# how many years before my build is feasable?



## Roy Von Rogers (Mar 21, 2009)

Ever heard of Tesla

Roy


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## datbino (Oct 12, 2013)

Roy Von Rogers said:


> Ever heard of Tesla
> 
> Roy



ive read alot about the tesla roadster which is the closest to what i want to build. however, the tesla weighs 2800lbs after gutting the engine out of a sub 2000lb vehicle. minus the engine, radiator, and othe motor related things on the s2000 would put me at about 2100. 

as far as ive seen, there isnt battery technology out there to get all of this done for less than 900lbs-is there?

please correct me if im wrong, and I meant to post this in the 'chat' section if a mod doesnt mind


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## Duncan (Dec 8, 2008)

Headway cells - 100 watt-hours/Kg
I think the others, CALB etc are about the same

100 miles at 200 watt-hours/mile (very slippery - taking it easy)
= 100 x 200 /100 = 200Kg

Motor - 100kg
Controller - 20Kg

total 320Kg = 704lbs

So 200lbs left over, you can have nearly 300Kg of batteries to get a definite 100 miles range - maybe even 150 if you are going slower

300Kg = 30Kwhrs

Sounds like the answer is about now


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## datbino (Oct 12, 2013)

Duncan said:


> Headway cells - 100 watt-hours/Kg
> I think the others, CALB etc are about the same
> 
> 100 miles at 200 watt-hours/mile (very slippery - taking it easy)
> ...


wow!! ok, ill start doing the more in depth research now. thanks!!


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## dragonsgate (May 19, 2012)

datbino said:


> ive read alot about the tesla roadster which is the closest to what i want to build. however, the tesla weighs 2800lbs after gutting the engine out of a sub 2000lb vehicle. minus the engine, radiator, and othe motor related things on the s2000 would put me at about 2100.
> 
> as far as ive seen, there isnt battery technology out there to get all of this done for less than 900lbs-is there?
> 
> please correct me if im wrong, and I meant to post this in the 'chat' section if a mod doesnt mind


The Tesla is already electric. Are you talking about the Lotus Elise that the tesla roadster is based on? As for the technology, it is here the big question is, is your bank account up to it? 900 pounds? About the only way to get under 900lbs is a motorcycle, maybe a trike.


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## datbino (Oct 12, 2013)

dragonsgate said:


> The Tesla is already electric. Are you talking about the Lotus Elise that the tesla roadster is based on? As for the technology, it is here the big question is, is your bank account up to it? 900 pounds? About the only way to get under 900lbs is a motorcycle, maybe a trike.


yes the lotus elise. and i meant 900lbs for my battery, controller, and motor/adapter to my transmission


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## dougingraham (Jul 26, 2011)

datbino said:


> my goals are:
> 300hp to the rear wheels
> 100-150mile range when being nice to it
> and less than 3000lbs for the vehicle(900lbs of stuff)


The bottom end of the desired range is possible. The 150 is just reachable. The 900 lbs is motor+controller+charger+cables+around 25kwh battery. The 300 hp is the problem. You can do that but it will add around 200 more lbs. Why do you think you need 300hp? Torque is what you need to make the car feel fast and electrics have that. ICE motors tend to have torque in ft-lbs similar to their horsepower ratings. So to get high torque you need high horsepower with an ICE. A single WarP 9 motor will do 277 ft-lbs at 1000 amps from the dyno tests I have seen. You would need a 250-300hp ICE to get that and it would be over a limited RPM range of 3500 to 5500 RPM The electric will do that from zero RPM to about 4000 tapering off somewhat to the 5500 RPM redline. Unless you are racing you probably don't need 300 hp. The WarP9 will briefly do wheel HP of about 150 but it doesn't feel anything like 150HP in an ICE powered vehicle.

What is your goal with this project? Just to keep the car feeling like it does now or perhaps a bit stronger?


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## datbino (Oct 12, 2013)

dougingraham said:


> The bottom end of the desired range is possible. The 150 is just reachable. The 900 lbs is motor+controller+charger+cables+around 25kwh battery. The 300 hp is the problem. You can do that but it will add around 200 more lbs. Why do you think you need 300hp? Torque is what you need to make the car feel fast and electrics have that. ICE motors tend to have torque in ft-lbs similar to their horsepower ratings. So to get high torque you need high horsepower with an ICE. A single WarP 9 motor will do 277 ft-lbs at 1000 amps from the dyno tests I have seen. You would need a 250-300hp ICE to get that and it would be over a limited RPM range of 3500 to 5500 RPM The electric will do that from zero RPM to about 4000 tapering off somewhat to the 5500 RPM redline. Unless you are racing you probably don't need 300 hp. The WarP9 will briefly do wheel HP of about 150 but it doesn't feel anything like 150HP in an ICE powered vehicle.
> u
> What is your goal with this project? Just to keep the car feeling like it does now or perhaps a bit stronger?


