EV Digest 3986
Topics covered in this issue include:
1) Re: Questions to those who have done a restoration + conversion
by "Ryan Stotts" <[EMAIL PROTECTED]>
2) Re: EVLN(Jr Not Changing tho talks clean)
by Derrick J Brashear <[EMAIL PROTECTED]>
3) Re: Low Rolling Resistance Tires?
by "Ryan Stotts" <[EMAIL PROTECTED]>
4) RE: acceleration
by "Philip Marino" <[EMAIL PROTECTED]>
5) Maybe this is your long range EV
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
6) power vs torque
by Jeff Shanab <[EMAIL PROTECTED]>
7) Re: The Amazing Little Hawkers That Refuse to Die!
by David Dymaxion <[EMAIL PROTECTED]>
8) Re: Questions to those who have done a restoration + conversion
by David Dymaxion <[EMAIL PROTECTED]>
9) Re: Acceleration
by "John Haskell" <[EMAIL PROTECTED]>
10) Re: Questions to those who have done a restoration + conversion
by "John Westlund" <[EMAIL PROTECTED]>
11) motor current higher than batt current?
by "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
12) RE: motor current higher than batt current?
by "Mark Fowler" <[EMAIL PROTECTED]>
13) Re: motor current higher than batt current?
by James Massey <[EMAIL PROTECTED]>
14) Re: motor current higher than batt current?
by Mike Chancey <[EMAIL PROTECTED]>
15) RE: Queastion about 300zx
by "Chris Tromley" <[EMAIL PROTECTED]>
16) RE: acceleration
by "damon henry" <[EMAIL PROTECTED]>
17) Zamboni batteries,lead acid/AGM
by "Deuville's Rink" <[EMAIL PROTECTED]>
18) RE: Low Rolling Resistance Tires?
by "Adams, Lynn" <[EMAIL PROTECTED]>
19) 144V vs 108 V performance
by "Adams, Lynn" <[EMAIL PROTECTED]>
--- Begin Message ---
----- Original Message -----
From: "John Westlund" <[EMAIL PROTECTED]>
Subject: Questions to those who have done a restoration + conversion
>What tools would those who have done projects like this recommend, for
>starters?
Once you start, you will see what you need and buy them as you need them.
>I want to know how much money I'm going to need to invest in tools.
I wouldn't worry about it.
>I'm a little hampered by the fact that I don't have a two car garage, it's
>more like a 1.5 car garage that fits one car and has plenty of leftover
>space
If it's cleaned out, it will be enough room.
>I only possess the basic tools that most households have.
That's enough to get you started.
>I'm certainly going to need to rent an engine crane.
If you have one of these stores nearby, they go on sale often:
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=46766
Auto parts stores and discount tool stores also sell them. I've seen them
priced lower then $150.
You could also use it for installing and removing the 100+lb electric motor.
>a photograph conversion diary of the whole process
I look forward to that as I plan on taking on a project like this myself in
the future.
>1) Strip the interior
>b) Remove all carpets(-15 lbs)
>c) Remove all sound deadener(-25 pounds)
>e) remove bumpers(-15 to -40 pounds)
You can start on all that now and do it for free with the tools you have.
>a) Drive car up to get weighed
Truck stops and drag strips have scales that you can use for a small fee.
Another, albeit more expensive option is a set of 4 scales:
http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=191719&prmenbr=361
.
I'm sure lower cost scales can be found somewhere.
What I like about that option is the amount of weight on each tire can be
known and helps with choosing a tire size that has the proper load rating.
>d) Fabricate adaptor plate for tranny
Some really good info here:
http://www.electroauto.com/catalog/adaptors.shtml
Also you might request one of these free catalogs. Even if you don't
purchase anything from it, it's still very informative in regards to
restoration. Paints, sanding, grinding, polishing, metal working, and all
sorts of immensely useful tools.
http://www.eastwoodco.com/catalogrequest/catalogrequestmain.jsp
Another catalog with a wide variety of low cost tools:
http://da.harborfreight.com/cpiweb/emailopt/presentOptions.do
Good luck.
Ryan
--- End Message ---
--- Begin Message ---
On Wed, 29 Dec 2004, Rich Rudman wrote:
And planting flowers on the roof of a factory? Oh please, give us a
break!
[]
As I recall Ford has 100s of acres of plant roof.
You rather see this as solid Asphalt???
It also save him Kilobucks in heating and cooling cost.
And it retains stormwater rather than just letting it drain all at once,
which means no (or fewer) retention ponds, or less of a surge if there
were no ponds before.
I'm not knocking solar panels, either, but there's value in doing this.
--- End Message ---
--- Begin Message ---
----- Original Message -----
From: "Derrick J Brashear" <[EMAIL PROTECTED]>
Subject: Re: Low Rolling Resistance Tires?
>> I've seen mentions on the net about the "Michelin Energy MXV4 Plus" tire
>> being LRR, but I can't find anything actually saying it is.
>There's something hidden in the page you mention below explaining the
>history of the tire (google finds it, but i don't see it in the page).
