EV Digest 5182
Topics covered in this issue include:
1) Battery Desulfators (Was: Flooded Battery Questions From A Newbie)
by Brendan Miller <[EMAIL PROTECTED]>
2) Re: Why not more AC conversions vs DC conversions...
by Nick Austin <[EMAIL PROTECTED]>
3) Re: Flight Systems - Do they still sell EV kits?
by Doug Weathers <[EMAIL PROTECTED]>
4) Re: Why not more AC conversions vs DC conversions...
by Electro Automotive <[EMAIL PROTECTED]>
5) Re: Battery Desulfators (Was: Flooded Battery Questions From A Newbie)
by "David Roden" <[EMAIL PROTECTED]>
6) Optima YT's
by Ben Apollonio <[EMAIL PROTECTED]>
7) Re: Electric truck
by "STEVE CLUNN" <[EMAIL PROTECTED]>
8) Re: Hawker AeroBattery 'correct' Info
by "Dave" <[EMAIL PROTECTED]>
9) Re: Why not more AC conversions vs DC conversions...
by Neon John <[EMAIL PROTECTED]>
10) Re: Why not more AC conversions vs DC conversions...
by "David Roden" <[EMAIL PROTECTED]>
11) Town Car (was: Re: critical mass-battery weight vrs amp hour ratings,
Comments)
by Tim Clevenger <[EMAIL PROTECTED]>
12) Re: Motor Temperature
by Eric Poulsen <[EMAIL PROTECTED]>
13) RE: Why not more AC conversions vs DC conversions...
by Jeff Shanab <[EMAIL PROTECTED]>
14) RE: Why not more AC conversions vs DC conversions...
by "Myles Twete" <[EMAIL PROTECTED]>
15) Anyone have experience with MK Battery AGMs or Gel Cells?
by Mark Freidberg <[EMAIL PROTECTED]>
16) RE: Why not more AC conversions vs DC conversions...
by "Andre' Blanchard" <[EMAIL PROTECTED]>
17) Re: Why not more AC conversions vs DC conversions...
by Victor Tikhonov <[EMAIL PROTECTED]>
18) Re: Why not more AC conversions vs DC conversions...
by Victor Tikhonov <[EMAIL PROTECTED]>
19) RE: contactor weld/arc ... OT vid clip
by Cor van de Water <[EMAIL PROTECTED]>
20) Re: Why not more AC conversions vs DC conversions...
by "Tom Shay" <[EMAIL PROTECTED]>
21) Re: Busted in Blue Meanie!
by Ryan Stotts <[EMAIL PROTECTED]>
22) Re: Why not more AC conversions vs DC conversions...
by Ryan Stotts <[EMAIL PROTECTED]>
23) Volumetric energy density of Lithium battery
by Victor Tikhonov <[EMAIL PROTECTED]>
24) RE: RE : critical mass-battery weight vs amp hour ratings
by "Roger Stockton" <[EMAIL PROTECTED]>
25) Re: A trip to the referee station
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
26) Re: Why not more AC conversions vs DC conversions...
by Christopher Zach <[EMAIL PROTECTED]>
27) RE: Busted in Blue Meanie!
by "Myles Twete" <[EMAIL PROTECTED]>
28) Re: Why not more AC conversions vs DC conversions...
by Lee Hart <[EMAIL PROTECTED]>
--- Begin Message ---
Thanks for all the great information. Sounds like I'll need to invest a little
time if I want to save these. But I expected that.
Does anyone have any experience with these desulfators? Would this be a
worthwhile investment, or am I just going to shake all the junk off and short
out the plates with it anyway? Any experiences (good or bad) would be helpful
(assuming that the batteries have some hope of being saved in the first place).
-Brendan Miller
(EV coming soon)
Phoenix, AZ
Chip Gribben Wrote:
Congrats on your new truck.
What I would do if I were you would be to make an assessment on each individual
battery. First open up each one to see if the plates are covered with water. If
any plates are exposed those batteries could be done for. But if the water just
barely clears the plates you may be able to save them. Fill the low ones with
just enough distilled water so its about a half inch below the case or cap. You
don't want to over fill them because they could boil over during charging.
Then test each with a voltmeter to see where they are. If they are down to 4
volts you may be able to bring them back to life. I've done this with some GE
Elec-Traks I've worked on for people.
