EV Digest 4988
Topics covered in this issue include:
1) Re: Setting up a Direct Drive
by "Paul G." <[EMAIL PROTECTED]>
2) Re: AC prop reductive charger
by Otmar <[EMAIL PROTECTED]>
3) Re: Setting up a Direct Drive
by "Chris Robison" <[EMAIL PROTECTED]>
4) RE: EV crashes Corvette Challenge party at Moroso!
by Otmar <[EMAIL PROTECTED]>
5) RE: AC prop reductive charger
by "Roger Stockton" <[EMAIL PROTECTED]>
6) RE: Am I Killing Batteries?(+)
by "Roger Stockton" <[EMAIL PROTECTED]>
7) Re: Setting up a Direct Drive
by "Rodney A" <[EMAIL PROTECTED]>
8) Link 10 setup / operation question
by TiM M <[EMAIL PROTECTED]>
9) links on evproduction.org wiki
by Rush <[EMAIL PROTECTED]>
10) An Electric Guy's thoughts on "Syriana" ) OT
by Steven Lough <[EMAIL PROTECTED]>
11) RE: AC prop reductive charger
by Cor van de Water <[EMAIL PROTECTED]>
12) Re: ev desgin
by Ron Archer <[EMAIL PROTECTED]>
13) Re: links on evproduction.org wiki
by Shawn Rutledge <[EMAIL PROTECTED]>
14) Re: Setting up a Direct Drive
by "Dave" <[EMAIL PROTECTED]>
15) Re: Setting up a Direct Drive
by "Chris Robison" <[EMAIL PROTECTED]>
16) Re: The "open-source car" wiki
by Shawn Rutledge <[EMAIL PROTECTED]>
17) RE: Setting up a Direct Drive
by "Roger Stockton" <[EMAIL PROTECTED]>
18) RE: Setting up a Direct Drive
by "Roger Stockton" <[EMAIL PROTECTED]>
19) RE: links on evproduction.org wiki
by "Don Cameron" <[EMAIL PROTECTED]>
20) Re: Setting up a Direct Drive
by David Dymaxion <[EMAIL PROTECTED]>
21) RE: Setting up a Direct Drive
by Cor van de Water <[EMAIL PROTECTED]>
22) RE: AC prop reductive charger
by James Massey <[EMAIL PROTECTED]>
23) RE: AC prop reductive charger
by "Rodney A" <[EMAIL PROTECTED]>
24) Re: advice on batteries
by "David Roden" <[EMAIL PROTECTED]>
25) RE: Am I Killing Batteries?(+)
by "David Roden" <[EMAIL PROTECTED]>
--- Begin Message ---
On Dec 12, 2005, at 8:07 AM, Chris Robison wrote:
These ratios are taller than I'd like in both cases given the lack of a
transmission. A higher redline from the motor will enable me to
shorten it
somewhat. If I can get 6500 rpm out of the motor (which I understand a
prototype ran at and beyond in testing without the reinforcement) then
that will help a lot.
--chris
If you have the voltage to get the motor to take enough amps to make
the required power at the higher rpm. Your motor may have the torque of
Zeus and require an unholy voltage to make power over 5000rpm (or not.)
John's secrets are series parallel motor shifting (2 motors worth of
torque at low rpm, higher motor voltage at speed) and *lots* of voltage
so the motors will make the required power at high rpms. That, plus
lots of practice and testing.
Paul "neon" G.
--- End Message ---
--- Begin Message ---
At 5:09 PM -0500 12/12/05, Lee Hart wrote:
Lee Hart wrote:
[using the controller as a charger] can be (and has been) done for either
AC or DC... you need:
- An EV controller that supports regenerative braking (i.e. it can
charge the batteries).
- A very high power AC receptacle.
- Sufficient control logic to avoid blowing something up!
Otmar wrote:
It also needs about a 336V or higher pack voltage. That becomes a
problem since high voltage packs end up being so very expensive per
mile of use.
No; you can charge an arbitrarily low pack voltage. But the semiconductors in
the controller need to withstand the peak voltage of the rectified AC line.
Let's say your EV has a 96v pack, a series DC motor, and a PWM controller.
Suppose your controller has 200v (or higher) rated transistors, diodes, and
input capacitors. Then you could wire it like this to charge from 120vac
(view with a fixed-width font):
_________ ______________ _ _ _
120vac____| |______|______________|_____| | | |_______
hot AC| |+ B+| | _|_ | motor field __|__+
| | | _|_ /_\ | ___
| | | ___ |___|___________________| -
| | | | |_| |M- 96v
| | | | ||_ | battery
| | | | | | | pack
neutral___| -|______|___|______| |
AC|_________|- B-|______________|
bridge rectifier controller
The controller's throttle pot controls the charging voltage and current.
