EV Digest 5434
Topics covered in this issue include:
1) Re: EV Charging station
by Jeff Shanab <[EMAIL PROTECTED]>
2) Re: EV Charging station
by "Ryan Stotts" <[EMAIL PROTECTED]>
3) Re: EV Charging station
by Neon John <[EMAIL PROTECTED]>
4) RE: EV Charging station
by "Roger Stockton" <[EMAIL PROTECTED]>
5) Re: WarP 9" motor efficiency and max voltage?
by Ryan Bohm <[EMAIL PROTECTED]>
6) New in Hawaii
by Zaff and Bryan <[EMAIL PROTECTED]>
7) $67K for a RAV4 EV?!
by Marvin Campbell <[EMAIL PROTECTED]>
8) Deka Dominators - latest Jetta conversion brainstorm..
by [EMAIL PROTECTED] (Brad Baylor)
9) Re: Link to video of Who Killed the Electric Car
by nikki <[EMAIL PROTECTED]>
10) The big debate. Gearbox or not with an AC motor.
by nikki <[EMAIL PROTECTED]>
11) RE: The big debate. Gearbox or not with an AC motor.
by "David Ankers" <[EMAIL PROTECTED]>
12) Re: What is it with CVTs?
by "Peter VanDerWal" <[EMAIL PROTECTED]>
13) DIY air-conditioning (was Re: Prius air-conditioning)
by "Peter VanDerWal" <[EMAIL PROTECTED]>
14) RE: EV Charging station
by "Roger Stockton" <[EMAIL PROTECTED]>
15) Re: The big debate. Gearbox or not with an AC motor.
by "Peter VanDerWal" <[EMAIL PROTECTED]>
16) Re: WarP 9' motor efficiency and max voltage?
by "Peter VanDerWal" <[EMAIL PROTECTED]>
17) Does the following make sense?
by "David Ankers" <[EMAIL PROTECTED]>
18) Re: The big debate. Gearbox or not with an AC motor.
by James Massey <[EMAIL PROTECTED]>
19) Re: DIY air-conditioning
by Neon John <[EMAIL PROTECTED]>
20) Re: Does the following make sense?
by James Massey <[EMAIL PROTECTED]>
21) Hot solenoid
by "Richard Acuti" <[EMAIL PROTECTED]>
22) Civic, DC motors, was: RE: The big debate.
by James Massey <[EMAIL PROTECTED]>
--- Begin Message ---
EV1.1 standard 3 prong, yes agreed, people are comfortable with this
level of safety/shock. But it will be have a simple hangdown cover to
keep rain out like they sell at Home depot etc.
EV1.2
I Absolutly disagree here. The standard blade style is not intended
to be pluged and unpluged and it is so freaking easy for someone to get
their fingers accross the contacts.
So far I would use the waterproof versions of the recessed twistlock
or even pin style that boat people use. They are commonly avail, but
over priced. That can change easily enough.
I haven't looked at the avcon's yet, but compatibility with existing
rangers and rav4's may be a impitus here.
--- End Message ---
--- Begin Message ---
Jeff Shanab wrote:
I haven't looked at the avcon's yet, but compatibility with existing
rangers and rav4's may be a impetus here.
How much longer are these OEM vehicles still going to be on the road?
Has anyone swapped out a RAV4 pack yet? With what?
--- End Message ---
--- Begin Message ---
On Mon, 1 May 2006 12:06:30 -0700 (PDT), Chet Fields
<[EMAIL PROTECTED]> wrote:
>How about striking a deal with Starbuck's or someone similar? They already
>have recycled cups and
>Ethos drinking water and such. Seem's like a good match.
I bet you'll have a lot better chance of success following up on my
"Dollars for volts" proposal to Wallyworld for RVers that I wrote
about a couple of weeks ago. You're not going to get anywhere trying
to beg power for the 2 or 3 EVs in most areas but you MIGHT by riding
on the backs of RVers. RVs and Wallyworld have been wedded for
decades so this is familiar territory.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
Don't let your schooling interfere with your education-Mark Twain
--- End Message ---
--- Begin Message ---
Jeff Shanab wrote:
> EV1.2
> I Absolutly disagree here. The standard blade style is not intended
> to be pluged and unpluged and it is so freaking easy for
> someone to get their fingers accross the contacts.
> So far I would use the waterproof versions of the recessed
> twistlock or even pin style that boat people use.
Have you considered the IEC 309 style connector (perhaps this is the
pin-style you refer to)?
<http://www.tequipment.net/EricsonSplashProof.html>
Available in 60A 250V (among other sizes), with finger-proof design.
If you go with a NEMA standard twistlock, you appear to be limited to
30A maximum (L6-30), which is a bit low if you are going to the trouble
of providing a 240V outlet. Might as well allow at least the 50A @
240VAC that people would typically have available at home.
I don't know if *any* of the AC connectors are rated for high
mate/unmate cycle life, so that aspect of your concern may be moot.
The IEC 309 series price ($100-150) really isn't ~that~ bad when you
compare it to 30A or (non-NEMA) 50A twistlocks or the cost of an Avcon
receptacle...
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Hi Dmitri and all,
My first question is, what is the WarP 9" motor's efficiency at 1000
amps and 150+ motor volts?
