EV Digest 3411
Topics covered in this issue include:
1) RE: Motor shaft temperature
by David Brandt <[EMAIL PROTECTED]>
2) RE: Newbie Questions About Traction Battery Pack Design
by Fortunat Mueller <[EMAIL PROTECTED]>
3) Electrical connectors: was Motor shaft temperature
by Ryan Bohm <[EMAIL PROTECTED]>
4) RE: Electrical connectors: was Motor shaft temperature
by David Brandt <[EMAIL PROTECTED]>
5) Conference on military electric power
by "T Humphrey" <[EMAIL PROTECTED]>
6) Re: Newbie Questions About Traction Battery Pack Design
by Lee Hart <[EMAIL PROTECTED]>
7) Re: Newbie Questions About Traction Battery Pack Design
by "Diana Trevino" <[EMAIL PROTECTED]>
8) RE: Newbie Questions About Traction Battery Pack Design
by David Brandt <[EMAIL PROTECTED]>
9) Re: Newbie Questions About Traction Battery Pack Design
by Fortunat Mueller <[EMAIL PROTECTED]>
10) exide orbitals
by keith vansickle <[EMAIL PROTECTED]>
11) RE: exide orbitals
by David Brandt <[EMAIL PROTECTED]>
12) Re: Newbie Questions About Traction Battery Pack Design
by Victor Tikhonov <[EMAIL PROTECTED]>
13) Re: dV/dt = 0?
by "Michael A. Radtke" <[EMAIL PROTECTED]>
14) Motor RPM sensors
by James Massey <[EMAIL PROTECTED]>
15) RE: exide orbitals
by James Massey <[EMAIL PROTECTED]>
16) Re: Sad news.
by "David Roden" <[EMAIL PROTECTED]>
17) Re: Source for Deka 8G27 batteries?
by "David Roden" <[EMAIL PROTECTED]>
18) Re: Portugal EV conference and the 'One Liter Car'
by "David Roden" <[EMAIL PROTECTED]>
19) Re: Portugal EV conference and the 'One Liter Car'
by "David Roden" <[EMAIL PROTECTED]>
20) Re: Newbie Questions About Traction Battery Pack Design
by "David Roden" <[EMAIL PROTECTED]>
21) Re: Newbie Questions About Traction Battery Pack Design
by Victor Tikhonov <[EMAIL PROTECTED]>
--- Begin Message ---
Check out what Dave Luiz did http://home.pacbell.net/evranger/motorto.htm
The magnetic sensor goes in the bell housing and senses notches on the
flywheel edge. Very slick installation.
> -----Original Message-----
> From: Mark Farver [mailto:[EMAIL PROTECTED]
> Sent: Thursday, March 18, 2004 4:54 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Motor shaft temperature
>
> On Wed, 2004-03-17 at 16:51, Ryan Bohm wrote:
> > I'm building a tach unit using a Hall effect sensor and magnets. I'm
> trying
>
> I've been thinking of this same problem, except my Kostov lacks a
> tailshaft.
>
> My only idea at this point is to mount the hall effect sensor in such a
> place that it can count the blades of the fan. I do not know if the fan
> is magnitized enough to trigger it (doubtful, and will the motor field
> affect it)) or if magnets need to be attached (difficult).
>
> Other option is to drill a hole in the adapter plate, and matching tiny
> holes in the flywheel. I have some tiny (1/8" diameter, 1/4" long) high
> power magnets that could be glued into the holes in the flywheel.
--- End Message ---
--- Begin Message ---
Bob,
I think Victor's system is basically an unregulated
hybrid pack. The current flow is all determined by
relative voltage levels. So once the Caps are drained
to below the LiIon pack voltage, you will be driving
on batteries alone (until regen charges them back up).
This system is great because it is so simple.
But Victor, I have a few additional questions :
-do you have this system up and running ? do you have
a layout drawing for it that i can look at ? are you
collecting info about current/energy flow ?
-how much of the useable energy are you getting our of
the caps this way (as a % of total capacity)? it seems
you can only 'sip' off the top of the caps cause once
you reach pack voltage, the batteries start doing a
lot of the work, no ?
-do you find that if you let off the 'gas' and coast
after acceleration that the LiIon pack recharges the
caps thus limiting the regen you can capture if you
apply the brakes ? [as an interesting note: there was
a session at SAE last week where Honda presented their
power flow strategy for the FCX (fuel cell/capacitor
hybrid). They dealt with just this problem, that
during regen they wanted to make sure that the regen
and not the FC was charging the caps. I would imagine
that batteries present a similar issue.].
-What do you do to match the voltage on the caps and
Li Ion before you close the contactors ?
-i know this is probably on your web page, but what is
the low and high voltage limits for the input to your
inverter ?
This kind of hybrid makes a lot of sense to me and I
am glad to see that someone is working on it. If I had
the $$, i certainly would be also, and perhaps i will
be sometime.
BTW, Honda also presented about the development of
their Super Cap modules and the balancing and cooling
systems. At the risk of wasting bandwidth, other talks
i attended that might be of interest to some on this
list includ (if you are interested in more info, let
me know):
-LiIon battery and BMS development by Gaia
-Motor (BLDC) development for FCX by Honda (based on
EV+ motor)
-Li Ion battery dvlpment by Toyota
-Thermal analysis of PM BLDC motor
I also chatted a bit with someone from Wavecrest (they
had a good looking Smart roadster there). They are
apparently starting to ramp up and make batteries now
as well as hub motors. I asked where I could buy some,
but naturally, unless i want 1000, it would be tough.
