EV Digest 6266
Topics covered in this issue include:
1) Re: Circuit Breaker and Contactor
by Jack Murray <[EMAIL PROTECTED]>
2) Re: efficiency comparison - 2 speed gearbox or series/parallel
by "Michael Perry" <[EMAIL PROTECTED]>
3) User name, etc. (NOT FOR LIST INCLUSION)
by "Roger Daisley @ R J Ranch" <[EMAIL PROTECTED]>
4) Re: Rats attacking EV wiring (was Hairball control wire sizing
by "Ted C." <[EMAIL PROTECTED]>
5) Re: Newbie questions (batteries)
by [EMAIL PROTECTED]
6) Re: DC to DC converter - why isn't it just a big transformer?
by "Dave Wilker" <[EMAIL PROTECTED]>
7) Re: DC to DC converter - why isn't it just a big transformer?
by Jack Murray <[EMAIL PROTECTED]>
8) Re: AltairNano Completes ORDER to Phoenix Motorcar
by =?ISO-8859-1?Q?Jukka_J=E4rvinen?= <[EMAIL PROTECTED]>
9) Exide orbitals
by Steve Powers <[EMAIL PROTECTED]>
10) Re: Exide orbitals
by "jerryd" <[EMAIL PROTECTED]>
11) Newbie Questions (Batteries)
by "Roger Johnsonbaugh" <[EMAIL PROTECTED]>
12) Re: DC to DC converter - why isn't it just a big transformer?
by [EMAIL PROTECTED]
13) Re: Rats attacking EV wiring (was Hairball control wire sizing
by "Joseph H. Strubhar" <[EMAIL PROTECTED]>
14) Re: DC to DC converter - why isn't it just a big transformer?
by "Roland Wiench" <[EMAIL PROTECTED]>
15) Re: Joe Sixpack Geo: best controller SCR, Curtis or contactors? (Or some
combination)
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
--- Begin Message ---
yes indeed I am eliminating the contactor by using electromechanics to
turn on/off the breaker. This is basically moving the precharge safety
check out of the controller itself and putting it in the on/off switch.
I'll have a microprocessor which gets an on/off signal (from the key
switch), and it does the automated checking, it turns on the precharge
and confirms there is not a short or load before it turns on the
breaker, perhaps turn on some leds to indicate stop, precharge, go.
It seems to me the breaker should never weld shut, it is designed
specifically not to fail in that way, otherwise, its value as a safety
device is rather diminished. A second breaker could be used for a
backup manual emergency off switch.
I've looked at the contactors available at evparts.com, and the SW200
just doesn't seem big enough with 360amps max, the SW201 at 450amps
seems OK, but it is $255, that seems rather expensive if it can be
eliminated, and it consumes 12v power while on (how much?) Of course
the electromechanics to turn on/off the breaker add cost, but its
something I can build. And using the surplus $30 breakers, the setup
would end up rather inexpensive as I see it.
Jack
Cor van de Water wrote:
Hi Jack,
You are trying to re-design a contactor with built-in breaker?
Note that the functions of breaker and contactor are quite
different, the contactor being an electrically controllable
HV switch and the breaker being an automatic safety disconnect
in case of overload, to protect wiring and other circuitry
from destruction.
I know several EV'ers who strung a wire through the breaker's
handle eyelet, so from the dashboard you could open the breaker
manually as an added security feature.
The issue not yet addressed is the safety that is provided
by using a combination of contactors and pre-charge, which can
be used by your controller to avoid runaway conditions:
1. Before even closing any contactors, the controller can sense
is there is HV on its input, which would indicate a welded
contact, so the controller can refuse to start the motor, as
it has no backup to break the current.
(This can be mildly annoying if your controller is prone to
faulting out or shutting the motor control off before the
contactors drop, so the capacitors will stay charged for
a while - I must wait 30 sec before I can re-start my EV)
2. After pre-charge contactor closing, the controller senses
the voltage to see if it rises high enough to indicate the
HV bus is not unexpectedly loaded, which can indicate one
of the power components has failed. This will avoid a high
current when the main contactor is closed, so it should
never weld shut, allowing it to break in emergencies.
3. Controller *could* include a crow-bar feature, which will
deliberately short-circuit the HV bus and rely on blowing
the breaker or fuse open, if it detects a serious failure,
such as a continuing current draw even after the contactor
was dropped (indicating a weld-shut and runaway).
Note that all these require the use of sensing and deciding
to take a next step, which is best automated. It is possible
to do this manually (as with a breaker) but it would be very
prone to operator faults, you would need a kind of
"pre-flight inspection list" to do the same as most modern
controllers provide built-in.
THe risk is that the driver will learn that simply throwing
the breaker makes the car go, without going through the
safety list, so better automate it, even if it occasionally
can be annoying to see a fault detected - better avoid
driving than encountering a runaway...
Just my 2 contactor's worth,
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
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Jack Murray
Sent: Sunday, December 31, 2006 10:21 AM
To: [email protected]
Subject: Circuit Breaker and Contactor
I've been looking at contactors, fuses, and circuit breakers, and had
the idea of using a circuit breaker as a contactor by creating a setup
that can switch the breaker on and off. This would eliminate the
contactor as well as reduce the continuous power draw of the coil to it.