I don't know the answer to this. But I do know that you better not be
running 1000 amps for any extended period of time. For hard
accelerations - okay. Try continuous at that current and things aren't
going to last long. Do you still need to know the efficiency?
You might see numbers like 2500 RPM at 50 amps going about 50 MPH.
That's a pretty good target. Something in the ballpark of 250 amps
going 65 mph at 3000 RPM could become a concern if ran that way for
extended periods.
What is the highest motor voltage the WarP 9" will take safely
(without arcing and destruction) for a regular street vehicle?
NetGain recommends staying at no more than 170V - 160V is the number
that I hear more often.
-Ryan
--
- EV Source <http://www.evsource.com> -
Selling names like Zilla, PFC Chargers, and WarP Motors
E-mail: mailto:[EMAIL PROTECTED]
Toll-free: 1-877-215-6781
--- End Message ---
--- Begin Message ---
Aloha,
I am new to the list and new to EV. I am seaching for help in Hawaii
(O'ahu) to convert my 1991 Toyata Tercel. My Tercel is sitting in the
yard with oil leaking into the spark plug but other wise it's in working
order. I could donate it or convert it. I'm not a mechanic nor an
electrician, actually I was a theatrical technical director untill I
retired to homeschool my 2 teenage kids.
Anyway, the problem here is finding the parts without shipping them from
the mainland. If there is someone here to guide me and point me toward
mostly local parts then perhaps I could convert it. Everyone, so far
have told me just to buy a GEM car -- which cannot go on the freeways.
I thought maybe I could get the Tercel to go a little faster???
Thanks for any help,
Zaff
--- End Message ---
--- Begin Message ---
Let's not get carried away. It only listed for $42,510.00:^O
> From: "Dr. Polsinelli" <[EMAIL PROTECTED]>
> Date: Mon, 01 May 2006 14:49:28 -0400
> To: Electric Vehicle Discussion List <[email protected]>
> Subject: Re: $67K for a RAV4 EV?!
>
> Not bad for a car that originally sold for $43,000.
--- End Message ---
--- Begin Message ---
Product brochure:
http://www.eastpenn-deka.com/products/pdfs/epm0909.pdf
In Deka's technical manual about these gel batteries:
http://www.eastpenn-deka.com/products/pdfs/0139.pdf
Typical life cycles:
Capacity Withdrawn - Cycles
100% 450
80% 600
50% 1000
25% 2100
10% 5700
Interesting eh?
Their group 31 battery is 70 lbs, 97.6 AH/20HR rate, 64.5 AH/1HR rate,
and rated at 780 A at 32 degrees F. About $160 each I believe.
For my Jetta conversion project (design which has flip-flopped a
bizillion times with many different battery/controller ideas....), I'm
now considering a string of 20 of these for 240 V, battery current
limit of 500 A, and a motor current limit of 1000 A, on a Warp 9.
Should give good enough 0-40 MPH to deal with rush hour traffic
merges, about 35% DOD with 20 miles round trip non-freeway commutes,
and exceptionally long life. Even though people have posted not to use
gels with DC systems, the figures seem reasonable when using 240 V and
larger than typical gels.
The catches seem to be the charge regimen of using a temperature
sensor on each battery, strict charge voltage dependant on
temperature, and because such, charging to 100% possibly taking longer
than overnight. But if I only drain 35% each day, charge with a 500
watt charger per battery (50 AMP 240 VAC circuit), should be
sufficient.
For chargers I'm thinking of doing the multi approach people have
recommended not doing for various reasons. But these batteries seem to
demand it, and I'm itching for a PIC project. :)
Jameco sells Meanwell (Astrodyne designed it looks like) PSP-500-15
for $129.35 each for 25. Power factor corrected, isolated, 500 watts,
13.5 to 18 V output. Input 90 to 264VAC or 127 to 370VDC. They are
gangable for up to 2000 watts output. Which means I could use 20 for
the batteries, and use 4 for the DC/DC (gonna have a MR2 power
steering unit), and have a spare.
For each battery, use a PIC with a built in A/D for the temperature
sensor, and digital pot to vary the output voltage (measured at the
battery for best accuracy and to make up for the voltage drop of the
charge cabling). Then have a master controller to power up the
supplies one at a time to limit the inrush, and to make battery eye
candy on a dash mounted display. Yeah. I'm liking this brainstorm.. :)
Brad Baylor
--- End Message ---
--- Begin Message ---
Does anyone know if this film is showing in the UK? I'm thinking of
writing to the production company to find out.
Regards,
Nikki
On May 2, 2006, at 3:01 AM, Dr. Polsinelli wrote:
Just a clip. Not a trailer.
http://news.com.com/1606-2_3-6067099.html?
part=rss&tag=6067099&subj=news
--- End Message ---
--- Begin Message ---
I'm still at a very early stage in my research as you all know but
I'm wondering if I may ask for all your opinions on the AC motor with
gearbox/without gearbox debate.
I have some prerequisites for my car which I believe will end up with
me using an AC motor. They are:
Good range. (Anything between 50 to 150 miles would be ideal)
High voltage as oppose to high current system. I'm a great believer
in having a high-voltage, low current system wherever possible (and
as I recall isn't there less voltage drop on a low current system? -
A long time since I did my high school physics and I really should
brush up!!!)