~Fortunat
PS- sorry to stray a little OT, but i imagine some
people on this list might be interested in some of the
above.
__________________________________
Do you Yahoo!?
Yahoo! Mail - More reliable, more storage, less spam
http://mail.yahoo.com
--- End Message ---
--- Begin Message ---
Thanks for all the great input on the magnet mounting for the
Hall-effect sensor.
Does anyone know where you can buy automotive style/quality electrical
connectors? Google usually has the answers, but I'm not having much
success on this one.
Thanks,
Ryan
David Brandt wrote:
Check out what Dave Luiz did http://home.pacbell.net/evranger/motorto.htm
The magnetic sensor goes in the bell housing and senses notches on the
flywheel edge. Very slick installation.
-----Original Message-----
From: Mark Farver [mailto:[EMAIL PROTECTED]
Sent: Thursday, March 18, 2004 4:54 PM
To: [EMAIL PROTECTED]
Subject: Re: Motor shaft temperature
On Wed, 2004-03-17 at 16:51, Ryan Bohm wrote:
I'm building a tach unit using a Hall effect sensor and magnets. I'm
trying
I've been thinking of this same problem, except my Kostov lacks a
tailshaft.
My only idea at this point is to mount the hall effect sensor in such a
place that it can count the blades of the fan. I do not know if the fan
is magnitized enough to trigger it (doubtful, and will the motor field
affect it)) or if magnets need to be attached (difficult).
Other option is to drill a hole in the adapter plate, and matching tiny
holes in the flywheel. I have some tiny (1/8" diameter, 1/4" long) high
power magnets that could be glued into the holes in the flywheel.
--
Ever thought of driving an Electric Car? Visit http://www.evsource.com
<http://www.interwebber.com/redirects/evsource/index.html?id=4487643>
--- End Message ---
--- Begin Message ---
www.waytekwire.com. Every automotive style you can buy, as well as all the
"ordinary" stuff we use.
> -----Original Message-----
> From: Ryan Bohm [mailto:[EMAIL PROTECTED]
> Sent: Friday, March 19, 2004 8:52 AM
> To: [EMAIL PROTECTED]
> Subject: Electrical connectors: was Motor shaft temperature
>
> Thanks for all the great input on the magnet mounting for the
> Hall-effect sensor.
>
> Does anyone know where you can buy automotive style/quality electrical
> connectors? Google usually has the answers, but I'm not having much
> success on this one.
>
> Thanks,
>
> Ryan
>
> David Brandt wrote:
>
> >Check out what Dave Luiz did http://home.pacbell.net/evranger/motorto.htm
> >
> >The magnetic sensor goes in the bell housing and senses notches on the
> >flywheel edge. Very slick installation.
> >
> >
> >
> >>-----Original Message-----
> >>From: Mark Farver [mailto:[EMAIL PROTECTED]
> >>Sent: Thursday, March 18, 2004 4:54 PM
> >>To: [EMAIL PROTECTED]
> >>Subject: Re: Motor shaft temperature
> >>
> >>On Wed, 2004-03-17 at 16:51, Ryan Bohm wrote:
> >>
> >>
> >>>I'm building a tach unit using a Hall effect sensor and magnets. I'm
> >>>
> >>>
> >>trying
> >>
> >>I've been thinking of this same problem, except my Kostov lacks a
> >>tailshaft.
> >>
> >>My only idea at this point is to mount the hall effect sensor in such a
> >>place that it can count the blades of the fan. I do not know if the fan
> >>is magnitized enough to trigger it (doubtful, and will the motor field
> >>affect it)) or if magnets need to be attached (difficult).
> >>
> >>Other option is to drill a hole in the adapter plate, and matching tiny
> >>holes in the flywheel. I have some tiny (1/8" diameter, 1/4" long) high
> >>power magnets that could be glued into the holes in the flywheel.
> >>
> >>
> >
> >
> >
> >
>
> --
> Ever thought of driving an Electric Car? Visit http://www.evsource.com
> <http://www.interwebber.com/redirects/evsource/index.html?id=4487643>
--- End Message ---
--- Begin Message ---
I can't make it, but thought someone on the list might be
interested in attending this conference.
http://www.ttcus.com/pr-c/index.html
Stay Charged!
Hump
--- End Message ---
--- Begin Message ---
Bob Mason wrote:
>> dreaming of an EV conversion... Li-Ion cells (in series) plus
>> Ultracapacitor cells (in series) in parallel to keep the voltage
>> up for acceleration.
>> 1. Do I need to size the 2 packs at the same voltage level?
Victor Tikhonov answered:
> Short answer - no.
> Long answer - you can, but don't have to, which allows to save costs.
> Each stack max voltage depends on the max voltage it will ever see.
I would say that you can simply parallel the Li-Ion and Ultracapacitor
packs, but this would result in a higher cost and poorer performance
than other systems.
The voltage of a battery hardly changes between 0% and 100% SOC (State
Of Charge). You might see 3v at 0% SOC and 4v at 100%.
