EV Digest 3823
Topics covered in this issue include:
1) Re: Thunder Sky & AGM hybrid pack Re: Thundersky Lithium
by Victor Tikhonov <[EMAIL PROTECTED]>
2) Re: newbie questions, Diablo conversion
by Lee Hart <[EMAIL PROTECTED]>
3) Re: resistor question
by "Mark Thomasson" <[EMAIL PROTECTED]>
4) Re: 750w scooter
by [EMAIL PROTECTED]
5) Re: FW: controller precharge circuit
by Lee Hart <[EMAIL PROTECTED]>
6) RE: Deafscooter's 1 St place on Route 66 Rally 9/25
by "Roger Stockton" <[EMAIL PROTECTED]>
7) RE: newbie questions, Diablo conversion
by "Klemkosky, Mark A" <[EMAIL PROTECTED]>
8) Re: newbie questions, Diablo conversion
by "Simon Sandvik" <[EMAIL PROTECTED]>
9) Re: Calculating size of Capacitor for Electric PS Pump
by Victor Tikhonov <[EMAIL PROTECTED]>
10) Re: newbie questions, Diablo conversion
by Victor Tikhonov <[EMAIL PROTECTED]>
11) RE: End CyberSquatting
by "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
12) RE: Calculating size of Capacitor for Electric PS Pump
by "Don Cameron" <[EMAIL PROTECTED]>
13) Re: EV Units and Capacitors
by "Arthur Matteson" <[EMAIL PROTECTED]>
14) Re: Current Eliminator News...New major sponsor!!!
by [EMAIL PROTECTED]
15) Re: Street legal?
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
16) Zivan Charger
by "EV Racer" <[EMAIL PROTECTED]>
17) Re: Thunder Sky & AGM hybrid pack Re: Thundersky Lithium
by Lee Hart <[EMAIL PROTECTED]>
18) Everything breaks at once
by Rod Hower <[EMAIL PROTECTED]>
19) Do the ultracapacitors work? (with links to data, was: Diablo conversion)
by Victor Tikhonov <[EMAIL PROTECTED]>
--- Begin Message ---
Emil Naepflein wrote:
On Sat, 25 Sep 2004 07:20:55 -0700, "Don Cameron"
<[EMAIL PROTECTED]> wrote:
On Victor's page for Ultacaps
(http://www.metricmind.com/ac_honda/ultracaps.htm), he cites many benefits
for using Ultra Caps vs PbA:
- no charging and equalization
You definitely need equalization. Because of the lower voltage range you
even need more equalization circuits.
What I meant was you don't need the same equalization complexity
as for a battery (shunt regulators, or like). Simple resistor
network will do. You cannot practically equalize batteries
with resistors in parallel.
Perhaps I should edit the web site to clarify this.
--
Victor
'91 ACRX - something different
--- End Message ---
--- Begin Message ---
Don Cameron wrote:
> Simon, I think you should still have a open mind to the ultracap
> solution... Victor's page for Ultacaps cites many benefits...
> - no charging and equalization
> - lifecycles > 500,000
> - DOD to 100%
> - no maintenance
I agree; we should keep an open mind. That means not writing them off as
a "wild, unproven solution" -- and also not embracing them as "miracle
cure" that should be adopted without question. Ultracapacitors are just
another tool in our designer's toolbox. Use them when they solve a real
problem -- and don't use them when they don't!
A feature list like the above is written by Marketing. It's what they
HOPE is true, and what they WANT you to believe so you'll buy them. But
it has NOT been proven as fact.
- no charging...
Obviously, you need to charge them. Every watt you take out must have
been put in (plus a bit more, because they aren't 100% efficient). I
think it is inevitable that there will be some kind of charge controller
for the capacitors -- this is just another name for a charger.
If you avoid such a controller (by parallelling the capacitors with a
main pack, perhaps with a diode or contactor or two), then you can't
control the capacitor's state of charge. You won't get any large voltage
change on the capacitors, and so won't be able to use most of their
energy storage capability. In effect, it's like having a battery that
you can't fully charge or discharge, so you can never make use of its
full capacity.
And, if you depend on trading energy back and forth with a main battery,
then you are suffering an efficiency "hit" for each transfer in/out.
> - no equalization...
Just as for batteries, if you have no equalization, then you have no way
to balance out differences between cells. It only works if you have
perfectly identical cells, that never drift. This isn't true in the real
world. So, you still need an equalization method with capacitors. Leave
it out, and you'll have capacitor failures from reversed polarity or
excessive voltage.
I think Victor is using resistors across his capacitor cells (equivalent
to Rudman regulators for lead-acid batteries). Can you elaborate,
Victor?
> - lifecycles > 500,000
Note that *every* new technology always claims "infinite" life. That's
before they've run any life tests, and so don't know what the failure
mechanisms are.
Ultracapacitors are a lot like electrolytic capacitors. Electrolytics
have been around long enough that we know they have serious life and
performance limitations, especially due to temperature and aging. They
are better than batteries, but still among the least reliable electronic
components we have.
So, I have to assume that ultracapacitors will have a life expectancy
like electrolytic capacitors. That means you get long cycle life only at
very shallow depth of discharge, serious performance degradation at low
temperatures, major reductions in life at high temperatures, and big
changes in performance if they are left sitting for long periods.
However, batteries have these problems, too. So, the big (unanswered)
question is whether ultracapacitors will turn out to be better (or
worse) than similarly-priced batteries.