Reasonable top speed. Capability to do freeway speeds would be
essential.
Acceleration Isn't a problem. My current car takes a year to get to
60... or did before I removed the ICE.
So - to the question.
Gearboxes. I understood that they weren't allways needed on an EV and
especially not on an AC car. But are there any benifits of having a
gearbox that I should consider (Such as the ability to enable the
motor to always be turning at a fairly constant RPM, or perhaps a
better gear for hill climbing?)
Thanks in advance!
Nikki
--- End Message ---
--- Begin Message ---
>From my understanding, you'll always need some form of gearbox but you might
only need a single gear with an AC system.
Like this guy has done:
http://www.austinev.org/evalbum/455
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of nikki
Sent: Tuesday, 2 May 2006 3:55 PM
To: [email protected]
Subject: The big debate. Gearbox or not with an AC motor.
I'm still at a very early stage in my research as you all know but
I'm wondering if I may ask for all your opinions on the AC motor with
gearbox/without gearbox debate.
I have some prerequisites for my car which I believe will end up with
me using an AC motor. They are:
Good range. (Anything between 50 to 150 miles would be ideal)
High voltage as oppose to high current system. I'm a great believer
in having a high-voltage, low current system wherever possible (and
as I recall isn't there less voltage drop on a low current system? -
A long time since I did my high school physics and I really should
brush up!!!)
Reasonable top speed. Capability to do freeway speeds would be
essential.
Acceleration Isn't a problem. My current car takes a year to get to
60... or did before I removed the ICE.
So - to the question.
Gearboxes. I understood that they weren't allways needed on an EV and
especially not on an AC car. But are there any benifits of having a
gearbox that I should consider (Such as the ability to enable the
motor to always be turning at a fairly constant RPM, or perhaps a
better gear for hill climbing?)
Thanks in advance!
Nikki
--- End Message ---
--- Begin Message ---
> I think the variable voltage is throwing off my thinking...
>
> The graph for a ADC 6.7" L type (for example) says that you loose 2%
> (88% peak down to 86%) efficiency when you go below 1100RPM or above
> 2700RPM. This *is* at a voltage of 75VDC fixed though. This also means
> anything below ~22MPH in a direct drive setup is on the steep slope of
> the efficiency curve. How does a variable voltage change that curve?
THe curve moves depending on the applied voltage. Reduce the voltage and
the whole curve moves over to a lower RPM. The shape of the curve changes
as weel. At lower voltages the peak efficeincy area tends to get narrower
and start to slope down to the right.
The main point here is that when you reduce the power output requirement,
you generally need to reduce the input voltage. This moves the curve over
to where the peak efficiency happens at a lower RPM and, if the voltage
drops low enough, the high RPMs may even move off onto the low efficiency
slope.
> The efficiency of said underdrive unit is 99.75% (parasitic loss of less
> then 1HP per 400HP as tested). Since it would only raise a motor
> spinning 1000RPM (%85) to 1250RPM (87%), I suppose any net gain would
> depend on how long you stay below 25MPH. A 2:1 low would perhaps provide
> some *real* benefit versus a 1.28:1.
I doubt that efficiency number is completely accurate. Even if it is, it
assumes that you are running high power through it. At lower power the
minimum losses from striction, etc. will be more significant and could
possibly drop the efficiency down into the low 90s / high 80s.
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
--- Begin Message ---
> EVs have it a little better because of lack of engine heat but 22 is
> still a bad choice for mobile AC. An R-134a or even better,
> hydrocarbon (isobutane or a mix of isobutane and propane) is much more
> suitable.
I've seen this mentioned on the list before.
Can you adapt an existing AC system to work with isobutane or would
you have to build it from scratch?
If you can adapt which would be better to start with, a window AC or
and Auto AC?
What would be involved?
Finally, are there any stoopid laws prohibiting this?
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
--- Begin Message ---
Rich Rudman wrote:
> I was yakking with a Pape Service Guy this week. He services
> the fork trucks at the Big new Kingston Lumber yard that
> Shares the buisness park with my production shop.
>
> He also agrees that there is a big question on why folks
> don't make really high rate chargers for the Bigger packs.
The technology is already available to those who are serious. For
instance:
<http://www.etecevs.com/marine/index_frame_marine_marine-100.htm>
These guys produce chargers up to 150kW that will automatically charge
anything from 36-350V, be it flooded PbA, VRLA PbA, or NiCad.
The models they list include the MARINE-400SP, a 33kW unit that will
charge aything from 36-350V at up to 400A.
Their little model is the LSV-100, a 10kW unit that automatically
charges anything from 36-96V at up to 100A. This puppy is used for 72V
NEVs with flooded or sealed (gel) batteries.
Fast charging material handling packs is not uncommon; I've seen
presentations illustrating the sort of overall cost savings heavy users
can enjoy as a result of using fast chargers instead of having extra
battery packs and the associated dedicated battery rooms and labour
overhead associated with returning a lift truck to the battery room for
a battery swap, etc. (in really physically large operations, the travel
time between the work site and the nearest battery room can represent a
considerable cost).
