EV Digest 5400
Topics covered in this issue include:
1) battery choice (was Battery patent rights)
by "Steve Arlint" <[EMAIL PROTECTED]>
2) Re: 156v VW Bus with 156kZilla
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
3) Re: Precharge alternatives
by Neon John <[EMAIL PROTECTED]>
4) Re: Precharge alternatives
by Janez Svetlin <[EMAIL PROTECTED]>
5) Measuring little capacitors
by Christopher Zach <[EMAIL PROTECTED]>
6) High current 200 V Schottkys for freewheeling- who makes them?
by [EMAIL PROTECTED] (Brad Baylor)
7) Re: [uselectricar] Measuring little capacitors
by [EMAIL PROTECTED] (Brad Baylor)
8) Re: Precharge alternatives
by "Rich Rudman" <[EMAIL PROTECTED]>
9) Re: High current 200 V Schottkys for freewheeling- who makes them?
by [EMAIL PROTECTED] (Brad Baylor)
10) Re: Precharge alternatives
by "Robert Chew" <[EMAIL PROTECTED]>
11) Re: High current 200 V Schottkys for freewheeling- who makes them?
by Lee Hart <[EMAIL PROTECTED]>
12) Re: CURRENT ELIMINATOR NEWS
by [EMAIL PROTECTED]
13) RE: Precharge alternatives
by "Garret Maki" <[EMAIL PROTECTED]>
14) Re: High current 200 V Schottkys for freewheeling- who makes them?
by Danny Miller <[EMAIL PROTECTED]>
15) Etek-ed Hybrid
by [EMAIL PROTECTED]
16) Re: High current 200 V Schottkys for freewheeling- who makes them?
by Rod Hower <[EMAIL PROTECTED]>
17) Re: Precharge alternatives
by Neon John <[EMAIL PROTECTED]>
18) Re: Potbox and contractor
by Stefan Peters <[EMAIL PROTECTED]>
19) Re: White Zombie Update...360 Volts...More HP!
by James Massey <[EMAIL PROTECTED]>
20) Flying car - or, it "runs" in midair
by Seth Rothenberg <[EMAIL PROTECTED]>
21) What people want/level of expertise to get an EV started?
by Bob Bath <[EMAIL PROTECTED]>
22) Fw: bmw in Vegas. Need storage help & or transport
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
--- Begin Message ---
Greetings,
Well, I am a little more relaxed on that whole NIMH patent issue. I still
don't like the fact that someone can patent the whole concept of a battery.
Patent a manufacturing process definately, but battery concept; no.
To reply on the Lead acid suggestion, yes they are inexpensive in initial $
cost. Most of the electric motor scooters use lead acid for that reason. In a
system that is engineered from the ground up, Nicad/NIMH does not have to be
expensive.
For example, on a 20 Hr rate NIMH has more capacity per Kg. than lead acid.
Couple in Peukert's effect for a 40-80 min discharge, a cold day, and carrying
the extra weight of lead acid that has to compensate for the above listed
deficiencies (which mans a heavier scooter thus more power needed), and
perhaps Nicad/NIMH isn't that much more. Then take into consideration the
longer cycle life offered by Nicad/NIMH.
By no means am I saying don't use lead acids ever. It is just that my
application calls for a Nicad or NIMH battery. I will use cylindricals just
because they can be had for a stupid low cost compared to prismatics. This
means that I will have to work out the balancing issues.
As for Lithuim based batteries. I would love for Lithuim's to come down in
price and solve our battery problems. Changing my battery management to
lithuim would be a task but not impossible. Unfortunately that is not the case
and I cannot put my faith in the future. I have to make the best of what is
available today.
VR,
Steven Arlint
Team Umpqua Electric Vehicles
--------------------------------------------------------------------
Danny Miller wrote:
SLA is just so readily available and cheap. It's been the solution
of choice so far.
You might think about the product life cycle too. I mean, if you
design am expensive NiMH/NiCd system that will last for 20+ years, it
will probably be discarded in 5 yrs as someone outgrows the idea or
they become obsolete. In 5 yrs there may be relatively cheap,
long-life LiPo cells available that would obsolete the NiMH design.
Danny
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--- Begin Message ---
On the west coast vehicles last a long time. VW buses aren't exactly rare
but as time goes by are getting rare. I was thinking of the slightly larger
70's van as a choice. Lots of room and carrying capacity. At 156v 60 mile
range should be about right. Maybe more but not at high speed. Maybe 45 to
50mph max. It would perform better than the orginal. LR.....
----- Original Message -----
From: "Lee Hart" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Sunday, April 23, 2006 9:58 AM
Subject: Re: 156v VW Bus with 156kZilla
Lawrence Rhodes wrote:
I have a client that wants to do a family vehicle and I recommended
a VW bus. I think it will handle 156volts of flooded(26) with a 156v
Zilla, Iota DC/DC, Rudman PFC20, & a 9" ADC or similar.