The same would work for a 240vac input if you had 400v transistors, diodes,
and capacitors.
That is one way to do it, but not how AC Propulsion does it.
AC propulsion uses a boost converter, not the buck converter that you've drawn.
The trouble with the buck converter system is that it is not possible
to provide very good power factor correction.
The buck and boost systems each can handle some range of battery
voltages, but not all of them. So one solution is to use both a buck
and boost in one unit like Rudman does on his chargers. This provides
a super wide output voltage range but does not integrate with the
controller as well and provides a slightly lower efficiency.
As usual, there are many tradeoffs. :)
--
-Otmar-
http://www.CafeElectric.com/ Home of the Zilla.
http://www.evcl.com/914 My electric 914
--- End Message ---
--- Begin Message ---
On Mon, December 12, 2005 5:53 pm, Paul G. said:
>
> On Dec 12, 2005, at 8:07 AM, Chris Robison wrote:
>
>> These ratios are taller than I'd like in both cases given the lack of a
>> transmission. A higher redline from the motor will enable me to
>> shorten it
>> somewhat. If I can get 6500 rpm out of the motor (which I understand a
>> prototype ran at and beyond in testing without the reinforcement) then
>> that will help a lot.
>>
>> --chris
>
> If you have the voltage to get the motor to take enough amps to make
> the required power at the higher rpm. Your motor may have the torque of
> Zeus and require an unholy voltage to make power over 5000rpm (or not.)
>
> John's secrets are series parallel motor shifting (2 motors worth of
> torque at low rpm, higher motor voltage at speed) and *lots* of voltage
> so the motors will make the required power at high rpms. That, plus
> lots of practice and testing.
>
> Paul "neon" G.
>
>
This is a good point, and something I've been a bit concerned with. As
you've pointed out the Warp13 produces more torque per amp ("Torque City"
being the designation reportedly bestowed by an impressed Warfield
engineer at the dyno recently), but since you don't get anything for free,
it also makes much higher back EMF per RPM. I'm planning to run 348V, but
even still it may be a problem. The real problem is how little i know. I
wish I had better data with which to estimate where it'll start to drop
off (and a more complete understanding of all the influencing factors). I
also don't know how much control I'll have over the maximum voltage before
the comm arcs itself to death, even if I design a moveable brush mount for
it.
When I bought the motor, I knew I was taking a leap by buying an obscure,
still-experimental product with very little recorded data available. I
hope I can rise to the challenge of accurately reporting what I experience
with mine, to help others know more about it and help Netgain improve it
in the future.
I saw pictures for the first time today of pretty close to what my motor
will look like -- they're of a motor made recently for another customer.
The size of it certainly does give one pause. It's not small.
--chris
--- End Message ---
--- Begin Message ---
At 5:10 PM -0500 12/12/05, Matthew D. Graham wrote:
Hey Brian,
. . . And 3) none of the limits are hit.
I think you're exactly right about the wheel spin. That's what I figured,
and it fits with the behavior of the car in that first second of the run.
The tires bit pretty well at first, but then let loose just a few feet into
the track -- around 0.3 seconds into the run. The current dropped to nothing
during the shift for another three or four tenths of a second, allowing the
tires to hold onto the ground again, then hold tight for the rest of the run
in parallel mode. I can't wait to put in the Viscous LSD from the 300ZX and
get some drag radials on the wheels.
Great going Matt,
You make us proud!
As for the wheel spin, I know you don't want to hear this, but there
is a very simple fix. Just turn the current down a bit in series
mode, or start in a taller gear (if you have one).
If you have a peak holding meter then you can do a launch and read
the max motor current. That should happen at max traction. Then just
set the motor amps at about 50 amps less than that and you'll have a
great launch.
Have fun!
--
-Otmar-
http://www.CafeElectric.com/ Home of the Zilla.
http://www.evcl.com/914 My electric 914
--- End Message ---
--- Begin Message ---
Otmar [mailto:[EMAIL PROTECTED] wrote:
> AC propulsion uses a boost converter, not the buck converter
> that you've drawn. The trouble with the buck converter system
> is that it is not possible to provide very good power factor
> correction.