Not to dissuade you, just be aware that there is already established
competition in this area. LEM, for instance already offers a
sophisticated data-logging state-of-health monitor targeted at
individual VRLA cells:
<http://www.lemusa.com/category/27.html>
You'd probably even like it... it uses an RJ-connector based network,
and shades of EViLBus, there is even a translator node to convert
between the proprietary bus and RS485! ;^>
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
It all depends on which motor you finally decide on. The key to running a
single speed reduction is having a motor/controller that can produce
enough torque to handle hills and acceleration at a reduction ratio that
still allows you to reach your desired top speed without over reving the
motor.
AC has a slight advantage of DC here because they typically have a very
wide RPM range (often twice the max RPM of DC motors).
I have a suggestion that might work for you and should be fairly economical.
Victor recently announced a very low cost AC setup. It has a couple minor
shortcomings. It has a low max RPM and it's a little on the low power
side.
Both of these can be overcome by using a multispeed gearbox and you will
still get the slightly better efficiency of the AC setup as well as Regen.
Top speed in your car will easily be 70 mph or perhaps a bit more.
Acceleration will be a little low, but probably not to bad in a light car
like the Minor.
The motor he is offering comes with an adapter plate designed for a VW
golf gearbox. Unfortunately the GOlf has a front wheel drive transmission,
but perhaps you can adapt this to fit your existing transmission or
perhaps some other transmission. If nothing else it already comes with a
flywheel adapter which will save you a few pounds.
> I'm still at a very early stage in my research as you all know but
> I'm wondering if I may ask for all your opinions on the AC motor with
> gearbox/without gearbox debate.
>
> I have some prerequisites for my car which I believe will end up with
> me using an AC motor. They are:
>
> Good range. (Anything between 50 to 150 miles would be ideal)
> High voltage as oppose to high current system. I'm a great believer
> in having a high-voltage, low current system wherever possible (and
> as I recall isn't there less voltage drop on a low current system? -
> A long time since I did my high school physics and I really should
> brush up!!!)
> Reasonable top speed. Capability to do freeway speeds would be
> essential.
> Acceleration Isn't a problem. My current car takes a year to get to
> 60... or did before I removed the ICE.
>
> So - to the question.
>
> Gearboxes. I understood that they weren't allways needed on an EV and
> especially not on an AC car. But are there any benifits of having a
> gearbox that I should consider (Such as the ability to enable the
> motor to always be turning at a fairly constant RPM, or perhaps a
> better gear for hill climbing?)
>
> Thanks in advance!
>
> Nikki
>
>
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
--- Begin Message ---
>> My first question is, what is the WarP 9" motor's efficiency at 1000
>> amps and 150+ motor volts?
>
> I don't know the answer to this. But I do know that you better not be
> running 1000 amps for any extended period of time. For hard
> accelerations - okay. Try continuous at that current and things aren't
> going to last long. Do you still need to know the efficiency?
>
> You might see numbers like 2500 RPM at 50 amps going about 50 MPH.
Huh?? What kind of little bitty car are you driving that only needs 7kw
to go 50 mph?
Unless you're driving something like a Carmen Ghia, 75-100 amps would be a
more realistic number.
> That's a pretty good target. Something in the ballpark of 250 amps
> going 65 mph at 3000 RPM could become a concern if ran that way for
> extended periods.
Yeah, unless your driving a large pickup, that would be a bit high. Of
course, chances are, at that high a current you'd probably run out of
battery power in about 30 minutes. I think the motor can handle that.
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
--- Begin Message ---
Regarding EVs right now, the follow equation seems to make sense to me:
1. Range
2. ICE equivalent performance
3. Costs less than a small family home
Chose only two of the above.
--- End Message ---
--- Begin Message ---
At 06:55 AM 2/05/06 +0100, Nikki wrote:
I'm still at a very early stage in my research as you all know but
I'm wondering if I may ask for all your opinions on the AC motor with
gearbox/without gearbox debate.
An AC motor needs a gear reduction - of some sort - because they normally
rev relatively high which needs to be reduced to the wheels. However, this
may be (and in a production vehicle normally is) one ratio. It seems that
many converters that use AC then just leave the gearbox in second gear and
drive it. Some motors lend themselves to the reduction ratio of the
differential being enough (see solarvan - http://www.solarvan.co.uk/ ).
I have some prerequisites for my car which I believe will end up with
me using an AC motor. They are:
Good range. (Anything between 50 to 150 miles would be ideal)
Good range is a function of drag, weight and amount of energy on board. In
hilly country AC will provide a 2% to 10% gain by regeneration braking. To
get the range you are asking in the vehicle you are intending to use you
will probably need advanced batteries such as Lithium-Polymer batteries,
which tend to lend their characteristics towards that of an AC system.
High voltage as oppose to high current system. I'm a great believer
in having a high-voltage, low current system wherever possible (and
as I recall isn't there less voltage drop on a low current system? -
A long time since I did my high school physics and I really should
brush up!!!)
A high voltage system is made with smaller wire than a low voltage system
of the same power. If the wire is proportionally smaller than that of the
low voltage system, then the losses in the high voltage system may be more
than the losses of the low voltage system.