Which one? The old 60's Microbus, the Vanagon, or current Eurovan?
There were many microbus conversions in the 60's and 70's. They are
small and light, and carry a lot of weight for their size; but nowdays
are pretty scarce and old, and had some serious safety problems.
The Vanagons were nicer vehicles, but also bigger and heavier and so
couldn't carry as many batteries.
The Eurovans are very nice, but *really* heavy -- mine is 4300 lbs with
a 5800 lbs GVWR. It would be an expensive conversion.
With any van, aerodynamics are poor. It won't be practical to get good
range at high speeds.
Something I've thought about is making my Eurovan into a hybrid. The
inside ends of the rear axles are exposed, with places for the yokes of
universal joints for a rear differential (for the 4WD option). I've
thought of adding the rear differential, and driving it with an electric
motor. Put a smallish battery pack under the floor. Drive it around town
as an EV, with the ICE off or just idling to provide power steering,
brakes, heat, air conditioning, etc. Use the ICE normally for long
trips.
--
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
--- End Message ---
--- Begin Message ---
On Sun, 23 Apr 2006 08:56:07 -0700, "Chris Brune"
<[EMAIL PROTECTED]> wrote:
>Hi John,
>First, I really enjoy your posts. You're breadth of technical knowledge is
>amazing.
Thanks!
>
>I think you hit the nail on the head with the concern you listed below. We
>both know that if you don't have enough capacitance at the controller and
>the controller is mounted far from the batteries you will get ringing on the
>input line. This will result in a significant loss of power. However, when
>you have a say 450A buck converter the worst case input ripple is 50% of
>this, or 225A RMS. Well I haven't seen (in the EV market) a contoller yet
>that actually has front end capacitors rated for this ripple. It has been
>discussed here before that the capacitors should have a ripple current rated
>for about 1/20th the output current rating (assuming electrolytics are
>used). And if you have this much ripple rating you have way more
>capacitance than is necessary.
>
>But depending on how the vehicle is wired I wouldn't be surprised if some of
>this input ripple current gets passed back to the batteries. So the stress
>on the caps would be reduced some what. Adding a series inductor would
>essentially eliminate any ripple current getting back to the batteries.
All true. The devil is going to be in the details of the component
values. I'm going to do some measuring in a bit but it looks like I
also ought to do some Spice'ing. OTOH, I'm the kinda guy who likes to
take an educated guess first stab and things. If it works, great. If
not, then time to do some math.
>
>It would be interesting to measure the ripple going to the batteries before
>and after adding the inductance.
That I will do. My pack is wired with either 2/0 or 1/0 welding cable
but OTOH, my pack consists of golf cart batteries that have relatively
high impedance. It'll be interesting to see what the ripple result
actually is.
I don't have any problems if this doesn't work. I'll just punt and
pre-charge. But I want to give this a try anyway.
It's been raining all day and I don't have a drive-in garage so I've
been rather frustrated today trying to get anything done. The sun's
peaking out right now so maybe I can drag out some test gear and do
some testing.
I had a similar problem with an industrial client on Friday. He
called me in on a power quality problem. He'd just purchased a
Brother laser printer for his office and every time he turned it on,
his UPS would trip and sometimes the computer would reset. His
electrician had told him that he had "bad outlets" and was prepared to
change out all the convenience outlets in the office. Fortunately he
got a second opinion :-)
Based on the telephone call I brought along my Dranetz line
disturbance analyzer and a digital storage scope. I plugged in the
analyzer and had him turn on the printer. When the fuser heater
turned on inside the printer, the fluorescent lights strobed, the UPS
tripped and the computer reset.
The Dranetz told me that the voltage had dipped to 95 volts for 55
cycles, then surged to 145 volts. I recognized the light flicker as
half-cycling (where an SCR controller fires on only half the cycles,
resulting in a DC component on the line) and my scope confirmed it.
The laser printer was drawing about 25 amps inrush and was
half-cycling. I figured that the half-cycling was being caused by the
power line disturbance and that the two phenomena were feeding on each
other.
I stepped off the conduit between the office and the service entrance.
150 ft. Hmmm. For that kind of distance the office should have
gotten a sub-panel. I popped the cover from the lighting breaker
panel and saw the obvious cause. This "electrician" had run 14 gauge
wire to the office! A 300 ft round trip of #14 wire is about a half
ohm. No wonder the voltage was dropping. Worse, he had the whole
office on only two branches. That's 4 computers, 2 printers, 2 space
heaters in the winter and the lighting.
