

700+ hp electric Honda S2000 built by high school senior - ek
http://hackaday.com/2012/09/16/700-hp-electric-honda-s2000-built-by-high-school-senior/

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Tossrock
There's much more information in the linked forum thread:
[http://www.s2ki.com/s2000/topic/975497-wait-that-isnt-
an-f20...](http://www.s2ki.com/s2000/topic/975497-wait-that-isnt-an-f20c/)

For example, he also built a keyless entry system with an arduino board and an
iPod. This kid is pretty amazing.

~~~
andyjsong
Does anyone else not see any of the pics submitted by the OP in the forum?

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cantbecool
There's no way he's getting 700+ HP from those two warp 9 motors. It says each
motor is capable of outputting 34HP continuously:
[http://electriccarinternational.com/media/img-
prod/WarP_9_Sa...](http://electriccarinternational.com/media/img-
prod/WarP_9_Sales_Sheet-1.gif)

~~~
Zak
That appears to be at 144 volts and 500 amps. His stated plan is to deliver
343 volts and 2000 amps. Assuming this doesn't melt the motors, he'll get more
power than the datasheet claims. That said, his calculations might be a bit
off.

144Vx500A = 72KW or 96.5HP. He's assuming 85% efficiency, which would give
82HP, not 34. Furthermore, if the motor were to deliver 100 ft-lbs of torque
as stated at its stated maximum speed of 5800 RPM, that would be 110HP. This
would obviously require more than 72KW of electrical power input.

Taking the ratio between the motor's stated performance and the electrical
numbers given on the datasheet, and multiplying by the electrical power he
intends to supply, we get 34/96x920 = 326HP. This too seems a bit off, as 35%
efficiency is quite low for an electric motor. My guess is that the motor is
actually incapable of producing its full torque at higher RPM.

My guess is he will actually produce something resembling the amount of power
he's hoping for, but only briefly, after which they will deliver no power at
all, ever.

~~~
jrabone
Without the torque-speed curves for these motors, you just can't tell.

The actual graphs are at <http://www.go-
ev.com/images/003_09_01_WarP_9A_Graph.jpg> and <http://www.go-
ev.com/images/003_09_02_WarP_9_SpreadSheet.jpg>

_My guess is that the motor is actually incapable of producing its full torque
at higher RPM._

Correct. At 100 ft/lbs the speed drops to just over 2000 rpm.

I would guess these motors have a thermal fuse wound into the stator coil
(source: spent a summer in a rewinding shop), and if he tries to drive them
much outside the design limits, they'll simply cut out, perhaps permanently.

EDIT: the datasheet mentions a temperature snap switch, so it sounds like they
have a non-permanent cut-out on thermal overload.

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SunboX
Let´s see if he get´s this thing working. Building two e-motors and some
batteries inside a car is a very "easy" task compared to building the "control
unit" and cooling the batteries down. This two motors will draw a lot current,
the electrics to control this huge amount of current will be a hard task to
figure out. Another one is the battery cooling. 700hp will take a lot energy,
the batteries will get very hot. If you ever had played a 3D game on your
phone, you know what I mean. ;o)

If he get´s this thing working, it would be really great! I can´t wait to call
a electric car my own. :D

If you interested in such kind of work, you should search on Youtube for
"electric VW Golf II", "electric VW Polo" or "electric VW Käfer". ;o)

~~~
SunboX
And if he want´s to build a "good" electric car, he should keep an eye on the
EMF and EMI radiation.

~~~
eckyptang
Good point, although I can see the ricers using this to cause trouble instead
of their boom boxes instead :(

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Zak
Introductory blog post here:
<http://electrichonda.blogspot.de/2011/05/introduction.html>

Juan's project is impressive, no doubt, but his analysis of the superiority of
electric cars is suspect. He writes:

 _The average car uses about 20% of the potential energy of the fuel in useful
motion while wasting the other energy as heat, noise and pollution. Electric
cars use upwards of 80% of their 'fuel', a percentage which can be increased
relatively easily as most of its losses are electrical._

The biggest problem is that he's treating the electricity in the battery as
raw fuel. He does acknowledge that most electricity in the US comes from
sources like coal, but ignores various losses between that coal and his car
flying down the road. Let's add those in.

The best we can do from a coal plant is about 49%[0]. It may be possible to
use the waste heat from such a plant for other purposes; I am not including
such uses in this calculation as they do not have anything to do with powering
the electric car.

The US power grid is around 93-94% efficient[1].

Electric cars don't get all the power from the grid in to the batteries as
chemical energy. Charging batteries generates quite a bit of heat. The EPA
estimates that the best electric cars are 62% efficient at converting power
from the grid in to kinetic energy[2].

So we have 49% * 94% * 62% = 28.6% efficient at converting the chemical energy
in coal to propelling the car. This is not a dramatic improvement over
internal combustion. There is, of course the advantage of using power sources
other than coal and oil, but the claimed efficiency is not quite what electric
vehicle proponents would like it to be.

[0] <http://en.wikipedia.org/wiki/Aved%C3%B8re_Power_Station>

[1]
[http://en.wikipedia.org/wiki/Electric_power_transmission#Los...](http://en.wikipedia.org/wiki/Electric_power_transmission#Losses)

[2] <http://www.fueleconomy.gov/feg/evtech.shtml>

~~~
jsight
If you want to include the efficiency of the entire electrical pipeline, then
you need to do the same for the gasoline/diesel engine.