You can also test the batteries with a battery tester that draws the water out
of each cell and a needle will point to whether the battery is in the good,
fair or bad range. Geez, I can't remember the name of the thing off hand but I
use it when testing the batteries as well.
Once you determine their current state of charge take a 12/6 volt charger that
charges deep cycle batteries, set it to 6 volts-deep cycle and charge each one
up individually. This could take awhile but its worth it in the long run. Once
you get each one up to about 2.5 volts per cell which would be 7.5 volts or
their abouts charge them with the trucks original charger to get them
equalized. Do this for a couple hours. Turn the charger off and wait about 15
minutes. Take the voltmeter and test each one to see where they are.
You should check to see what your batteries recommended SOC is per cell. 2.5 is
a guess and that may be wrong.
Now the thing is you may have some bad ones in the bunch. You may be able to
get a few good used ones from the AZ EAA folks. Once you get them up to snuff
drive the truck around a few miles to discharge them.
Then take the voltmeter out and test each battery to see where they stand. You
may need to do some individual charging again on a couple of them. Then
equalize them again. And keep exercising them a bit going a little bit further
each time you drive it.
If the batteries are salvagable you may also consider getting a desulfator. I'm
not sure if they come in 120 volts or not but you may able to get a 60 volt one
and do half the pack at a time. This should shake off any stuff that hangs on
the batteries. I haven't really used these much so I can't really say if they
make any difference or not.
This is what I do to bring back the flooded cells back to life. Its easy to do
on GE Elec-Traks because there are only 6 batteries. But with this method I had
someone bring in a tractor with batteries down to 4 volts and I've been able to
bring them back to life. But if they read 1, 2 volts or in millivolts they are
probably done for.
Chip Gribben
--- End Message ---
--- Begin Message ---
On Thu, Feb 16, 2006 at 05:16:10AM -0600, Joel Hacker wrote:
> Any ideas as to why DC systems with PWM, and
> series wound motors (especially the Advanced DC ones)
> are so popular for conversions?
I can think of three reasons.
1) Cost: DC kits seem much cheaper when you think of bang for buck. You
can get a Z2K for ~2500, and an ADC 9" for ~1700 that seems to have great
performance.
2) Support: Many people on this list have done DC conversions with these
components, so you are likely to have lots of community support for them.
This is less true today, because AC systems have become somewhat more
common.
3) Performance: I touched on this in the cost section, but if your goal is
really high performance, it seems this is much easier to do with a DC system
cost wise.
These are just my impressions, and I may be wrong.
Thanks!
--- End Message ---
--- Begin Message ---
On Feb 15, 2006, at 8:25 PM, [EMAIL PROTECTED] wrote:
If you're talking about http://www.fsindl.com/, they're on the MAEAA
link site,
http://www.geocities.com/MotorCity/Downs/4214/links.html, with various
other
conversion companies. The Flight Systems site appears to only have
industrial
equipment, not on-road vehicle kits.
They have a section of "conversion kits", which appear to be upgrades
to existing electric vehicles. I recognized a golf cart and some
scooters (on-road, if you are willing to stretch the point). Go here
<http://www.fsip.biz/ECATALOG/> and click on "Conversion Kits".
--
Doug Weathers
Bend, OR, USA
<http://learn-something.blogsite.org/>
--- End Message ---
--- Begin Message ---
At 10:14 AM 2/16/2006, you wrote:
> Hey mabye this is another one of those dumb
> questions where I need slapped upside the head,
> but everything I read recently speaks to how more
> efficient AC motors because they don't need the
> series windings in the armature (rotor) and
> operate as an induction motor.
>
> 1. Is this right?
Not quite. The more common AC (induction) motors still have a winding on
the rotor, it's just powered by magnetically induced current instead of
directly by DC voltage via a commutator (like series wound motors).
The lack of a mechanical comutator is the main reason why AC setups are
slightly more efficient.
Slightly? We did some test driving up here in the mountains with a
Solectria Force, 156V, and the MOST current we ever pulled out of the
battery pack was ~30A. DC systems are usually set up to meaure motor
current, not battery current, so there is some difference, but that
seems much more than "slight" to me. It surprised me at the time, as
I did not expect that much difference.
As for more people preferring DC to AC, that has been true
historically, largely due to lack of avialability of AC. Despite the
higher cost (yes, it is about twice as much) our current sales are
running about half and half between AC and DC systems. If range is
important, an AC system coupled with flooded 6V or 8V golf cart
batteries is hard to beat for the price.