I suggested that my client have his electrician install a 100 amp
sub-panel at the office and give the printer its own branch outlet and
break out the lighting and each office onto separate branches. He
agreed and his electrician did that Friday evening. I went back
Saturday morning and ran the same test. With the sag threshold set to
5 volts on the Dranetz, it didn't make a peep when the laser printer
was turned on. No half-cycling, no light flickering, just a nice hum
from the printer. The UPS, the computer and my client were all
beaming :-)
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 ---
Neon John wrote:
I'm thinking about (and probably will) applying that to my EV. This
will involve adding a suitable inductor in series with one of the pack
to controller leads. There will then be no precharge resistor and the
contactor will close in on a discharged controller. The inductor will
limit the inrush to a safe value. No delays and no quiescent energy
consumption.
I'm just thinking out loud here before I go out tomorrow and do some
testing. Has anyone else used this approach and if so, any gotchas?
<snip>
There is a theoretical issue; The energy stored in the inductor during
the precharge has to go somewhere. There are three places for it to go:
a)Wire resistance
b)Controler capacitor
c)Back to the battery
The controler capacitors and serial inductance form an LC circuit. The
thing might exhibit dampened oscillations and capacitors can see as much
as sqrt(2)*Ubat.
I never managed to get any substantial rise of voltage because I was
using rectified AC and the cored choke was saturating.
I still have an ugly precharge circuit for my AC inverter design; a
power resistor bypassed by a relay. If you figure out something better,
please let me know.
Janez
--- End Message ---
--- Begin Message ---
Is there a tool that can measure the value of a small surface mounted
capacitor in a circuit? I'm working on repairing an EV1/Dolphin 120kw AC
controller that was damaged in shipping with the result of a number of
components sheared off the board. One of them is a capacitor, my guess a
noise reducer.
Or should I just go with the old standard of .1mfd and leave it at that?
Chris
--- End Message ---
--- Begin Message ---
I've seen posts here that a 200 V 400 A Schottky exists.
I've seen posts here that a 200 V 400 A Schottky exists.
Is it ok to parallel them as long as they are on a big enough heat
sink? Say a 1/4 inch thick copper slab with water cooling pipes on the
back side. Or will I still need some small value resistors in series
with each? If I still need resistors, what value? Would ones allowing
.2 V drop at the device's rated current be enough?
The highest I found so far:
Ixys DSS 2x101-02A 200 V 100 A, 2 on a SOT-227 package
http://www.ixys.com/L703.PDF
APT APT2X101S20J 200V 120A, 2 on a SOT-227 package
http://www.advancedpower.com/Communities/APT/Products/2X101S20J.PDF
How much do these cost?
Correct my understanding if incorrect:
The current in the freewheeling diode is highest at low rpm, moderate
to high throttle settings (like when accellerating).
Besides the obvious function of keeping stuff from blowing up, it is
the device that makes possible the torque multiplication effect. For
example, during acceleration when 300 A RMS is coming from the
battery, but motor current is 1000 A, 700 A RMS would be going through
the freewheeling diode.
The diode's reverse recovery time is very important, or else shoot
through occurs. Schottkys have near 0 recovery time and are best for
200 V or less.
Synchronous rectification with MOSFETs is useless at these current
levels unless using an unreasonable number of devices (or else the
intrinsic diode with relatively slow recovery turns on, causing shoot
through).
Synchronous rectification with IGBTs is useless due to the higher 1.8
V drop (unless at voltages that would require putting Schottkys in
series).
All correct?
Brad Baylor
--- End Message ---
--- Begin Message ---
Been there done that.. :)
If you have the capacitor, you can rig some little probes. Tape some
tape flat to your workbench, such that the sticky part faces you and
put the part on it. Use some solid 24 awg or thereabouts hookup wire
as your probes.
If the capacitor is still in the circuit, remove it, or else anything
else in the circuit will skew your readings.
If it's missing, well you can guess what it did by looking at the
traces and other parts, or get a schematic.
Brad Baylor
--- End Message ---
--- Begin Message ---
Uhhnnn.
Precharge on a 48 volt controller??
Most don't need it or use it.
On 72 volts.. nice idea..still not really needed. How big a Crack does it
make when you hook up the last battery wire???
Polite snaps OK, blowing the leads off a 12 gage wire.. NOT OK.
Does Altrax recomend it? if not.. don't bother.
The precharge on my Zilla2K at 156 volts is like Miliseconds. It's just
barely perseptable when you rotate the Key over to run.
That's OK with me.
Even the DCPs had a VERY quick precharge. Like you could not tell to about
the time you took your hand off the Start key you were on line.
I Say this since the Altrax is the successfull Son of any DCP controller.
And I had a hand in the designs of DCP controllers.