I'm surprised this hasn't been done before or is offered as a product,
so there must be some downside to it.
It would turn on-off much slower than a contactor, so my guess is that
might be an issue in general, but for a car, I don't see that as a problem.
In fact, I see a combination of a power-turn-on device that does a
pre-charge to the controller and once complete will turn on the breaker.
The breaker will still break if over-current, but then can be turned off
electrically.
Is there some issue I'm missing?
Thanks,
Jack
--- End Message ---
--- Begin Message ---
If you are on the East coast, you don't have to spend a lot of money. Try Mt
Washington. It's been challenged for years using EVs of all price range.
For that "race" (hill climb, actually) many of the EVs didn't have regen...
which makes coming back down very interesting, to say the least. The first
success I heard was by Charlie MacArthur, riding an EV MC. Well, sort of
successful. The rig pulled itself to the peak, but he had to get off and
walk beside it on the last bit of climb.
For those on the West coast (who maybe haven't been up this mountain)...
it's not a huge mountain compared to, say, some of the Cascades. Still, for
a spectacular climb, there's none to top it. <g>
----- Original Message -----
From: "David Dymaxion" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, January 02, 2007 1:25 PM
Subject: Re: efficiency comparison - 2 speed gearbox or series/parallel
> I did the math, and for a poor, self-funded racer wannebe like myself road
racing is out of the question -- you need expensive advanced batteries. I
figure I can have fun with autocross, drag racing, and land speed on lead
acid batteries. Since regen isn't much help in these kinds of racing, I went
with RWD for a better launch. Well, enough talking, I should go fire up the
used plasma cutter I got for Christmas and do some more work on my
conversion.
--- End Message ---
--- Begin Message ---
I've been receiving this discussion list for several years. I'm now starting
to build up an EV conversion ('86 VW Cabriolet) and plan on adding
either/both a solar or windpower battery charging system. I would like to
become active in the group again.
Somehow, I've lost both my user name and password. Can you advise me about
that. If it is totally gone, perhaps you can assign a new one ... See below.
Suggested user name: PalouseBuilder
Temp password: pbz1
Regards,
Roger Daisley
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
BLOG: http://rdaisley.blogspot.com
[New messages/photos daily]
-----Original Message-----
From: Electric Vehicle Discussion List [mailto:[EMAIL PROTECTED]
Sent: Monday, January 01, 2007 8:29 PM
To: Electric Vehicle Discussion List
Subject: EV digest 6262
EV Digest 6262
Topics covered in this issue include:
1) Re: Electric for diesel swap in sailboat.
by "Paul Hannah" <[EMAIL PROTECTED]>
2) CG, Re: Gens in EV's, Re: Current Eliminator news
by "jerryd" <[EMAIL PROTECTED]>
3) Scoot, electric scooter from the Netherlands
by Lock Hughes <[EMAIL PROTECTED]>
4) Re: battery rebuilding, desulfating, additives,
by "David Roden" <[EMAIL PROTECTED]>
5) RE: Electric for diesel swap in sailboat.
by "David Roden" <[EMAIL PROTECTED]>
6) Rats attacking EV wiring (was Hairball control wire sizing
by "David Roden" <[EMAIL PROTECTED]>
7) Re: Electric for diesel swap in sailboat.
by "jerryd" <[EMAIL PROTECTED]>
8) Re: Recycled 4/0, 0000 guage cables
by "Harry Houck" <[EMAIL PROTECTED]>
9) 100F caps
by [EMAIL PROTECTED]
10) My boat (was: RE: Electric for diesel swap in sailboat.)
by "Myles Twete" <[EMAIL PROTECTED]>
11) Re: AltairNano Completes ORDER to Phoenix Motorcar
by Nick Austin <[EMAIL PROTECTED]>
12) Re: Electric for diesel swap in sailboat.
by pekka <[EMAIL PROTECTED]>
13) Belgiums going e-Postal, Valence L-Ion Oxygen e-scooters
by Lock Hughes <[EMAIL PROTECTED]>
14) Re: Electric for diesel swap in sailboat.
by Robert Lemke <[EMAIL PROTECTED]>
15) Re:Current Eliminator Dragster News 1st 07 win
by [EMAIL PROTECTED]
16) Re: Joe Sixpack Geo: EV-1 controller & only 2 terminals
by "Darin - MetroMPG.com" <[EMAIL PROTECTED]>
17) Re: Current Eliminator news
by "Rich Rudman" <[EMAIL PROTECTED]>
18) Lost Messages on EVDL
by "David Roden" <[EMAIL PROTECTED]>
19) Happy new year from Manzanita Micro
by "Rich Rudman" <[EMAIL PROTECTED]>
__________ NOD32 1951 (20070101) Information __________
This message was checked by NOD32 antivirus system.
http://www.eset.com
--- End Message ---
--- Begin Message ---
From what I've heard, Moth balls work pretty good.
Ted
Olympia, WA
N47 02.743 W122 53.772
Thank GOD for Thomas Edison. Without him we would all be watching TV by
candle light.
----- Original Message -----
From: "Rush" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, January 02, 2007 7:42 AM
Subject: Re: Rats attacking EV wiring (was Hairball control wire sizing
Here is what is done around here -
- get some cats or dogs...