Shari Prange
Electro Automotive POB 1113 Felton CA 95018-1113 Telephone 831-429-1989
http://www.electroauto.com [EMAIL PROTECTED]
Electric Car Conversion Kits * Components * Books * Videos * Since 1979
--- End Message ---
--- Begin Message ---
The "science" behind them strikes me as questionable. There's a fair bit of
"woo-woo" stuff about crystalline structure resonance and such. It reads as
if the manufacturers are looking for a way to explain an effect they've
produced (which may or may not have anything to do with the pulsing).
Some people have reported anecdotal positive results with desulfators, and a
few swear by them. This includes some people for whom I have a fair bit of
respect, and also some I think are probably borderline nutcases. ;-)
However ... I may have missed some, but I don't know of any impartial tests
comparing these pulsers or desulfators with a simple long, slow equalization
charge which could be done with an ordinary charger. I suspect that the
latter would work just as well, and cost less, but to be truthful I'm not
interested enough in them (and too darn busy and lazy ;-) to perform a test
myself to confirm this.
David Roden - Akron, Ohio, USA
EV List Assistant Administrator
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--- Begin Message ---
I recall hearing a while ago that the quality/reliability of Optimas
had degraded significantly in recent months/years. Has anyone had
recent experience that can confirm/disprove this? I think YT's would
fit my conversion better than orbitals, but obviously I don't want a
shoddy battery.
Thanks
-Ben
--- End Message ---
--- Begin Message ---
more like 1/2 the space , arn't Valance 135 ah 12v the same sixe a a golf
carter?
Peter VanDerWal wrote:
...
FWIW though the Li-Ions/Li-Poly weigh less than Lead-Acid, they take up
almost the same amount of physical space.
Peter,
--- End Message ---
--- Begin Message ---
"Hole Shot" means he got off the line quickly and up to speed very fast
Dave
From deep within our secret soul
do demons dwell and take their toll
----- Original Message -----
From: "Mike Ellis" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, February 16, 2006 7:27 AM
Subject: Re: Hawker AeroBattery 'correct' Info
What is "hole sot?"
-Mike
On 2/16/06, John Wayland <[EMAIL PROTECTED]> wrote:
One of the changes we're doing to White Zombie very soon, is a rear end
ratio change to a taller 4:11 compared to the present 4:57. This change
'could' negatively affect the incredible hole sot the car presently has
with its 4:57 ratio, but upon careful evaluation...
--- End Message ---
--- Begin Message ---
On Thu, 16 Feb 2006 10:00:18 -0800, Electro Automotive
<[EMAIL PROTECTED]> wrote:
>At 10:14 AM 2/16/2006, you wrote:
>
>> > Hey mabye this is another one of those dumb
>> > questions where I need slapped upside the head,
>> > but everything I read recently speaks to how more
>> > efficient AC motors because they don't need the
>> > series windings in the armature (rotor) and
>> > operate as an induction motor.
>> >
>> > 1. Is this right?
>>
>>Not quite. The more common AC (induction) motors still have a winding on
>>the rotor, it's just powered by magnetically induced current instead of
>>directly by DC voltage via a commutator (like series wound motors).
>>
>>The lack of a mechanical comutator is the main reason why AC setups are
>>slightly more efficient.
>
>Slightly? We did some test driving up here in the mountains with a
>Solectria Force, 156V, and the MOST current we ever pulled out of the
>battery pack was ~30A. DC systems are usually set up to meaure motor
>current, not battery current, so there is some difference, but that
>seems much more than "slight" to me. It surprised me at the time, as
>I did not expect that much difference.
That is completely irrelevant. Solectria did it with high voltage and
low current. Most DC apps do it with moderately low voltage and
moderately high current. Six of one, half a dozen of the other.
What matters is the watts drawn and the WH per mile. For equally well
designed systems, the difference between DC and AC is almost
insignificant. It does no good to compare literally state-of-the-art
AC motor designs that cost tens of thousands of dollars to
bottom-of-the-barrel designed-for-cheapness overblown forklift motors.
That the forklift motors do so well is amazing in itself.
This opinion is based on my testing only but the only place I've found
some "AC" (actually brushless DC with permanent magnet rotor) to have
a significant advantage is at low load.