But the voltage of a capacitor changes drastically; 0 volts at 0% SOC,
and peak voltage at 100% SOC. The equation is E = 1/2 x C x V where E is
the energy stored in the capacitor in watt-seconds, C is its capacitance
in farads, and V is the voltage on it.
If you directly parallel the LiIons and Ultracapacitors, then you only
utilize a small fraction of the energy storage capability of the
Ultracapacitors. At 4v, capacitors store E = 1/2 x 1f x 4v = 2
wattseconds per farad. At 3v, the capacitors still hold E = 1/2 x 1f x
3v = 1.5 wattseconds per farad. So, you only used (2-1.5)/2 = 25% of the
ultracapacitor's energy storage capability.
So, a much better way is to connect the ultracapacitors thru a DC/DC
converter. When you need power from the ultracapacitors, run them down
to as low a voltage as the DC/DC will allow. For example, taking them
from 4v to 1v per cell will give you (2-0.5)/2 = 75% of their stored
energy. When recharging the ultracapacitors, the DC/DC also lets you
charge them right up to their maximum voltage, not just that of the
LiIons. For example, if your ultracapacitors can go up to 5.5v, stored
energy goes from 2 wattsec/farad to 2.75 wattsec/farad.
The end result is that adding the DC/DC converter drasticlaly reduces
the number of ultracapacitors needed.
> Ultracaps stack is easy - they should not exceed 2.5V/cap.
> Figure the highest voltage your drive system will have.
> If you want AC system, consider highest voltage during regen.
Ultracapacitors have exactly the problem of LiIons. You must watch the
voltage of very single cell, and not let it go too low or too high. If
you just string them in series with no measurement or equalization, you
can't come anywhere near using their maximum capabilities without at
least one cell getting overvoltaged or reverse-voltaged.
>> 5. Should the regen be routed to both of the packs or just one
>> (which one is better for regen)?
> Regen is dynamic and short in duration. Ultracaps are the
> only device which can take it and benefit from energy recovery.
The big problem during regen is, "Where do you put the energy?"
If the batteries are already at or nearly fully charged, you can't put
it there. Likewise, if the ultracapacitors are already fully charged, it
can't go there, either. To handle this this situation, you either need a
huge resisive load to dump the excess power, or (what is really done)
disable regen and use the regular friction brakes.
Next point: In normal driving, most people do not brake any harder than
they accellerate. If the batteries can handle the peak current for
accellerating, they can handle the braking current generated during
decelleration. Ultracapacitors aren't really required for this.
If you want to capture braking energy during extreme conditions
(high-speed panic stops, or long downhill grades), then ultracapacitors
or some other form of fast-charge system would be needed. But as a
practical matter, you almost never do this. You would be adding a great
deal of cost and complexity for a problem that rarely occurs.
--
"Never doubt that a small group of committed people can change the
world. Indeed, it's the only thing that ever has!" -- Margaret Meade
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
Has anyone ever tried hydraulic energy storage during braking? Or end cells
for acceleration? Just curious,
Jack
42' Electric Yacht
----- Original Message -----
From: "Lee Hart" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, March 19, 2004 3:07 PM
Subject: Re: Newbie Questions About Traction Battery Pack Design
> Bob Mason wrote:
> >> dreaming of an EV conversion... Li-Ion cells (in series) plus
> >> Ultracapacitor cells (in series) in parallel to keep the voltage
> >> up for acceleration.
> >> 1. Do I need to size the 2 packs at the same voltage level?
>
> Victor Tikhonov answered:
> > Short answer - no.
> > Long answer - you can, but don't have to, which allows to save costs.
> > Each stack max voltage depends on the max voltage it will ever see.
>
> I would say that you can simply parallel the Li-Ion and Ultracapacitor
> packs, but this would result in a higher cost and poorer performance
> than other systems.
>
> The voltage of a battery hardly changes between 0% and 100% SOC (State
> Of Charge). You might see 3v at 0% SOC and 4v at 100%.
>
> But the voltage of a capacitor changes drastically; 0 volts at 0% SOC,
> and peak voltage at 100% SOC. The equation is E = 1/2 x C x V where E is
> the energy stored in the capacitor in watt-seconds, C is its capacitance
> in farads, and V is the voltage on it.
>
> If you directly parallel the LiIons and Ultracapacitors, then you only
> utilize a small fraction of the energy storage capability of the
> Ultracapacitors. At 4v, capacitors store E = 1/2 x 1f x 4v = 2
> wattseconds per farad. At 3v, the capacitors still hold E = 1/2 x 1f x
> 3v = 1.5 wattseconds per farad. So, you only used (2-1.5)/2 = 25% of the
> ultracapacitor's energy storage capability.
>
> So, a much better way is to connect the ultracapacitors thru a DC/DC
> converter. When you need power from the ultracapacitors, run them down
> to as low a voltage as the DC/DC will allow. For example, taking them
> from 4v to 1v per cell will give you (2-0.5)/2 = 75% of their stored
> energy. When recharging the ultracapacitors, the DC/DC also lets you
> charge them right up to their maximum voltage, not just that of the
> LiIons. For example, if your ultracapacitors can go up to 5.5v, stored
> energy goes from 2 wattsec/farad to 2.75 wattsec/farad.
>
> The end result is that adding the DC/DC converter drasticlaly reduces
> the number of ultracapacitors needed.