well, 300 hp is about 90 more than the car has now, and currently the car has a peak torque of 163ftlbs. ill need more power if I add 2-300lbs to the vehicle. I understand it never will, but, I would love to keep it as honda s2000ish as possible-thats why the weight goals are so key since i still want it to turn and feel good


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## IamIan (Mar 29, 2009)

datbino said:


> well, 300 hp is about 90 more than the car has now, and currently the car has a peak torque of 163ftlbs. ill need more power if I add 2-300lbs to the vehicle. I understand it never will, but, I would love to keep it as honda s2000ish as possible-thats why the weight goals are so key since i still want it to turn and feel good


Keep in mind the difference at low RPM between an ICE and a Electric Motor.

ICEs are rated for their peak , best case power... not sustained rate.

To compare Apples to Apples ... look at the Electric motor's peak pulse ... like ~10Second power rate ... and look at the peak torque needs you have ... for this high peak power you will only use for short periods.

For Example:
The Emrax 228 Electric Motor Link
Itself Weighs 
12.2 kg (~27 Lbs ) for Liquid Cooled
It is rated for a continuous sustained load of up to 50kw ( ~67HP ).. 125nM ( ~92FtLBs) continuous torque.

But it can do short bursts of up to 100kw ( ~134 HP ) ... but , unlike the ICE ... the electric motor keeps it's torque at the lower RPMs ... thus this ~134 HP peak produces up to 240nM or ~177FtLBs of torque.

So because the electric motor keeps it's torque at low RPMs ... and the ICE doesn't ... this little ~27 Lb Electric motor with a continuous rating of only ~67HP ... can produce more peak torque than the 300HP ICE ... more torque means more acceleration ... from a dead stop this little ~67HP rated electric motor will accelerate faster than the 300HP ICE will ... it is only at higher RPMs that the gap in power shows up in performance... It is not until higher than 2,500 RPMs that the ICE has any chance at all to catch up in torque.

But still ... if you wanted a monster ... put one of these on each of the 4 wheels ... you'd have a peak of ~536 HP and all 4 motors combined would themselves weigh ~108 Lbs... or 1 on each of two wheels ... for ~268 peak HP from ~54 Lbs of Electric motor.

This is also available now... has been for several years ... cost a fortune ... but it is available.


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## datbino (Oct 12, 2013)

IamIan said:


> Keep in mind the difference at low RPM between an ICE and a Electric Motor.
> 
> ICEs are rated for their peak , best case power... not sustained rate.
> 
> ...


im NOT trying to build a monster, but im trying to understand what you are saying. your saying ill need much less if i want low 14's quarter mile acceleration and 110mph top speed?
i understand hp is just torque over rpm. im just not sure how to translate the acceleration needs i have to an electric motor.


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## frodus (Apr 12, 2008)

The same way you translate acceleration from a Gas engine. 

Torque gives you acceleration
HP gives you top speed

If you want a certain acceleration, then calculate the weight of the vehicle, aerodynamics, and calculate the torque needed. Forget about HP, as that controls the top speed. Torque controls acceleration.


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## IamIan (Mar 29, 2009)

datbino said:


> im NOT trying to build a monster, but im trying to understand what you are saying. your saying ill need much less if i want low 14's quarter mile acceleration and 110mph top speed?
> i understand hp is just torque over rpm. im just not sure how to translate the acceleration needs i have to an electric motor.


Your almost there.

The first step is understanding a 300HP rated ICE will NOT give you 300HP under all RPMs... it maxes out at ~168 FtLBs of Torque... if you look at the torque and / or power curve for that ~300HP ICE you'll see this same thing.

At 3,000 RPMs 168FtLBS of Torque only gives you ~96HP... due to the 168FtLB torque limit ...it gives you even less HP at lower RPMs.

Like you said Power is Torque & RPM.

If you want the same acceleration you have now ... than you need the same torque curve you have now.

At any RPM that the little electric motor has more Torque ... you will have more vehicle acceleration... any RPM where the electric motor has the same torque you have the same vehicle acceleration.

177FtLBs of Electric motor torque will have the vehicle accelerate faster than 168FtLBs... it is not until above 2,500 RPMs that the Emrax shows the Torque start to dip bellow that ~177 FtLBs ... thus at any Engine RPM bellow 2,500 RPMs the 300HP ICE accelerates slower... even though the ICE was rated for 300HP and the Emrax was only rated for 67HP.