The reason DC motors predominate is that no one has built the Ford of
motors in the AC format. As long as there are only the Cadillacs of
AC motors available, most folks will opt to save several tens of
thousands of dollars and stick with DC.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
A foolish consistency is the hobgoblin of little minds.-Ralph Waldo Emerson
--- End Message ---
--- Begin Message ---
On 16 Feb 2006 at 13:45, Neon John wrote:
> That is completely irrelevant. Solectria did it with high voltage and
> low current.
Not at all. Did you read what Sherry wrote? It used 30a at 156v. That's
no higher voltage than a typical DC conversion. Power consumption at that
current would be 4.7kW.
> What matters is the watts drawn and the WH per mile.
In my experience, a Solectria Force uses about 120-160 Wh per mile from the
battery in gentle suburban driving, with speeds not exceeding 45mph. And
that's not just me; many dozens of Force owners report that level of energy
usage. Typically, unless you have a lead foot, the amp hour counter ticks
about once per mile.
In all fairness I should point out that these are probably some of the most
highly optimized conversions ever done. Solectria junked the stock trans
and replaced it with a very light, low friction, aluminum-cased transaxle.
There are other modifications to reduce drag and rolling resistance. It's
not just the drive system, although that's certainly designed with
efficiency as a primary consideration.
Ah, nothing like a good AC vs. DC flame war to get things heated up on a
cool February day. <g>
David Roden - Akron, Ohio, USA
EV List Assistant Administrator
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--- End Message ---
--- Begin Message ---
After renting one of those, I was thinking what a great hybrid it would
make. Swap in a four or six cylinder transverse setup for the front and
take advantage of the rear differential and massive under-trunk-floor area
to put in a direct-drive regen setup and get pseudo-AWD.
Stock weight is 4,345 pounds. Swap in some manual seats, eliminate the air
junk and put in Crown Vic suspension bits and make up the extra weight with
the lighter engine and transmission up front. It already seats six fairly
comfortably, and gets 25-27 mpg on the freeway even with a V8.
Tim
------
From: Evan Tuer <[EMAIL PROTECTED]>
To: [email protected]
Subject: Re: critical mass-battery weight vrs amp hour ratings, Comments
On 1/1/00, Bob Rice <[EMAIL PROTECTED]> wrote:
>
> Or putting that pack in say a newer aerodynamicly? Limcoln, Town Car,
> they the newer ones seemed faired off pretty nicely?Decent CD? Better than
a
> pickup, or really go crazy with a stretch limo PLENTY of room for
batteries.
> Maybe Kokans or something more exhotic and maybe 600 volts of power.
--- End Message ---
--- Begin Message ---
Roland -- sounds like you have thermal cutout switches rather than
thermocouples.
Roland Wiench wrote:
In my 11.5 inch GE motor, the thermo couple is place in the windings of the
field in the front place over the top of the commentator. The other one is
place at the rear also place on top over the rotor.
Both thermo couplers are wire in series. The temperature range of these
thermo couplers are 140 degrees F OFF and 120 degrees ON which is a 20
degree differential.
This temperature sense circuit operates a 12 volt plug in class relay that
turns on the 12 volt control circuit of a controller which I have now have
with the Zilla.
A green LED comes on showing the temperature is normal. I also install a
Stewart Warner engine temperature sender which just bolts down to aluminum
housing at the rear exhaust screens of the Warp 9. This goes to a Stewart
Warner temperature gage that reads from 0 to 600 degrees F.
There is a bypass switch on the console, where I can by pass the thermo
coupler circuit in case of a emergency. I never had to used that in 30
years of running the GE motor. The maximum temperature I ever saw was about
100 degrees which was the same ambient temperature of the air which is
brought in by a large 6 inch filter blower fan.
Roland
----- Original Message -----
From: "Peter VanDerWal" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Friday, February 10, 2006 2:28 AM
Subject: Re: Motor Temperature
At what temperature is the motor running too hot ?
Depends on the motor.
Are temperature gauges being used ?? Temp. cutoff ?
Generally not.
Where/how are they being mounted ??
Depends on the motor. The few folks that are monitoring temperature on
D/C motors generally mount a thermo couple in one of the brushes.
I think some of the A/C motors montior coolant temperature.
--
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 take:
The losses are in parts. Magnetic losses, resistance losses, and
windage; sum them all up
Series DC torque is related to i^2 R so resistance losses under load are
high, Windage also High, the "rotor" is not smooth. But the Freq is low
and the iron is simple so magnetic losses are low.