>
> > Ultracaps stack is easy - they should not exceed 2.5V/cap.
> > Figure the highest voltage your drive system will have.
> > If you want AC system, consider highest voltage during regen.
>
> Ultracapacitors have exactly the problem of LiIons. You must watch the
> voltage of very single cell, and not let it go too low or too high. If
> you just string them in series with no measurement or equalization, you
> can't come anywhere near using their maximum capabilities without at
> least one cell getting overvoltaged or reverse-voltaged.
>
> >> 5. Should the regen be routed to both of the packs or just one
> >> (which one is better for regen)?
>
> > Regen is dynamic and short in duration. Ultracaps are the
> > only device which can take it and benefit from energy recovery.
>
> The big problem during regen is, "Where do you put the energy?"
>
> If the batteries are already at or nearly fully charged, you can't put
> it there. Likewise, if the ultracapacitors are already fully charged, it
> can't go there, either. To handle this this situation, you either need a
> huge resisive load to dump the excess power, or (what is really done)
> disable regen and use the regular friction brakes.
>
> Next point: In normal driving, most people do not brake any harder than
> they accellerate. If the batteries can handle the peak current for
> accellerating, they can handle the braking current generated during
> decelleration. Ultracapacitors aren't really required for this.
>
> If you want to capture braking energy during extreme conditions
> (high-speed panic stops, or long downhill grades), then ultracapacitors
> or some other form of fast-charge system would be needed. But as a
> practical matter, you almost never do this. You would be adding a great
> deal of cost and complexity for a problem that rarely occurs.
> --
> "Never doubt that a small group of committed people can change the
> world. Indeed, it's the only thing that ever has!" -- Margaret Meade
> --
> Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
>
--- End Message ---
--- Begin Message ---
Some years ago there was a machine design or design news article (can't
rightly remember which) about a hydraulic braking energy capture mechanism
that was installed on a bus to increase fuel economy and decrease brake
wear. It only functioned during braking and acceleration, and increased the
fuel economy about 15%, IIRC.
> -----Original Message-----
> From: Diana Trevino [mailto:[EMAIL PROTECTED]
> Sent: Friday, March 19, 2004 2:29 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Newbie Questions About Traction Battery Pack Design
>
> Has anyone ever tried hydraulic energy storage during braking? Or end
> cells
> for acceleration? Just curious,
> Jack
> 42' Electric Yacht
> ----- Original Message -----
> From: "Lee Hart" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Friday, March 19, 2004 3:07 PM
> Subject: Re: Newbie Questions About Traction Battery Pack Design
>
>
> > Bob Mason wrote:
> > >> dreaming of an EV conversion... Li-Ion cells (in series) plus
> > >> Ultracapacitor cells (in series) in parallel to keep the voltage
> > >> up for acceleration.
> > >> 1. Do I need to size the 2 packs at the same voltage level?
> >
> > Victor Tikhonov answered:
> > > Short answer - no.
> > > Long answer - you can, but don't have to, which allows to save costs.
> > > Each stack max voltage depends on the max voltage it will ever see.
> >
> > I would say that you can simply parallel the Li-Ion and Ultracapacitor
> > packs, but this would result in a higher cost and poorer performance
> > than other systems.
> >
> > The voltage of a battery hardly changes between 0% and 100% SOC (State
> > Of Charge). You might see 3v at 0% SOC and 4v at 100%.
> >
> > But the voltage of a capacitor changes drastically; 0 volts at 0% SOC,
> > and peak voltage at 100% SOC. The equation is E = 1/2 x C x V where E is
> > the energy stored in the capacitor in watt-seconds, C is its capacitance
> > in farads, and V is the voltage on it.
> >
> > If you directly parallel the LiIons and Ultracapacitors, then you only
> > utilize a small fraction of the energy storage capability of the
> > Ultracapacitors. At 4v, capacitors store E = 1/2 x 1f x 4v = 2
> > wattseconds per farad. At 3v, the capacitors still hold E = 1/2 x 1f x
> > 3v = 1.5 wattseconds per farad. So, you only used (2-1.5)/2 = 25% of the
> > ultracapacitor's energy storage capability.
> >
> > So, a much better way is to connect the ultracapacitors thru a DC/DC
> > converter. When you need power from the ultracapacitors, run them down
> > to as low a voltage as the DC/DC will allow. For example, taking them
> > from 4v to 1v per cell will give you (2-0.5)/2 = 75% of their stored
> > energy. When recharging the ultracapacitors, the DC/DC also lets you
> > charge them right up to their maximum voltage, not just that of the
> > LiIons. For example, if your ultracapacitors can go up to 5.5v, stored
> > energy goes from 2 wattsec/farad to 2.75 wattsec/farad.
> >
> > The end result is that adding the DC/DC converter drasticlaly reduces
> > the number of ultracapacitors needed.
> >
> > > Ultracaps stack is easy - they should not exceed 2.5V/cap.
> > > Figure the highest voltage your drive system will have.
> > > If you want AC system, consider highest voltage during regen.
> >
> > Ultracapacitors have exactly the problem of LiIons. You must watch the
> > voltage of very single cell, and not let it go too low or too high. If
> > you just string them in series with no measurement or equalization, you
> > can't come anywhere near using their maximum capabilities without at
> > least one cell getting overvoltaged or reverse-voltaged.