- Antifreeze in small containers on the engine block to poison the rats,
but if they die in the engine compartment then it tends to smell...
- There is a spray that a local 'rats r us' store sells that supposedly
stops the rats from eating wire if you spray it on, tired it and just
didn't like spraying something unknown.
- Hang a light in the compartment, rats don't like light. Got to be a drag
to turn it on and off daily.
- drive it daily to move it...
- just prop open the hood by about a foot or so, they don't like light and
the circulation of air makes it hot and cold, not condusive for a 'home'.
So after trying them all, the best and easiest for me is prop open the
hood (but I have to tie the hood down against the prop cause the wind
would pick up the hood and blow it back).
It also helps to clear all the nests within a 100 ft radius, and keep them
cleared out. They are very persistent animals.
Rush
Tucson AZ
www.ironandwood.org
www.Airphibian.com
--- End Message ---
--- Begin Message ---
Hello Roger
If your going to do an AC system such as from Metric Mind the Siemens is
limited to 400 volts. That would be 26 batteries and plenty of energy. I would
highly recommend you get the Deka MK Gel batteries. You will have less problems
with them over an AGM battery.
For low cost it is hard to beat the flooded batteries. Disadvantage is
maintenance and acid eating up everything it contacts. AGM batteries cost more
but
have great power and are sealed so no mess. However if you expect to get
their full life you will need a very good BMS. Even with the very best BMS
they
will not last as long. I think a better solution would be Lee's battery
balancer. This would be a little more than one just starting off would build.
The number of batteries is not the issue with regen. It is their state of
charge. Ask anyone who lives at the top of a hill. When you leave you could
regen but there is no where to put it the batteries are full. It will be a few
miles if the batteries are fully charged before you can really take advantage
of it. The Siemens regen is adjustable so you can set it to the rate you like
when the batteries can accept it.
I have been driving an S-10 AC system with regen for over three years every
day it is 99 percent of all my miles driven.
The Deka Mk Gel would be in your best battery from the information you have
provided.
If your serious about doing this contact Victor at Metric Mind.
Don
In a message dated 1/2/2007 4:16:45 PM Pacific Standard Time,
[EMAIL PROTECTED] writes:
On Jan 2, 2007, at 10:41 AM, Roger Johnsonbaugh wrote:
> I have been reading about batteries for about 8 months now
> and I
> know about as much as I did when I started.
>
> I am in the planning stages of a 94 S-10 conversion. I will be using a
> siemens A/C drive from MetricMind, and I am hoping
>
> I will be able to fit 29 group 31 lead acid batteries in it. (Other
> chemistries would be nice, but the control/protection circuits
29? You may want to talk to Victor about this. I may be mistaken, but I
think that will limit regen. That would be only 13.1 volts per battery
(pretty low for a charging voltage) to bring the system voltage up to
380 volts (I *think* that is the limit.) If 380v is the limit you might
want to hold the pack voltage (for lead acid batteries) to 300-324
volts to improve regen. You are proposing a pretty heavy vehicle and AC
systems tend to be quite good at regen (a plus for your idea.)
>
> are over my head at the moment.) So the question is: Flooded, Gel, AGM?
> Brand names: Deka(same as MK?), Trojan, Lifeline
If you want to use group 31 batteries I would recommend using AGMs. The
flooded group 31 batteries seem to be a compromise between deep cycle
and lighter SLI (Starting Lighting Ignition) construction. They tend to
not have the life span of true deep cycle batteries. Of course, AGMs
can be destroyed even faster if you don't include a good (and more
expensive) charging system. Perhaps some flooded Group 31 batteries
would be a good set of learner batteries for you. I would recommend
making your battery boxes so they can fit any of the available group 31
batteries (if you choose this route.) This is looking toward the future
- any one choice may become unavailable or something better may come
along packaged in that group size.
This looks like it could be a good application for around 40 8v Golf
Cart batteries. These are true deep cycle batteries but each cell
doesn't have as many plates as the 6v GC batteries (plates split into 4
cells instead of 3) so they don't take high amp discharges very well.
If your AC drive is limited to less than 300 amps it could be a good
choice. Much of the bad rap that 8v GC lead has gotten with EVers seems
to be situations where the idea was to go from 120v of 6v batteries to
120v of 8v batteries (or similar, lower voltage, application) to reduce
weight and improve performance. The 8v battery complaints (excess
voltage sag) with higher amps killed off most of the performance gains
and demanding 400 amps or more reduced their life.
>
> The list goes on. The manufacturer's claims seem to be fairly
> similar, and
> I am wondering if these batteries actually perform
>
> as advertised. I am hoping for some real world experience to help me
> with a
> choice. I could go on for a while with a bunch of
>
> disjointed questions, but I would rather let you guys and/or gals tell
> me
> what you want to tell me.
I bet a bunch of us would love to build your pickup on your dime :-)
You have to build what you want. There are a lot of list members here
with plenty of experience. I'm sure you have already spotted a number
of names that stand out (I won't name any names to avoid embarrassment
from naming, or failing to name, individuals.) The key is to listen to
the opinions here and try to glean the pro's and con's they present.
Then make up your mind and 'go for it.' My first EV was a VW based
beach buggy (Manx style.) If I only listened to the negative I wouldn't
have attempted to convert it. I have been enjoying it since 1999.