AC induction has minimum 5% loss called slip, without which it wouldn't
work, but it has lower torque, so we run them at rpm and gear them down,
This is usually a high voltage low amp system, so resistance losses are
lower, windage loss is lower. In an AC traction motor, special materials
are chosen to limit losses due to the high freq needed to get usefull rpm.
IF a commutated motor was capable of running at 12,000 rpm and we ran it
high voltage, low amps and geared it down instead of loading it down, I
wonder what the effiency would look like.
The real truth is "All motors run on AC. "
All motors have a stationary field and an alternating one(rotateing).
The argument becomes internally vs externally commutated
Excited vs Permenant magnet
synchronous vs slip
expensive vs expensiver
Each type has it's advantages and dis-advantages but the main difference
is really what is available for us hobbiest.
At the "plunk down all the money at once end", there isn't too much
difference between avil AC systems and a complete DC system, but you can
do a DC system on the cheap and with used components and one part at a
time easier than AC systems. Maybe if there were more manufactures of
controllers and motors and they were not so tied togather....
There is one argument I have heard about the AC induction motor being
cheaper and more robust than the DC series wound motor, but the flat
torque of the induction motor either leads to a huge motor or a gear
reduction off of a high rpm motor. THis carries with it the necessity of
higher frequency and control of the slip energy at startup, or you melt
the rotor. This places the AC induction drive in a more
exclusive/expensive setting until the quantities being sold gets a boost.
BLDC BLAC
Induction Shunt wound Series Wound Wound
rotor
Effiency high *highest med high and
broad range med med high
Torque high but drops fast with rpm med and
broad little less than SW High at stall High and broad
motor price high high
med med med
high, rare
controller price med higher
high med,kinda rare low->high
high, rare
Regen capability generator style Handle it or smoke
controller controllable scary Controllable
The wound rotor is an induction motor with slip rings removeing slip
energy from rotor, it can be regenerated back to the batteries and the
characteristics of the rotor can be made to allow huge torqes at very
low amps from the start. As the speed increases the char of the rotor
are changed and can even go to synchronous lock in by injecting voltage.
It seams an ideal AC drag motor.
Ok, we are splittin hairs here. BLDC, also called trapisodial or 6 step
is actually more efficint at certain speeds when switching losses
dominate and BLAC is more efficient when iron losses dominate or rpm is
to low to smooth out ripple.
Haveing done 1 conversion, it is DC. I am considering an AC system for
the second one. I believe the AC system is more palateable after doing a
DC one.
--- End Message ---
--- Begin Message ---
> In my experience, a Solectria Force uses about 120-160 Wh per
> mile from the battery in gentle suburban driving, with speeds not
exceeding
> 45mph.
And with the 96v of Hawkers (8 batts) in my tiller-shifter, tiller-steered
1921 Milburn Light Electric I guess I'm in good company at under 45mph
speeds (my top speed hit was a scary 40mph):
wh/mile(30mph) ~ 95v * 40a / 30mph ~ 127wh/mi
wh/mile(35mph) ~ 90v * 60a / 35mph ~ 154wh/mi
We've come a long way since 1921...
-Myles Twete
1921 Milburn Light Electric: http://milburn.us/myles_twete1921.htm
--- End Message ---
--- Begin Message ---
Has anyone used them in a street EV or other application?
www.mkbattery.com
Mark Freidberg
---------------------------------
Relax. Yahoo! Mail virus scanning helps detect nasty viruses!
--- End Message ---
--- Begin Message ---
At 01:52 PM 2/16/2006, you wrote:
My take:
<< snip >>
IF a commutated motor was capable of running at 12,000 rpm and we ran it
high voltage, low amps and geared it down instead of loading it down, I
wonder what the effiency would look like.
<< snip >>
What do you mean "if". Check out a hand held wood router some time, 20,000
to 30,000 RPM universal motor. I have seen them up to 3.5 HP, which is
flat out insane for something you hold in your hands. No reason they could
not be built in EV sizes with RPM's in the 10,000 to 12,000 range.
__________
Andre' B. Clear Lake, Wi.
--- End Message ---
--- Begin Message ---
David Roden wrote:
Ah, nothing like a good AC vs. DC flame war to get things heated up on a
cool February day. <g>
I'm not going to initiate AC/DC debate, it's been beaten to death
quite a few times.