>> http://www.michelinman.com/catalog/tires/MichelinEnergyMXV4Plus.html?tiretype=2&tire=4
Hmm... Indeed. I didn't even notice those yellow boxes when I viewed that
page earlier..
http://www.free-image-host.org/images/184114298lrr.jpg
Thanks for clearing that up.
--- End Message ---
--- Begin Message ---
time = mass * speed * speed / power
time = 2400 pounds * 0.4536 kg/pound * 60 miles/hr * 60 miles/hr .....
* 1609 m/mile * 1609 m/mile * 0.0002778 hr/s * 0.0002778 hr/s ....
/ 54000 w
time = 14.5 seconds (assuming no losses)
Assuming 90% efficiency in the motor and drivetrain, that goes up to 16.1
seconds. This seems much more likely that than the 12 seconds Lee
remembers.
The first equation here is in error by a factor of two. The equation
substitutions that were used to derive it are only valid if the
acceleration ( and force) are constant over the time interval ( and they are
not in this case).
Since acceleration ( and force) are varying with time, you have to use
calculus (and integration) to correctly derive the relationship between
time, power, speed, and mass starting from these equations.
The easy way to do it ( and avoid calculus) is by equating the kinetic
energy of the vehicle at time t ( 1/2 mass * velocity squared) to the total
energy input during that time period ( time * power).
If you do that, (and, divide both sides by the power - you can do that,
since the power is constant) you get the right relationship :
time = 1/2 * speed * speed / power.
This equation predicts 7.25 seconds for no losses. ( I just took half of
your calculated time)
But you have to consider a lot more than just the losses in a 90%
efficiiency drive train. The motor itself is 90% efficient at best. You
also have to acount for all of other drivetrain losses, and, even more
important, all the sources of vehicle drag - tire rr, air drag, etc.
For example, at 50 mph, a lot of the available power (maybe half??) is used
to overcome drag, and cannot be applied to acceleration. It's not a
simple calculation.
To get even close to the right time prediction, you have to calculate the
drag effects at each speed, the acceleration at each speed ( using the force
left over after you overcome the drag) , and the resultant acceleration time
for each speed interval ( for example, how long it takes to get from 5 to 10
mph). Then add up all of these time intervals to get the total 0 - 60 mph
time. The smaller interval you use, the more accurate the final answer will
be.
Phil Marino
Rochester, NY
_________________________________________________________________
Don’t just search. Find. Check out the new MSN Search!
http://search.msn.click-url.com/go/onm00200636ave/direct/01/
--- End Message ---
--- Begin Message ---
Lynch Motorcycle http://www.paulcompton.vispa.com/lynch1.htm
More URL's below
As a member of the Battery Vehicle Society, Cedric Lynch wished to
build an Electralight vehicle to take part in the Electrathon events
organized by the society. Frustrated by the cost and often poor quality of
suitable motors, Cedric designed his own motor. The Lemco is now well
established as a very efficient and high power-to-weight brushed DC motor
and has recently been licensed by Briggs and Stratton.
The Lynch Motorcycle is one of the vehicles built by Cedric to take
part in Electrathon events. In original specification, running on a single
165 Ah 12 volt battery and with a top speed of 30 mph, the motorcycle was
ridden from London to Birmingham (a distance of 125 miles) on a single
charge. The specification was later changed to four Optima YellowTop
batteries. The top speed was up approximately 65 mph and the range a
calculated 80 miles at a constant 40mph.
In its latest form it's fitted with 18 100Ah ThunderSky Lithium cells
and as a result has shed some 40Kg. Cedric has ridden 400 miles in a day
and rode from Honiton to Potters Bar, a journey of 175 miles, on a single
charge at an average speed of 50mph.
On display at the Brooklands Museum Alterative Power Day
More pictures http://www.paulcompton.vispa.com/lynch2.htm
Home http://www.paulcompton.vispa.com/page1.htm
Lawrence Rhodes
Bassoon/Contrabassoon
Book 4/5 doubler
Electric Vehicle & Solar Power Advocate
[EMAIL PROTECTED]
415-821-3519
--- End Message ---
--- Begin Message ---
The way I understand it, Power is an aggregate measurement, It is a tool
to help with work/energy equations. The application of a force over
time. Torque is just a force applied at a distance that imparts rotary
motion.
(torque * rpm) /5250 if you can get usable gearing at 100,000 rpm, we
can drive 60mph with 12lb motors :-)
You can look at the work energy equation level and see if the power on
board will do the work of accelerating the mass to speed. This saves you
from working out all the details of gear ratios and such when it "just
won't work" Once you know you have enough overall power, you can devide
into rpm, torque, gear ratios and losses and figure out the details.
Power and horsepower are Loved by the marketers because it includes more
that 1 thing. it is a very misused term. We say things like "it has more
power", when we mean it has more torque, it is what we feel in the seat
of our pants.
real world example
88 mitsubishi PU 88HP 90lb-ft of torque but the peak HP is at 5600
rpm or so, just not usable, I had to shift before the peak got me anything.
replaced with 93 drivetrain, 104 HP, 124 lb-ft of torque but the
peak was at around 4000 rpm and this was very usable. My milage actually
increased with the larger engine that wasn't overworked, but I still
called the AC button the "turbo" button.
