EV Digest 4486
Topics covered in this issue include:
1) Supercaps/Ultracaps
by justin vandeusen <[EMAIL PROTECTED]>
2) Re: State of Charge calculations
by Victor Tikhonov <[EMAIL PROTECTED]>
3) Re: Supercaps/Ultracaps
by Victor Tikhonov <[EMAIL PROTECTED]>
4) Re: State of Charge calculations
by Eric Poulsen <[EMAIL PROTECTED]>
5) RE: State of Charge calculations
by "Roger Stockton" <[EMAIL PROTECTED]>
6) RE: OT: Another idea that probably won't work
by "Stu or Jan" <[EMAIL PROTECTED]>
7) RE: Supercaps/Ultracaps
by "Don Cameron" <[EMAIL PROTECTED]>
8) RE: State of Charge calculations
by "Roger Stockton" <[EMAIL PROTECTED]>
9) Re: OT: Another idea that probably won't work
by Victor Tikhonov <[EMAIL PROTECTED]>
10) LiIon vs LiPoly
by "Don Cameron" <[EMAIL PROTECTED]>
11) Re: State of Charge calculations
by Victor Tikhonov <[EMAIL PROTECTED]>
12) Re: Supercaps/Ultracaps
by Victor Tikhonov <[EMAIL PROTECTED]>
13) RE: Supercaps/Ultracaps
by justin vandeusen <[EMAIL PROTECTED]>
14) RE: State of Charge calculations
by "Roger Stockton" <[EMAIL PROTECTED]>
15) Re: Supercaps/Ultracaps
by justin vandeusen <[EMAIL PROTECTED]>
16) Re: LiIon vs LiPoly
by Victor Tikhonov <[EMAIL PROTECTED]>
17) Re: State of Charge calculations
by Victor Tikhonov <[EMAIL PROTECTED]>
18) Re: State of Charge calculations
by Travis Raybold <[EMAIL PROTECTED]>
19) Re: OT: Another idea that probably won't work
by Jim Coate <[EMAIL PROTECTED]>
20) Re: LiIon vs LiPoly
by keith vansickle <[EMAIL PROTECTED]>
21) RE: LiIon vs LiPoly
by "Jake Oshins" <[EMAIL PROTECTED]>
22) Source For Miniature Ball-Joints/Ball-Socket?
by Marvin Campbell <[EMAIL PROTECTED]>
23) TS quality and simple hybrid pack, was Re: LiIon vs LiPoly
by "Doug Hartley" <[EMAIL PROTECTED]>
24) Re: Source For Miniature Ball-Joints/Ball-Socket?
by Ryan Stotts <[EMAIL PROTECTED]>
25) Re: State of Charge calculations
by Jeff Shanab <[EMAIL PROTECTED]>
--- Begin Message ---
I have started looking into Supercaps/Ultracaps for
use in my AC conversion. I read through Victor's site
which briefly described the reason to use them and how
to calculate how many to use and the voltage drop
across them. I am looking for more information (as
usual) such as:
1. How are these charged? (I know from experience caps
are open to dc but pass ac) Is the low ESR allowing dc
charging or am I way off base here?
2. Equilization. What are some techniques to
accomplish this? Will this require extra circuitry,
etc. ?
3. Any other usefull information. What are good
mounting practices? Should these be placed as close to
motor as possible or battery? etc....
As always, thanks for the information/help for an EV
noobie!
Justin
____________________________________________________
Sell on Yahoo! Auctions no fees. Bid on great items.
http://auctions.yahoo.com/
--- End Message ---
--- Begin Message ---
Roger Stockton wrote:
Victor Tikhonov [mailto:[EMAIL PROTECTED] wrote:
If I have voltage squarer circuit, I feed 2V in it, i get 4V
out. I feed 3V i get 9V out. It is Vout=Vin^2, bit volts as
units are not squared, expression on the right *does not* get
V*V or V^2 unit.
But, have you ever seen a voltage squarer circuit? ;^> Voltage doubler,
tripler, etc. sure, but these are all volts + volts types of things, not
volts * volts.
Of course I have. I'm sure you also have seen "square rooter" circuits
based on op amps; same consept. Units do not become (sqrt)V, it is
still volts.
You attach a value afte you do you math of raising a number
in ulitless power.
I may be wrong, but I think this is the source of eror here.
No, I think Pillip is correct in his analysis. Your reasoning would
have us multiply length * width (both in mm) and end up with the area of
a square in mm (a linear measure) rather than mm^2 (since length =
width, so area = length ^ 2 = length * length).
No, picky man :-), I specifically stated it *may or may not* be the case
depending if units are inside the brackets (and *everything* in brackets
is rased into a power) or outside. I did not mean mistake in discussion,
just merely typo type error in equasion.
What may actually be the error is the CECO document's author assigning
the units of Ah to the right hand side of the questionable equation.
May be, I didn't check and, sorry, not motivated enough.