Paul "neon" G.
WAR IS PEACE
FREEDOM IS SLAVERY
IGNORANCE IS STRENGTH
George Orwell, "1984"
--- End Message ---
--- Begin Message ---
A transformer will only work while the field is collapsing or expanding,
such as when AC changes polarity, or if the primary coil current is being
shut off and on (points).
David C. Wilker Jr.
USAF (RET)
----- Original Message -----
From: "Jake Oshins" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, January 02, 2007 3:33 PM
Subject: DC to DC converter - why isn't it just a big transformer?
I'm looking for a little basic education here. Why isn't a DC to DC
converter as simple as a big transformer?
Is it because building a transformer for 200VDC+ is prohibitive, either
for cost or weight?
Is it because we want a well-regulated output voltage?
I ask because I'm looking at making the existing power steering pump
work in my conversion project and I'm looking at using various surplus
motors that run on voltages significantly smaller than my pack voltage.
Using my fancy DC/DC converter to drive a 12V motor would use a lot of
its capacity for this task and I don't really care if the voltage this
aux motor runs on is well-regulated.
Thanks for any replies,
Jake Oshins
P.S. My main traction motor has only one output shaft, so running the
power steering pump from it would be difficult, though not impossible.
That's why I'm looking for other alternatives.
--- End Message ---
--- Begin Message ---
To not answer the question but solve the problem, you can buy permanent
magnet treadmill motors that will run on 160vdc, surpluscenter.com has a
2.5hp motor for $22,
http://www.surpluscenter.com/item.asp?UID=2007010301284115&item=10-1783&catname=electric
I bought one recently to run an AC compressor, they are brand new and
look good.
Jack
Dave Wilker wrote:
A transformer will only work while the field is collapsing or expanding,
such as when AC changes polarity, or if the primary coil current is
being shut off and on (points).
David C. Wilker Jr.
USAF (RET)
----- Original Message ----- From: "Jake Oshins"
<[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, January 02, 2007 3:33 PM
Subject: DC to DC converter - why isn't it just a big transformer?
I'm looking for a little basic education here. Why isn't a DC to DC
converter as simple as a big transformer?
Is it because building a transformer for 200VDC+ is prohibitive, either
for cost or weight?
Is it because we want a well-regulated output voltage?
I ask because I'm looking at making the existing power steering pump
work in my conversion project and I'm looking at using various surplus
motors that run on voltages significantly smaller than my pack voltage.
Using my fancy DC/DC converter to drive a 12V motor would use a lot of
its capacity for this task and I don't really care if the voltage this
aux motor runs on is well-regulated.
Thanks for any replies,
Jake Oshins
P.S. My main traction motor has only one output shaft, so running the
power steering pump from it would be difficult, though not impossible.
That's why I'm looking for other alternatives.
--- End Message ---
--- Begin Message ---
This thread has some very interesting points.
The cycle life of the pack is greatly reduced in real life. Numbers you
get in lab with one cell might be misleading.
If one wants to simulate laboratory enviroment in vehicle thats not very
easy. And far from practical.
For example the vehicle has to have quite effective cooling/heating to
keep ALL cells in similar tempereaures. Elevated temperatures and more
effective cooling for some cells will kill the cells unevenly. Some will
die sooner than others.
Same goes if you paraller the cells to get capacity up.
Same goes with cycles and vibration and terminal impedances.
Many of these effects can be "softened" but not removed with proper
management system. They are there. That's it.
It seems to be quite univerla regardless how with what you store the
energy.
The thing is that in what parameters we accept the operation of the
batteries. Generally we see lover mile-lifetime in EVs since the chassis
is eaten by rust long before bearings give up. That will change.
The usability of EV will be better with new batteries due longer range
and longer cycle life. Compared to Pb. Many of us drive with EVs even
with Pb. If performance is doubled... Imagine that. I remember my first
drives with Lithium three years ago. Still hooked. It's like drug.. The
feeling of freedom is unreal.. still. Drive 150 miles with one seating
and uh.. Before with Pb I worried about getting back from town which is
less than 10 miles away. Roundtrip 20 miles and mostly 50 mph.
Every Nano-thing seems to be so much better than other existing ones. I
have hard time to digest it all. This usually is more or less
generated by the marketing department.
BUT...
More these things pop up we are again closer to rEVolution. And I just
have to love it !! Go Altair, Go Valence, Go TS ! Go everybody with
new tech !
-Jukka
p.s.- Check out my "familycar" :) I fed up to be scared with my small EV
in the traffic... Now... I have my Finger up for Hummers. Let's see
who's the chiken now.... Eh he ehhee..
p.p.s.- http://www.austinev.org/evalbum/1009
Nick Austin kirjoitti:
On Tue, Jan 02, 2007 at 12:06:00PM -0500, Peter Eckhoff wrote:
<..snip..>
However, when you start to put cells together to form a battery, cycle
life tends to go down.
Interesting.
A 20,000 cycle battery (as opposed to a cell)
would be a 2.6 million mile pack at an average of 135 miles per cycle.
I'm sure the average miles per cycle will be MUCH less then that. 135 miles
is higher then the max range isn't it?
The contract for the initial order was for $750,000 for 10 vehicles. I
could see where someone would come up with $75K for each pack.