>
> The buck and boost systems each can handle some range of battery
> voltages, but not all of them. So one solution is to use both a buck
> and boost in one unit like Rudman does on his chargers. This provides
> a super wide output voltage range but does not integrate with the
> controller as well and provides a slightly lower efficiency.
Another option is to take advantage of the fact that the controller
switches at highish frequency and use an appropriate transformer
(relatively small and light at 15kHz+) to both provide isolation from
the AC grid and to allow the controller to be configured for boost
operation without then needing a pack voltage near the peak of the AC
line voltage.
My understanding is that one of the hassles with the AC propulsion
system is the need to double insulate the drive system since the motor
is connected to the line during charging; transformer isolation could be
easier...
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Roland Wiench [mailto:[EMAIL PROTECTED] wrote:
> Let me see, The 12 volt battery coming in from a temperature
> of 5 below is been cold soaking down to 30 degrees. This
> time I install the smart charger on board, but when I drove
> the EV into a warm building, and try to charge the battery,
> the smart charger was warm up to 60 degrees and only charge
> the battery for only 5 minutes. The SG was still at 1.225 SG.
> Letting the battery warm up to 60 degrees and try again,
> the smart charger would not charge it.
This sounds very much to me as if your "smart" charger relies on an
internal temperature sensor to estimate the battery temperature, and
this sensor is reacting much faster to the change in ambient temperature
than the battery is.
Neon John is familiar with your charger model and sounded like he was
impressed with its performance; I'm not familiar with it, but I respect
Neon John's technical opinion. Perhaps his testing did not include
verifying the charge performance in this sort of situation, or he can
otherwise clarify why a charger he found to be decent is doing such a
poor job for you.
In any event, to avoid confusion it might be better not to refer to this
particular charger as "smart" since it does not seem to be a
particularly smart design and reflects rather poorly on better
implemented chargers. Perhaps we can just refer to it as an "automatic"
charger? ;^>
> I left the smart charger on continuous for over 24 hour, but
> the next day, the battery percentage was still at 55 percent
> and barely had 10 volts when I apply a 20 amp startup load.
I think there is something truly ironic about a charger with a % charge
guage that indicates that it *knows* the battery is not fully charged,
yet does not take action to correct the situation! ;^>
> So there is nothing wrong with the battery or charging it
> with the PFC-50B or alternator. But there is something wrong
> with the design of these Smart Chargers.
You've definitely hit the nail on the head: there is definitely
something wrong with the design of *this* charger. Neon John's
experience seems to be that this is quite a decent charger when used
within its limits, however, you seem to have identified its weakness,
which is that it does not accurately sense battery temperature and so
does not charge properly when the battery temperature differs
significantly from the charger temperature. Not all automatic/smart
chargers suffer this fault, but all manual chargers do in the sense that
a manual charger will not properly charge the battery unless the user
measures the battery temperature and adjusts the charger accordingly. I
would guess that the average user has no means of readily measuring
actual battery temperature and adjusts their charger based on the
ambient temperature (if they take temperature into account at all)...
exactly what your automatic charger is doing. You are an exception to
the rule as you appear to have the means (and motivation) to measure the
battery temperature and adjust your manual charger accordingly, which
allows it to properly charge the battery.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
As far as I know, most two motor direct drive systems physcially connect the
motors together (belt or chain, etc) and then connect to the driveshaft or
reduction gearbox.
What about running two motors on the rear axle, one attached to each wheel
(via a lightweight reduction gearbox) thus eliminating the differential
(which would make up for the extra weight of the additional reduction
gearbox)? The advantage of this setup might be a little more torque and
power (less mechanical losses) plus with the motors in parallel (which they
would be most of the time) you get an electronic traction control.
Rod
--- End Message ---
--- Begin Message ---
I installed my meter a week ago on my 144V
flooded pack of US-145s. I set the capacity for 240AH
per the battery page and left the Peukert's set at the
default 1.25...
I went on a trip yesterday that I would never in
my wildest dreams want to repeat... between my
daughters reconfiguring of my alarm clock, my GPS
dying, dead recharging stations, wimpy 110V circuits,
being placed on display by the porta potties, and a
main circuit breaker that decided it wanted to trip at
will. I did drive about 160 miles in one day, the day
just took about 16 hours.
At the darkest hour of the trip as I coaxed my
truck up the hill to the AQMD charging station the
E-meter was showing 7% reaming and blinking red. I was
seeing red as I was thinking about what I was doing to
my batteries, but at 7% indicated on the E-meter under
~100 amp load I was at 132V(this is the low voltage
limit I've set in the Zilla) this works out to
1.81V/cell which is low, but I was under the
impression it would be about 20% to 25%, not 7%.