> - DOD to 100%
Well; yes, with limitations. The big one is that go go from 0% to 100%,
you have to take the voltage from 0v to max. This is too wide a range to
be practical. Even with an expensive DC/DC converter, you are unlikely
to be able to get more than a 4:1 range. That limits the range to
15-100%.
Without equalization, you can't get near 0% or 100% without risking some
cells going negative or overvoltage. That means you probably can't go
any higher than 90%, for a 15-90% range.
> - no maintenance
Which is the same claim made for all sealed batteries. I don't think we
have any evidence yet that ultracapacitors have any less maintenance
than sealed batteries.
In any system consisting of dozens or hundreds of sealed cells
(batteries or capacitors), "maintenance" really means periodically
checking them, and replacing the bad cells. This has to be done on some
time frame, usually 6 months to a few years.
Of course, in many cases, the cells are bonded together in groups (a
"battery"), and you *can't* replace individual cells. Sure -- this
lowers maintenance cost -- by replacing it with higher replacement cost.
I think it is important to make a distinction between an experimental
solution and a practical solution.
Summary
So, where does this leave us? Why should we consider
super/ultra/whatever capacitors? Because, they are another tool in our
"toolbox", one that can do things the other solutions can't.
Capacitors, batteries, and fuel cells are all very similar devices. They
do much the same job, and can be rated with the same specifications.
They are built much the same; two plates, with an electrolyte between
them. There is a continuous range of products blurring all the way from
dry film capacitors at one extreme, to fuel cells at the other extreme.
Energy storage, peak energy
watthours/pound technology watts/pound
--------------- ------------------------------ -----------
worst dry film capacitor best
oil-impregnated film capacitor
| electrolytic capacitor /|\
| super- or ultra-capacitor |
| sealed battery |
\|/ flooded battery |
electroplating cell
best fuel cell worst
Energy storage is what gives you range; like "gallons of gasoline". It's
your "fuel" tank. Once you know a technology's watthours/pound, you can
readily figure out how many pounds of it you need for a given range.
Peak energy is what gives you power to accellerate or climb hills; like
"horsepower". Once you know a technology's peak energy capability, and
how many pounds of it you have, you know how many horsepower it can
produce.
If you have only one type of energy storage device in your car, then
energy storage and peak energy are tied together -- pick one, and you
have picked the other. For instance, pick sealed batteries; you get
"fairly good" range and "fairly good" accelleration.
Or if you want more range, you pick flooded batteries. Range goes up,
but accelleration goes down because they can't deliver the sustained
high currents needed. This is the classic tradeoff we are stuck with in
EVs.
Ultracapacitors provide an alternative. If part of the flooded back is
replaced with capacitors, then they provide the high peak current. You
get your acceleration back (at least briefly; until the capacitors run
out of stored energy).
But, you have also reduced your range. If your pack weight now consists
of 90% flooded batteries and 10% capacitors, you have lowered your
energy storage (to around 91% of what it was with an all-battery pack).
The key question you have to decide is... is the increase in peak energy
enough to compensate for the loss in energy storage?
The farther your main pack goes down this chart (toward high energy
storage and worse peak energy), the more attractive something like
ultracapacitors look.
But ultimately, you have to run the numbers (and do the tests to verify
that the numbers aren't just marketing lies).
--
"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
--- End Message ---
--- Begin Message ---
Sharon, Try one on the bench at 48 volts. Use your finger on the coil to
see if it gets hot. If you can still leave your finger on the coil after
its been energized for its typical service time (say 1 hour), you are good
to go.....don't bother using a resistor. Mark T.
----- Original Message -----
From: "goodsharonwbird" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, September 27, 2004 5:47 PM
Subject: resistor question
> Hi Guys, I have a problem, I need to know how big a risistor I will
> need to go from 48 volts to 36 volts..its for a few main contactors
> I have to put on a Ranger im converting I have a bunch of older
> contactors,that are in great shape, so why not use them ,,Thanks
> again Sharon
>
--- End Message ---
--- Begin Message ---
Lawrence,
The El Chopper guy is John Bidwell. You can find his plans listed on
_http://www.megawattmotorworks.com/_ (http://www.megawattmotorworks.com/)
Mike Bachand
Denver Electric Vehicle Council
Newsletter Editor and Web Administrator
--- End Message ---
--- Begin Message ---
Markus L wrote:
>
> >
> > You generally don't use relays alone for measuring voltage;
> > the pull-in and drop-out voltages for the coil vary too much.
> > There are special relays to do this (meter relays), but I
> > doubt that's what you're thinking of. A better solution is to
> > use a voltage-sensing part; for example, a zener diode in
> > series with the coil.
>
> Lee thanks for your reply. The type of relay you mention here is exactly
> what I was talking about - I refered to them as voltage monitoring relays.
> The one I found can monitor up to 500Vdc
> (http://www.pilz.com/english/products/cmt/monitoring/voltage.htm)
> and costs a bit over $100. I know these relays from large machine controls
> that e.g. monitor if all three phases of AC voltage are present etc.
>
> I had exactly the same thing in mind that you do with your circuit below
> except that I wanted to use the voltage monitoring relay instead of the
> Zener diode ... however the zener would be much cheaper. The one thing I
> thought of that would be a nice to have is the ability to mutually exclude
> the possibility to
> try and move the vehicle while the main positive contactor has
> not yet closed. As this would result in a fused precharge
> relay and burned precharge resistors.