I just wanted to comment that 160Wh/mile for Solectria is
really outstanding achievement - without unconventional
tricks and optimal light vehicle to begin with you will
be hard pressed to get power consumption below 200Wh/mile
with normal driving (accelerating with traffic, not trying to
save energy but not needlessly wasting it either).
Victor
David Roden - Akron, Ohio, USA
EV List Assistant Administrator
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--- Begin Message ---
There is, centrifugal forces are square of the rotation speed and
distance from the center. Only twice as large diameter rotor will
have to be much more than twice stronger not to fly apart
at high RPM. Miniature DC motors with 30k RPM - no problem. 100k rpm
I think has been demonstrated, the motor dia was 5.5mm (1/3 of an inch).
Victor
Andre' Blanchard wrote:
At 01:52 PM 2/16/2006, you wrote:
My take:
<< snip >>
IF a commutated motor was capable of running at 12,000 rpm and we ran it
high voltage, low amps and geared it down instead of loading it down, I
wonder what the effiency would look like.
<< snip >>
What do you mean "if". Check out a hand held wood router some time,
20,000 to 30,000 RPM universal motor. I have seen them up to 3.5 HP,
which is flat out insane for something you hold in your hands. No
reason they could not be built in EV sizes with RPM's in the 10,000 to
12,000 range.
__________
Andre' B. Clear Lake, Wi.
--- End Message ---
--- Begin Message ---
Actually this is an example of how a series-connection of
switches that each cannot handle the full voltage can be
catastrophic if one element fails.
Note that the moving switch is not supposed to break load,
only to keep it broken once opened.
The current breaking switches are located in the 2 horizontal
tubes to the right of the air switch.
Each of these switches is not rated at 500kV, thats why they
placed two in series. Here one of them is failing, you can
tell it is the rightmost one that is failing, because the
left switch opens and is experiencing flashover outside the
switch tube.
This causes the air switch to open under load, which it can't.
It will open allright, but continue to carry current.
Once it opens you will see that the flashover in the tube
switch stop, as the switch returns to its default (closed) state
(the air switch is supposed to isolate now)
The air discharge continues until someone upstream cuts power
because the 50 ft or so arc threatens to hit other nearby lines.
I read this story somewhere else, it did not show here, so it
is just an example of how a design decision can lead to a
big failure.
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: +1-610-423-5743
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Darin
Sent: Wednesday, February 15, 2006 5:31 PM
To: [email protected]
Subject: Re: contactor weld/arc ... OT vid clip
> (prevent
> the main contactors from welding together is close or open under load).
OK, this has little to do directly with EVs, but whenever I read about
contactor welding/arcing, I always think of this amazing video clip at
Google of a 500 kV switch being thrown open at a Nevada power switching
station:
http://video.google.com/videoplay?docid=4468957986746104671
Darin
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----- Original Message -----
From: "Electro Automotive" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, February 16, 2006 10:00 AM
Subject: Re: Why not more AC conversions vs DC conversions...
(stuff snipped out)
Slightly? We did some test driving up here in the mountains with a
Solectria Force, 156V, and the MOST current we ever pulled out of the
battery pack was ~30A. DC systems are usually set up to meaure motor
current, not battery current, so there is some difference, but that seems
much more than "slight" to me. It surprised me at the time, as I did not
expect that much difference.
You should have been surprised. It takes considerably more than 30 amps at
156 volts to drive a car the size of a Force in the mountains. It takes
about
170 watthours per mile on the level. It doesn't matter if the system is AC
or DC or
whether it's a Metro or a Rabbit or other similar sized car. At 60 mph a
156-volt
Metro or Rabbit will draw about 65 amps at constant speed on the level
and considerably more if accelerating or going uphill. 30 amps would be
enough for about 30 mph. Are you sure that the ammeter was measuring
battery current?
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Wayland wrote:
> If I stand on the
> brakes, in the fading light of the day the bright red brake lights will
> signal I'm having to use the binders to hunker down from speed. I decide
> against >that and instead shift down to 3rd....damn, it's an electric...no
> compression to
> slow me down! Where's that regen when I need it?
No parking brake to scrub off speed?
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Andre' Blanchard wrote:
> Not long ago someone here claimed to have build a 3 PH inverter from 6
> solid state relays and a bit of logic (basic stamp or something). The
> battery was a 36 volts and the low voltage AC was then run thru 3
> transformers to get up to 208 VAC and used to run a fairly large air
> compressor. I think he just did it to see if it would work but it does
> prove that AC does not have to be as high tech as it is sometimes made out
> to be.