We did not use nor ever contimplate a inductive precharge. It would just get
in our way. I mean it would limit our currents in a way that we did not
wish.
So either don't waste you time on a precharge circuit at that low a
voltage...or.... Use a suitable sized resistor.
I never had a precharge on my Curtis...Even at 120 volts.
Madman
----- Original Message -----
From: "Neon John" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Sunday, April 23, 2006 1:08 AM
Subject: Precharge alternatives
>
> I'm unhappy with the current practice and techniques of precharging
> the controller caps. It seems that one has only a couple of choices,
> neither good nor convenient. One is to leave the controller charged
> all the time which wastes energy and will drain the pack if left
> sitting for awhile or have a pre-charge circuit and put up with the
> delay while it functions. (No, I'm not interested in hearing that you
> don't find the delay annoying. I do and I started this thread!)
>
> I've been pondering this today. The goal really isn't to fully charge
> the caps. The goal is to limit the inrush to something that is safe
> for the contactor, safe for the caps and which will not generate
> enough ring voltage to hurt the semiconductors. That means that some
> inrush is OK.
>
> One of the standard industrial methods of limiting inrush or fault
> current is a high current air core inductor in series with the load.
> The resistance and inductance are low enough that it has no effect on
> normal operations. The inductance is high enough, however, to limit
> inrush or fault current to a design value.
>
> I'm thinking about (and probably will) applying that to my EV. This
> will involve adding a suitable inductor in series with one of the pack
> to controller leads. There will then be no precharge resistor and the
> contactor will close in on a discharged controller. The inductor will
> limit the inrush to a safe value. No delays and no quiescent energy
> consumption.
>
> I'm just thinking out loud here before I go out tomorrow and do some
> testing. Has anyone else used this approach and if so, any gotchas?
>
> One potential gotcha I can think of has to do with ripple current back
> to the battery from the PCM action. For a controller with little or
> no input filtering, inductance in the battery lead could result in
> unstable operation or loss of power. At this point I'm assuming that
> any controller with enough input capacity to need worry about inrush
> has enough to limit or eliminate input ripple. True? False?
>
> Physical size won't be a problem since it'll only take a few (hundred)
> microhenerys to limit the inrush to a few hundred amps.
>
> Any idea how much input capacitance in, say, an Alltrax 7845? My
> digital capacitance meter generated "unusual" results, probably
> because of all the other stuff connected to the input. I'll get my
> LCR bridge out tomorrow but just in case someone already knows, saving
> me the work, I thought I'd ask.
>
> Discussion?
> ---
> 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 ---
>I've seen posts here that a 200 V 400 A Schottky exists.
>
>I've seen posts here that a 200 V 400 A Schottky exists.
Bahh.. bad copy and paste from another editor.. :-P
Brad..
--- End Message ---
--- Begin Message ---
HI All,
Hadn't used a pre-charge on my Alltrax controller for months, i totally
overlooked the pre-cjharge resistor. until Clauddio pointed it out to me. So
i installed a 250 ohm resistor between the line contactor terminals.
I spoke to Cliff Rees, the techy at Alltrax and he strongly advised that i
have a pre-charge resistor in there to stop the surge ruining the electronic
components. In terms of delay, i have never ever noticed any sort of delay,
or at least the delay is not enough to be a problem.
Cheers
From: "Rich Rudman" <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: <ev@listproc.sjsu.edu>
Subject: Re: Precharge alternatives
Date: Sun, 23 Apr 2006 15:21:18 -0700
Uhhnnn.
Precharge on a 48 volt controller??
Most don't need it or use it.
On 72 volts.. nice idea..still not really needed. How big a Crack does it
make when you hook up the last battery wire???
Polite snaps OK, blowing the leads off a 12 gage wire.. NOT OK.
Does Altrax recomend it? if not.. don't bother.
The precharge on my Zilla2K at 156 volts is like Miliseconds. It's just
barely perseptable when you rotate the Key over to run.
That's OK with me.
Even the DCPs had a VERY quick precharge. Like you could not tell to about
the time you took your hand off the Start key you were on line.
I Say this since the Altrax is the successfull Son of any DCP controller.
And I had a hand in the designs of DCP controllers.
We did not use nor ever contimplate a inductive precharge. It would just
get
in our way. I mean it would limit our currents in a way that we did not
wish.
So either don't waste you time on a precharge circuit at that low a
voltage...or.... Use a suitable sized resistor.
I never had a precharge on my Curtis...Even at 120 volts.