>
> What type of Zener diode would I need to make your circuit
> work at about 300V?
The zener I needed was 90v, but that's not a standard value. I actually
used two 24v zeners in series and a 3k pot (because it was what I had
handy). It also made it easier to adjust it to get the voltage I wanted.
For your case, I'd use a string of however many zeners it takes as long
as they add up to something close to the desired voltage. Including a
pot also makes it easy to adjust it, in case your pack voltage changes
someday.
--
"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
--- End Message ---
--- Begin Message ---
Lawrence Rhodes [mailto:[EMAIL PROTECTED] wrote:
> I have got to say this is an inspiration to all electric
> racers. In his class he has squashed all the gassers. To be
> honest though he is in a much higher class than the gassers
> performance wise. It's nice to see an ev beatup all the
> gassers.
Not to belittle Craig's accomplishments, but first place in a field of
one electric scooter is not really inspirational. How do we know he
beat up all the gassers when we don't know anything about the
performance achieved by any other participant in the rally?
57MPH peak speed is impressive, but was it downhill, uphill, or on the
flat? And, how does it compare to the peak speeds of the other
scooters?
What was the average speed (Craig and everyone else)? It seems Craig
used 2 sets of batteries to complete the rally, one 48V set of 40Ah
Hawkers, and one 48V set of 12Ah batteries. This is a total of nearly
2.5kWh, which works out to 50Wh/mi over 50mi. A typical scooter with a
pair of 12Ah batteries that goes 10mi achieves 29Wh/mi. So, was Craig's
performance reasonable or exceptional? Does it appear to verify that
his latest high performance/high efficiency motor is more efficient than
a typical scooter's?
Is there any place that actually documents the participants in each
class of this event along with what prizes/titles were won and by who?
The AMMRA site <http://www.ammra.com/Rt.66Rally4.html> only seems to
keep a photo album of each event; no record of who won what place in
what class, out of what field of competitors, etc.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
After all this discussion on ultracaps, I started wondering if it is
better to have dual strings of smaller batteries or one string of larger
batteries with a string of ultracaps in parallel. The 2600F ultracap
that Maxwell sells can product 600A according to their spec. Wouldn't
just having the caps in parallel with the battery pack provide a
significant boost when the motor is under heavy demand and then just
sit by idly during normal operation? I'm just curious what the thoughts
may be on this arrangement.
On a side note, I asked Maxwell for a quote on the 2600F 2.5v caps
that they sell. The quote they gave me had a confidentiality statement
attached, but in the range of volumes that I wanted (~100), the cost
per Farad is not close to what their website has as their "goal" price.
Until prices come down, I'm not quite sure of the viability of their
units for normal home fabricated EV's...
Mark
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Lee Hart
Sent: Tuesday, September 28, 2004 3:40 PM
To: [EMAIL PROTECTED]
Subject: Re: newbie questions, Diablo conversion
Don Cameron wrote:
> Simon, I think you should still have a open mind to the ultracap
> solution... Victor's page for Ultacaps cites many benefits...
> - no charging and equalization
> - lifecycles > 500,000
> - DOD to 100%
> - no maintenance
I agree; we should keep an open mind. That means not writing them off as
a "wild, unproven solution" -- and also not embracing them as "miracle
cure" that should be adopted without question. Ultracapacitors are just
another tool in our designer's toolbox. Use them when they solve a real
problem -- and don't use them when they don't!
A feature list like the above is written by Marketing. It's what they
HOPE is true, and what they WANT you to believe so you'll buy them. But
it has NOT been proven as fact.
- no charging...
Obviously, you need to charge them. Every watt you take out must have
been put in (plus a bit more, because they aren't 100% efficient). I
think it is inevitable that there will be some kind of charge controller
for the capacitors -- this is just another name for a charger.
If you avoid such a controller (by parallelling the capacitors with a
main pack, perhaps with a diode or contactor or two), then you can't
control the capacitor's state of charge. You won't get any large voltage
change on the capacitors, and so won't be able to use most of their
energy storage capability. In effect, it's like having a battery that
you can't fully charge or discharge, so you can never make use of its
full capacity.
And, if you depend on trading energy back and forth with a main battery,
then you are suffering an efficiency "hit" for each transfer in/out.
> - no equalization...
Just as for batteries, if you have no equalization, then you have no way
to balance out differences between cells. It only works if you have
perfectly identical cells, that never drift. This isn't true in the real
world. So, you still need an equalization method with capacitors. Leave
it out, and you'll have capacitor failures from reversed polarity or
excessive voltage.
I think Victor is using resistors across his capacitor cells (equivalent
to Rudman regulators for lead-acid batteries). Can you elaborate,
Victor?
> - lifecycles > 500,000
Note that *every* new technology always claims "infinite" life. That's
before they've run any life tests, and so don't know what the failure
mechanisms are.
Ultracapacitors are a lot like electrolytic capacitors. Electrolytics
have been around long enough that we know they have serious life and
performance limitations, especially due to temperature and aging. They
are better than batteries, but still among the least reliable electronic
components we have.
So, I have to assume that ultracapacitors will have a life expectancy
like electrolytic capacitors. That means you get long cycle life only at
very shallow depth of discharge, serious performance degradation at low
temperatures, major reductions in life at high temperatures, and big
changes in performance if they are left sitting for long periods.