> >
> > >> 5. Should the regen be routed to both of the packs or just one
> > >> (which one is better for regen)?
> >
> > > Regen is dynamic and short in duration. Ultracaps are the
> > > only device which can take it and benefit from energy recovery.
> >
> > The big problem during regen is, "Where do you put the energy?"
> >
> > If the batteries are already at or nearly fully charged, you can't put
> > it there. Likewise, if the ultracapacitors are already fully charged, it
> > can't go there, either. To handle this this situation, you either need a
> > huge resisive load to dump the excess power, or (what is really done)
> > disable regen and use the regular friction brakes.
> >
> > Next point: In normal driving, most people do not brake any harder than
> > they accellerate. If the batteries can handle the peak current for
> > accellerating, they can handle the braking current generated during
> > decelleration. Ultracapacitors aren't really required for this.
> >
> > If you want to capture braking energy during extreme conditions
> > (high-speed panic stops, or long downhill grades), then ultracapacitors
> > or some other form of fast-charge system would be needed. But as a
> > practical matter, you almost never do this. You would be adding a great
> > deal of cost and complexity for a problem that rarely occurs.
> > --
> > "Never doubt that a small group of committed people can change the
> > world. Indeed, it's the only thing that ever has!" -- Margaret Meade
> > --
> > Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
> >
--- End Message ---
--- Begin Message ---
Jack
FEV is working on a series hydraulic hybrid vehicle
under a grant from DOE. They had it on display in
detroit last week. It is a full size SUV, series
diesel hybrid and they say the can make it (in volume)
for only a thousand dollars more than the stock truck.
There is some info, and links to a couple informative
.pdf files at :
http://www.epa.gov/otaq/technology/#hydraulic
~Fortunat
--- Diana Trevino <[EMAIL PROTECTED]> wrote:
> Has anyone ever tried hydraulic energy storage
> during braking? Or end cells
> for acceleration? Just curious,
> Jack
> 42' Electric Yacht
> ----- Original Message -----
> From: "Lee Hart" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Friday, March 19, 2004 3:07 PM
> Subject: Re: Newbie Questions About Traction Battery
> Pack Design
>
>
> > Bob Mason wrote:
> > >> dreaming of an EV conversion... Li-Ion cells
> (in series) plus
> > >> Ultracapacitor cells (in series) in parallel to
> keep the voltage
> > >> up for acceleration.
> > >> 1. Do I need to size the 2 packs at the same
> voltage level?
> >
> > Victor Tikhonov answered:
> > > Short answer - no.
> > > Long answer - you can, but don't have to, which
> allows to save costs.
> > > Each stack max voltage depends on the max
> voltage it will ever see.
> >
> > I would say that you can simply parallel the
> Li-Ion and Ultracapacitor
> > packs, but this would result in a higher cost and
> poorer performance
> > than other systems.
> >
> > The voltage of a battery hardly changes between 0%
> and 100% SOC (State
> > Of Charge). You might see 3v at 0% SOC and 4v at
> 100%.
> >
> > But the voltage of a capacitor changes
> drastically; 0 volts at 0% SOC,
> > and peak voltage at 100% SOC. The equation is E =
> 1/2 x C x V where E is
> > the energy stored in the capacitor in
> watt-seconds, C is its capacitance
> > in farads, and V is the voltage on it.
> >
> > If you directly parallel the LiIons and
> Ultracapacitors, then you only
> > utilize a small fraction of the energy storage
> capability of the
> > Ultracapacitors. At 4v, capacitors store E = 1/2 x
> 1f x 4v = 2
> > wattseconds per farad. At 3v, the capacitors still
> hold E = 1/2 x 1f x
> > 3v = 1.5 wattseconds per farad. So, you only used
> (2-1.5)/2 = 25% of the
> > ultracapacitor's energy storage capability.
> >
> > So, a much better way is to connect the
> ultracapacitors thru a DC/DC
> > converter. When you need power from the
> ultracapacitors, run them down
> > to as low a voltage as the DC/DC will allow. For
> example, taking them
> > from 4v to 1v per cell will give you (2-0.5)/2 =
> 75% of their stored
> > energy. When recharging the ultracapacitors, the
> DC/DC also lets you
> > charge them right up to their maximum voltage, not
> just that of the
> > LiIons. For example, if your ultracapacitors can
> go up to 5.5v, stored
> > energy goes from 2 wattsec/farad to 2.75
> wattsec/farad.
> >
> > The end result is that adding the DC/DC converter
> drasticlaly reduces
> > the number of ultracapacitors needed.
> >
> > > Ultracaps stack is easy - they should not exceed
> 2.5V/cap.
> > > Figure the highest voltage your drive system
> will have.
> > > If you want AC system, consider highest voltage
> during regen.
> >
> > Ultracapacitors have exactly the problem of
> LiIons. You must watch the
> > voltage of very single cell, and not let it go too
> low or too high. If
> > you just string them in series with no measurement
> or equalization, you
> > can't come anywhere near using their maximum
> capabilities without at
> > least one cell getting overvoltaged or
> reverse-voltaged.
> >
> > >> 5. Should the regen be routed to both of the
> packs or just one
> > >> (which one is better for regen)?
> >
> > > Regen is dynamic and short in duration.