Another poster indicated that there are many nonrecurring costs built into the
price of the first packs.
Nick: Is your quote of approximately $14K per for a 35 kWh pack
correct?
Note that this was not my quote, it was from Kaido Kert.
($ 14K for a pack / 250K miles = 5.6 cents / mile.)
250Kmiles/135mile per cycle = 1851 cycles.
I think your miles per cycle figure is questionable.
Also, 250K miles sounds like another way of saying we don't know how long
this will last, but we do know that it'll be a very long time.
--- End Message ---
--- Begin Message ---
Well, the Festiva finally got here last night about 10:30, and I have to say
the T-875s in there are compleyely shot. It has 9500 miles on those batts, and
2 were so bad they were already taken out, so it is only running 88 V now.
What do you think about 8 x 12 V exide orbitals for my 4 mile round trip
commute? The car is about 2500 lb with the 13 T-875's. It has a 9" ADC motor
and 400 A Curtis controller. There is no DC-DC (all accys run off a seperate
battery). I like the idea of sealed batts.
My only concern is the BC-20 charger. Will it kill those batts? Also, I
heard real bad things about Exide 6 V flooded batts. FYI, I planned to buy
them at the Sam's Club. I think they are around $100 / ea.
Thanks,
Steve
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
--- End Message ---
--- Begin Message ---
Hi Steve and All,
----- Original Message Follows -----
From: Steve Powers <[EMAIL PROTECTED]>
To: [email protected]
Subject: Exide orbitals
Date: Wed, 3 Jan 2007 03:50:57 -0800 (PST)
>Well, the Festiva finally got here last night about 10:30,
>and I have to say the T-875s in there are compleyely shot.
>It has 9500 miles on those batts, and 2 were so bad they
>were already taken out, so it is only running 88 V now.
Congrats on your new EV!!
>
> What do you think about 8 x 12 V exide orbitals for my 4
>mile round trip commute? The car is about 2500 lb with the
>13 T-875's. It has a 9" ADC motor and 400 A Curtis
>controller. There is no DC-DC (all accys run off a
>seperate battery). I like the idea of sealed batts.
I don't think it's a good choice. Much better would
be some 60-72lb Trojan, USBattery 12vdc flooded batts to the
max your charger, controller can do. They will have over
2.5x's the range of Orbitals/batt while costing less and
much less likely to get murdered ;^D. Now add to that the
BMS regs you need to keep AGM's alive and the costs are just
too high for what you get. Maybe if you had a Zilla
controller it might be different.
Flooded batts are easy to take care of if you coat
the terminals and spray them down with a hose every month or
so.
>
> My only concern is the BC-20 charger. Will it kill those
>batts? Also, I heard real bad things about Exide 6 V
>flooded batts.
Orbitals are the only good Exide batt product and
they were/ are designed made in Spain when they bought it's
maker. Exides 6-8-12vdc batts ar not very good in EV's,
dieing early.
Jerry Dycus
FYI, I planned to buy them at the Sam's
>Club. I think they are around $100 / ea.
>
> Thanks,
>
> Steve
>
> __________________________________________________
>Do You Yahoo!?
>Tired of spam? Yahoo! Mail has the best spam protection
>around http://mail.yahoo.com
>
--- End Message ---
--- Begin Message ---
I wanted to thank you all for your input. It is always helpful to hear
another perspective.
I especially want to thank you, Paul for reminding me that there are two
sides to every problem. When choosing pack voltage, my thought was to keep
it as high as possible to reduce current thus increasing capacity/charge as
well as cycle life. I was concerned about voltage sag under load and had
completely ignored charge voltage. Which brings us to the next point: Is
there a quick way to predict what the voltage sag will be at a given
current? Also, is it a similar relationship under charge? (Charge current
being limited by internal resistance in the same proportion that discharge
current is limited) And along those lines, is there a way to predict
capacity at higher currents than are stated on the spec sheets? (Typically
75 amps) I do not completely understand the Peukert's number calculations
yet, but intuitively I think that it can not predict performance above a
measured current value.
Thanks for the help,
Roger
--- End Message ---
--- Begin Message ---
A DC-DC converter's main ingredient is a transformer. However, since
transformers require AC to work, a lot of additional circuitry is needed to
convert the DC to AC to supply the transformer, and then back to DC after the
transformer. Voltage or current ratings are not prohibitive for transformers.
Actually, none of the individual parts in a DC-DC converter is especially
expensive; it's just that there are lots of parts involved.
Hope that helps...
Ken
-----Original Message-----
From: [EMAIL PROTECTED]
To: [email protected]
Sent: Tue, 2 Jan 2007 8:05 PM
Subject: RE: DC to DC converter - why isn't it just a big transformer?
Transformers can only work with an alternating current (AC). Therefore some
special circuitry is required to change the voltage of a DC current.