Madman
----- Original Message -----
From: "Neon John" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Sunday, April 23, 2006 1:08 AM
Subject: Precharge alternatives
>
> I'm unhappy with the current practice and techniques of precharging
> the controller caps. It seems that one has only a couple of choices,
> neither good nor convenient. One is to leave the controller charged
> all the time which wastes energy and will drain the pack if left
> sitting for awhile or have a pre-charge circuit and put up with the
> delay while it functions. (No, I'm not interested in hearing that you
> don't find the delay annoying. I do and I started this thread!)
>
> I've been pondering this today. The goal really isn't to fully charge
> the caps. The goal is to limit the inrush to something that is safe
> for the contactor, safe for the caps and which will not generate
> enough ring voltage to hurt the semiconductors. That means that some
> inrush is OK.
>
> One of the standard industrial methods of limiting inrush or fault
> current is a high current air core inductor in series with the load.
> The resistance and inductance are low enough that it has no effect on
> normal operations. The inductance is high enough, however, to limit
> inrush or fault current to a design value.
>
> I'm thinking about (and probably will) applying that to my EV. This
> will involve adding a suitable inductor in series with one of the pack
> to controller leads. There will then be no precharge resistor and the
> contactor will close in on a discharged controller. The inductor will
> limit the inrush to a safe value. No delays and no quiescent energy
> consumption.
>
> I'm just thinking out loud here before I go out tomorrow and do some
> testing. Has anyone else used this approach and if so, any gotchas?
>
> One potential gotcha I can think of has to do with ripple current back
> to the battery from the PCM action. For a controller with little or
> no input filtering, inductance in the battery lead could result in
> unstable operation or loss of power. At this point I'm assuming that
> any controller with enough input capacity to need worry about inrush
> has enough to limit or eliminate input ripple. True? False?
>
> Physical size won't be a problem since it'll only take a few (hundred)
> microhenerys to limit the inrush to a few hundred amps.
>
> Any idea how much input capacitance in, say, an Alltrax 7845? My
> digital capacitance meter generated "unusual" results, probably
> because of all the other stuff connected to the input. I'll get my
> LCR bridge out tomorrow but just in case someone already knows, saving
> me the work, I thought I'd ask.
>
> Discussion?
> ---
> 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
>
_________________________________________________________________
Test drive new cars from the comfort of your desk at carpoint.com.au
http://secure-au.imrworldwide.com/cgi-bin/a/ci_450304/et_2/cg_801459/pi_1004813/ai_833884
--- End Message ---
--- Begin Message ---
Brad Baylor wrote:
> I've seen posts here that a 200 V 400 A Schottky exists.
Well, sort of. The Schottky design only works well below about 50v. As
they redesign to increase the reverse breakdown voltage, the forward
conduction voltage goes up, too. Over 100 volts, Schottkys hardly have
any advantage over a normal diode.
> Is it ok to parallel them as long as they are on a big enough heat
> sink?
Diodes do not parallel well. The hotter one has less forward drop, so it
hogs more current, which makes it get hotter yet, so it hogs even more
current, etc. To parallel them, you generally have to hand-match them
*and* insure that they are very close to the same temperature at all
times.
> APT APT2X101S20J 200V 120A, 2 on a SOT-227 package
> How much do these cost?
I don't know, but I'd expect tens of dollars!
> Correct my understanding if incorrect:
> The current in the freewheeling diode is highest at low rpm, moderate
> to high throttle settings (like when accellerating).
Roughly correct. It would be more correct to say the diode current is
motor current times percent PWM on-time.
> The diode's reverse recovery time is very important, or else shoot
> through occurs. Schottkys have near 0 recovery time and are best for
> 200 V or less.
Yes, except that they have a lot of capacitance. This capacitance can
cause shoot-thru current, too.
> Synchronous rectification with MOSFETs is useless at these current
> levels unless using an unreasonable number of devices
Well, it's no worse than the number of MOSFETs needed for the main
switch.
> Synchronous rectification with IGBTs is useless due to the higher 1.8
> V drop (unless at voltages that would require putting Schottkys in
> series).
Except that people use IGBTs as the main transistor switch; so they
would work as synchronous rectifiers for the freewheel diode, too. It
all depends on how much money you want to spend, and how low you want
your controller losses.
--
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
--- End Message ---
--- Begin Message ---
CE lost in the 1st round on fri.nite a real heartbreaker by .001 to last
years ADRA and Summit points champ.A close race right to the finish line.
Dennis
Berube Next race next fri. nite 6pm at
Speedworld for NHRA Summit points and a $1000.
--- End Message ---
--- Begin Message ---
I think I am missing something. The Alltrax manual shows the pre-charge
resistor unswitched and this is what I have done.
John wrote:
"...One is to leave the controller charged all the time which wastes
energy and will drain the pack if left sitting for awhile..."
Is this true? I haven't seen any accumulation on my emeter. I thought
once the caps were charged they stopped draining from the battery. If
not, I certainly haven't observed a noticeable loss of any significant
energy.