Torque is what develops acceleration, but if you are out of power, then
you can't develop torque.
The area under the torque/rpm curve is what we should look at.
Duel overhead cams widen the curve, increaseing its area
Electric motors, well, depends on the type. but potential for very
wide and not as rigid, add some cooling and maybe it can be increased.
It all seems clearer in the electrics world vs the ICE
Power is Volts times Amps: Volts lets you use amps, amps create
torque :-) but power is still power
my 1949 case tractor had a 40HP engine, with a magneto, limited to
2500RPM one time I pulled my dads truck out of the mud, when I got up
to the house I was informed that the back wheels werern't turning, it
seems I forgot to take it out of park, now thats gearing!
--- End Message ---
--- Begin Message ---
If you can truly stay near the power peak (like with a variable
transmission, sepex, or a good AC setup) you get more area under the
curve, and it is amazing how much better acceleration can result.
Without going into heavy mathematics, let's just scale from some well
known examples:
Sundancer type vehicle: assume 2400 lbs and 54 kw.
EV1: ~3000 lbs, 0-60 mph in ~8 seconds, 103 kw.
Scale to EV1:
8 seconds * (2400 lbs / 3000 lbs) * (103 kw / 54 kw) = 12.1 seconds
Scale to Tzero:
4 seconds * (2500 lbs / 2400 lbs) * (150 kw / 40 kw) = 11.6 seconds
I'd wager putting a good AC system and appropriate gearing into a
Sundancer would put it close to 12 seconds 0 to 60, even limited to
54 kw.
Now in John's defense, Lee did say 54 kw ~ 54 hp (true after losses
to the wheels), but 54 kw = 72 hp (or conversely, 54 hp = 40 kw) if
you are talking hp before those losses. 54 hp would slow the above
times to 16.1 and 15.6 seconds.
If you grunge out the "area under the curve" math for acceleration,
it is a powerful argument for sepex or AC.
--- John Wayland <[EMAIL PROTECTED]> wrote:
> Lee Hart wrote:
> > Say you have 1200 lbs of golf cart batteries. At 65 lbs each,
> that's
> > about 18 65 lbs batteries; a 108v pack. Your peak power is about
> 108v x
> > 500a = 54kw, or 54 HP. You can draw this for 5-10 seconds without
> harm.
> >
> > Now put this pack in a lightweight EV that weighs (say) 1200 lbs,
> and
> > you have 50% battery weight. You'll have great range; 50-100
> miles on a
> > charge.
> >
> > If the car has a motor/controller/transmission combination that
> lets you
> > stay reasonably close to peak power as you accellerate, such an
> EV is
> > going to do a lot better than 0-60 mph in 20 seconds. Bob McKee's
> > Sundancer had this 50% golf cart battery setup, and did 0-60 mph
> in 12
> > sec.
>
> Lee, I think you've got some figures wrong. A 2400 lb. vehicle with
> just 54 hp, in no way,
> will it hit 0-60 in 12 seconds! Even factoring in a good controller
> and the awesome torque
> of an electric motor, it's just not going to happen. The Datsun
> 1200 sedan only weighed 1587
> lbs. and with 15 more horses under the hood, 69 hp, it ran 0-60 in
> 14.5 seconds. How does
> a car weighing 1000 'more' pounds, with 15 'less' hp, get to 60 mph
> nearly 3 seconds quicker?
> Another thing to consider, is that the original subject of
> discussion, was using golf car
> batteries in a conversion, not a ground-up concept car like the
> flimsy, foam board rolling science
> project creation called the Sundancer.
> ...
=====
__________________________________
Do you Yahoo!?
Jazz up your holiday email with celebrity designs. Learn more.
http://celebrity.mail.yahoo.com
--- End Message ---
--- Begin Message ---
Comments interspersed.
--- John Westlund <[EMAIL PROTECTED]> wrote:
> ...
> What tools would those who have done projects like this
> recommend, for starters? I want to know how much money I'm
> going to need to invest in tools. I'm a little hampered by
> the fact that I don't have a two car garage, it's more like
> a 1.5 car garage that fits one car and has plenty of
> leftover space, and I only possess the basic tools that most
> households have. I'm certainly going to need to rent an
> engine crane. I haven't been able to arrage converting the
> car at my university, it is possible but unlikely, and I
> wouldn't want nothing getting stolen.
In general buy tools only as you need them. Rent occasional use
things like engine hoists.
> ...
> d) Fabricate adaptor plate for tranny
You might be able to use the machine shop at your school. Another
possibility is to get the http://www.grassrootsev.com videos. He
shows how to machine an adapter hub using the electric motor and
adaptor plate inexpensively.
> ...
> a) Professionl driving course
Great idea. Your local car club, SCCA club, or track will have
"drivers education" events that may cost less than you think. You can
get informal tips for free in SCCA by riding along with others and
asking good drivers to ride along with you.
> ...
> c) Machine down flywheel
This is cheap enough I wouldn't wait, have it done before hooking it
up to the electric motor. You might also be able to use your school's
machine shop to do this yourself.