Does the E-meter consider 20% to 100% to be the
equivalent of full scale making the assumption that
20% is the minimum you want to discharge to and set
that level to 0%? Or am I totally confused and need to
do some re-setting of the values on the E-meter?
Thanks,
TiM
PS Being displayed by the porta potties did give my
truck plenty of exposure while people were waiting for
a stall to open up ;-)
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
--- End Message ---
--- Begin Message ---
Hi all,
put up some links on http://evproduction.org/wiki/index.php?title=Links, they
are basically the same as on our www.teva2.com site, more to come.
Rush
Tucson AZ
www.ironandwood.org
--- End Message ---
--- Begin Message ---
Well, I was asked by Rod Wilde, to comment on "syriana" it is fairly
OT... but relates to EV's as EV's relate to OIL....
It is Hard to follow.
There are 4 plots going on at one time.
1. George Clooney is a kind of over the hill CIA agent, specializing in
Mid-East stuff.
2. Matt Damon.. a Wall Street Type broker who befriends the Older
Brother of a 'aman' who is aging and about to give over the throne to
one of the brothers..Of course OIL is at the heart of the transfer of
POWER...
3. Washington DC Lawyer, trying to shmooz the FEDS on a big Oil Mirger
4. Yong Muslum's being kicked and mis-treated by their governments being
radicalized towards terrorists acts by other Muslem teachers.
In my estimation, it is well done, and thought provoking, and of course
he WAS on the Jay Lenno Show, with his TANGO... talking about the movie...
I guess any thing that can give more "legs" to the fact that we should
be looking towards alternatives... is OK by me...
PS: Obviously.. the Big Oilyes are made out to look bad, in the back
pockets of Big Government, ...........probably not far from the truth.
--
Steven S. Lough, Pres.
Seattle EV Association
6021 32nd Ave. N.E.
Seattle, WA 98115-7230
Day: 206 850-8535
Eve: 206 524-1351
e-mail: [EMAIL PROTECTED]
web: http://www.seattleeva.org
--- End Message ---
--- Begin Message ---
Hi Rod,
Not sure about Australia's default breaker limit, I know that
The Netherlands (Europe) has a default 16A wiring on household
circuits, though it is possible to wire a circuit for 25A or more
and use a higher current breaker, it's just not the default in
most homes.
3-phase is certainly possible, you will need the 3-phase rectifier
(6 diodes) to supply DC to the "motor" side of a DC controller.
Question is if the controller is setup for battery charging - all
the voltage/current limits and tapering, temp control and so on.
Basic braking-regen is usually much more rudimentary in only
requiring a battery voltage limit to avoid destroying anything
when starting with 100% full batteries on a long down-grade...
(There ARE of course smart systems, like my Prius stops charging
the battery from regen when the BMS indicates the battery is "full")
NOTE that not all batteries can be charged fast - at least not
according the manufacturers recommendation.
My AGMs have a 30A max, while they are 110Ah so it is voiding the
manufacturers recommendation (and warranty) to try to fast-charge.
With 312V pack and 30A max you already need a serious service
outlet to reach this power. 240V 50A range outlet is maxed out
when the pack is taken to around 400V charging voltage....
So, unless you plan on TWO battery packs to dump-charge one with
the other, there is not much you can do to get more power, unless
you are willing to upgrade your grid connection.
Regards,
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-501-641-8576
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Rodney
Sent: Wednesday, December 07, 2005 4:51 AM
To: [email protected]
Subject: AC prop reductive charger
Just wondering if the charger guys out there have found a way to replicate
AC prop's 'reductive charger' for DC charging use? They claim it can
recharge the batteries in the tzero to 60% in 30 min!
Is this just an AC charger/inverter thing, or can we make those chargers for
DC charging as well? I am from Australia, so I think our outlets are capped
at either 10 or 15 Amps though (240V), so thats a problem, unless you
install 3 phase...
Cheers
Rod
--- End Message ---
--- Begin Message ---
Yep, forgoing range meant I'd be happy with 25-50 miles I see quoted;
instead of three hundred... with a filling station on every corner. I
have a spare '94 Volvo (2.3L turbo, 162 hp, 195 ft lbs torque, 0-60
7.09 sec and 1/4 mile 15.5 sec/90.7 mph). I'm convinced it's too heavy
(3,200 lbs) to make it a good donor.