Is this design scalable up to Zilla levels? What are the upper limits
of limitation of this setup?
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Peter, this gets interesting.
When I said that Li has more volumetric energy density
than lead battery did not take into account discharge rate.
Technically, if I store 20 kWh in 1m^3 volume and you store
only 15 kWh in the same volume, my battery has higher
volumetric energy density period, even if I can discharge
mine only at 1/5 of the rate you can discharge yours.
I may not need (or can't take advantage of) higher discharge
rates, so this is not specified.
Siemens inverter in ACRX is limited to 282A battery current,
this gives 100 kW power at highest voltage. Practically
very rarely see anything above 180A.
My 90Ah TS cells need to dish out 2C to provide that.
4 of them together are about the voltage of Optima under
the same load (OCV more, but sag is more too),
and are "about" the same volume as one Optima.
Say, I drive at 90A at all times (actually it is
[EMAIL PROTECTED] and [EMAIL PROTECTED]). Optima at that rate will have
about 30Ah available (my guess); good TS cells still have 90Ah.
So TS cells have 3 times volumetric energy density than
Optima. Who cares that Optima can give 500A or 1,500A
out if I can only possibly consume 280A out of a battery?
So power capability is of no relevance *to me*.
If you care, compare then to LiP with higher power
output, but volumentic energy density advantage over lead
will be about the same as for less powerful LiIons.
Since we're not comparing power, we're comparing energy
stored per volume *provided* the battery
is usable for the application. I wouldn't need an
amazing (energy density wise) 100kWh battery size of a
cell phone if I can discharge it only at 1uA rate.
So, my TS cells are *usable* because can provide
more power than drive system can take. How much
more beyond that is of no concern then.
Now, LiPo are more powerful ones (10C-20C are common)
but not more energy dense than LiIons by volume.
So racers could benefit from it but not long rangers.
I'd say in general, today Lithium batteries have 3x
volumetric energy density of a lead battery *at usable
discharge rates* (though not as high rates as for lead,
which may or may not be relevant, see above).
Victor
--
'91 ACRX - something different
Peter VanDerWal wrote:
Victor,
My statement was based on my memory of research I did several years ago,
it's quite possible that I'm wrong, especially when you consider that I
wasn't thinking about 5C-10C discharges when I was looking into it.
Obviously you are in a better position to comment on this. How many wh
does you pack store when drained at the 5C rate, we can compare this to
YTs/Orbitals.
Thanks.
Peter VanDerWal wrote:
...
FWIW though the Li-Ions/Li-Poly weigh less than Lead-Acid, they take up
almost the same amount of physical space.
Peter,
If you mean space per Wh, stored (volumetric energy density),
I find this statement somewhat inaccurate. Do you have numbers
by chance? I can compare with what I had physically in ACRX.
Victor
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Mark Freidberg [mailto:[EMAIL PROTECTED] wrote:
> Of interest is that folks on the list seem to be focused on
> AGMs and regs. I ask, for street EVs with modest peak power
> demands (not racing) why not gel cells and no regs? I raised
> the AGM vs. gel cell issue a while back, there was some
> feedback but not a lot.
The drawback with gels is that they can't handle the sort of current
that AGMs do, but still cost significantly more than floodeds. If you
really want the lower maintenance of sealed batteries and have very
modest current requirements (not only not racing, but econobox street
performance at best), then gels may be an option.
For most, the choice is either low cost, which means flooded lead acid,
or high performance, which tends to mean AGMs. With AGMs, you can use a
similar system voltage as a flooded car would (i.e. similar cost for
controller and DC/DC, etc) and have improved performance; with gels, the
lower peak current capability forces you to a higher system voltage to
maintain the same performance as the floodeds, which can mean a
controller and/or DC/DC upgrade to handle the higher pack voltage.
I'm not sure that it is safe to make the assumption that it will be any
less necessary to run regs with gels than with AGMs; both are sealed
batteries and have similar end of charge concerns. Someone will
probably point out Solectria as an example of successful use of gels in
a long string without regs, and my response will be that Solectria also
did not use the sort of cheap, dumb chargers that hobbiests tend to;
either you ante up for a smart charger or add regs to a dumber one, the
final cost of the charging system will be comparable.
Cheers,
Roger.
