open differentials front and
> rear... like an ICE AWD basically.
>
> I looked and didn't get much info in Proev's build section of the Subaru.
> How do they clock both motors electrically? They have a speed sensor or
> something that feeds back to the controller? Am I missing something basic
> about EV? I get the no engine drag/braking thing but we are talking the
> differential of 4 tires going around a corner at 4 different points on the
> ground with a center turning point without rear steer.
>
> Chris


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

Great links guys! I'll join NEDRA as well.



>I had considered a similar design with 2 smaller 8 inch DC motors but was 
>concerned about keeping both excelerating at the same rate. How could I 
>match the controller, motor tolerances, electrical resistance of the wire 
>etc that close? I figured without a mechanical link, one would always 
>either have more torque or speed at any given load or RPM causing it to
drag 
>the other a bit. It seems it would have the same effect as a 4WD truck with 
>spools and suck in the handling dept at highway speed on concrete.
Depending 
>on which one is end lagging, I'd expect over or under steer and terrible 
>tire wear. Thus the thought of a center differential either planetary gear 
>or viscous coupling style AWD set up and open differentials front and 
>rear... like an ICE AWD basically.

>I looked and didn't get much info in Proev's build section of the Subaru. 
>How do they clock both motors electrically? They have a speed sensor or 
>something that feeds back to the controller? Am I missing something basic 
>about EV? I get the no engine drag/braking thing but we are talking the 
>differential of 4 tires going around a corner at 4 different points on the 
>ground with a center turning point without rear steer.

Hey Chris
The use of dual dc motors with an AWD car has been talked about before. I
do not know of anyone who has done one yet. Check the archives for parallel
series shift with a Zilla controller. Its an instant two speed electronic
transmission. Google the White Zombie for the most infamous application.
My understanding of why 4WD gets squirly in dry highway conditions is that
the front and rear wheels are locked together in matching RPM'S. The AWD
fluid coupling allows enough slop to let each wheel turn at its own speed.
The independent electric motors act as AWD with some self adjusting slop
allowed. They are not locked together like a 4WD setup. This is basically
what Cliff from Proev had to say about his Subaru.

Brad

-- 
View this message in context: http://www.nabble.com/Re%3A-Newbie%2C-Hot-Rod-truck-AWD-EV-project-tp19484865p19503974.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

AHH I think I get it now. Because they are NOT mechanically linked, and EV 
will easily freewheel, what little difference will be taken up so to speak 
by the second.
Looks like 2 DC motors in direct drive it is. So what about gear ratio? 
Where can I get solid info on how to choose?

hris

> Hey Chris
> The use of dual dc motors with an AWD car has been talked about
> before. I do not know of anyone who has done one yet. Check the
> archives for parallel series shift with a Zilla controller. Its an
> instant two speed electronic transmission. Google the White Zombie
> for the most infamous application. My understanding of why 4WD gets
> squirly in dry highway conditions is that the front and rear wheels
> are locked together in matching RPM'S. The AWD fluid coupling allows
> enough slop to let each wheel turn at its own speed. The independent
> electric motors act as AWD with some self adjusting slop allowed.
> They are not locked together like a 4WD setup. This is basically what
> Cliff from Proev had to say about his Subaru.
>
> Brad 

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

Yes in the case of using a separate motor on the front and back diffs, you
still get the differential action on the front and on the back and the front
and back are not locked together. In that case to you could probably put
Detroit lockers on the front and back and not have the binding problem the
4WD guys have on the pavement. 

Now if you want bang for buck and want this thing to go crazy fast, like
that mustang you built, you'll need motors that will take the abuse. Two 8"
motors would do, 9's will give you a quicker acceleration. Now if you want
to find out gear ratios just find the redline of the motors you want to use.
8" motors (someone correct me) approximately 6000 rpm, or 9" motors about
5000 rpm. Then figure out the top speed you want to go. Then play the game
with tire size and gear ratio to make the numbers work. Once you determine
how fast you want to go then you can figure out how fast you want to get
there. If you want quick acceleration that would make your Mustang green
with envy then you'll go with a Cafe Electric Zilla 2K controller. It's a
2000 amp controller that (depending on the model you buy) will handle up to
a 360V pack. 