> d) RACING
Now you're talking, http://www.SCCA.org is alot of fun, safe, and
cheap. Get the rules before you do anything to the car, you'll cry if
you do the wrong metal or thickness on the roll bar, get the wrong
flywheel, etc. With your good aero you might want to try land speed:
http://www.saltflats.com . Finally, don't forget drag racing
http://www.nedra.com . I'm planning to do all three with my
conversion (the gasser already does SCCA and hopefully land speed
this summer). I may not set any records but it'll be fun.
I lost the quote, but last comment is you'll want to go to zero toe,
but probably not zero camber. You'll eat up your tire shoulders if
you do SCCA racing. Toe is what will really eat up the energy, not
camber anyway.
=====
__________________________________
Do you Yahoo!?
Yahoo! Mail - 250MB free storage. Do more. Manage less.
http://info.mail.yahoo.com/mail_250
--- End Message ---
--- Begin Message ---
Phil wrote:
The first equation here is in error by a factor of two. The equation
substitutions that were used to derive it are only valid if the
acceleration ( and force) are constant over the time interval ( and they are
not in this case).
and
But you have to consider a lot more than just the losses in a 90%
efficiiency drive train. The motor itself is 90% efficient at best. You
also have to acount for all of other drivetrain losses, and, even more
important, all the sources of vehicle drag - tire rr, air drag, etc.
For example, at 50 mph, a lot of the available power (maybe half??) is used
to overcome drag, and cannot be applied to acceleration. It's not a
simple calculation.
You are correct on both counts. I see where I went wrong on the derivation
(Oops - let me try again). Acceleration is not constant in the case of
constant power, it is a function of the speed. So neglecting all losses,
7.25 seconds is the time for a 2400 pound vehicle to accelerate to 60 mph
with 54 kW.
And of course, the drag makes a big difference, but I don't think that the
drag at 50 or 60 mph would be 27 kW, that would mean that the Sundancer was
using 250 amps at cruising speed. This seems a little high for a small car.
The aero drag would be 0.5 * area * density of air * Cd * V^2 I don't
know the Coefficient of drag or the area of the Sundancer, but I'll guess
0.3 for Cd and 1.8 m^2 for area. At 60 mph, the power to overcome this drag
is 6.3 kW (58 amps at 108 volts)
I have no idea what the actual rolling resistance drag might be, but I'll
guess it is close to a constant force.
Acceleration as a function of velocity is now
a = ((power / speed) - 0.5 * Cd * density * speed^2 - fixed drag
force)/mass
and speed after a given time period is
speed(N+1) = speed(N) + a * t
Once again, I'll make a wild guess at rolling resistance as a fixed 40 pound
force, lower the efficiency to 80%, and put this in Excel.
For these guesses, the time to 60 mph comes out to about 11 seconds.
-John
--- End Message ---
--- Begin Message ---
Again, sorry about the long post, but I'm very excited to
build an EV. I'll be sure to shorten it up in my next
response after this.
Klemkosky, Mark A wrote:
>Hmmm... I hope the car is around $2000 or less.
Less. I won't say how much or where, as I'm worried some
lurker might find out about the exact car. It would make
such an awesome EV...
>Triumphs and Midgets are pretty cheap.
Cheap, but the former owners often sink more money into them
than they can ever hope to sell them for. Money that would
much better be invested into an EV that doesn't have all the
problems the gas cars have. :)
Needless to say, a GT6+ in the kind of condition I am
looking at would go for well over $2k on Ebay with stock
parts. With these upgrades the car has on its engine,
tranny, and diff, a significant amount more could be had. It
mainly just needs a paint job and a nice smoothing out of
the body to be capable of faring well in a Concurs
d'Elegance.
>Although your plan seems well thought out, you forgot >a
couple weaknesses of the car. The trannies and rear
>end are pretty whimpy in the brit cars.
That's my main worry. The stock GT6 tranny/dif would not
have a prayer to handle the torque I'm going to throw at it.
I've been told that a TR6 J-type gearbox without overdrive
is considered "bulletproof" by racers, but I have no idea
how much torque it can really handle. I know it can handle
at least 200 lb-ft, as indicated by Picton Sportscars
Ultimate spec Spitfire. At 1,000 motor amps counting in
efficiency losses at that current, an ADC 9'' would put out
about 200 lb-ft according to Rudman(This figure when used in
simulation theoretically allows 1/4 mile times well into the
14s), although calculations I have done, which neglect such
high efficiency losses at that motor current, indicated 380
lb-ft(Simulations using this exagerrated figure indicated
low 13s, which seemed WAY off!). The WarP 9'' I plan on
using is very similar, but beefed up with modified brush
timing and stronger field windings, ect., so I don't know
how much torque I will put out. I will limit the motor
current to 600 amps to be on the safe side, until I take the
converted EV to get dyno tested somewhere, and increment the
max motor current by about 50 amps each time until I hit
about 200 lb-ft. I'll quit increasing it from there until I
do a transmission upgrade or until I get some specifics on
the max torque the TR6 gearbox can handle. If that magic 200
lb-ft number is hit with a Zilla 1k, and I find out the
gearbox/differential can handle more than 200 lb-ft, I'd
consider a stronger controller.