However, batteries have these problems, too. So, the big (unanswered)
question is whether ultracapacitors will turn out to be better (or
worse) than similarly-priced batteries.
> - DOD to 100%
Well; yes, with limitations. The big one is that go go from 0% to 100%,
you have to take the voltage from 0v to max. This is too wide a range to
be practical. Even with an expensive DC/DC converter, you are unlikely
to be able to get more than a 4:1 range. That limits the range to
15-100%.
Without equalization, you can't get near 0% or 100% without risking some
cells going negative or overvoltage. That means you probably can't go
any higher than 90%, for a 15-90% range.
> - no maintenance
Which is the same claim made for all sealed batteries. I don't think we
have any evidence yet that ultracapacitors have any less maintenance
than sealed batteries.
In any system consisting of dozens or hundreds of sealed cells
(batteries or capacitors), "maintenance" really means periodically
checking them, and replacing the bad cells. This has to be done on some
time frame, usually 6 months to a few years.
Of course, in many cases, the cells are bonded together in groups (a
"battery"), and you *can't* replace individual cells. Sure -- this
lowers maintenance cost -- by replacing it with higher replacement cost.
I think it is important to make a distinction between an experimental
solution and a practical solution.
Summary
So, where does this leave us? Why should we consider
super/ultra/whatever capacitors? Because, they are another tool in our
"toolbox", one that can do things the other solutions can't.
Capacitors, batteries, and fuel cells are all very similar devices. They
do much the same job, and can be rated with the same specifications.
They are built much the same; two plates, with an electrolyte between
them. There is a continuous range of products blurring all the way from
dry film capacitors at one extreme, to fuel cells at the other extreme.
Energy storage, peak energy
watthours/pound technology watts/pound
--------------- ------------------------------ -----------
worst dry film capacitor best
oil-impregnated film capacitor
| electrolytic capacitor /|\
| super- or ultra-capacitor |
| sealed battery |
\|/ flooded battery |
electroplating cell
best fuel cell worst
Energy storage is what gives you range; like "gallons of gasoline". It's
your "fuel" tank. Once you know a technology's watthours/pound, you can
readily figure out how many pounds of it you need for a given range.
Peak energy is what gives you power to accellerate or climb hills; like
"horsepower". Once you know a technology's peak energy capability, and
how many pounds of it you have, you know how many horsepower it can
produce.
If you have only one type of energy storage device in your car, then
energy storage and peak energy are tied together -- pick one, and you
have picked the other. For instance, pick sealed batteries; you get
"fairly good" range and "fairly good" accelleration.
Or if you want more range, you pick flooded batteries. Range goes up,
but accelleration goes down because they can't deliver the sustained
high currents needed. This is the classic tradeoff we are stuck with in
EVs.
Ultracapacitors provide an alternative. If part of the flooded back is
replaced with capacitors, then they provide the high peak current. You
get your acceleration back (at least briefly; until the capacitors run
out of stored energy).
But, you have also reduced your range. If your pack weight now consists
of 90% flooded batteries and 10% capacitors, you have lowered your
energy storage (to around 91% of what it was with an all-battery pack).
The key question you have to decide is... is the increase in peak energy
enough to compensate for the loss in energy storage?
The farther your main pack goes down this chart (toward high energy
storage and worse peak energy), the more attractive something like
ultracapacitors look.
But ultimately, you have to run the numbers (and do the tests to verify
that the numbers aren't just marketing lies).
--
"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
--- End Message ---
--- Begin Message ---
Hi all!
Well how about this t�hen:
Why not use Li-Ion with AGMs AND UltraCaps(for racing)?
/Simon
----- Original Message -----
From: "jerry dycus" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, September 28, 2004 9:36 PM
Subject: Re: newbie questions, Diablo conversion
> Hi Simon and All,
> --- Simon Sandvik <[EMAIL PROTECTED]> wrote:
>
> > Thanks Victor.
> > Ok people what should I go with?
> > Li-Ions and Ultracaps or Li-Ions and lead acids?
> > What about the difference in weight?
>
> It will be interesting the numbers Victor comes up
> with. I believe they will show the uselessness of UC's
> for an EV on the road in the real world.
> For the road you need multipile and prolonged
> power surges that UC's can't handle. If you only
> needed them for a sec or two, they would be costly but
> cool, but real world EV power needs don't stick to
> very short bursts.
> Notice Victor is the only one using them in a road
> EV I know about and he just annouced it recently. He
> also uses them in a low power AC system, not a high
> power unit like you are going for.
> >
> > It looks like the best alternative would be to use
> > 62x TS (223V)
> > and 18x Exides/Optimas(216V).
> > Am I right?
>
> The problem with Orbitals for you is keeping the
> weight down to your goals, otherwise they are quite
> good in the power department, in fact they can't be
> beat by anything I know of and put UC's to shame.
> That's why I was talking about Hawker's, to save
> weight.
> Optima YT are not what they use to be after they
> were bought out so would go with the Orbitals which
> put out more power anyway for the same weight.
> One way to save weight is go to a lower voltage
> system like the top voltage of the low voltage version
> of the Zilla. Then get your range with li-ions.
> At your weight this will still give you plenty of
> power while keeping your weight and costs down
> compared with the higher voltage version. Hawker 26
> amphr batts would save weight even more at the cost of
> some power.