Should I look at adding a switch for the pre-charge resistor? I know
Damon Henry did for his bike, but I haven't had a problem without it.
Any idea what the drain current is?
Thanks all,
Garret
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Robert Chew
Sent: Sunday, April 23, 2006 6:04 PM
To: ev@listproc.sjsu.edu
Subject: Re: Precharge alternatives
HI All,
Hadn't used a pre-charge on my Alltrax controller for months, i totally
overlooked the pre-cjharge resistor. until Clauddio pointed it out to
me. So
i installed a 250 ohm resistor between the line contactor terminals.
I spoke to Cliff Rees, the techy at Alltrax and he strongly advised that
i
have a pre-charge resistor in there to stop the surge ruining the
electronic
components. In terms of delay, i have never ever noticed any sort of
delay,
or at least the delay is not enough to be a problem.
Cheers
>From: "Rich Rudman" <[EMAIL PROTECTED]>
>Reply-To: ev@listproc.sjsu.edu
>To: <ev@listproc.sjsu.edu>
>Subject: Re: Precharge alternatives
>Date: Sun, 23 Apr 2006 15:21:18 -0700
>
>Uhhnnn.
>Precharge on a 48 volt controller??
>Most don't need it or use it.
>On 72 volts.. nice idea..still not really needed. How big a Crack does
it
>make when you hook up the last battery wire???
>Polite snaps OK, blowing the leads off a 12 gage wire.. NOT OK.
>
>Does Altrax recomend it? if not.. don't bother.
>
>The precharge on my Zilla2K at 156 volts is like Miliseconds. It's just
>barely perseptable when you rotate the Key over to run.
>That's OK with me.
>Even the DCPs had a VERY quick precharge. Like you could not tell to
about
>the time you took your hand off the Start key you were on line.
>I Say this since the Altrax is the successfull Son of any DCP
controller.
>And I had a hand in the designs of DCP controllers.
>
>We did not use nor ever contimplate a inductive precharge. It would
just
>get
>in our way. I mean it would limit our currents in a way that we did not
>wish.
>
>So either don't waste you time on a precharge circuit at that low a
>voltage...or.... Use a suitable sized resistor.
>
>I never had a precharge on my Curtis...Even at 120 volts.
>
>Madman
>
>----- Original Message -----
>From: "Neon John" <[EMAIL PROTECTED]>
>To: <ev@listproc.sjsu.edu>
>Sent: Sunday, April 23, 2006 1:08 AM
>Subject: Precharge alternatives
>
>
> >
> > I'm unhappy with the current practice and techniques of precharging
> > the controller caps. It seems that one has only a couple of
choices,
> > neither good nor convenient. One is to leave the controller charged
> > all the time which wastes energy and will drain the pack if left
> > sitting for awhile or have a pre-charge circuit and put up with the
> > delay while it functions. (No, I'm not interested in hearing that
you
> > don't find the delay annoying. I do and I started this thread!)
> >
> > I've been pondering this today. The goal really isn't to fully
charge
> > the caps. The goal is to limit the inrush to something that is safe
> > for the contactor, safe for the caps and which will not generate
> > enough ring voltage to hurt the semiconductors. That means that
some
> > inrush is OK.
> >
> > One of the standard industrial methods of limiting inrush or fault
> > current is a high current air core inductor in series with the load.
> > The resistance and inductance are low enough that it has no effect
on
> > normal operations. The inductance is high enough, however, to limit
> > inrush or fault current to a design value.
> >
> > I'm thinking about (and probably will) applying that to my EV. This
> > will involve adding a suitable inductor in series with one of the
pack
> > to controller leads. There will then be no precharge resistor and
the
> > contactor will close in on a discharged controller. The inductor
will
> > limit the inrush to a safe value. No delays and no quiescent energy
> > consumption.
> >
> > I'm just thinking out loud here before I go out tomorrow and do some
> > testing. Has anyone else used this approach and if so, any gotchas?
> >
> > One potential gotcha I can think of has to do with ripple current
back
> > to the battery from the PCM action. For a controller with little or
> > no input filtering, inductance in the battery lead could result in
> > unstable operation or loss of power. At this point I'm assuming
that
> > any controller with enough input capacity to need worry about inrush
> > has enough to limit or eliminate input ripple. True? False?
> >
> > Physical size won't be a problem since it'll only take a few
(hundred)
> > microhenerys to limit the inrush to a few hundred amps.
> >
> > Any idea how much input capacitance in, say, an Alltrax 7845? My
> > digital capacitance meter generated "unusual" results, probably
> > because of all the other stuff connected to the input. I'll get my
> > LCR bridge out tomorrow but just in case someone already knows,
saving
> > me the work, I thought I'd ask.