Lithium-ion batteries will certainly be your friend in the power to weight
ratio. However they will eat your wallet for a really light snack. Your
idea to start with lead is good. You maybe able to show it off some, maybe
race, maybe pick up some sponsorship for advertising and then one day afford
the lithium. But there are really high power density lead acid batteries.
The second best I've found are the Enersys Geneis XE16's that we run in the
Crazyhorse Pinto 
http://www.dragtimes.com/Ford-Pinto-Timeslip-15453.html
http://www.evalbum.com/1093

and John Wayland runs in the White Zombie
http://www.dragtimes.com/Datsun-1200-Timeslip-7484.html
http://www.evalbum.com/035.html

The first best (on paper anyway) I cannot find anymore. I saw them,
inquired but never got anyone who wanted to sell me any. They were only
slightly more power dense than the Enersys batteries though.

If you can cram enough of them into that small frame then you'll be set to
bur some rubber.

Now you are considering the AWD thing. But for me I drag race the Pinto and
don't need to drive the front wheels. I have been looking at those Gear
Vendors planetary overdrive units for a second gear. They say they'll shift
very well under load. But they are like $2800 new. They claim to put them
in a lot of OEM motor homes so I'm going looking for a wreck that I can
salvage the OD unit from. 

Anyway its getting late here and someone is up kicking me off the computer
at my house. More later as you have more questions.

Mike



> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Chris Stephens
> Sent: Tuesday, September 16, 2008 8:40 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Newbie, Hot Rod truck AWD EV project
> 
> AHH I think I get it now. Because they are NOT mechanically linked, and
> EV
> will easily freewheel, what little difference will be taken up so to speak
> by the second.
> Looks like 2 DC motors in direct drive it is. So what about gear ratio?
> Where can I get solid info on how to choose?


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*



> MIKE WILLMON wrote:
> >
> >
> >
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

Chris,

> I noticed you are useing the stock rear diff. Did you upgrade to posi or 
> are
> they open? What gear ratio is working for your direct drive?

We are running an open diff. We are not having any problem with inside 
wheel spin. Between the car being slightly heavy (for a racecar) and an 
effective suspension, we seem to be able to keep enough weight on the inside 
tire. A Quiaffe limited slip would bolt in but might increase the rolling 
resistance cutting racing range.

We are running a 3.9 ratio. This longer gearing helps maximize acceleration 
in the speed range we see on the track (50-120 mph). We are going to try 4.4 
ratio to try and put the motor into a more efficient rpm range.

Cliff
www.ProEV.com



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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

No you didn't miss it. I cannot remember the name of them. I found them on some gasser race list I was perusing, made a couple inquiries and got no responses. I can't even remember their names. I may have posted them here on the EVDL , but there's been a lot of water under the bridge since then. I'll try to look them up again.

Mike

----- Original Message -----
From: Tim Humphrey <[email protected]>
Date: Wednesday, September 17, 2008 5:13 am
Subject: Re: [EVDL] Newbie, Hot Rod truck AWD EV project
To: [email protected]

> 
> 
> 


> > MIKE WILLMON wrote:
> > >
> > >
> > >
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

No you didn't miss it. I cannot remember the name of them. I found them on some gasser race list I was perusing, made a couple inquiries and got no responses. I can't even remember their names. I may have posted them here on the EVDL , but there's been a lot of water under the bridge since then. I'll try to look them up again.

Mike

----- Original Message -----
From: Tim Humphrey <[email protected]>
Date: Wednesday, September 17, 2008 5:13 am
Subject: Re: [EVDL] Newbie, Hot Rod truck AWD EV project
To: [email protected]

> 
> 
> 


> > MIKE WILLMON wrote:
> > >
> > >
> > >
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

Thanks Mike..

Here's a funny for ya.....