> As your pervious post about trans, with the Zilla
> the torque is so high it destroy's them quickly. Since
> the torque is high, you can go direct drive straight
> to the diff, saving weight, costs of the trans,
> adaptor, clutch not to mention the hassle of making
> all them to work together. All production EV's go the
> direct drive route.
> I see no reason for you to go the high tech
> chassis route as kit cars are well known and much
> better suited to EV's as much lighter than the ICE
> conversions giving more performance for the same
> power.
> HTH's,
> jerry dycus
>
>
> >
> > / Simon
>
>
>
>
> __________________________________
> Do you Yahoo!?
> Yahoo! Mail - Helps protect you from nasty viruses.
> http://promotions.yahoo.com/new_mail
>
--- End Message ---
--- Begin Message ---
[EMAIL PROTECTED] wrote:
Evan - thanks. I feel sorta silly - of course the SLA acc battery should
handle the peak current! No need to mess around with ultra caps.
thanks
Don
A good small SLA battery will help with the peak surge current
the pump will require. A cap can do it easily too, and will be
far smaller, lighter, but more expensive solution. What I told Ron
was that technically it is easy task for an ultracap; that doesn't
mean is it best solution for his particular case.
A battery is a battery. It may discharge, it has limited (though
long in this case) life time and in general - it is one more
disposable item which we know will fail sooner or later (grid
corrosion, etc).
A capacitor will not fail unless is defective to begin with,
and will not need replacement. For the info, BMW uses steering
pump run entirely off of ultracaps, although of course they realise
there is cheap SLA solution. Perhaps SLA is one more component to
keep charged, temp compensated, etc. No matter how easy it is,
for OEM a cap is the same as resistor - "install and forget" part.
Don is not a BMW (yet :-) ) so optimal solution for an individual
can be different. Just know what all the choices are and pick the
best *for you*.
--
Victor
'91 ACRX - something different
--- End Message ---
--- Begin Message ---
Simon Sandvik wrote:
Thanks Victor.
Ok people what should I go with?
Li-Ions and Ultracaps or Li-Ions and lead acids?
What about the difference in weight?
OK, what is the best for me for the dinner tonight - a meat
or fish? More to EV topic: IS it better to use LiIons
or Lead Acids?
There is no yes/no answer to what you've asked. There are
particular circumstances you need to weigh and consider
*for your application* and, of course, for your pocket
book, skill level, knowledge of what to insist on in case
you subcontract the labor, etc.
The best solution for a vehicle with certain specs if I were
to do it will likely be different from the case if you will
make identical vehicle with identical specs.
It looks like the best alternative would be to use 62x TS (223V)
and 18x Exides/Optimas(216V).
Am I right?
/ Simon
May be. Other solution will work too, you need to do some
calculations. Sorry, I think no one can do your real home work for
you - too much depends on your personal situation and abilities.
--
Victor
'91 ACRX - something different
--- End Message ---
--- Begin Message ---
Folks, please take the "cybersquatting" discussion offline. It's threatening to
degenerate into name calling and personal attacks. That is NOT what we want on
this list.
Message to all, especially newbies:
Whatever the subject, if you feel you've been insulted or wronged, please address
your defensive responses directly to the person who allegedly wronged you. This is
especially important if you're angry and are having trouble controlling your temper
well enough to be civil in responding. Please don't post your responses here - to
most of us, it's just noise and it does nothing to help further the EV cause. In
fact,
"defending" yourself through public catfights just makes you and the entire EV
movement look bad. That we don't need or want.
By the same token, please cut one another some slack. I don't intend to get
involved in this particular discussion, but I do want to point out that criticizing
someone on the basis of a first impression is pretty likely to provoke a heated
response. Seek clarification before accusing.
In other words, lighten up! The EV list is one of the most cordial on the net. Let's
keep it that way.
Thanks,
David
Assistant EV List Administrator
--- End Message ---
--- Begin Message ---
Good point Victor. I should have said: since I am going to have an
accessory battery anyway, I will not require an ultracap for the PS Pump.
If I decide to go without an acc battery, I will investigate using
ultracaps.
Thanks
Don
See the New Beetle EV Conversion Web Site at
www.cameronsoftware.com/ev/
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Victor Tikhonov
Sent: September 28, 2004 2:24 PM
To: [EMAIL PROTECTED]
Subject: Re: Calculating size of Capacitor for Electric PS Pump
[EMAIL PROTECTED] wrote:
> Evan - thanks. I feel sorta silly - of course the SLA acc battery
> should handle the peak current! No need to mess around with ultra caps.
>
> thanks
> Don
A good small SLA battery will help with the peak surge current the pump will
require. A cap can do it easily too, and will be far smaller, lighter, but
more expensive solution. What I told Ron was that technically it is easy
task for an ultracap; that doesn't mean is it best solution for his
particular case.
A battery is a battery. It may discharge, it has limited (though long in
this case) life time and in general - it is one more disposable item which
we know will fail sooner or later (grid corrosion, etc).
A capacitor will not fail unless is defective to begin with, and will not
need replacement. For the info, BMW uses steering pump run entirely off of
ultracaps, although of course they realise there is cheap SLA solution.
Perhaps SLA is one more component to keep charged, temp compensated, etc. No
matter how easy it is, for OEM a cap is the same as resistor - "install and
forget" part.