I'm not saying you have to use the Emrax in particular ... it is just an example... there are many other electric motor options... ICEs are rated for their Peaks or best case ... Electric motors often are not ... and ICE's always loose torque fast at lower RPMs , which is why a ICE vehicle needs a much much higher rated ICE in order to get the same low RPM acceleration from a stop.

Does that help any?


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## datbino (Oct 12, 2013)

IamIan said:


> Your almost there.
> 
> The first step is understanding a 300HP rated ICE will NOT give you 300HP under all RPMs... it maxes out at ~168 FtLBs of Torque... if you look at the torque and / or power curve for that ~300HP ICE you'll see this same thing.
> 
> ...


yes, but my motor makes 160+ft lbs at above 7krpm. from my perspective, even if i have a motor making 170ftlbs to 5k then shift, will still be slower than my motor kept in its power band(simply more torque pulses per second)


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## IamIan (Mar 29, 2009)

datbino said:


> yes, but my motor makes 160+ft lbs at above 7krpm. from my perspective, even if i have a motor making 170ftlbs to 5k then shift, will still be slower than my motor kept in its power band(simply more torque pulses per second)


Yes.

But remember it only applies at 7,000 RPMs ... you are not pulling out from a stop at 7,000 RPMs... thus it doesn't apply to accelerating from a stop ... or for 0-60 ... or for 1/4 mile.

How fast do you have to already be going to get 7,000 RPMs for that case to apply?

And thus ... at 3,000 RPMs the 168FtLB limit means you only have ~96HP to the shaft ... and the 177FtLB 67HP Electric motor WILL accelerate faster than you at 3,000 RPMs and bellow.

If you want the same acceleration you need the same torque curve ... not the same HP ... Look for electric motors that give you the Torque you want.


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## datbino (Oct 12, 2013)

IamIan said:


> Yes.
> 
> But remember it only applies at 7,000 RPMs ... you are not pulling out from a stop at 7,000 RPMs... thus it doesn't apply to accelerating from a stop ... or for 0-60 ... or for 1/4 mile.
> 
> ...


I think our misunderstadings are coming from the differences in a-b cars and performance cars. * the f22c makes little torque at low rpm, but once you get the rpms above 6k, its an entirely different motor.*

in 'normal a-b' car this would seem silly or stupid. how much time would you actually spend up there? what about taking off?

these are solved by gearing in this situation. *to launch fast, you spin the tires get it in vtec, and the gearing keeps the car above vtec with each upshift. *
while it seems impractical in theory, this works out to be amazing to drive. *heavenly, in my opinion.*


i want this same 'eagerness,' fun to drive attitude out of an electric powertrain- im not sure if its possible. **

will a 6k rpm electric motor be able to do this? or will i find it lacking even though its producing more torque?

I understand my lack of knowledge but Im trying to learn


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## kennybobby (Aug 10, 2012)

For 14 to15 sec 1/4 mile times with a 3000 lb vehicle requires 215 to 200 hp just for the acceleration power. You will need additional power to overcome aerodynamics and rolling resistance, so for drag racing 300 hp is a fair estimate of your power requirement. 

But very few drag racers also want or need to get 150 miles of range. 

What is your prime directive--you wantin to go drag race or get lotsa range? Just like in racin it's only a matter of how fast you want to go, how much money you got...By the time you optimize everything and build it to do both, you will have spent enough to buy a Tesla S.


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## frodus (Apr 12, 2008)

By the time you spun the tires to get into Vtec and slipped the clutch to attempt to deliver SOME (not all) of that 168ftlbs @7krpm on the gas vehicle, the EV powered vehicle with 170ftlbs would be half way down the track.


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## IamIan (Mar 29, 2009)

datbino said:


> i want this same 'eagerness,' fun to drive attitude out of an electric powertrain- im not sure if its possible. **


Possible = Yes
That and even more / better performance is possible.
No Question at all.

Only a question is weather you want to invest the time and money to make it happen.



datbino said:


> will a 6k rpm electric motor be able to do this? or will i find it lacking even though its producing more torque?
> 
> I understand my lack of knowledge but Im trying to learn


It can't be lacking if it has more torque at that same RPM ... if it has more torque it will accelerate faster ... there is no way out of that.

What I've been trying to explain is that ICE and electric motor are not the same thing ... the performance curves are very different ... a 300HP rated ICE is significantly weaker / slower / etc ... than a 300HP rated Electric Motor ... that's just the way it is.