Don Cameron, Victoria, BC, Canada
see the New Beetle EV project www.cameronsoftware.com/ev
---------------------------------------------------
"It is not the critic who counts: not the man who points out how the strong
man stumbles or where the doer of deeds could have done better. The credit
belongs to the man who is actually in the arena, whose face is marred by
dust and sweat and blood, who strives valiantly, who errs and comes up short
again and again, because there is no effort without error or shortcoming,
but who knows the great enthusiasms, the great devotions, who spends himself
for a worthy cause; who, at the best, knows, in the end, the triumph of high
achievement, and who, at the worst, if he fails, at least he fails while
daring greatly, so that his place shall never be with those cold and timid
souls who knew neither victory nor defeat." - Teddy Roosevelt
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Jake Oshins
Sent: January 2, 2007 3:33 PM
To: [email protected]
Subject: DC to DC converter - why isn't it just a big transformer?
I'm looking for a little basic education here. Why isn't a DC to DC
converter as simple as a big transformer?
Is it because building a transformer for 200VDC+ is prohibitive, either for
cost or weight?
Is it because we want a well-regulated output voltage?
I ask because I'm looking at making the existing power steering pump work in
my conversion project and I'm looking at using various surplus motors that
run on voltages significantly smaller than my pack voltage.
Using my fancy DC/DC converter to drive a 12V motor would use a lot of its
capacity for this task and I don't really care if the voltage this aux motor
runs on is well-regulated.
Thanks for any replies,
Jake Oshins
P.S. My main traction motor has only one output shaft, so running the power
steering pump from it would be difficult, though not impossible.
That's why I'm looking for other alternatives.
________________________________________________________________________
Check out the new AOL. Most comprehensive set of free safety and security
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--- End Message ---
--- Begin Message ---
The guy that told me about the radio said that he used that method for over
2 years successfully on an ICE car in storage.
Joseph H. Strubhar
E-mail: [EMAIL PROTECTED]
Web: www.gremcoinc.com
----- Original Message -----
From: "Lee Hart" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, January 02, 2007 11:52 AM
Subject: Re: Rats attacking EV wiring (was Hairball control wire sizing
> Roland Wiench wrote:
> > If rats do not like light, then how about a bright flashing LED's that
will
> > work off 9 to 12 volts. Could keep it on all the time while the
ignition is
> > off.
>
> The problem with lights (or noises, or smells, or whatever) is that
> animals get used to them. At first, they're scared off by their fear of
> the unknown. But when nothing bad happens, they learn to ignore them.
>
> --
> 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
>
>
>
>
> --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.432 / Virus Database: 268.16.1/611 - Release Date: 12/31/2006
12:47 PM
>
>
--- End Message ---
--- Begin Message ---
In mounting this type of treadmill motor, it is best to mounted a
reinforcing plate to the front large flange that holds the bearing. The
force in one direction apply to the motor shaft, will provide wear on this
flange until the rotor will hit the fields.
Our local motor shop replace 100's of these motors, instead of rebuilding
them because the front flange collaspes to one side which is weaken by the
air flow holes in this flange.
I am installing a 1/4 inch aluminum plate on the face with holes for air
flow and another 1/4 inch plate behind this motor flange that is tight
fitting against the body of the motor.
Ran two of these motors on my test bench in series on 180 volts battery pack
which drop the voltage to each motor to 89.9 volts at 18.5 amps.
The load I use is a 63 amp alternator that has been converted to 110 vdc
which I can switch in a 120V resistance load such as heater coils or lamps.
Roland
----- Original Message -----
From: "Jack Murray" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, January 03, 2007 12:27 AM
Subject: Re: DC to DC converter - why isn't it just a big transformer?
> To not answer the question but solve the problem, you can buy permanent
> magnet treadmill motors that will run on 160vdc, surpluscenter.com has a
> 2.5hp motor for $22,
> http://www.surpluscenter.com/item.asp?UID=2007010301284115&item=10-1783&catname=electric
> I bought one recently to run an AC compressor, they are brand new and
> look good.
> Jack
>
> Dave Wilker wrote:
> > A transformer will only work while the field is collapsing or expanding,
> > such as when AC changes polarity, or if the primary coil current is
> > being shut off and on (points).
> >
> >
> >
> > David C. Wilker Jr.
> > USAF (RET)
> >
> >
> > ----- Original Message ----- From: "Jake Oshins"
> > <[EMAIL PROTECTED]>
> > To: <[email protected]>
> > Sent: Tuesday, January 02, 2007 3:33 PM
> > Subject: DC to DC converter - why isn't it just a big transformer?
> >
> >
> >> I'm looking for a little basic education here. Why isn't a DC to DC
> >> converter as simple as a big transformer?
> >>
> >>
> >>
> >> Is it because building a transformer for 200VDC+ is prohibitive, either
> >> for cost or weight?
> >>
> >>
> >>
> >> Is it because we want a well-regulated output voltage?
> >>
> >>
> >>
> >> I ask because I'm looking at making the existing power steering pump
> >> work in my conversion project and I'm looking at using various surplus
> >> motors that run on voltages significantly smaller than my pack voltage.
> >> Using my fancy DC/DC converter to drive a 12V motor would use a lot of
> >> its capacity for this task and I don't really care if the voltage this
> >> aux motor runs on is well-regulated.
> >>
> >>
> >>
> >> Thanks for any replies,
> >>
> >> Jake Oshins
> >>
> >>
> >>
> >> P.S. My main traction motor has only one output shaft, so running the
> >> power steering pump from it would be difficult, though not impossible.
> >> That's why I'm looking for other alternatives.