>You might want to break out the ruler as well because
>there isn't a whole lot of room for batteries. With
>decent sized batteries, you can at best squeeze in
>18 of them (if you are looking for performance rhat
>is).
I figured that might be a problem, but I just don't know how
many batteries this will hold. It appears to be able to hold
at least 192V of Optimas, although I'd prefer more. GT6 is a
bit longer than a Midget, and it appears a Midget will be
able to handle 16 batteries looking at conversions on
AustinEV.org. 20 might be pushing it for what I want to do,
but it can't hurt trying. After all, John Wayland can stuff
288V of Exide Orbitals into a tinier Datsun 1200, although
that comparison may be bunk since that car was originally a
4-seater, after all.
>The extra battery weight will tax your suspension.
>I had custom springs made by Alcan to handle an extra
>800 lbs in the rear.
800 lbs!? Holy sheep s... I think I'll be giving them a call
when the time comes. GVWR on the GT6+ is about 2,200 lbs,
conversion weight will not exceed 2,600 pounds and I hope to
keep it under 2,500 pounds(including driver) without
lightweight addons but I look at the most pessimistic
outcome. With lightweight addons, it may be possible to get
it below 2,300 pounds. One can hope...
>Finally, if this vehicle has a rusted
>tub, be wary. A big part of the vehicle support
>employs the main tub. There are plenty of these
>vehicle in rust free territory to be had.
I thoroughly inspected the body with a magnet and there is
no bondo anywhere on the car, and rust is so minimal that
there isn't any place a magnet doesn't solidly stick. I
asked the seller about the car and it originally came from
Florida, of which I wouldn't think of much as a rust free
area. But it is in great condition.
The floor is pretty solid, rocker panels have a thin layer
of rust that can be sanded off but there isn't a single
place the magnet can't be left to stick on its own with
nothing holding it up on the rockers, bulkhead is perfect,
area under the 12V battery has no corrosion, floors have
rust that can also be simply sanded off. Chassis outriggers
are again excellent.
Not only that, but the gear synchros work just fine, the
brakes are great with a flawless master cylinder, electrical
system is in working order(although most of that will be
replaced anyway), and my God does that engine purr. It is so
refined and flawless. That car screams when floored, and may
be capable of embarassing my dad's Audi as it is.
I'm really going to feel awful tearing this poor car up.
>I don't want to discourage. You have the right idea.
>I'm just adding for some more food for thought.
Your insight is appreciated. I'll again mention I'm no car
expert, let alone know anything about maintaining/restoring
little British cars. The only car modification I've done is
a performance chip addition to my gasser and changing the
oil/battery. I don't even know what most tools are named,
and although I'm capable of figuring things out, I'm not
that knowledgable about cars by any means. This has me
nervous, but being bitten by the EV bug will drive people to
do strange things and actually learn a thing or two.
I am anxious to see how yours will turn out. MG Midgets have
horrible aerodynamics though(On par with a Caterham 7 or
such), you might want to look into the Ashley hardtop and
bonnet made for the Midget. Another Midget that has caught
my interest is that of George Tylinski. It looks to have
that Wayland influence and I'm anxious to see how it turns
out. 192V of Optimas, an XP-1227 motor, and a Zilla 1k are
mentioned on his austinev entry. At 2,400 pounds converted,
that will fly. Speaking of which, I should email that guy. I
have a few questions to ask about it.
Ryan Stotts wrote:
>Once you start, you will see what you need and buy
>them as you need them.
That's my problem. I don't know what a lot of tools are
called. What would I use to sand the body down with? How
about shaving down the door handles? Painting the car? That
kind of stuff. I have things planned out, I just need to
figure out what tools to use and how to use them. I've never
did any kind of body work on a car before, so now's as good
a time to learn as any.
>I wouldn't worry about it.
That's a comforting thought. I hope to spend no more than
$1k in tools.
>Good luck.
Thanks. I'll need it. When my step mom and I went to look at
the GT6 and I told the guy wanting to sell it my intentions
and after a series of questions he asked, I eventually
mentioned my college major, he told her "Lord help you
now..." It seems I'm just asking for trouble. :)
This will not at all be an easy task, but I see it as
worthwhile to spend 500+ hours on(Quadruple that if
necessary) and $10k give or take a few grand.
David Dymaxion wrote:
>In general buy tools only as you need them. Rent
>occasional use things like engine hoists.
That's the intent.
>You might be able to use the machine shop at your
>school. Another possibility is to get the
>http://www.grassrootsev.com videos. He shows how to
>machine an adapter hub using the electric motor and
>adaptor plate inexpensively.
I intend to do both those things. I talked to one of the
folks that runs the machine shop, and I'd be able to use it
after being taught how to safely use the tools. Sure beats
paying $1.5k for an adaptor plate, not to mention, I have
multiple shots at it incase I screw up something. It will
have to fit snuggly, or the torque + RPMs will tear that
plate apart in no time.