Here in Australia the electrical legislation allows non-electricians to
work legally on systems with DC voltages up to 120 volts (bizarely AC only
up to 50 volts) when hard wired. Plug-in things (like an EV) become quite
blurred about what is legal and what isn't (so my EV is going to be 120V).
And just to add to things, I'm working on a system design that uses 504
volts nominal (at 600+ amps), but to access the batteries I will make it so
as to require breaking the pack into 11 parts, none of which are over 48V.
Although this is hard wired, the 48V blocks (and 1 x 24V block) will be
then disconnected - and may or may not be legal for a non-electrician to
work on, but will be safe.
Reasonable top speed. Capability to do freeway speeds would be
essential.
Most EVs that are meant for on-road use (milk floats excepted) are capable
of 'freeway' speeds.
Acceleration Isn't a problem. My current car takes a year to get to
60... or did before I removed the ICE.
So - to the question.
Gearboxes. I understood that they weren't always needed on an EV and
especially not on an AC car. But are there any benifits of having a
gearbox that I should consider (Such as the ability to enable the
motor to always be turning at a fairly constant RPM, or perhaps a
better gear for hill climbing?)
You will probably need a gear ratio, and you already have a gearbox that
can provide it. If you restrict your motor choices to motors that don't
need a gearbox (just the differentials' reduction) you may not be able to
optimise your vehicle.
Thanks in advance!
Nikki
IMHO the range requirement will dictate advanced battery chemistry which
will probably lead to a high voltage battery pack. A high voltage battery
does not automatically define an AC system, Zilla EHV takes up to a 348V
nominal system (400V peak). The DC motor that this feeds needs to be
capable of withstanding the pack voltage peaks, but the average voltage and
current can be kept right under control to suit the motor (maybe an 120V
motor). An AC system is probably a better system to make a more refined
vehicle for others to drive and have a little less maintenance than a DC
system (since regen makes the brakes last longer and the motor has no
brushes to be maintained).
Hope this helps (but probably doesn't much!).
Regards
James
--- End Message ---
--- Begin Message ---
On Tue, 2 May 2006 01:05:07 -0700 (MST), "Peter VanDerWal"
<[EMAIL PROTECTED]> wrote:
>> EVs have it a little better because of lack of engine heat but 22 is
>> still a bad choice for mobile AC. An R-134a or even better,
>> hydrocarbon (isobutane or a mix of isobutane and propane) is much more
>> suitable.
>
> I've seen this mentioned on the list before.
> Can you adapt an existing AC system to work with isobutane or would
>you have to build it from scratch?
A mix of propane and isobutane in the right proportions is a direct
drop-in replacement for R-12. Google back about 15 years in
rec.autos.tech for my name (real name, not handle) or George Goble to
read more than you can stand about this. George is a computer
scientist at Perdue and fellow nerd. We both got pissed off at the
EPA's CFC ban because it was being driven mostly by commercial
interests using dubious science as the excuse. We more or less in
parallel developed the drop-in replacement, met on the net and joined
forces. He went on to develop and patent R-406a while I went BBQ'ing
:-)
We used the blend because we wanted it to be a drop-in with no other
system changes necessary. If you're willing to tweak the expansion
valve or orifice tube a bit, straight isobutane works even better. The
vapor pressure curves of isobutane and R-12 are similar but it works
better to change the expansion device to match.
Both propane and isobutane have ASHRAE-assigned R- numbers and are
recognized as very good refrigerants. Europe has gone to hydrocarbons
in a big way, driven, I think, but the distaste of seeing the large
corps using the EPA to push the US toward patented molecules.
Back when the CFC ban first loomed, everyone had visions of $1000
conversions of R-12 systems to R-134a and everyone was going to get
rich. MACS (mobile air conditioning society), the lobbying group for
this bunch did a pretty good job of cooking the government books, at
least for awhile. EPA let the MACS president write the "Green card"
regulations, the ones that require you to get a card in order to buy
freon. MACS also slid a little jewel in the regs that banned the use
of homemade refrigerant recovery units. Using the chimera of safety,
they stuck in language that required recovery units to be UL approved.
Another case where everyone profits except the ones paying the bills -
the end users. Really dirty politics.
Anyway, MACS was terrified of George and me and a few others working
on hydrocarbon refrigerants. This MACS prez told George at an ASHRAE
meeting that MACS would do whatever was necessary to keep hydrocarbons
and his R-406a off the market. They succeeded fairly well but that's
another story.
Anyway, MACS mounted a massive legislative hysteria campaign with the
aim of banning hydrocarbons because, you guessed it, SAFETY. They
even distributed an ABC Exploding Gas Tank level of fraudulence video
tape purporting to show a station wagon blowing up from a "hydrocarbon
refrigerant leak". That they'd rigged the wagon with a 20 lb propane
tank only came out later.
They managed to get laws passed in 14 states that banned commerce in
hydrocarbon refrigerants. Unfortunately, Florida being one of 'em.
They need good refrigeration probably as much as anyone. I don't
recall the other 13 states but George could tell you. He's was at
[EMAIL PROTECTED] last time we chatted.