> >
> > Discussion?
> > ---
> > 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
> >
>
_________________________________________________________________
Test drive new cars from the comfort of your desk at carpoint.com.au
http://secure-au.imrworldwide.com/cgi-bin/a/ci_450304/et_2/cg_801459/pi_
1004813/ai_833884
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Well, you could use it in parallel with the sync rectifier element, right?
That means the diode keeps the voltage across the transistor very low
while it's switching, and makes the timing less critical since the gaps
between forward transistor turning off and rectifier transistor turning
on (and vice versa) are not very critical. The Schottky need not be
enormous, the current just eneds to be within its max surge rating not
the continuous rating.
Danny
Lee Hart wrote:
Brad Baylor wrote:
I've seen posts here that a 200 V 400 A Schottky exists.
Well, sort of. The Schottky design only works well below about 50v. As
they redesign to increase the reverse breakdown voltage, the forward
conduction voltage goes up, too. Over 100 volts, Schottkys hardly have
any advantage over a normal diode.
Is it ok to parallel them as long as they are on a big enough heat
sink?
Diodes do not parallel well. The hotter one has less forward drop, so it
hogs more current, which makes it get hotter yet, so it hogs even more
current, etc. To parallel them, you generally have to hand-match them
*and* insure that they are very close to the same temperature at all
times.
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Interesting project:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=4634264304
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I have a few 200V , 400A Schottky's, very rare
International Rectifier parts. If you really need
some email me off list.
Rod
P.S. good luck finding them anywhere else!!!!
--- Brad Baylor <[EMAIL PROTECTED]> wrote:
> I've seen posts here that a 200 V 400 A Schottky
> exists.
>
> I've seen posts here that a 200 V 400 A Schottky
> exists.
>
> Is it ok to parallel them as long as they are on a
> big enough heat
> sink? Say a 1/4 inch thick copper slab with water
> cooling pipes on the
> back side. Or will I still need some small value
> resistors in series
> with each? If I still need resistors, what value?
> Would ones allowing
> .2 V drop at the device's rated current be enough?
>
> The highest I found so far:
> Ixys DSS 2x101-02A 200 V 100 A, 2 on a SOT-227
> package
> http://www.ixys.com/L703.PDF
>
> APT APT2X101S20J 200V 120A, 2 on a SOT-227 package
>
http://www.advancedpower.com/Communities/APT/Products/2X101S20J.PDF
>
> How much do these cost?
>
> Correct my understanding if incorrect:
>
> The current in the freewheeling diode is highest at
> low rpm, moderate
> to high throttle settings (like when accellerating).
>
> Besides the obvious function of keeping stuff from
> blowing up, it is
> the device that makes possible the torque
> multiplication effect. For
> example, during acceleration when 300 A RMS is
> coming from the
> battery, but motor current is 1000 A, 700 A RMS
> would be going through
> the freewheeling diode.
>
> The diode's reverse recovery time is very important,
> or else shoot
> through occurs. Schottkys have near 0 recovery time
> and are best for
> 200 V or less.
>
> Synchronous rectification with MOSFETs is useless at
> these current
> levels unless using an unreasonable number of
> devices (or else the
> intrinsic diode with relatively slow recovery turns
> on, causing shoot
> through).
>
> Synchronous rectification with IGBTs is useless due
> to the higher 1.8
> V drop (unless at voltages that would require
> putting Schottkys in
> series).
>
> All correct?
>
> Brad Baylor
>
>
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On Sun, 23 Apr 2006 20:47:18 -0400, "Garret Maki"
<[EMAIL PROTECTED]> wrote:
>I think I am missing something. The Alltrax manual shows the pre-charge
>resistor unswitched and this is what I have done.
>
>John wrote:
>"...One is to leave the controller charged all the time which wastes
>energy and will drain the pack if left sitting for awhile..."
>
>Is this true? I haven't seen any accumulation on my emeter. I thought
>once the caps were charged they stopped draining from the battery. If
>not, I certainly haven't observed a noticeable loss of any significant
>energy.
It's not the tiny leakage current of the caps that is of concern but
the power consumption of the controller's electronics, at least for
controllers like the Alltrax that operates its electronics from pack
power.
The most usual setup with the Alltrax is to jumper the "ignition on"
terminal over to the B+ terminal so that the electronics power up at
the same time the controller does. One could, I guess, install
another switch but it would have to handle the pack voltage. The 72
volt Alltrax will NOT run on 12 volts.
If your controller has a separate power input for the electronics then
you probably don't have a problem.
Your E-meter probably wouldn't see the drain even if you had any, as
there is a threshold, variously reported as 100 or 200 ma, below which
the E-meter ignores any current signal. This is to stop insignificant
offset and/or thermocouple signals in the shunt loop from being
integrated into significant error over time.