Are you talking about the Braille batteries that "YOU AND I" discussed last
October??

http://www.evdl.org/archive/index.html#nabble-p13169278

Stay Charged!
Hump





> MIKE WILLMON wrote:
> >
> > No you didn't miss it. I cannot remember the name of them. I found them
> > on some gasser race list I was perusing, made a couple inquiries and got
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

Yeah thats pretty funny. Thats them. I inquired pricing from a dealer but never heard back. I'd still be interested.
Cutting 126 lbs would be nice but If I recall they coast like 30% more than the Hawkers. That would make a $6k pack coast $8k. Would still be nice though, if they would hold up to the abuse. Maybe we can try a fewer number in a Jr Dragster 

Mike

----- Original Message -----
From: Tim Humphrey <[email protected]>
Date: Wednesday, September 17, 2008 12:12 pm
Subject: Re: [EVDL] Newbie, Hot Rod truck AWD EV project
To: [email protected]

> 
> Thanks Mike..
> 
> Here's a funny for ya.....
> 
> Are you talking about the Braille batteries that "YOU AND I" 
> discussed last
> October??
> 
> http://www.evdl.org/archive/index.html#nabble-p13169278
> 
> Stay Charged!
> Hump
> 
> 
> 


> > MIKE WILLMON wrote:
> > >
> > > No you didn't miss it. I cannot remember the name of them. I
> > found them
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

Cliff, this is interesting comment.

My calcs for an Audi show that 5.5:1 to 6:1 are optimal for the motors
I will be using and your motors too. Even 4.4:1 might be too tall, but 
this depends on the tire size which I don't see being very small on
the Imp. What is the tire diameter you're using?

I took off stock diff (4.11:1) for this very reason and it would make my
life much simpler if I could reuse it, but the numbers make no sense.
Simulation shows that 0-100 km/h time becomes like 160% if I replace
5.7:1 diffs I'm installing now with stock 4.11:1 one.

Victor




> ProEV wrote:
> > Chris,
> >
> >> I noticed you are useing the stock rear diff. Did you upgrade to posi or
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

Hi Victor,

>
> My calcs for an Audi show that 5.5:1 to 6:1 are optimal for the motors
> I will be using and your motors too. Even 4.4:1 might be too tall, but
> this depends on the tire size which I don't see being very small on
> the Imp.

Remember our vehicles are designed to do different jobs. You are putting 
together an impressive street car. We have built a race car.

For the street, it is all about 0-60 (OK, Mr Metricmind, 0-100 km per 
hour<G>). This is the speed range that the car normally operates in and 
where it needs it's best acceleration.

For the track, it is different. In fact, for every track it is different. We 
have the most data from Moroso Motorsport Park, so I will use that track as 
an example. We can get through the slowest chicane at about 50 MPH (80 KPH). 
The fastest speed we reach is around 120 MPH (193 KPH) at the end of the 
longest straight. So our operating range is 50 MPH to 120 MPH (80-193 KPH).

We take the car out and accelerate from 0-120 MPH (0-193 KPH) in a straight 
line. The SIADIS program gives us the motor torque curve. We do an 
acceleration spreadsheet and put in our tire size and final drive gearing. 
The calculate time to speed matches fairly closely to the real world data 
which is reassuring.

Next we put in another figure for the final drive ratio. For this example, 
we will use 4.6. Then we look at how long it should take us to get from 0 to 
10 mph (0-16 KPH):

3.9 = 1.1 seconds
4.6 = 0.8 seconds

The 4.6 ratio will save us 0.3 seconds from 0-10 MPH (0-16 KPH).

On the other hand, the all important <G> 100-110 MPH (161-177 KPH) range.

3.9 = 3.2 seconds
4.6 = 3.9 seconds

The 4.6 ratio will cost us 0.7 seconds from 100-110 MPH (161-177KPH) range.

Since we never go below 50 MPH (80 KPH), we can give up better acceleration 
at slower speeds if it will help us on top.

Our next step is to take data from a lap at Moroso and break it down into 
how much time we spend in each speed range accelerating. For example, on a 
normal lap with 3.9 gearing, we spend 12.5 seconds during the lap 
accelerating between 70-80 MPH ( 113-129 KPH). The 4.6 gearing would take 
120% longer in that speed range so we would increase our time to 15 seconds.

Add all the speed range times together and keep the no throttle times the 
same gives a rough lap time with the 4.6 ratio.

Of course, the motor torque changes with Depth of Discharge. It is also 
different when we need to run a lower current limit to finish a longer race. 
Which means the best gear ratio might be different. Also running a higher 
rpm might give a percent or two better efficiency which would mean a high 
current limit on a long race...


Cliff
www.ProEV.com



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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Newbie, Hot Rod truck AWD EV project*

Excellent information Cliff. Keep at it and let us know how the racing goes.

Dave Cover



> ProEV <[email protected]> wrote:
> 
> > Hi Victor,
> >
> ...


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