At this point, I'm just trying to understand the system components
required and cost. Next, I'll decide if it's worth buying a 2,500 lb
donor (perhaps a kit car).
Today, I'm wondering if the biggest system constraint might be Maine
winter. Will a ceramic heater really melt the snow on the windshield?
Ron
Jonathan Smith wrote:
I am new here, too. And, I had to grin at your statement about forgoing range.
The range that you have sketched would be excellent for most most
conversions except the premium ones with Lithium, NiMH or monster
battery packs. Range is the "dead white elephant in the middle of the
living room" that EVers try to ignore.
Additional information that might be helpful in answering your
question would be the weight of the donor vehicle and the temperature
ranges at your location.
desire a minimum amount of performance. I'd appreciate hearing
recomendations for system components to meet the following requirements.
1. 25 mile round-trip commute - freeway; however short on-ramp with
quick acceleration from 35-55 mph needed
2. Travel in-town requires climbing a steep hill (18% incline) at 45
mph - 1/2 mile
|
--- End Message ---
--- Begin Message ---
Cool!
On 12/12/05, Rush <[EMAIL PROTECTED]> wrote:
> Hi all,
>
> put up some links on http://evproduction.org/wiki/index.php?title=Links, they
> are basically the same as on our www.teva2.com site, more to come.
>
> Rush
> Tucson AZ
> www.ironandwood.org
>
>
--- End Message ---
--- Begin Message ---
This reminds me of the real HMMWV (Hummer). It has a gear reduction gear box
at each wheel. This gives it a torque advantage and a height boost, as the
drive axles attach at the top of the backing plates instead of the center.
I'll bet this would do well as an EV feature...
David C. Wilker Jr.
United States Air Force, Retired
----- Original Message -----
From: "Rodney A" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, December 12, 2005 6:25 PM
Subject: Re: Setting up a Direct Drive
As far as I know, most two motor direct drive systems physcially connect
the motors together (belt or chain, etc) and then connect to the
driveshaft or reduction gearbox.
What about running two motors on the rear axle, one attached to each wheel
(via a lightweight reduction gearbox) thus eliminating the differential
(which would make up for the extra weight of the additional reduction
gearbox)? The advantage of this setup might be a little more torque and
power (less mechanical losses) plus with the motors in parallel (which
they would be most of the time) you get an electronic traction control.
Rod
--- End Message ---
--- Begin Message ---
On Mon, December 12, 2005 8:25 pm, Rodney A said:
>
> As far as I know, most two motor direct drive systems physcially connect
> the
> motors together (belt or chain, etc) and then connect to the driveshaft or
> reduction gearbox.
>
> What about running two motors on the rear axle, one attached to each wheel
> (via a lightweight reduction gearbox) thus eliminating the differential
> (which would make up for the extra weight of the additional reduction
> gearbox)? The advantage of this setup might be a little more torque and
> power (less mechanical losses) plus with the motors in parallel (which
> they
> would be most of the time) you get an electronic traction control.
>
> Rod
I'm not sure of anyone who's actually tried this, but it gets brought up
from time to time so I'm sure there's someone out there who has. Hopefully
someone will correct me if I'm wrong, but I don't think the electrical
"limited slip differential" action of two motors configured this way and
wired in parallel would be all that great. Probably not worth the
complexity of each motor having its own gearbox and CV shaft.
It makes sense that as one motor spins free and its back-emf climbs, the
other motor that has traction will get more current. But first of all, it
doesn't seem like it'd produce much more torque than it was producing
before the other wheel slipped. With an LSD you have the potential of
transferring a large proportion of the torque of the slipping wheel on top
of the one that's grabbing, and with locking diffs and spools all of it
transfers so the axle on the grabbing wheel momentarily sees twice the
normal torque. (When buying racing axles they tell you to size them for
the total torque in first gear after the final drive, even though they'll
usually only see half that.) But with the dual motor setup instead, the
only thing making the grabbing wheel push harder is the reduced voltage
sag due to the other, unloaded motor. I can't see that limiting the RPM
difference between axles very much beyond an open diff.
Second, it doesn't seem like it would react very quickly. A spool "reacts"
instantly to a loss of traction on one wheel, transferring it all
immediately to the other. An engaged locker would be about the same, and
LSDs not much far behind. But it seems that using motors, the one wheel
would have to break completely loose and spin up pretty significantly for
torque to start to transfer to the other side, meaning your "differential"
would allow a lot more difference in axle RPMs than a viscous or
clutch-type LSD.