Here are the actual facts. Isobutane is about half the density of
R-12. That means it takes only about half as much on a mass basis to
fill a given system as it did R-12. A large system that might hold
3.5 lbs of R-12 only needs about 1.75 lbs of isobutane. This is, of
course, sealed inside a closed system.
Isobutane/propane is also known as A-10. This is the designation
given to the blend that drops right in to replace R-12 as an aerosol
propellant. A-10 is one of the most common aerosol propellants in use
today. A typical can of spray paint or deodorant is from 1/2 to 3/4
propellant. That means that a can of paint that weighs maybe a pound
and a half contains up to a pound of A-10. This is contained in a
foil-thin steel can with rolled edges.
A couple of cans of spray paint in the front seat contain as much A-10
as the AC does. Yet no one gives them any thought while according to
MACS, one will die a horrible fiery death if even a whiff of
hydrocarbon is put into a sealed AC system. But those aerosol cans
are OK. I could go on for pages but you get the idea. Isobutane is
safe and effective but technically it's illegal to sell as a
refrigerant in some states.
> If you can adapt which would be better to start with, a window AC or
>and Auto AC?
> What would be involved?
Definitely start with an R-12/R-134a system. R-22 hermetic
compressors don't work well in R-12 systems. I've tried but they
invariably overheat and burn out.
I'd definitely use a hermetic compressor. There are several
approaches. Danfoss makes a line of DC-powered BLDC motored hermetic
compressors. I don't know if they make one large enough for
automotive use and their web site is so horrid that I couldn't tell.
You might drop them a note.
Another approach is to use a single phase compressor and an inverter.
This isn't the most efficient approach but it might be the least
expensive. It's something that you could whip up with cheap consumer
parts.
Probably the best approach would be a three phase compressor and a
variable frequency drive. I expect this kind of single phase in, 3
phase out drive to work like many SMPSs and work equally well on high
voltage DC. Something off the shelf would probably work in 144 volt
and up cars.
One advantage of a VFD is that you could run the compressor faster
than standard to get more refrigeration out of a given size
compressor. That would save weight and space. I'd expect the
compressor to behave similarly to conventional 3 phase motors. They
don't generally object by overheating to higher speed operation. The
sub-5 hp VFDs have gotten very inexpensive.
If you can mitigate some of the greenhouse, perhaps with window
tinting and maybe even e-glass for the windows, you could probably do
the job with about 2 hp (approx 2 tons.) of refrigeration.
The more condensing capacity you can provide, the better. Conventional
cars are pretty lame in this area. The condenser is out there in
front of the radiator, taking the full brunt of radiant heat from the
radiator, especially when stationary.
I've done some simple testing that involves nothing more than sticking
some shiny aluminum sheet between the radiator and condenser of a car
and seeing the evaporator exit temperature drops precipitously with no
other changes. My GMC cube van has the AC condenser mounted below and
to the side of the main radiator, complete with its own little fan.
The condenser is less than a quarter the size of the one on my Caprice
and yet the cooling capacity is similar.
Mounting and ducting the condenser were it does not receive any
sunlight and where the low pressure air behind the car aids air flow
would work great on an EV without all that engine heat.
There are other things you can do to minimize the amount of
refrigeration needed. Insulating the car's interior is obvious.
Refrigerating the seat, particularly in the lower back area is
remarkable in the comfort it provides. ASHRAE says that if you can
spot-cool the face, the upper chest and mid to lower back, the average
person can be comfortable in quite high ambient temperatures.
In my 280Z, I accomplished this by removing the seat cover, stitching
and gluing small diameter tygon tubing on the inside of the area in
contact with my back and re-installing the cover. The tubing received
chilled glycol/water from a small liquid evaporator/heat exchanger
installed upstream of the main AC evaporator. With the AC at full
performance, the exit temperature of the glycol at the evaporator was
in the freezing range. I included a 3-way manually operated tempering
valve to control the seat temperature.
The Z's OEM AC was very lame but with this one mod, it went from
miserable to quite nice. I built a DC/DC converter to run the fan on
up to 24 volts and installed a large GM compressor to round out the
package. Finally, I insulated the glove box and installed some glycol
coils to turn the glove box into a little refrigerator for a few cokes
or whatnot. I was putting almost a hundred miles a day on the car
back then so the glove box 'fridge and the cold seat were greatly
appreciated.
Other less dramatic but important improvements include insulating the
lines from ambient heat and using a de-superheater. The later
involves tightly thermally bonding the evaporator return line and the
liquid supply line together. The cold refrigerant and residual liquid
mist in the return line cools the liquid headed for the evaporator
down to about the evaporator temperature.
When hot liquid refrigerant expands into the evaporator, the first
increment of refrigeration is used cooling the liquid itself down to
the ambient temperature inside the evaporator. In very hot weather
where the liquid might come out of the condenser at 120-140 degrees
and with an evaporator temperature of 35-40 degrees, most of the
refrigeration goes to cooling the liquid and little is left for
cooling air.
OTOH, if the liquid is cooled to near the evaporator ambient,
essentially the heat of vaporization goes to cooling air. If the evap
is at 40 degrees and 40 degree liquid is expanded into the evaporator,
all of the refrigeration goes to cooling air.