> Ultracaps are the
> > > only device which can take it and benefit from
> energy recovery.
> >
> > The big problem during regen is, "Where do you put
> the energy?"
> >
> > If the batteries are already at or nearly fully
> charged, you can't put
> > it there. Likewise, if the ultracapacitors are
> already fully charged, it
> > can't go there, either. To handle this this
> situation, you either need a
> > huge resisive load to dump the excess power, or
> (what is really done)
> > disable regen and use the regular friction brakes.
> >
> > Next point: In normal driving, most people do not
> brake any harder than
> > they accellerate. If the batteries can handle the
> peak current for
> > accellerating, they can handle the braking current
> generated during
> > decelleration. Ultracapacitors aren't really
> required for this.
> >
> > If you want to capture braking energy during
> extreme conditions
> > (high-speed panic stops, or long downhill grades),
> then ultracapacitors
> > or some other form of fast-charge system would be
> needed. But as a
> > practical matter, you almost never do this. You
> would be adding a great
> > deal of cost and complexity for a problem that
> rarely occurs.
> > --
> > "Never doubt that a small group of committed
> people can change the
> > world. Indeed, it's the only thing that ever has!"
> -- Margaret Meade
> > --
> > Lee A. Hart 814 8th Ave N Sartell MN 56377
> leeahart_at_earthlink.net
> >
>
__________________________________
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--- Begin Message ---
I have a new 120V pac of orbitals and would like to
know what the charge recommendations are from those of
you who regularly use this type of battery.
have any of you on this list used these batteries
enough to wear out a set?
if so how many cycles?
does anyone have an e-meter for sale?
does anyone know of a "quick disconect" cam operated
post battery connection?
if there is no such thing is there any reason it
cannot be done-- i hate using a wrench to connect and
disconnec all those batteries.
thanks
kevs
70 vw conversion
74 porsche 1/2 done
ev bikes
__________________________________
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--- Begin Message ---
I can answer the connection question - www.waytekwire.com offers all sorts
of battery terminal products, including ones with quick disconnect bolts
instead of regular bolts. I can't recall if they come in a crimp-on
variety, though, and I don't know if you have to buy the whole thing or if
you can get just the bolts.
I used their "extra heavy duty" tinned copper crimp-on battery terminals and
lugs, 2/0 size, and they are great. Heavier, I believe, than the magnalugs
that seem to be the de facto standard.
No affiliation, I just like their products and their prices.
By the way, I can't seem to get anywhere trying to locate orbitals. And
Exide doesn't list distributors on their website. They do list stores, but
all that comes up in my area is Wal-Mart, which doesn't know an orbital from
a parakeet (they don't sell those either), and won't order anything special
for you. Where has everyone else gotten theirs? I'd like to get 4 for the
go-cart I'm building.
> -----Original Message-----
> From: keith vansickle [mailto:[EMAIL PROTECTED]
> Sent: Friday, March 19, 2004 3:05 PM
> To: [EMAIL PROTECTED]
> Subject: exide orbitals
>
> I have a new 120V pac of orbitals and would like to
> know what the charge recommendations are from those of
> you who regularly use this type of battery.
>
> have any of you on this list used these batteries
> enough to wear out a set?
>
> if so how many cycles?
>
> does anyone have an e-meter for sale?
>
> does anyone know of a "quick disconect" cam operated
> post battery connection?
>
> if there is no such thing is there any reason it
> cannot be done-- i hate using a wrench to connect and
> disconnec all those batteries.
>
> thanks
> kevs
> 70 vw conversion
> 74 porsche 1/2 done
> ev bikes
>
> __________________________________
> Do you Yahoo!?
> Yahoo! Mail - More reliable, more storage, less spam
> http://mail.yahoo.com
--- End Message ---
--- Begin Message ---
Lee Hart wrote:
> The voltage of a battery hardly changes between 0% and 100% SOC (State
Of Charge). You might see 3v at 0% SOC and 4v at 100%.
But the voltage of a capacitor changes drastically; 0 volts at 0% SOC,
and peak voltage at 100% SOC. The equation is E = 1/2 x C x V where E is
the energy stored in the capacitor in watt-seconds, C is its capacitance
in farads, and V is the voltage on it.
This is interesting one.
E = 1/2 x C x V but useful to *you* energy is delta V during
discharge or regen-charge, not absolute V on the cap.
So if you discharge 25%, then, yes, you use 25% of the max potential
storage. But:
If C is low and V is high,(many caps in series) you don't need DC-DC,
but as you said use small fraction of capacity to store energy.
If C is high and V is low (one cap), energy is the same but you need
DC-DC to convert, say, 200A 250V battery regen current to
20,000A 2.5V suitable for a capacitor. Then you will use 100% of the
capacitor energy storing ability. Just show me such a DC-DC converter!
You can compromise by having 10 or 20 capacitors, so the
current DC-DC must handle drops to 2,000A or 1,000A respectively.
At some point the cost of capacitors + DC-DC cost will be
minimal and may be less than full stack of capacitors.
Just in my case I got them so cheap that this wasn't
a decision point for me, no way I can find a suitable DC-DC
for the price of my caps.
But, in general case, DC-DC should be considered even
despite added complexity.
--
Victor
'91 ACRX - something different
--- End Message ---
--- Begin Message ---
Lee,
Thanks for the specific information. Exactly what I needed.