> >>
> >
> >
>
>
--- End Message ---
--- Begin Message ---
Here is what Lee Hart had to say about modifying an SCR for better
effeciency. It's basically a capacitor bank to eliminate ripple effect.
Lawrence Rhodes.....
Lawrence Rhodes wrote:
> I have an SCR based controller in the Electravan that switches
> at 1500 hz with inadequate filtering on the battery side.
> Is it possible that the battery sees high current pulses and
> behaves more like it is discharging at 1000 amps than 100 and
> consequently has much less capacity.
Yes, it is possible; even probable. You can measure the battery ripple
current with a multimeter. Measure across your battery current shunt, or
pick two spots along one of the wires from your batteries to the
controller. For example, the positive terminal of the battery and the
other end of that wire that connects to the controller. The voltage drop
in this wire is proportional to current.
Connect wires from these points to your multimeter, and go for a drive.
While cruising at some constant speed, measure the DC voltage and the AC
voltage. Their ratio is the percent ripple current. If the AC voltage is
more than about 10% of the DC voltage, then your batteries would benefit
from the addition of filter capacitors.
These old SCR controllers usually didn't have a large input filter
capacitor bank. There were several reasons.
First, they expected them to be used with huge forklift batteries, which
already have lots of capacitance (a "mere" 1000 amp load for these
batteries isn't a high rate :-) They may not have been aware that lack
of capacitors would be a problem for lower-capacity higher-resistance
batteries.
Or they knew, but were concerned about the reliability of electrolytic
capacitors. Modern electrolytics are merely bad -- back then they were
even worse! Note that a 20-year-old SCR controller still works; if they
had used electrolytics, it wouldn't!
Or, they knew and just wanted to save money.
You can add the filter capacitors yourself. You need to connect them as
close to the controller's input as you can, with as short and heavy a
wire as possible.
We don't have enough data to calculate a value, but it's going to take
thousands of microfarads. If it were me, I'd look for some surplus
electrolytics intended for switching power supply filtering, and put in
1,000uf worth. Measure your ripple current again, and see how much it
dropped. Then you can guess how much more it will take.
--
Ring the bells that you can ring
Forget your perfect offering
There is a crack in everything
That's how the light gets in
-- Leonard Cohen, from "Anthem"
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
Lawrence Rhodes wrote:
> I have a 120v 20 battery pack. Weighs 1400 pounds. Lee recommended
> 1000uf and check again. What is the problem of putting in a few
> thousand?
No direct harm; the more, the merrier.
However, the goal here is to reduce the battery ripple current. With
perfect zero-resistance capacitors, 1000uF is plenty because almost all
the controller's ripple current will then flow in the capacitors, not
the batteries.
However, real capacitors also have resistance, called ESR on the data
sheets (Equivalent Series Resistance). Capacitor ESR diverts ripple
current back to the batteries. ESR also produces heat, making the
capacitors get hot. It ultimately determines the maximum ripple current
that the capacitor can stand without overheating.
So, your goal is a capacitor with:
a. At least 1000uF of capacitance.
b. An ESR at least as low as your batteries ESR.
For example, an Optima has an ESR of about 0.003 ohms.
A pack of 10 has a total ESR of 10x0.003 = 0.03 ohms.
Add 20 connections at 0.001 ohm each = 0.05 ohms total.
So you want a capacitor with an ESR of 0.05 ohms or less.
c. A ripple current rating of at least 1/4th your motor current.
400 amp motor current means the controller is switching between
0 and 400, which is +/-200 amps peak AC ripple, which is about
100 amps RMS.
What you'll find is that its easy to find a 1000uF electrolytic
capacitor; but its ESR will be 1 ohm and its ripple current rating is
only 5 amps. Just one provides the capacitance, but you'd need 20 of
them in parallel to satisfy the ESR and ripple current requirements.
This is what you see in many controllers; a large number of cheaper
electrolytics, with far more capacitance than needed just to get the
ripple and ESR ratings.
Or, oil-filled paper or polypropylene film capacitors can easily meet
the ESR and ripple current requirements; but their capacitance is low. A
big metal can oil-filled capacitor can have 20uF of capacitance, 0.1 ohm
ESR, and a 25-amp ripple current rating. You'd need only 4 of them for
ESR and ripple, but 50 to get the capacitance. These capacitors would be
a lot larger and more expensive than electrolytics. So what you see in
some controllers are a smaller number of electrolytics (just to get the
capacitance), in parallel with a smaller number of oil or film
capacitors (to get the ESR and ripple ratings).
That's why I suggested that you experiment.
--
Ring the bells that you can ring
Forget your perfect offering
There is a crack in everything
That's how the light gets in
-- Leonard Cohen, from "Anthem"
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart
Lawrence Rhodes wrote:
> Lee I hop I'm not bothering you too much but I didn't want to blow
> anything up.
Aw, you're no fun! You should always have kids around when you blow up
capacitors. They enjoy the pyrotechnics. :-)
When you get an electrolytic capacitor that has been sitting unused for
a long time, you have to re-form its dielectric. Connect it to a high
voltage power source (like 150 vdc) with a resistor in series to limit
the current to no more than a few milliamps (like 100k ohms). Let it sit
until the capacitor voltage stops rising -- it will take 1-24 hours
depending on how long they have sat. If a capacitor won't rise to its
rated voltage without drawing more than 1 ma, consider it "bad".