>Great idea. Your local car club, SCCA club, or track
>will have "drivers education" events that may cost
>less than you think. You can get informal tips for
>free in SCCA by riding along with others and
>asking good drivers to ride along with you.
Thanks for the advice. Sure beats getting someone else or
myself killed stupidly trying to push an overpowered car to
its limits without knowing how to drive it properly. I think
I know how to heel and toe properly, but I'll wait and see
about that.
>I lost the quote, but last comment is you'll want to >go to
zero toe, but probably not zero camber. You'll
>eat up your tire shoulders if you do SCCA racing. Toe
>is what will really eat up the energy, not camber
>anyway.
Thanks. I'll try to figure out what levels I'd want
everything at when the time comes. I want to avoid tires
that don't have much grip, but if possible, I'd also like to
find a decent handling LRR tire. I'm guessing I could find a
tire with a .008-.0085 coefficient of resistance that with
the proper suspension, could allow .85 or better on a 200ft
skidpad. I'm not looking to break any track records, but I'd
like to be able to outperform cars that cost $30k+ with a <
$15k EV. Not to mention embarrassing those obnoxious ricers
in my neighborhood each chance I get. That car would be
famous in no time and people would remember what powered it.
Maybe even win a few converts, which is part of the
intent...
--- End Message ---
--- Begin Message ---
Hi, I just joined the list, but have been at my conversion for about a year
now. I'm about to start some HV wiring, and want to know where to put my
current shunt (in the motor loop, or in the battery supply lead). I read some
posts about current levels in the motor loop being higher than the battery
current, and need some clarification.
Can someone break this down for me? How can you get more current into the
motor, than provided by the batteries? I'm looking at the controller as a
"linear" type of regulator (current out=current in), so is this where I'm
missing something? Is this a resonance thing?
My plan now, is to put the shunt in the negative lead of the battery pack.
Thanks, Jim Seibert
--- End Message ---
--- Begin Message ---
Hi Jim,
Some controllers take high volts and low amps from the batteries and
turn it into low volts and high amps to the motor.
The overall power (volts x amps) stays pretty much the same (with a
small loss in the controller since nothing is 100% efficient)
Mark
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Thursday, 30 December 2004 9:42 PM
To: ev@listproc.sjsu.edu
Subject: motor current higher than batt current?
Hi, I just joined the list, but have been at my conversion for about a
year now. I'm about to start some HV wiring, and want to know where to
put my current shunt (in the motor loop, or in the battery supply lead).
I read some posts about current levels in the motor loop being higher
than the battery current, and need some clarification.
Can someone break this down for me? How can you get more current into
the motor, than provided by the batteries? I'm looking at the controller
as a "linear" type of regulator (current out=current in), so is this
where I'm missing something? Is this a resonance thing?
My plan now, is to put the shunt in the negative lead of the battery
pack.
Thanks, Jim Seibert
--- End Message ---
--- Begin Message ---
At 04:41 AM 30/12/04 -0600, Jim Seibert wrote:
Hi, I just joined the list, but have been at my conversion for about a
year now. I'm about to start some HV wiring, and want to know where to put
my current shunt (in the motor loop, or in the battery supply lead). I
read some posts about current levels in the motor loop being higher than
the battery current, and need some clarification.
Can someone break this down for me? How can you get more current into the
motor, than provided by the batteries? I'm looking at the controller as a
"linear" type of regulator (current out=current in), so is this where I'm
missing something? Is this a resonance thing?
My plan now, is to put the shunt in the negative lead of the battery pack.
Hi Jim
Welcome to the best resource of EV information and support that you could
hope to come across.
This being a 'tech' question, and me being a tech, I have a go at a 'plain
language answer' for you. I'll try and put this simply, not knowing how
much technical knowlege you have. Modern EV controllers are fancy, fast
switches. Typically 15,000 times per second, with varying rate of on time
to off time. Lee Hart has done a very good parable on the operation of a
controller, but I can't remember where it is posted (I saved a copy).
When the controller is at half throttle, it is on for half the time and off
for the other half. Motors can't come on and off like that, so they need
the 'free-wheeling diode' in the controller, which is a device that allows
the motor current to keep flowing.
So as an example, there is 100 amps in the motor, and when the controller
is on, it is supplying the 100amps. when it is off, there is no amps from
the controller, but still 100A in the motor. Since in this example the
controller is on for half the time, the average battery current is half of
the 100A, so is 50A. The capacitors in the controller smooth out a lot of
the on/off pulsing, so the current from the battery is fairly steady.
The trap is that if you put an amp meter in the battery loop, you can have
the situation where you are cruising along with 200A from the batteries
(thinking all is fine), but the controller on for 20% of the time means you
are putting 1000A through the motor, which will cook most motors in short
order.
However, if you just measure the motor current, and you use flooded
batteries, you don't know if you are exceeding the continuous discharge
rate for the batteries and so are killing them!