Mike
-------- Original Message --------
Subject: Re: dV/dt = 0?
Date: Thu, 18 Mar 2004 23:29:20 -0800
From: Lee Hart <[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
References: <[EMAIL PROTECTED]>
<[EMAIL PROTECTED]> <[EMAIL PROTECTED]>
Michael A. Radtke wrote:
> So, how close to 0 should dV/dt be? For that matter how long is dt?
Dv is usually zero, or rising very slightly. Dt is usually 15-30
minutes. For example, my Lester 72v charger with dv/dt shuts off when
the voltage has risen less than 15 millivolts in the past 30 minutes.
--
"Never doubt that a small group of committed people can change the
world. Indeed, it's the only thing that ever has!" -- Margaret Meade
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
David Brandt wrote:
Check out what Dave Luiz did http://home.pacbell.net/evranger/motorto.htm
The magnetic sensor goes in the bell housing and senses notches on the
flywheel edge. Very slick installation.<snip>
On Wed, 2004-03-17 at 16:51, Ryan Bohm wrote:
I'm building a tach unit using a Hall effect sensor and magnets. I'm
trying
Magnets? Hall effects? (and also: optical sensors?)
Why? (this in a real question, don't 'bag' me for it, please)
Off-the-shelf you can get industrial proximity switches, run from 12VDC,
put out 12V pulses at speed rates in excess of 10kHz (at 4 PPR, that allows
a shaft speed of 150,000RPM). Rally cars use them to detect the inside end
of the wheel studs for speed detection. Detection range is short, for small
sensors less than 1mm, but if you have that much runout in anything to do
with your motor, then get it fixed.
I know they are not cheap, but they are as soon as you add in the cost and
hassle of magnets etc. My conversion I am doing a set of recesses in the
aluminium flywheel, and directly detecting them with a 12mm diameter
proximity switch, mounted from the bell housing adaptor. Smaller sensors
are usually slower, but "so what", I don't think many EV motors are going
to be able to get close to 150,000RPM [although Rich and others will keep
trying :^) ].
If you cannot mount something on the flywheel end, why not cut (grind) a
cross into the brush end of the motor shaft a couple of mm deep (1/16") and
use a proximity switch? side viewing switches only need 12mm (1/2") or so
to fit, so few conversions would not have the room.
So why the use of all these sensor types more suited to golf carts, OEM
system designers and off-road vehicles?
Hall effects: need fixed magnets, Optical sensors: get dirty, home-made
sensors: hard to keep the moisture out. So why do people not use Proximity
switches?
Thanks
James Massey
Launceston, Tasmania, Australia
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--- Begin Message ---
At 04:15 PM 19/03/04 -0600, David Brandt wrote:
By the way, I can't seem to get anywhere trying to locate orbitals. And
Exide doesn't list distributors on their website. They do list stores, but
all that comes up in my area is Wal-Mart, which doesn't know an orbital from
a parakeet (they don't sell those either), and won't order anything special
for you. Where has everyone else gotten theirs? I'd like to get 4 for the
go-cart I'm building.
Hi David.
Assuming you are in the USA, I can't directly help you (I drove 5 miles to
the Exide state distribution warehouse...).
However, If you let the List know where you are, there may be someone near
you who can help.
James Massey,
Launceston, Tasmania, Australia
--- End Message ---
--- Begin Message ---
On 18 Mar 2004 at 7:47, Lawrence Rhodes wrote:
> A car with 6k on
> it is lost.
Unless the other driver is indigent, you might consider talking to an
attorney. If you win a judgement, you could probably have the driver's
wages garnisheed to pay it.
David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea 36vdc
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
All we learn from history is history repeats.
-- Andrew Ratshin
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
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--- Begin Message ---
On 18 Mar 2004 at 15:55, Mike Chancey wrote:
> Anyone know of a source for Deka 8G27 batteries?
Solectria used to sell them to their customers, and might still. I might be
remembering incorrectly, but I think the price was actually lower than one
quoted to me by a local battery retailer. Can't hurt to call.
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Want to unsubscribe, stop the EV list mail while you're on vacation, or
switch to digest mode? See http://www.evdl.org/help/
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David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea rider 36vdc
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
The question can arise whether with the development of such tech-
nological means of communication as radio, film, and the daily
press, freedom of thought is possible at all. Does this not mean
constant infection with whatever ideas are in circulation?
-- Czeslaw Milosz, 1942
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
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--- Begin Message ---
On 18 Mar 2004 at 11:09, Cliff Rassweiler wrote:
> Chili now seems to seat 3 adults and 5 crates of water. I think beer and a
> picnic basket would be more useful!
"Getr�nkekisten" actually means "cases of drinks," but these are college
students. They're talking about cases of beer. <g>
--- End Message ---
--- Begin Message ---
On 18 Mar 2004 at 17:03, Brad Waddell wrote:
> That's one of the dumbest things I have ever heard - the driver can't look
> away from the road anyway! He should be concentrating on controlling the car,
> not chatting away ...
Actually, I think it's a valid point. (FYI, Brad, I'm not dumb and neither
are my friends. ;-) You're not going to get people to stop conversing in
cars. Potential buyers are going to consider this matter.