Also, generally at slower speeds and lower power (like typical street
driving) you'd want the motors in series. And I think that wouldn't work
well at all -- one wheel slips free, and you *lose* torque from the other.
Has someone tried this, maybe even on a go-kart or something? It'd be
cool if it works better than I'm picturing in my head.
--chris
--- End Message ---
--- Begin Message ---
Earlier I wrote:
> Jerry has sent me the "knowledge base" so I will have a look at that
> tonight and try to figure out whether to assimilate it somehow, or
> just offer it as a downloadable file.
Well I found a nice web application for sharing bookmarks, called
SiteBar. It is not as good as a wiki, for both linking to other sites
and at the same time writing some significant description about those
links; but it does provide an easy way to maintain a simple tree of
bookmarks, just like the ones you can create from within your browser.
Supposedly you can use it as a sidebar in Mozilla or Firefox. So, I
installed this on the evproduction.org server, and you can all try it
out if you like. The main thing I like is it's pretty snappy to
expand and collapse folders, so you can navigate it like a real tree,
not wait a few seconds after every click.
Go to http://evproduction.org/sitebar/
and the first thing you need to do is create an account. (It does not
re-use the account usernames from the wiki, it's a completely separate
application with its own database. But it's not an involved process,
just give your email address and make up a password.)
After you create an account, you will have one folder. Right-click on
it to get a pop-up menu which will have options to create new links,
create sub-folders, etc.
You are supposed to be able to import your bookmarks file from your
browser, and it will allow others to see them.
I will try to import Dave Mcafee's bookmarks. (So far I have tried
and not succeeded. Its import function seems to be kindof picky about
the file format.)
Everyone can manage his own bookmarks there under his own account, but
I'm hoping maybe it will let us all work on one big tree as well.
So this is a playground, feel free to play and see if you like it.
--- End Message ---
--- Begin Message ---
Chris Robison [mailto:[EMAIL PROTECTED] wrote:
> I'm not sure of anyone who's actually tried this, but it gets
> brought up from time to time so I'm sure there's someone out
> there who has.
If you mean using two motors, each driving one rear wheel, the Tropica
was set up this way (with a fixed reduciton belt drive between each
motor and its driven wheel). However, I believe they also used a pair
of Curtis controllers, so each motor had its own controller and there
was no series/parallel switching.
If you mean the two motor direct drive setup, and series/parallel
switching, my son's PowerWheels jeep is set up like this. I upgraded it
from the original 6/12V two-speed system to a 24V 75A PWM controller
with manual series/parallel switching of the two drive motors using the
original hi/lo speed switch. (He was only 3 at the time of the upgrade,
but you gotta start them sometime ;^)
> Hopefully someone will correct me if I'm
> wrong, but I don't think the electrical "limited slip
> differential" action of two motors configured this way and
> wired in parallel would be all that great. Probably not worth
> the complexity of each motor having its own gearbox and CV shaft.
> Has someone tried this, maybe even on a go-kart or something?
> It'd be cool if it works better than I'm picturing in my head.
Actually it works quite well, and it is immediate; there is no delay.
It is late at the moment and I won't swear that it is the parallel
rather than series setting that provides the limited slip behaviour
though.
I had intended the series/parallel switch primarily as a hi/low speed
range, however, the limited-slip behaviour proved to be quite useful as
it makes the difference between the Jeep spinning its hard plastic
wheels on the grassy hill in our yard or creeping up it.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Dave [mailto:[EMAIL PROTECTED] wrote:
> This reminds me of the real HMMWV (Hummer). It has a gear
> reduction gear box at each wheel. This gives it a torque
> advantage and a height boost, as the drive axles attach
> at the top of the backing plates instead of the center.
> I'll bet this would do well as an EV feature...
Actually, it reminds me of the pre-'69 (possibly pre-'67?) VW Type II
(bus).
Same deal with a fixed reduction gear box at each wheel (2:1 ratio,
IIRC). Adapters for the VW tranny are readily available (if one were to
retain it as well as the reduction gears), and parts from an older VW
bus ought to be cheaper than HMMWV parts (!) and more amenable to
integration into a VW-based kit car, for instance. Of course, I think
the reduction gear boxes were only used on swing axle trannies, and one
would probably want to convert them to use IRS axles if ditching the
tranny and driving them directly with a pair of motors.
Cheers,
Roger.
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Can you add Canadian Electric Vehicles to stores?