Since I have yet to get my conversion on the road, I am not in the position
to comment on whether it is best to drive by motor current or battery
current - I am going to have both available, along with pack voltage and
motor voltage, too. I expect that you will find that everyone will have
their own opinion on where is the 'best' place to have the ammeter. But if
you are using AGM batteries, then I'd suggest the motor loop is the place -
to help avoid cooking the motor. This is electrically noisy, with all that
fast switching happening, so use twisted, screened wire up to your meter to
avoid getting that noise into every other piece of electronics in and
around your vehicle. The AGM batteries will not care what you are pulling
from them, but when you start looking to optimise your driving for best
range, then you need to know your battery draw - catch 22.
Just my $0.02
James Massey
Launeston, Tasmania, Australia.
'78 Daihatsu 1300kg truck under conversion
--- End Message ---
--- Begin Message ---
On my Civic EV I used two shunts, one in the motor loop, one in the battery
loop. The ammeter is connected to both through a rocker switch, but it
always ends up on the motor shunt. The E-meter also uses the same battery
loop shunt, so I can see both current flows at once if I wish. If I were
doing it again I would just wire the ammeter always on the motor shunt and
drop the switch. Motor amps on the analog ammeter, battery volts, amps,
amp/hours, and percent charge on the E-meter.
Thanks,
Mike Chancey,
'88 Civic EV
'95 Solectria Force
Kansas City, Missouri
EV List Photo Album at: http://evalbum.com
My Electric Car at: http://www.geocities.com/electric_honda
Mid-America EAA chapter at: http://maeaa.org
Join the EV List at: http://www.madkatz.com/ev/evlist.html
--- End Message ---
--- Begin Message ---
Jeff Shanab wrote:
> Something in the agm/flooded discussion caught my attention. The
> statement about a unibody car with 25 orbitals cracking.
> 25*45=1125 lbs of lead I am planning 25 exides (25*40=1000 +
> 25lb aux ) so only 100 lbs less.
> Does anyone know how strongle a 1987 300 zx is? it appears to
> be unibody
> :-( but quite heavy.
Hi Jeff,
The correct answer is that it depends not only on what you do, but how you
do it. The 300ZX may be known as a very stout car, but if you add even a
fairly light load without thinking it through, it might fail.
Be very, very cautious of the blanket generalizations sometimes offered
here, and even more cautious of the occasional specific example offered as
"proof" of those generalizations. I have no doubt that there exists a car
that had 25 Orbitals added to it, which then started cracking due solely to
that change. I also have no doubt that 25 Orbitals could be added to the
same car in a way that *increases* the overall structural strength of the
car. The saying "the devil is in the details" applies to many things. It
applies especially well to unibody construction.
How many ways can you think of to support a book on the edge of a dollar
bill? If you're not confident in dealing with that question, you probably
should not try to support lots of battery weight in a unibody. You need to
fully understand how steel can best support loads in its sheet, tube and
angle shapes. And most critically, how to transition from one type of load
to another, as in an angle battery rack to a unibody. The design of the
attachments is frequently the difference between success and failure.
Or if you're going to support your batteries by replacing existing sheet
with new sheet, how must the new sheet be shaped to maintain (or increase)
strength, and how and where should it be reinforced? Can you visualize how
the chassis supports its loads currently, and how those load paths will
change with the new shape?
Many people here could look at examples of failed and successful integration
of batteries into a unibody, see the differences, but not be able to explain
why each worked or didn't. Subtle differences are indeed critical.
Understand the subtleties and you'd be amazed how much a unibody can
support. Think back to the dollar bill and the book.
> Some specs
>
> weight stock is listed as 3080 and gvwr is 3665 (1984FR,2205RR)
>
> does that mean (3665 - weight of passengers) > = (3080-engine
> weight-fuel load+165{warp9}+ batteryweight) does curb weight include
> passengers?
Curb weight is empty with fluids. GVWR is the maximum total weight the
manufacturer is comfortable with. It's not a hard limit, and you don't know
how conservative the manufacturer is or what the limiting factor was in
coming up with that figure. I treat the GVWR as the point after which you
need to pay a lot more attention to what you're doing the more you exceed
it.
The total of the axle weights is greater than the GVWR, because you
typically load one axle more than the other when carrying a load. Nissan
says you can put 2205 lbs. on the rear axle, which leaves only 1460 lbs. on
the front, for a F/R balance of 40/60. In a car that was probably around
55/45 before loading. You can do it, but I wouldn't want to drive it like
that on a permanent basis without making modifications to accommodate it.
The most important being re-shuffling your brake balance. Work hard at
maintaining the forward bias, maybe allowing a minor shift to the rear. The
effort will pay off in better handling and braking, or a savings in
time/money to deal with the new chassis dynamics.
> 19gallons*6.25 =123.5lbs of gas ( @72F)
>
> 3080-365-123.5+165 = 2756.5
>
> 3665 -300(passengers) -2756.5 =608 max battery weight :-(
>
> How much can I fudge this? if the original weight bias was
> 57%front and
> 47% back and the gvwr is more in back, this sounds like I
> will need to
> replace the motor difference up front with batteries
> about 3 batteries then add equally front and rear, again I
> will have to
> fudge this a little because of space, just how much weight bias can I
> get away with?
Assuming you want to use AGMs (floodeds would be a crime in 300ZX), 192 V
and a Z1k would make it peppy but not a road-burner. A Z2k would be nicer.