Don is not a BMW (yet :-) ) so optimal solution for an individual can be
different. Just know what all the choices are and pick the best *for you*.
--
Victor
'91 ACRX - something different
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> Thanks for the correction, I've always took / as
> per but you are right.
"Divided by" basically means the same as "per", and this case is no
exception. "Per" can be used as a way of emphasizing undivided units and is
less mathematical - miles per hour, watts per hour. If we were describing a
resistor, we could say "this part drops 100 volts per amp" - meaning the
same as saying its value is 100 ohms but without using the simpler unit.
The correct way to say W*h*mile^(-1) is "watt hours per mile".
Want to avoid confusion while discussing range? Take 200Wh/mile and...
W*h s J J MJ
200 ---- * 3600 - * 1 --- = 720,000 ---- = 0.72 ----
mile h W*s mile mile
...The last being "point seven two megajoules per mile."
Physics and dimensional analysis are important to know because they are one
way to undeniably prove the advantages of EVs.
And on capacitors...a nice rule to remember is that with a fixed resistive
load, a capacitor will exhibit 37% of its original voltage after one R*C
time constant. Why?
+----------+
| <---- | dvC(t) vR(t) vC(t)
+ | iC z + iC = C * ------ iR = ----- = -----
----- = z dt R R
----- -iR z
- | C R z - dvC(t) vC(t)
| | iC + iR = 0 C * ------ + ----- = 0
+----------+ dt R
dvC(t)
Rewritten as: R * C * ------ + vC(t) = 0
dt
[ 1 ]
Therefore: s * (RC) + 1 = 0 and s = - sqrt |-----|
[ R*C ]
[ t ]
The solution is: vC(t) = k * exp | - --- |
[ R*C ]
Our initial conditions are vC(0) = v0.
[ t ]
By solving: vC(t) = v0 * exp | - --- |
[ R*C ]
At t = R*C, the solution universally equals 0.3665 * v0.
(Like Martin said.)
I thought someone might be interested in a refresher! Nothing like a little
calculus!
- Arthur
http://mywebpages.comcast.net/awmatt
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To my friends in Vegas and all others visiting the SEMA show november
2-5.Come out and see the CE hanging on the front entrance wall of the Sands
Convention Center.Try your luck at winning the great prizes in our booth. Dennis
Kilowatt Berube 3900 qt.mi.ev.passes in 14 years.
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I think he is selling the whole business. Lawrence Rhodes........
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: "EV Discussion List" <[EMAIL PROTECTED]>
Sent: Tuesday, September 28, 2004 10:20 AM
Subject: Street legal?
> This guy keeps trying to sell his "adult pedal car" on eBay -
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3842499544 - almost
$100K
> over a year ago to under $40K now.
>
> What I was wondering is how these can be street legal. If electric, they'd
have
> to fit the nEV class requirements (with no suspension?), if pedalled,
they're
> not really "cars" but quadricycles, and if gas, it doesn't seem they'd be
legal
> on any public street. The "mini Auburn" body is nice, but they need a
better
> frame to sit on.
>
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I have a Zivan NG3 charger posted on eBay.
Specifics are found at:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=2491154462&category=6755
Thanks!
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--- Begin Message ---
Victor Tikhonov wrote:
>
> Emil Naepflein wrote:
>
> > On Sat, 25 Sep 2004 07:20:55 -0700, "Don Cameron"
> > <[EMAIL PROTECTED]> wrote:
> >
> >
> >>On Victor's page for Ultacaps
> >>(http://www.metricmind.com/ac_honda/ultracaps.htm), he cites many benefits
> >>for using Ultra Caps vs PbA:
> >>
> >>- no charging and equalization
> >
> >
> > You definitely need equalization. Because of the lower voltage range you
> > even need more equalization circuits.
>
> What I meant was you don't need the same equalization complexity
> as for a battery (shunt regulators, or like). Simple resistor
> network will do. You cannot practically equalize batteries
> with resistors in parallel.
No, that's true. It would work, but would also waste amphours. The
supercapacitor setups I've seen store so few amphours that it didn't
matter if they dumped it all when parked.
Victor, what value resistors are you using? How many watthours/day do
they use?
--
"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
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The TEVan blew a control and it's not fixed yet.
My 1995 Club Car stopped working and it appears there
are crappy connections on the 6 pin right angle
connector on the 400Amp, 72 Volt control. A pin is
broken so the control is in the oven (FYI to remove a
Curtis end piece you put it in the oven and then pry
off the plastic piece to get inside)
I'll replace the connector and hopefully be on the
road again. Someday I might have time to work on
things I've planned on working with.
I need to win the lottery so I can pay others to fix
my toys!!!!
Rod
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--- Begin Message ---
Don Cameron wrote:
Jerry:
Energy is expressed in units of Watt-hour or power multiplied by time. The
units are written as W-hr or Watt-hour or Watt*hour.
You expressed the units as Watt/hour. This is power divided by time, which
is incorrect for an expression of energy.
To help you out, take a look at the formulas on my web site under the
Electricity link on my EV Physics web page:
http://www.cameronsoftware.com/ev/EV_IndexPhysics.html
Yes, Energy storage is W*h, not W/h. But it is not Jerry's main problem.
Unfortunately, he speaks about ultracapacitors as if he ever held one
in his hands and tried it while he didn't. If he did, he wouldn't post
what he post.
jerry dycus wrote:
>
> So how would you say it?