Victoria, BC, Canada
See the New Beetle EV Conversion Web Site at
www.cameronsoftware.com/ev/
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Rush
Sent: December 12, 2005 7:42 PM
To: [email protected]
Subject: links on evproduction.org wiki
Hi all,
put up some links on http://evproduction.org/wiki/index.php?title=Links,
they are basically the same as on our www.teva2.com site, more to come.
Rush
Tucson AZ
www.ironandwood.org
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Some cars throttle back the power as a form of traction control when
a wheel slips, or apply the brakes when a wheel slips. It seems this
would be similar to the action of two motors in series, and probably
what you'd want on the street, better to slow down a bit and regain
traction.
Perhaps for racing, parallel is better. A moment of slippage can be
tolerated, or is even desirable in rare instances. Meanwhile the
other wheels is still working hard.
This gave me an idea. Perhaps you'd want series mode while in current
limit (start and low rpm), so if spinning started power would cut
back to regain traction. In constant power mode (out of current limit
and higher rpm), you'd want parallel mode. A constant power mode
naturally lessens torque as a wheel spins faster, so it is a built in
weak form of traction control.
So the thought suddenly hit me, this is what Otmar's Godzilla
controllers do already! Maybe this inherent form of traction control
is part of the success of the twin motor + Godzilla NEDRA racers.
A real life data point: My friend's 500 hp Camaro easily spins the
wheels in 2nd gear. It goes about 60 in first, so it can do almost
any autocross course entirely in 1st gear. In theory you'd think it
doesn't matter then which gear you use. In practice, he is faster in
first gear. We theorize that is because he is on the downsloping part
of the torque curve in 1st gear, giving an inherent traction control
(more rpm = less torque), whereas in 2nd gear torque is climbing as
RPM climbs (wheel spins, gets more torque, spins even faster, vicious
cycle).
--- Chris Robison <[EMAIL PROTECTED]> wrote:
> ...
> Also, generally at slower speeds and lower power (like typical
> street
> driving) you'd want the motors in series. And I think that wouldn't
> work
> well at all -- one wheel slips free, and you *lose* torque from the
> other.
>
> Has someone tried this, maybe even on a go-kart or something? It'd
> be
> cool if it works better than I'm picturing in my head.
> ...
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The ability to drive each wheel (relatively) independent is a
great asset and that alone can make it worthwhile.
Engaging a break on a slipping wheel (as some ABS do) is only
a trick to allow more motor power to go to the other wheel, but
when each wheel is independently driven you get the same benefits
that made the original CVT using 2 belts to drive each rear wheel
so perfect for rallysport - many times the DAF 55 Marathon was
present in the top ranks of crosses, even though the engine was
usually the weakest of the field. Low weight and independent
wheel control, combined with the automatic variable transmission
were the receipt to gaining seconds at each turn, where they
only lost were on long straight stretches.
(Even in 1993 I encountered Rally-drivers that still participated
in national rally events with their DAF 55 and often won.)
If you want to see the year 60's technology - scroll to the
bottom of the following page in the "DAF vehicle history":
http://www.ritzsite.demon.nl/DAF/DAF_cars_p10.htm
NOTE that 50 hp was the top-of-the-line for DAF (they started with
20 hp) and it was only topped by the 63 hp of the boosted version
for the 55 Marathon (named after the London-Sidney marathon that
two DAF 55 completed) which was the Sports version of the DAF 55.
Regarding the use of ordinary motors and reduction boxes plus two
half-shafts versus special in-wheel motors - I think that the price
difference alone will prevent most EV (especially conversions) from
using anything else than reduction on normal motors. The advantages
are a reduction of unsprung weight and the motors are not subjected
to the vibrations and impacts of the wheels.
Again, for conversions the reduction gearbox will need to be at the
motor, as it will be quite a challenge to add it to the wheel.
Anybody want to try a HMMWV-EV?
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-501-641-8576
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Dave
Sent: Monday, December 12, 2005 8:31 PM
To: [email protected]
Subject: Re: Setting up a Direct Drive
This reminds me of the real HMMWV (Hummer). It has a gear reduction gear box
at each wheel. This gives it a torque advantage and a height boost, as the
drive axles attach at the top of the backing plates instead of the center.
I'll bet this would do well as an EV feature...
David C. Wilker Jr.
United States Air Force, Retired
----- Original Message -----
From: "Rodney A" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, December 12, 2005 6:25 PM
Subject: Re: Setting up a Direct Drive
>
> As far as I know, most two motor direct drive systems physcially connect
> the motors together (belt or chain, etc) and then connect to the
> driveshaft or reduction gearbox.