The two usual methods of desuperheating are to bond the suction and
liquid lines together, say, by silver soldering or to run one inside
the other. The later is what I did with my Z. I ran 3/8" soft copper
liquid line inside 1-1/4" soft copper suction line and insulated the
line with tubular foam. Less than 3 feet of this assembly completely
desuperheated the liquid. The concentric tube heat desuperheater is
more efficient but the soldered-tube assembly is sometimes easier to
do if many bends are involved.
If you decide to go with R-134a, be sure to use POL oil. There are
two types of oil for R-134a, PAG (poly alkyl glycol) and POL (Polyol
ester). PAG is a first cousin to brake fluid. It isn't very slick,
is hygroscopic, breaks down in the presence of water and also breaks
down in the presence of even a few PPM free chlorine. PAG was the
first oil and is the reason R-12 retrofits were going to be so
expensive. Every trace of the old R-12 had to be removed which meant
new hoses, new dryer and flushing of the metal parts.
POL came along later. It's slightly hygroscopic, a little more
slippery than PAG but is not harmed by water or chlorine. This
lubricant is what enabled the little $50 retrofit kits that you see in
the parts stores. Just recover the R-12, change out the filter/dryer,
charge with POL and R-134a and away you go.
PAG was a disaster in early OEM systems. Its lubricity was so poor
that compressors failed right and left. POL saved the day. You can
now buy hermetic compressors precharged with POL.
If you decide to go with a motor-driven automotive compressor, I've
found Sanden compressors to be the most durable and quite efficient. I
use the SD series in all my conversions and upgrades. Sanden lets
their application engineers talk to individuals and not just megacorp
types.
I'd look very closely at hermetic, preferably scroll compressors
before I went with a car unit. Scrolls are very efficient and quiet
and the tall, small diameter form factor should make it easy to mount
in a car. As important as any other characteristic in a car
environment, a scroll is easy to start with minimal inrush - important
for an inverter application.
Oh, before I forget, isobutane is available as high altitude camping
fuel in convenient 1 lb cans that fit an R-12 blow-off can
side-piercing valve nicely. NOT the propane/butane blend but the pure
isobutane version. MSR is the brand that I buy locally. MSR product
number 322012.
Well, that should be enough of a brain dump to get you going. Feel
free to ask more questions if you like.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
Don't let your schooling interfere with your education-Mark Twain
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At 06:54 PM 2/05/06 +1000, David Ankers wrote:
Regarding EVs right now, the follow equation seems to make sense to me:
1. Range
2. ICE equivalent performance
3. Costs less than a small family home
Chose only two of the above.
G'day David
ICE equivalent performance is not hard or particularly expensive, it just
restricts your range more than if you let the performance slip a little.
* 20 mile range, ICE equivalent performance, budget price.
* 50 mile range, drop the performance or up the price, but not dramatically.
* Better than ICE performance, 50 mile+ range, half a small house
(depending on your location).
* 300 mile range, better than ICE performance, more than a house in many
suburbs.
The question is a range one. More range = more money. 300+ mile range is
do-able, if you can afford a US$130,000+ battery pack, plus the necessary
charging system (as I found when looking at what it would take for a Targa
car).
Just my $0.02aus.
James
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The way my Comuta-Van is currently set up, my Curtis controller is connected
to the power circuit by turning the key, which in turn engages a solenoid.
The solenoid connects the controller to the battery pack. The charging
pigtail is also attached to the (+) side of the solenoid and the (-) side is
connected to the controller where the (-) side of the battery connects to
it.
The (+) side of the battery pack is connected to one side of the solenoid
and the appropriate lead on the motor controller is connected to the other
side. Then of course, the solenoid has 2 smaller leads connected to ground
and the (+) side of my accessory battery via the keyswitch.
After a normal commute, I've traced the power cables hand-over-hand to check
for hot spots and this is now the only one. The solenoid gets pretty hot. I
cannot keep my hand on it for more than 5-10 seconds. I feel that this is a
point of loss in the circuit. The solenoid is kind of small...perhaps as
small as a child's fist.
Does anyone have a recommendation for a heavier duty solenoid that would not
have so much loss or perhaps a different solution altogether? I don't feel
that anything is in danger of melting down but I know that heat= waste/loss
and I hate to limit the circuit and possibly my performance or risk melting
something.
Whatever the solution is, it needs to handle 72 volts and at least 400 amps.
Thanks,
Rich A.
Maryland
_________________________________________________________________
Dont just search. Find. Check out the new MSN Search!
http://search.msn.click-url.com/go/onm00200636ave/direct/01/
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Hi Dave - and all
This is a response to an off-list question that Dave asked - and after I
finished doing it took so much effort I thought I'd share it with the list,
as this is sure to interest others. For those who understand motors, please
do not "pick" too hard, it is intended more as a generalised semi-technical
description rather than a full-on technical one.
At 07:46 PM 2/05/06 +1000, Dave Ankers wrote:
That's good information about working on EVs... Didn't realize the
government are that controlling, bastards.
You can "fly under the radar" in the grey area that legislation just
doesn't cover and make your EV any voltage you want. I'm in a slightly
different position in that my business is right on the edge of the things
that electricians do (they call us in to figure out problems for them,
amongst other things) but we are not electricians, so I'm being extra cautious.