Besides, tandem seating, with all its advantages, has some attitudinal
baggage. In most people's minds, the back seat is for kids and persons
being conveyed by a hired driver (taxicabs, limos). That association is
going to present a challenge for the Tango and other tandems, I think.
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Want to unsubscribe, stop the EV list mail while you're on vacation, or
switch to digest mode? See http://www.evdl.org/help/
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David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea rider 36vdc
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
It is impossible to defeat an ignorant man in argument.
-- William G. McAdoo
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--- End Message ---
--- Begin Message ---
On 19 Mar 2004 at 13:07, Lee Hart wrote:
> The end result is that adding the DC/DC converter drasticlaly reduces
> the number of ultracapacitors needed.
This is the method Solectria used in their tests a few years back, IIRC.
They found that using ultracaps to level the peak current demands from the
pack helped the range quite a bit, though I don't recall what the percentage
figure was any more. I'm pretty sure they issued a press release about it
at the time, but now I can't find it on their website. Sorry to be so
vauge; maybe someone else remembers more about those tests.
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Want to unsubscribe, stop the EV list mail while you're on vacation, or
switch to digest mode? See http://www.evdl.org/help/
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea rider 36vdc
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Cutting the space budget really restores my faith in humanity. It
eliminates dreams, goals, and ideals and lets us get straight to the
business of hate, debauchery, and self-annihilation.
-- Johnny Hart
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
--- End Message ---
--- Begin Message ---
Lee Hart wrote:
> I would say that you can simply parallel the Li-Ion and Ultracapacitor
packs, but this would result in a higher cost and poorer performance
than other systems.
What other systems do you have in mind?
This actually depends on many variables - primarily type of
LiIons and type of capacitors. And, for mortals, their cost.
The voltage of a battery hardly changes between 0% and 100% SOC (State
Of Charge). You might see 3v at 0% SOC and 4v at 100%.
Right.
But the voltage of a capacitor changes drastically; 0 volts at 0% SOC,
and peak voltage at 100% SOC.
No it doesn't. I mean, it can, but it doesn't have to.
If it follows LiIon 4V to 3V only, this is under utilizing
the caps but simplifying things.
So, a much better way is to connect the ultracapacitors thru a DC/DC
converter.
Better way for whom? In an academic discussion - it may be technically
better way.
If I have free capacitors, the best way is to connect a bunch
of them in parallel.
If I have free DC-DC, the best way becomes using *it*.
When you need power from the ultracapacitors, run them down
to as low a voltage as the DC/DC will allow
....
The end result is that adding the DC/DC converter drasticlaly reduces
the number of ultracapacitors needed.
Cost/size/efficiency of such a DC-DC *may* make you worse off
than just using bunch of extra underutilized caps.
I analyzed my circumstances, and this was the case, not to
mention I could not find affordable DC-DC.
Ultracaps stack is easy - they should not exceed 2.5V/cap.
Figure the highest voltage your drive system will have.
If you want AC system, consider highest voltage during regen.
Ultracapacitors have exactly the problem of LiIons. You must watch the
voltage of very single cell, and not let it go too low or too high.
Sorry, no. Just as for any cap, you can let it go to 0V, no problem.
If
you just string them in series with no measurement or equalization, you
can't come anywhere near using their maximum capabilities without at
least one cell getting overvoltaged or reverse-voltaged.
Very true, therefore you need aggressive equalization and use
of mid-range of its ratings deliberately under utilizing them.
The price for staying away from max they theoretically can
deliver is you overkill by using more of them.
5. Should the regen be routed to both of the packs or just one
(which one is better for regen)?
Regen is dynamic and short in duration. Ultracaps are the
only device which can take it and benefit from energy recovery.
The big problem during regen is, "Where do you put the energy?"
If ultracaps are full, use disk brakes.
If the batteries are already at or nearly fully charged, you can't put
it there. Likewise, if the ultracapacitors are already fully charged, it
can't go there, either. To handle this this situation, you either need a
huge resisive load to dump the excess power, or (what is really done)
disable regen and use the regular friction brakes.
Yes. Still, far better than using disk brakes at all times.
Next point: In normal driving, most people do not brake any harder than
they accellerate. If the batteries can handle the peak current for
accellerating, they can handle the braking current generated during
decelleration. Ultracapacitors aren't really required for this.
Depends on the batteries. PbA - yes, but only partially
discharged. Right off charger they can deliver say
500A but trying to charge with 500A is not possible.
For 18650 cells I'm not sure, but I haven't
seen a spec stating it's OK to charge LiIons with the
same rate you discharge them. Not to mention, individual
control is not possible.
If you want to capture braking energy during extreme conditions
(high-speed panic stops, or long downhill grades), then ultracapacitors
or some other form of fast-charge system would be needed. But as a
practical matter, you almost never do this. You would be adding a great
deal of cost and complexity for a problem that rarely occurs.
True. In my case main reason I use caps is to reduce stress on the
batteries for peak current demands. TS cells are not power ones.
Re-capturing regen current is very nice side-benefit, but not the
objective. If recapturing would not be possible, I'd still use
the caps to relieve the kind of battery I have.
As you say, for 18650 or other power type of batteries
using ultracaps in an EV is unlikely to be worthwhile,
at least with today's prices on them.
--
Victor
'91 ACRX - something different
--- End Message ---