How much energy is used for the extraction, refinery, transport, and
distribution of gasoline/diesel fuel? I suspect 26% efficiency for gasoline
would also be extremely high compared to reality if those costs were factored
in.

~~~
Zak
I'm talking about the efficiency of the pipeline starting with a fossil fuel
and ending with a car moving down the road. It's also fair to start the
comparison with a fossil fuel in the ground, but in that case you also have to
start the electric pipeline at a coal mine.

Electric might well win by a significant margin, but it isn't nearly the 85%
to 20% claimed.

~~~
jsight
Well, your car comparison started at electricity production. At the very
least, your gasoline example should start at the refinery.

Does anyone know the efficiency of the average refinery? Or distribution
costs? My suspicion is that they are actually just as bad as the overhead of
burning coal.

~~~
JoeAltmaier
I'm not sure what the 'efficiency' of a refinery is. In terms of energy
consumed per energy produced? How about equipment/installation costs, costs to
the environment, man-hours etc. All different units, hard to avoid
apples/oranges issues.

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hyperbovine
Props to the kid for being such a whiz, but DAE shudder at the thought of a
17-year old getting behind the wheel of this thing? My mom's minivan had about
150hp and I still managed to do incredibly stupid shit with it. All the while
believing I was an above-average driver...

~~~
jasonquinn
I've met anyone who doesn't describe them self as a above-average driver

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andyjsong
I just wondering where he's getting the cash to convert his s2k into an
electric drag racer. I wish I had that kind of access to car and batteries as
a kid.

~~~
nicholassmith
It says he runs his own CAD business, and I imagine he's from a fairly cash-
rich background.

~~~
patrickk
He also mentioned he's getting some sponsorship in the forum.

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ChuckMcM
Interesting that he bought the batteries "in china" (his scare quotes), I'm
wondering if they are off market copies? Having built high current battle bot
battery boxes I get really really twitchy around "good deal" battery packs.
That said, its amazing how 'off the shelf' this tech is becoming. Hats off to
this guy for taking the challenge.

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mtr
His project inspired me to write a blog post:
[http://blog.octanenation.com/news/high-school-senior-
builds-...](http://blog.octanenation.com/news/high-school-senior-
builds-700-hp-electric-honda-s2000/)

It's a complex undertaking and he will definitely learn more than his classes
in high school!

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BryanB55
Just read through the whole thread on the s2000 forum, I'm an auto enthusiast
but I was more interested in how this kid knows how to do all of this more
than I am interested in the car. 16 years old and you know how to retrofit an
s2000 with a custom electric motor and build CAD models of it!?

~~~
StavrosK
He's 16 years and 300 months old.

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djt
Only a 15% loss of power to the wheels is very low.

Just the drivetrain loss on muscle cars is around 30% approximately.

~~~
lloeki
Honda has fantastic performance gearboxes and drivetrain loss is usually in
the low 20%.

Also most muscle cars are slushboxes and the torque converter ruins
efficiency.

~~~
djt
looks like tesla's are about 88% efficient, so definitely in the range.

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chrsstrm
What's the weight of the 104 batteries and the gain/loss after removing the
gas engine and replacing with electric?

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ricksta
A123 cells are about 180wh per kg, hes using 20ah _4 at 104 cells in series.
so thats about 104_ 3.7 = 396 volts at 120ah. multiply that together you get
47kwh of energy. These batteries would be around 500lb.

These battery pricing must've came down a lot over the past couple years
because this would've cost something like $40k couple years ago, but a quick
google for pricing looks like the battery pack he is using can be bought for
around $13k pricing source:
[http://www.a123rc.com/goods-468-Excitingly+Powerful+A+123+20...](http://www.a123rc.com/goods-468-Excitingly+Powerful+A+123+20ah+PRISMATIC+CELLS.html)

~~~
chrsstrm
500lbs in batteries and a quick search shows each of his motors is 156lbs.
Since the gas motor he took out weighed 326lbs, he's got a net gain of ≈
480lbs. That's a lot to overcome.

~~~
harold
These cars offer excellent balance, handling and braking from the factory. I'm
guessing all of those _may_ suffer after gaining that much weight.

I had an '05 S2000. I wish I still had it, wonderful car.

~~~
networkburger
Agreed. Best car I ever had (and totalled).

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sukuriant
I'll be interested to see how he's going to deal with the torque problem that
Tesla had to solve.

~~~
s_henry_paulson
I'm interested in how he's dealing with even simpler problems like charge time
and battery life.

~~~
SunboX
Me, too. I don´t see any battery cooling system. This will be a problem, if
he´s getting it to work. With these big motors, the batteries will get very
hot ... and maybe, burn down ... or at least don´t work very long.