I've been meaning to ask you, where are you getting the Excide Orbital's
from? Are they stupid money here in Aus compared to the US? I was thinking
about 24 x 34XCD for the little Civic, even in the US these is expensive but
they are a nice battery. Best price I have found on the web in the US is
US$100 each, this works out at just over A$3,000 for 24 batteries. Do you
think their will be a large price increase just for buying them over here?
I got mine here - special price, and still $4kaus for 20 batteries (for
$3kaus at US prices of batteries). Not that bad though, as you would be up
for freight, plus GST when they get here. Made in Spain though, so freight
to the US vs to Aus shouldn't be that different, but maybe Exide Aus is
supplied from Exide USA making it cost to US + cost to Aus. Maybe if you
try and get onto an Exide dealer in Spain or Poland (the other place I
believe Orbitals are made) you may be able to do better.
24 x 18kg = 432kg, hmmm. Removal of the ICE stuff balances out pretty much
all of the EV components, battery racks etc, except the weight of the
batteries, so expect to be adding 432kg to your vehicle. With care you can
save another 100kg or so from the vehicle by using the lightest parts
possible, remove the wiring loom and put back the minimum you need,
removing sound deadener, etc. Do you think your Civic can take the weight?
If you really want it then consider getting the number of passengers
reduced, if a five seater, then make it legally a 4 seater, etc.
Also, a very quick thing regarding the reply you gave to Nikki; what are the
voltage spikes you refer to? My plan was to throw 288volts at the Zilla 1k
and set the max motor voltage on the Zilla to 160 volts (thinking of using a
8" or 9" Warp at this stage).
A not very quick answer, probably a lot more information than you wanted to
know, but hard to answer otherwise:
Short answer: during the time that the controller transistors are turned
on, the motor gets full pack voltage across it. When they are off, the
freewheel diodes are conducting so there is almost no voltage. Average
voltage is what gets limited.
Proper answer:
**Warning - technical discussion**
**Motor and controller basics**
(I don't know how much will make sense to you, or if I'm being too
simplistic, but here goes!)
A motor has a property called inductance. This property causes the motor to
"hold" a magnetic field. As you push current into a motor the inductance
sets up the magnetic field, and to increase the magnetic field requires an
increase in current, attempting to decrease the current causes the magnetic
field to collapse some, sustaining the current. If the current is abruptly
interrupted, the magnetic field will attempt to collapse *instantly*
causing a very high voltage spike (in the order of 1000s of volts) but this
is not the normally occurring voltage pulses.
On first turn on of the controller transistors, the motor has no magnetic
field, full battery voltage appears across the motor and current starts to
flow. The greater the inductance, the slower the build-up rate of the
current and the stronger the magnetic field is. The current reaches a
programmed limit in the controller, so it turns off.
The magnetic field then starts to collapse, pushing the current out of the
motor. The controller has diodes (electrical non-return valves) that allow
the current to go from the "bottom" of the motor back to the "top". In the
case of Curtis controllers and similar, after (x) milliseconds, the
controller turns back on. I believe that Zilla controllers will delay
turn-on until the current is back below the setting. Pack voltage again
appears across the motor, and the current starts to climb again. But now
(or soon) the motor is turning, and generating a voltage as well, so the
"slope" between the battery and the motor is now the amount of voltage
available to increase the current, so the controller stays on longer. This
results in the voltage pulses appearing across the motor, at 15,000 times
per second. The average voltage of these pulses is limited, but the peaks
are the battery voltage and are native to the way that DC motors work with
transistorised controllers.
The faster the motor spins, the more it generates, until at some speed the
"slope" is low enough that the controller can stay 100% on. (as a side
note, I believe that Zilla controllers switch off for a very small % - less
than 1% - during wide-open-throttle (WOT) to detect any failiures and can
shut down immediately. Curtis controllers (and others similar) can fail
100% on and you don't know until you lift your foot).
The motor voltage limit of the Zilla will prevent WOT from occurring,
unless your batteries sag to that voltage. When the average voltage that is
set into the Zilla is reached, the controller starts turning off again
earlier to prevent the average voltage from getting too high. The main
hazard to a DC motor (after excessive heat = amps x time) is high voltage
simultaneous to high current, causing arc plasma to form on the commutator
in a manner that it cannot "shed" and then carries around the commutator,
"fireballing" it.
My motor was designed for 45V, and I'll be running it at 120V, so I've
taken steps to increase its' electrical strength. An ADC or WarP 9" is
designed for something like 144V, so for 288V the motor may need to be
improved a little. John Waylands' "White Zombie" Datsun 1200 race car has a
pair of 8" motors (now "siamesed" together). During "burn-outs" he has to
force the controller to stay in series mode [I believe], as the controller
used to throw it into parallel mode, which on at least one occasion caused
the motors to 'flash over'. I believe in part this is due to the current
being interrupted abruptly by the series/parallel contactors, and when the
current can go no-where, the result is a very high voltage spike -
initiating the arc-over event.
I hope this makes sense, and helps Dave and others to understand the
operation of their motors.
Regards
James
[Technik James? if I use that name it'd differentiate me from the other
James' on the list]
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