But you're only talking about 16% of your weight being batteries, so range
will be dismal.
If it was me and a 300ZX was all I had to work with, I'd go over GVWR and
use a Z2k. Ideally I wouldn't use a 300ZX at all. If the goal is a
satisfying performance EV, a 3000 lb. starting weight as an ICE is too big a
disadvantage. You need to lose about 1000 lbs.
Chris
--- End Message ---
--- Begin Message ---
Snip ---- lots of math talk
To get even close to the right time prediction, you have to calculate the
drag effects at each speed, the acceleration at each speed ( using the
force left over after you overcome the drag) , and the resultant
acceleration time for each speed interval ( for example, how long it takes
to get from 5 to 10 mph). Then add up all of these time intervals to get
the total 0 - 60 mph time. The smaller interval you use, the more accurate
the final answer will
or ... you can just build the beast(ie) and report back to the list real
data, which I believe is where Waylands's whole argument comes from. He is
throwing out the theoritical numbers and screaming I've already built it (or
something very similar), and here is what happens...
I know, I know, it's awful tough to retire a perfectly good slide rule :-)
damon
--- End Message ---
--- Begin Message ---
Have been following your postings on the golf cart versus AGM batteries, I am
running a zamboni on lead acid, weight is no problem, I run the pack for 10
minutes and recharge for 45 minutes for each flood. The season consists of
about 1700 floods (or about 1700 recharges) The packs are only down 50-60% when
we recharge, I am on my second season of US batteries (12 6volt deep cycle) a
couple of the batteries had bad cells in the last month and had to be replaced
so I suspect the pack is most likely on it's last season and am thinking of
what I should replace them with.
Is the lead acid still the cheapest? and Based on my past record is that
typical of the batteries to last for 3500 recharges?
Thanks
Ellery
--- End Message ---
--- Begin Message ---
I just purchased a set of Toyo Ultra 800. These tires are rated at 44
psi and have 100,000 mile advertized life. I have not seen any change
in my seasonally adjusted range with these tires yet. Can'nt say if
they are good or bad, but will compare over time and let the list know.
Lynn
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Ryan Stotts
Sent: Wednesday, December 29, 2004 8:32 PM
To: ev@listproc.sjsu.edu
Subject: Low Rolling Resistance Tires?
What makes a LRR tire? It seems to me that having a high max PSI rating
is
what makes it LRR?
So are all 44+psi tires LRR and 35psi tires are not?
A LRR tire I've seen is the Goodyear Viva 2 that is sold at WalMart(low
cost
tire too). The little display card actually mentions it having low
rolling
resistance. It's 44psi and other tires are only 35psi. Pepboys tires
that
are made by Cooper for them air up to 44psi..
I've seen mentions on the net about the "Michelin Energy MXV4 Plus" tire
being LRR, but I can't find anything actually saying it is.
I didn't see it in the spec.pdf or on the page:
http://www.michelinman.com/catalog/tires/MichelinEnergyMXV4Plus.html?tir
etype=2&tire=4
This page makes reference too both tires being LRR:
http://www.ucsusa.org/publications/earthwise.cfm?publicationID=875
Although this "Michelin Energy MXV4 S8" tire mentions "lower rolling
resistance"..
http://www.michelinman.com/catalog/tires/MichelinEnergyMXV4S8.html?tiret
ype=2&tire=3
Anyone have any info on LRR tires?
Anyone know of any ~50psi tires?
Thanks
--- End Message ---
--- Begin Message ---
I am considering reducing my pack voltage from 144 V to 108 V in the
next battery pack replacement and am curious to know what performance
change I can expect. I currently am using 18 T875's 8V flooded golf
cart batteries and am considering changing to 18 T125's (cannot quite
fit T145's-maybe if I raise the hood...). My controller is a T-rex 600,
motor ADC 8 inch (name plate rated at 96V).
My commute is 43 miles, recharge at work and 43 miles home. To
comfortably handle this range, I need a solid usable 60 mile range of
mixed surface street and highway speeds. I have battery current draws
between 60A (on flat) to 200 (on the big hills), with an average draw of
about 90 amps. For the 43 miles I usually use less than 10KWH (by the
emeter) from the battery. The largest draw I have ever seen on the
emeter is 350A, while accelerating up a big hill to see how much current
I could draw.
To summarize, with the 144 V pack I am now getting:
Top range: 60 miles
Typical %discharge at 43 miles 75%
Typical KWH for 43 miles 10 KWH
Acceleration: stock civic like-keeps up with traffic easily, including
high speed merges
Pack life: about 12,000 miles
What could I expect with 108 V of T125's?
Range ?
%discharge at 43 ?
KWH used should be about the same?
Acceleration: slower, faster (ability to deliver more current), about
the same?
Pack life?
Of course the other option I'm actually considering (but searching for
funds)
156 V system using SAFT STM 5-140's. What could I expect from this
pack?
I'll be doing something in the next couple months and would be
interested to get the list's opinion.
Thanks
Lynn
Commuting through Denver Colorado every day!
See my 100% electric car at http://www.austinev.org/evalbum/379.html
--- End Message ---