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I drive freeways in California at 45mph. I have never had a problem going
45mph. I stay in the slow lane and mind my business. 45mph is the legal
minimum on California freeways. I have had the occasional idiot tailgate me
or flash me when I go the speed limit in the slow lane It's something I
just don't understand. Just keep your eyes forward and don't react. Going
slow on the freeway is the compromise. Lawrence Rhodes.......
----- Original Message -----
From: "Jeff Shanab" <[EMAIL PROTECTED]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Wednesday, February 15, 2006 6:29 PM
Subject: A trip to the referee station
I have an appointment with the referee for my gas car 7am wed the 22nd,
I have a 1pm appointment at the same place for the electric car and it
is not back togather yet!
I will have 288 Volts as 24 orbitals and it is 13 miles one way to the
place.
When I only had 204V, 17 orbitals I ran out of charge a 1/4 mile from
home unitil I got the regs and got the thing charged better. That was
only 8 miles. I made a couple of trips without incident once the regs
were in.
I will ask if I can plug the electric in when it gets tested while I am
haveing the ICE inspected.
I will top off the tires.
I will try and get a few test runs to wake up the batteries and get an
idea of range.
If not It will have to be towed, Ouch, $$$$
I have the choice of taking freeway or surface streets.
Which is better ? 60 and no stops (with a few people mad at me for
going so slow) or 20 to 30 stoplights of at least 1/2 we can count on
stopping at.
I don't have an emeter yet, and next appointment would be mid april :-(
(If I wait that long I loose plate "nomrgas" and go crazy)
I will have amp gauge and voltmeter, but not much experience judging
range off them.
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I just wanted to comment that 160Wh/mile for Solectria is
really outstanding achievement - without unconventional
tricks and optimal light vehicle to begin with you will
be hard pressed to get power consumption below 200Wh/mile
with normal driving (accelerating with traffic, not trying to
save energy but not needlessly wasting it either).
Mmm... Kinda depends. I've driven a 95 Solectra Force that was similar
in size and capacity to my Prizm. The motor is significantly smaller
(20kw Solectra to 50kw Prizm), air cooled, and it shows in performance.
The Prizm can easily keep up with traffic and seems to run around
280-300w/mile at 60mph highway cruise.
Oddly enough though it seems to be somewhat *less* efficient when driven
at 40mph or so. Maybe it's the computer programming of the torque curve
or the gearing. How efficient is a Solectra at 60mph highway driving?
Chris
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> > slow me down! Where's that regen when I need it?
>
> No parking brake to scrub off speed?
John needs a plug brake like my old Milburn has...wait, scratch that, I
almost caught the jalopy on fire a week ago when I left the speed select in
plug brake mode and then proceeded to have a friend tow the thing when I
wrongly thought the batteries were outta juice...45seconds later I started
to see smoke!
Careful with plug braking coil locations...
-Myles
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Joel Hacker wrote:
> everything I read recently speaks to how more efficient AC motors
> because they don't need the series windings in the armature (rotor)
> and operate as an induction motor.
>
> 1. Is this right?
>
> 2. Are they more expensive?
>
> Any ideas as to why DC systems with PWM, and series wound motors
> (especially the Advanced DC ones) are so popular for conversions?
The situation is complicated. People mix up theoretical performance with
the performance of motors you can actually get. They confuse sound
engineering with opinions and expediency.
All motors (AC or DC) need a field. The field can come from either
permanent magnets or electromagnets (windings). Technically, the field
supplies no power; it's just a "wall" for the armature or rotor to push
against.
An induction motor has its field windings on the rotor. It powers these
windings indirectly, by transformer action from the stator windings. The
transformer adds a couple percent of extra losses.
There is no fundamental efficiency difference between AC or DC motors
because all motors are actually AC. The commutator of a DC motor is an
inverter that converts DC to AC to run the actual motor. A "brushless
DC" motor just uses an electronic inverter to do this. An AC motor
separates the commutator/inverter from the rest of the motor.
Cost is mainly controlled by how many are being built per year, and how
cost-conscious the customer is. Induction motors are mass produced by
the millions for all sorts of consumer products, and so are pretty cheap
per horsepower. But they require a separate inverter to produce AC.
Most people use Advanced DC series motors because they are an expedient
solution. They are available (the company will actually sell you one),
they don't need an inverter (simple controllers work), and they work
"good enough" for most EV conversions.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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