With the known controller drain of my Alltrax, whether my E-meter sees
it depends mostly on the phase of the moon :-) Some days when the
moon (and ambient temperature) is right, the E-meter will see the
drain and sometimes it won't.
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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Michaela Merz wrote:
Hello:
A few people on the list suggested to wire the main contractor to the
potbox in order to disconnect the controller once one lifts the foot of
the accelarator (at least this is how I understood it).
First question: Did I understand the concept right?
Second question: I have a Raptor 1200 controller and it usually takes
about 1 or 2 seconds to come up to 'ready' mode. That would prohibit the
idea of doing it that way because in some circumstances, 2 seconds may
just a long time.
Thanks for the answers.
Michaela
Dumb question:
Why not put a safety contactor that pulls out on each dead throttle
event between the controller and motor? It wouldn't (shouldn't) be
breaking any current... so not much wear and tear. Would this be bad for
the controller or contactor? I take it I'm missing something here, or
else this would be more common.
~ Peanut Gallery ~
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At 11:04 AM 23/04/06 -0700, John Wayland wrote:
Hello to All,
<snip> I told Jay 'no' to going racing. <snip> Here's the deal. We've made
a commitment to show up at the High Voltage Nationals in Joliet, Illinois,
just three weeks from now,<snip>
and
Each weekend has been packed with EV building activity, <snip> new pack of
Aerobatteries
and
Other changes to the car include the high rpm field weakening circuit <snip>
Will Jim's mighty Siamese 8 hold up to this? Will the Hawker Aerobatteries
stay together?
G'day John (and all)
Aargh, no news on how you are getting on with making reverse happen?!!
Regards
James
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I thought I would post a link to my blog,
which began to live up to its name as an ev blog
today, as I posted my plan of action for my Saturn.
(pictures to follow).
I got it up on jack stands and tested with a couple
of somewhat-dead batteries, watching the tires spin
forward in first and second (and backward in reverse).
http://www.pachai.net/ev
(I didn't submit to the gallery yet...soon.)
I'm studying a bunch of EVAlbum pages to narrow
down what controller to get, thinking a Zilla2K
might be way more than I need....but I am
leaning right now toward more than 144V of
Lead Acid....thinking Flooded, because, if I understand
correctly, it is easier to fix "charging errors"
with floodeds. Per recent discussions, I would
love to get 65 miles.
"Floodeds" will bring us full-circle, my parents used
to have to add boiled water to the battery in
their 1969 air-cooled car (perhaps it was supposed
to be distilled water ? :-)
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The rise in gas prices has me once again, thinking
about what the "on-the-fence"-er needs to get their
project done. And what is my role in it all, based on
my experience.
In other words, I started with a Mike Brown Rabbit,
and after 4 years, wanted to build my own. While I
had electrical expertise, I had little auto
experience, per se. Yet somewhere along the way, I
learned enough to take the information from a video of
another Civic EV, and construct my own.
The point is that if I was to ask a fabricating
shop to crank out the front headlight rack, the
firewall batt. rack, the trunk rack, and the motor
mount, and I tossed in the controller mount, the
vacuum pump mount, and the controller mount, would
that be enough for those person(s) to hop off the
fence and get started.
My DVD is available, and comprehensive journal is
on-line, so there are few secrets left to doing a
92-95 Civic conversion. But we're talking about 100
lbs. of metal to be shipped, and the enthusiast would
still have to follow the schematic and order the
adapter plate and all of the components from
ElectroAutomotive, or KTA Services, or Metric Mind, or
whomever, building it on their own...
Of course, there is also just the thought that I've
got the uncontrollable urge to do another EV, and hope
that I can get the 11K for parts and glider + 4K
profit for doing it... Perhaps it's time to teach a
class on it, and have prospects show up with their
glider in Oregon...
(;-p
'92 Honda Civic sedan, 144V (video or DVD available)!
www.budget.net/~bbath/CivicWithACord.html
____
__/__|__\ __
=D-------/ - - \
'O'-----'O'-'
Would you still drive your car if the tailpipe came out of the steering wheel?
Are you saving any gas for your kids?
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
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[EMAIL PROTECTED] contact Dale. He needs help with an Ebay auction he won.
See below. Email [EMAIL PROTECTED] . Thanks for any help. Lawrence
Rhodes......
----- Original Message -----
From: "Dale Ice" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Sunday, April 23, 2006 9:06 PM
Subject: bmw in Vegas
Hi,
I won the supposed electric BMW on ebay. However the fellow wants it moved
immediately and I can't do it. Do you know anyone who might want the car
and can get it next weekend?
best regards,
Dale
Pt.Arena,Ca.
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