Sure you can get a 300HP Electric Motor ... or even more ... 4 Emrax motors at ~108 Lbs ( ~49kg ) of motors would be as much as ~536 HP... Duncan allowed for up to 100kg of motor ... there is plenty ... 300HP is easy ... but 300HP electric motor will smoke a 300HP ICE ... as it has much better performance.

If you want the same acceleration as the 300HP ICE ... stop looking at HP ... you need the electric motor to have at least the same torque ... if you want that same acceleration at the same vehicle MPH for some gear ... then you need to look for the torque at that RPM for that Gear.... ie look to match the torque ... not the HP ... you can match the HP if you want ... that would be improving / increasing the performance , better than it is as a ICE.

- - - - - - 

Perhaps a different example will help:

Many years ago John Wayland did his White Zombie BEV Conversion.
He can get 0-60 in ~1.8 Seconds 
1/4 Mile in 10.258 Seconds
Curb Weight 2,352 Lbs
He has a speed governed limit of 129MPH
Can do 100 Miles per Charge 
1,250 FtLb Of Torque.

He did better performance than you are asking for.

He used good stuff ... and it was expensive ... but even at that ... he did not use the very best.


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## Duncan (Dec 8, 2008)

Hi Datbino

I took your 300hp into account in my numbers
I was thinking of
An 11 inch DC series motor (100Kg)
and a Soliton controller

That combination can produce 300Kw (400hp) - for a few seconds
No good for a big truck going up a hill but a small car can only use that much power for a few seconds before you have to brake to avoid a crash

The limiting factor will be the batteries
30kwhrs of batteries - Headway will allow 15c for 10 seconds = 450Kw
I think the new CALB will allow 12c for 10 seconds = 360Kw

You should have plenty of power to be a hooligan - I take mine (Duncans Dubious Device) to the track and have a blast


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## datbino (Oct 12, 2013)

thanks guys!!! I have so much to learn!

ive been reading about the white zombie

getting the gearing right seems to be pretty crucial, im not trying to drag race. its more of a canyon/backroad car.


and 10 seconds should be plenty of oomph, how quickly does it recover?


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## dedlast (Aug 17, 2013)

This may (or may not) help clear up some confusion. It's usually easier to understand something when you can see it. 

This first link is a supposedly stock 2003 S2000 on the dyno:
http://www.dragtimes.com/2003-Honda-S2000-Dyno-Results-Graphs-11765.html

This link is for the new HPEVS AC76 at 144 volts:
http://www.hpevs.com/Site/images/to...erial/ac76 imperial peak 144 volt 500 amp.pdf

Look at where the torque starts for the AC motor--zero RPM. For the S2000 the graph doesn't even start until 3K, right about where the electric is starting to drop off. Different motor/controller combos will give somewhat different drop offs but this is just one example. Your shift points will obviously change, but all that torques is available from a dead stop. That's why the White Zombie is able to get the hole shots that he does.

And for canyon carving, that could mean fewer shifts and using higher gears in general. 

Bill


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## datbino (Oct 12, 2013)

dedlast said:


> This may (or may not) help clear up some confusion. It's usually easier to understand something when you can see it.
> 
> This first link is a supposedly stock 2003 S2000 on the dyno:
> http://www.dragtimes.com/2003-Honda-S2000-Dyno-Results-Graphs-11765.html
> ...


I do understand instant max torque from 0 rpm, my only concern is that it will suck to drive. i understand that 163ftlbs at 8k rpm is an insane amount of torque pulses per second, and I dont know how many ftlbs ill need to beat that when i have a max rpm of 5.5k

i get that if my car is out of its powerband, its slow. but its an animal when its in its powerband- and thats what i want out of my electric motor. not necessarilly 163ftlbs at 9000 rpm, but the torque to beat that when im limited to 5.5. i cannot make this car slower than it already is


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## datbino (Oct 12, 2013)

well, I know im being stupid. but i had an idea last night. 

build the car to my desired specs of weight with a 30ish mile range(looking at a chevy volt pack stripped of armor), then building a removable tray for another 3-400lbs of batteries and my charger for when im daily driving.

drive to the mountains, drop the tray, go hoon for 20 miles, come back, relift the tray back in(with a jack), drive home- 0 gasoline


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## piotrsko (Dec 9, 2007)

my $.02: get a engine data logger. Run your scenario in the canyon using the equipment you have. Do one with the whole trip. Now you have a base line of energy consumption to beat which makes number crunching so much easier than SWAG. convert engine data in HP to watts.

If you want more performance add some portion to your baseline.

FWIW my ranger with the Kostov 11" and 1/2 ton of FLA is way more fun than the same with the 2.9 and 1/2 ton of lead but it don't corner for poop. OTOH 25KWH for me is equivalent to 2 gallons of fuel.

YMMV


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