You can also estimate their real capacitance at the same time. R x C is
the time constant -- the time it should take to charge to 2/3rds of the
applied voltage. 440uf x 100k = 44 seconds, so it should take 44 seconds
to charge to 2/3 * 150v = 100v. This will also weed out any bad ones.
> These are the silver ones General Electric 92F311AMMA, 440UF -10+50%,
> 150vdc 200v surge, 85C Max Ambient. I got 10 of these. Should I put
> them all on the positive or negative side or split them on each leg?
> Do I have enough?
Put all of them in parallel, + to +, - to -. Since you're after the
lowest resistance, the usual method is to get two flat strips of copper
bus bar, drill holes for the capacitor's screws, and screw them to the
bar.
You connect the resulting "big" capacitor directly across the
controller's battery + and - inputs. Again, this should be done with
short, heavy wire or bus bars. If you don't have a precharge resistor,
you should add one; if the main contactor closes and tries to charge all
of these capacitors instantly, it will be murder on the contacts.
I described a method to find out how much/many capacitance is needed
based on the ripple current. Too few capacitors, and they will get hot
and not do much good. More is always better, but you reach a point where
the extra cost and weight isn't worth the slight improvement.
--
Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has! -- Margaret Mead
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
Lawrence Rhodes wrote:
> So I put the plus buss bar on the positive end of the big capacitor
> and the neg end of the big capacitor on the neg side of the pack.
> Now I have the caps in parallel with the pack. Won't they just
> charge by themselves now?
The capacitors connect directly across the CONTROLLER's B+ and B-
inputs, with the shortest fattest possible leads. The controller draws
pulses of current, and we want these pulses to come from the capacitors,
not the batteries.
I assume you have contactors, fuses, circuit breakers, a big disconnect
switch, or SOMETHING between the batteries and controller. That means
there will be times that one or more of these is open. When you close
it, the capacitors will try to charge INSTANTLY, leading to huge
currents which will damage the contacts of the last device to close. The
precharge resistor is intended to slowly charge the capacitors over a
second or two; then close the last switch.
> like the air pocket used in water system to stop the pipes from
> vibrating which I guess is what ripple current is.
Yes, it is basically the same thing that plumbers call "water hammer".
> I'll try 10 caps and check for heat. Then I'll add more. I'll also
> try weeding out the caps by charging with a variac.
...and a diode! Remember these are DC capacitors!
--
Humanity is acquiring all the right technology for all the wrong
reasons.
-- R. Buckminster Fuller
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
----- Original Message -----
From: "Darin - MetroMPG.com" <[EMAIL PROTECTED]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Tuesday, January 02, 2007 2:50 PM
Subject: Joe Sixpack Geo: best controller SCR, Curtis or contactors? (Or
some combination)
> With info & tips from Steve Powers and Roger Stockton, I got the old
> EV-1 controller properly hooked up on the bench and working (with a
> lightbulb to test output). A Rube Goldberg dimmer switch! Thanks, guys.
>
> Now the question is: *should* I use it in the car? :-)
>
> I've been spending time in the archive reading people's views about the
> relative advantages & disadvantages of MOSFET vs. SCR controllers vs.
> contactor controllers. If the goal is to do what's best for battery
> longevity & most range per charge (town driving), what should I do?
>
> Given these requiremente & constraints:
>
> - The car's intended use is as a low speed (35-40 mph max would be
> adequate), short-range (20 km would be fine) runabout in a small town.
>
> - Snappy performance isn't required by the driver or demanded by other
> (relatively sparse) traffic. Tooling along quietly will be satisfying
> "performance" in itself.
>
> - As mentioned, I've already got an OEM 24-48v SCR GE EV-1 controller
> (with OEM bypass circuit).
>
> - I have half a dozen beefy contactors (and a big field-weakening
> resistor) that could be used to make a contactor controller (CC).
>
> - I could spend 100 bucks (shoe-string budget) to pick up a low end
> 24-48v Curtis controller around 275 A.
>
> - Haven't bought batteries yet, but it'll likely be six or eight 6v
> floodies.
>
> Since I already have the SCR and it works, I'm tempted to just start
> with that. But I understand its lack of capacitors on the input side
> makes it relatively hard on the batteries (shortening life & range)
> compared to a Curtis or a CC.
>
> A hundred buck Curtis may be better for the batteries, but a cheap one
> will have much lower performance (acceleration & max speed, relative to
> the EV-1 or CC).
>
> The CC approach is appealing for its simplicity & efficiency, but I have
> read some people question its effect on range (since it draws lots of
> current each time the controller switches "up" until the motor gains
> speed after each switch). Of course on long stretches at constant
> speed, the CC is more efficient, but I'll probably be doing *mostly*
> sub/urban driving (not many long stretches at a time).
>
> What about a "hybrid" approach: the Curtis for starting and very low
> speed, with some contactors for cruising speed?
>
> Also: I'm perfectly willing to adapt my driving to make the best use of
> whichever setup, and to try not to wreck things (eg. avoiding full accel
> from stop with a CC setup). Learning how to drive the system for good
> range is a whole other thread...
>
> Darin
>
--- End Message ---