> Last time I checked Wt/hr is a measurement of
> power x time for total power and if you take the
> amount of power in wt/hrs put into the batts after a
> run and divide it by the miles you get the power in
> wt/hrs it takes to go a mile. No?
No. First, as Don mentioned, (and you wrote correctly),
power x time or W*h , not W/r.
Second, it is measurement for the amount of energy,
not total power
>>
>>Vastly? I suppose you can back this up with some
>>calculations?
>
> Yes, can you?
I can. Here are some stats for my ultracap setup.
Ultracapacitor type : PC2500
Manufacturer: Maxwell technologies
Capacitance: 2,700 Farads
Voltage: 2.5 Volts
Weight 0.725 kg (1.6 lb)
Amount of capacitors in the stack: 160 in series
Stack capacitance: 16.875 Farads
Max continuous stack voltage: 400 Volts
Max peak stack voltage: 432 Volts
Rated charge/discharge current: 100 Amps
Weight of the stack without interconnects: 116 kg (255 lb
Max charge/discharge current: 282 Amps (power inverter limit)
Max power available at full charge: ~120 kW (162 hp)
Max charge stored = 6,750 Coulombs
Max energy stored: = 1,350,000 Joules or 375 Watt-Hours
or ~1.8 miles drive distance
Cooling = none
I'm not going to bother with formulas here.
> To put it mildly, ultra caps suck. They are
> just hype.
>>
>>Sorry to disappoint you Jerry, but this claim is
>>totally false.
>>So the question remains - any data to back up your
>>opinion?
Well??
I take it as you have no data to back up your opinion.
I'd suggest to listen then.
>>Simon,
>>
>>My advise is if you want to try something, ask
>>someone
>>who *has done* exactly what you want how well it
>>works.
> So true, especially if that someone is selling it.
Get your facts straight Jerry, indeed seems you don't know
what you're talking about. Do I (or did I ever) offer(ed)
any ultracapacitors for sale?
> Show us how?
> Where are ultra caps realistic? Maybe in a drag
> racer where you only need 1 -12 sec burst but even
> then way too expensive. Batts give you many cycles and
> extended power availibility for minutes at a time.
Here are limited test results I managed to perform
since after Woodburn (I just finished wiring the
stack by Sep 26th). Later the data acquisition system
will be installed to monitor the battery and capacitor
stack currents separately. At the moment I don't have
two shunts handy.
So:
http://www.metricmind.com/misc/test1.gif
This is a snap shot of the plot generated by inverter's
software. This test run was for 20 minutes. The left half
represents parameters with ultracaps stack connected,
the right half - disconnected.
Zoomed in portion of the plot with connected stack.
Notice the battery (in parallel with the caps)
voltage swing.
http://www.metricmind.com/misc/caps.gif
Zoomed in portion of about the same drive demand
and disconnected ultracaps:
http://www.metricmind.com/misc/nocaps.gif
Side-by-side comparison of both:
http://www.metricmind.com/misc/compare.gif
Measurements: without caps:
For the drive current delta of 40A the voltage
sag is about 40V which works out to be
1 Ohm pack series resistance or 1/96=~0.0104 Ohm
(10 mOhm) per cell.
With the caps connected, the burst current demand
of 42A caused the voltage drop of ~4V or the "hybrid" pack
R_int = 4/42=0.095 Ohm or 0.000992 Ohm (0.992 mOhm)
per cell. No wonder the pack feels *very stiff*.
The beauty of this setup is that while absolute voltage
drops as I accelerate (I don't care since the voltage
acceptance range is wide enough to provide power I demand)
the stiffness remains the same as capacitors resist to
any voltage *changes* no matter what the absolute value is.
Frankly it works better than I expected.
As pre-calculated for average accelerating current of 70A
(0 to 140A - very hard acceleration, more throttle and
I loose traction) the total drop is about 80V in 12 seconds.
I don't feel the drop from 370V to 290V at all, and I am
not interested for longer times since at the end of
12th second I'm already at 65 MPH and have to release the
throttle.
Interesting observation - as I release accelerator and
coast, the system demand drops to around 0.8A but the
battery supplies about 25A recharging the caps and
total voltage rises. Recharging current completely
drops in about 40s total. If I regen after acceleration,
all the regen current goes into the ultracaps stack and
LiIons *continue to supply* the current in addition to
regen. Once the voltage rise enough, both the caps and
the battery start taking the current.
I only had a clamp meter to check what is going on, and it
is very clear that the battery current is smoothed out greatly.
With 140A demand, 30A max ever comes from LiIons, and 110A
comes from the capacitors, so the caps happily take all the
current abuse and softer LiIons yield the voltage easily.
In fact stiffer LiIons would be worse as they'd try to do all
the work (supply the power), not the caps.
Another great benefit I noticed - regen energy is never lost
now - the stack absorbs *everything* available since
last acceleration. Before, with soft LiIons the voltage shoots
to the top limit for the system (400V in my case) while charging
current is only 15-20A, so it cuts the regen current too early
forcing me to use disk brakes. Now the caps absorb as much as
they deliver - 110A easy (max I've observed so far). This tells
me that if I never cruise and only accelerate and brake (extreme
of city driving), regen may extend the range as much as 50% if
all of it is captured. And it is captured.
Of course, during cruising regen has no benefit, so the range
impact greatly depends on the driving pattern.