>
> What about running two motors on the rear axle, one attached to each wheel
> (via a lightweight reduction gearbox) thus eliminating the differential
> (which would make up for the extra weight of the additional reduction
> gearbox)? The advantage of this setup might be a little more torque and
> power (less mechanical losses) plus with the motors in parallel (which
> they would be most of the time) you get an electronic traction control.
>
> Rod
>
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At 08:34 PM 12/12/05 -0800, Rod wrote:
Just wondering if the charger guys out there have found a way to replicate
AC prop's 'reductive charger' for DC charging use? They claim it can
recharge the batteries in the tzero to 60% in 30 min!
Is this just an AC charger/inverter thing, or can we make those chargers for
DC charging as well? I am from Australia, so I think our outlets are capped
at either 10 or 15 Amps though (240V), so thats a problem, unless you
install 3 phase...
Hi Rod - and all
Domestic Aussie 230/240VAC 10 amp GPO (general power outlet) circuits run
from a 16A breaker, normally, or sometimes a 20A breaker. 15A domestic
outlets are run from a 20A or 25A breaker. There is a 20A version of the
normal Aussie 10A/15A pattern, but I've never seen one installed. Normally
once you get into heavy duty single phase are 20A or 30A outlets with round
pins like the standard 3-phase outlets normally breakered at up to 50A
(welders/etc). Bigger than that exists, but that becomes special. The real
single-phase domestic limit is the 80A or 100A service feed usually used.
If you are lucky to have 3-phase feed already (like I have) or put in a
heat pump in the 6kW plus range to get three phase, then there are three
feeds of 80 or 100A to play with. At home I have 80A/415V (3 x 240V) and at
work 100A/415V. Our state electricity supplier keeps most people on the
high side voltage wise. Both here at home and at the workshop we are
normally between 245 and 250V (what am I going to do with 50kW+?). Mainland
Australia is often on the low side of nominal 230, ie down closer to 220V.
When you ask about DC charging, are you meaning a DC supply instead of an
AC supply? As far as I can tell, a DC supply is what is actually used,
rectified and filtered (?) mains.
It would be a way of taking a random transformer of higher voltage than the
battery pack, and using the vehicle controller to charge the batteries. For
example, I have several 3-phase transformers that have single voltage
secondaries (135V), I could rectify the secondary and get a peak of around
180V and 50A, 3 in paralell for 150A. The 120V battery pack (dual strings
of Orbitals) could be brought up quite quickly. The catch is, that I could
only use the motor field OR armature as the series inductor, as to use both
would make the vehicle want to drive away!
A special-purpose controller for charging to take the close-to-400V
rectified & filtered 'mains' at 20 or 30A, or better yet just do something
like Rich Rudmans' PFC (or buy one of his) to get best energy transfer from
the supply.
Hope this helps
James
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Hey James and everyone else
I am looking at a Li-ion pack of 200 Ahr cells that can be charged at 2C
rate (so 400 Amps) and a 300 V pack.
Re DC, I actually meant through the DC controller rather than an AC setup. I
am looking to use one of Otmars Zilla 1k controllers, and looking at the
fastest way to charge the pack. So I have 300 V that I can charge up to 400
Amps! I guess 3 phase would be the go, but can you get up to those levels? I
assume it would need a custom charger (Rich?)?
Cheers
Rod
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On 12 Dec 2005 at 10:49, David McWethy wrote:
> I have
> heard Interstate might not be the best choice.
Interstate Workaholic is just another label for US Battery. They should be
fine. Eight volt golf car batteries have their limitations compared to six-
volters, but that's another matter.
David Roden - Akron, Ohio, USA
EV List Assistant Administrator
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On 12 Dec 2005 at 17:41, Roger Stockton wrote:
> you seem to have identified its weakness,
> which is that it does not accurately sense battery temperature and so
> does not charge properly when the battery temperature differs
> significantly from the charger temperature.
I don't know anything about the particular charger you're talking about, but
it wouldn't be the first charger which attempted to do temp comp by assuming
that the charger and the battery were always at the same temp. It never
works. In addition to the phenomenon noted here, as soon as you charge or
discharge the battery, its temperature changes.
I wonder if there's any way to do a little surgery on the charger and put
its temp sensor on a length of wire. Maybe you could epoxy it to one of the
battery posts, so it might have a hint of a clue.
David Roden - Akron, Ohio, USA
EV List Assistant Administrator
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