To me one of the main benefits of the ultracaps (besides enabling
very fun driving) is extending the life of the LiIons - I never
ask for more than 30A (0.3C) out of them.
One more plot (unrelated to having ultracaps) - overall
drive system efficiency:
http://www.metricmind.com/misc/eff.gif
On the bottom screen there are battery power and motor
power plotted. At 11:17.5s time point the battery power
peaked at about 58 kW while the motor output was 47 kW -
largest gap I cannot explain. The efficiency at this
moment was 47/58=0.81. But I'm happy to inform that
steady driving efficiency was 57kW/61kW=0.93 (the plot
shows 4 kW gap, or loss). This is everything - battery
to shaft. Divided equally between the motor and inverter
this means each must be 0.964 efficient. I'm impressed.
Overall I'm very pleased with the results so far.
Before this test I was in doubt whether it was right
decision to use ultracaps stack or I'd better off rather
use second similar LiIon pack in parallel (would cost me
about the same). Now it is clear that this was right
choice and extra pack would not lower total R_int as much
as ultracaps - it would be 2x improvement vs. >10x now.
A bit undersized 90Ah pack is ideal now for the car of
ACRX size. Regarding the range I don't want to try to run
it dead, but can extrapolate what I see so far in real life
(this is regardless if the ultracaps are present or not):
Provided 90Ah cells have 72Ah usable (settle 80% of the name
plate according to TS info), and 35A at 370V consumption at
65 MPH (or 12.95kW) the range for my 12.195kWh pack (3.5VPC
average by 72Ah) is (12.195/12.95)*65=61.2 miles.
At 35 MPH consumption drops to around 12A or 4.44kW (@370V)
to move, so the steady range (no stop/go and regen) is
(12,195/4.4)*35 = 97 miles.
>>>>I know I don't get 350 hp from that. but when
>>
>>using
>>
>>>>large capacitors, can't
>>>>I get
>>>>a lot more when I need it than 150 hp??
>>
>>You can get more power from ultracapacitors than you
>>need.
>>It is only matter of how much space/weight/money do
>>you have
>>and whether your drive system can take advantage of
>>them.
>
>
> His can? Can UC's deliver 150hp for 1 minute?
Why not ask for 1 hour?
Get real, 150hp for 1 minute may will yield 400 MPH or so.
I have 60 hp for 12 seconds and already at freeway speeds.
I cannot physically waste 150hp or even 60 hp for 1 minute
even if I wanted to (unless climb a steep hill).
>>I have a sample of mass produced 5kF ultracapacitor
>>weighting 850g delivering 10kW peak power,
>>4000A peak discharge current @ 2.5V starting voltage
>>-
>>I showed it to a few people at Woodburn. So just 12
>>capacitors
>>will provide your 115kW ("150hp") peak power - for
>>fraction
>>of second (and if you need it longer you start out
>>with
>>larger initial capacitance to increase RC constant).
>
> WoW!!! 115kw for a part of a second!!! That's going
> to do you a lot of good!
Yes, in fact it does. Not 115hp for fraction of
second, but 60 kW for 12 seconds - same order of
capacitance needed for both.
> So Victor how many UC's do you need to put out
> 1,000 amp's for 12 sec?
At what voltage drop? Please read the basics how a
capacitor works so you ask a question which has an answer.
For educational purposes I'll explain how to estimate it:
I will assume for example you can accept the voltage change
from 200V to 100V during discharge.
Amps amount will drop as you discharge, so I'll use
1000A as average:
I=C*(dV/dt) so C=I*dt/dV = 1,000*12/(200-100)=120F.
> How much do they cost,
As everything - depends on how many and where do you buy.
> weigh?
Maxwell 2.7kF ones I use are 725g each
> Do you use electronics to get the power from them?
No
> What do you do if you need another burst of power
> again like on any road driving in real life?
They just discharge deeper and the LiIons' share
of providing power increase. Eventually if you only
accelerate and never brake, capacitors will not
have any effect, but I can't imagine driving like that.
In my experience of actual city or highway driving
I do about equal amount of accelerating and braking,
so the caps in my setup *always* work and have burst power.
> Second, how many do you need to start up a hill of
> 3 degree grade that runs for a mile? Lets call it 400
> amps for for 2 minutes?
If you set up conditions that it is not possible
to take advantage of the stack, than obviously,
here is your answer - you run out of the power in the
cap perhaps in first 20 seconds and then LiIons alone
will provide all the power - I think it is quite obvious.
But U don't have such a driving conditions.
If you're trying to prove that capacitors are useless
devices, try with someone else. I'm getting tired.
> How much would they weigh, costs with electronics?
You already asked.
> How long before Li-ions can recharge them for
> another power burst like that?
40s totally, about 5s for 50% of the voltage to recover
(at least in my setup).
> As I said they are only good for people with more
> money than brains. It doesn't take a rocket scientist
> to figure out.
...
>
> No way as I have more brains than money!!! I also
> have common sense.
What can I say on this comment?
I probably have more money precisely because
I have more brains to make them.
And, you don;t have to like me or what I do, I couldn't
care less, but if you want keep insulting people, I'd
politely ask you to unsubscribe.
> Looking forward to you data proving me wrong as
> everyone elese is.
I already did, providing numbers, calculations,
plots and measurements. And still waiting for any
data from you. Where is it?
--
Victor
'91 ACRX - something different
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