As Lee said, the fit is imperical, so the math is done on a
number only to make outcome to fit empirical test results.
But the units must be the same on both sides of equasion,
regardless how close the numerical fit is to reality,
and as I understand it is not the same.
Two different issues.
--
Victor
'91 ACRX - something different
--- End Message ---
--- Begin Message ---
justin vandeusen wrote:
I have started looking into Supercaps/Ultracaps for
use in my AC conversion. I read through Victor's site
which briefly described the reason to use them and how
to calculate how many to use and the voltage drop
across them. I am looking for more information (as
usual) such as:
1. How are these charged?
From a charger :) And from an AC system during regen,
but this depends how do you hook them up - if there is
a DC-DC converter in between (which I doubt it is in your case).
What type of battery are you planning? E.g. what
exactly makes you think you'd benefit from ultracaps?
(I know from experience caps
are open to dc but pass ac) Is the low ESR allowing dc
charging or am I way off base here?
It is all DC in your case, and you need to re-phrase
it - caps are open to DC and pass any *changes* in DC.
*Changes* of DC is alternating DC value, which by
definition becomes "AC" and caused by AV (alternating
voltage).
2. Equilization. What are some techniques to
accomplish this?
Look on Maxwell's site. Passive - resistors ladder (as I did)
or active - similar to a battery equalizing.
Will this require extra circuitry,
etc. ?
Of course it will.
3. Any other usefull information. What are good
mounting practices? Should these be placed as close to
motor as possible or battery? etc....
How are you planning to connect
As always, thanks for the information/help for an EV
noobie!
Justin
____________________________________________________
Sell on Yahoo! Auctions – no fees. Bid on great items.
http://auctions.yahoo.com/
--
Victor
'91 ACRX - something different
--- End Message ---
--- Begin Message ---
Roger Stockton wrote:
Victor Tikhonov [mailto:[EMAIL PROTECTED] wrote:
If I have voltage squarer circuit, I feed 2V in it, i get 4V
out. I feed 3V i get 9V out. It is Vout=Vin^2, bit volts as
units are not squared, expression on the right *does not* get
V*V or V^2 unit.
But, have you ever seen a voltage squarer circuit? ;^> Voltage doubler,
tripler, etc. sure, but these are all volts + volts types of things, not
volts * volts.
Here's one:
http://www.ee.washington.edu/stores/DataSheets/linear/ad633.pdf
Just put the same voltage to both inputs.
You attach a value afte you do you math of raising a number
in ulitless power.
I may be wrong, but I think this is the source of eror here.
No, I think Pillip is correct in his analysis. Your reasoning would
have us multiply length * width (both in mm) and end up with the area of
a square in mm (a linear measure) rather than mm^2 (since length =
width, so area = length ^ 2 = length * length).
What may actually be the error is the CECO document's author assigning
the units of Ah to the right hand side of the questionable equation.
The equation itself is correct, but the value it computes is supposed to
be a constant, not necessarily one with units of Ah. Mistakenly
assuming that the equation I^n*Ti yields a value with units of Ah then
leads one to try to use that value in calculations that are in units of
Ah and may result in errors.
However, the proof is in the pudding. Now that Peukert's equation
without the questionable units manipulation has been identified it
should be a simple matter for someone to plug both versions into a
spreadsheet and compare the output. If both versions yield similar
results then questionable as the units manipulation may be, that
equation may still have practical value.
Well, besides
I^n * Ti = C
you can also do
C / I^n = Ti
To get the time remaining before discharge.
In a practical sense, C is no different from being the effective
"Peukert's Capacity" of the battery, for the 20C rate.
I^n * Ti = constant
Where
* I = discharge current [amp]
* N = battery constant (n=1.35 for typical lead-acid batteries)
* Ti = time to discharge at current I [seconds]
or,
C1 = C2 * (I2/I1)^(n-1)
Where:
C1 = capacity at discharge rate I1
C2 = capacity at discharge rate I2
n = Peukert exponent (= "N = battery constant", from above)
which also avoids the questionable units manipulation by applying the
Peukert exponent to the dimensionless ratio of I2 to I1.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Victor Tikhonov [mailto:[EMAIL PROTECTED] wrote:
> Of course I have. I'm sure you also have seen "square rooter"
> circuits based on op amps; same consept. Units do not become
> (sqrt)V, it is still volts.
Fair enough ;^>
> No, picky man :-), I specifically stated it *may or may not*
> be the case depending if units are inside the brackets (and
> *everything* in brackets is rased into a power) or outside. I
> did not mean mistake in discussion, just merely typo type
> error in equasion.
Sorry; I didn't notice that distinction. Mike Shipway suggested that if
the units were outside the brackets it might be acceptable, however, I
don't see how one can arbitrarily make a dimensioned value
dimensionless, manipulate it, and then arbitrarily reassign a dimension
to it.
It is standard practice to perform a units analysis on an equation as a
sanity check; one cannot do that if the units can arbitrarily be
dissassociated from the values and then reassigned later at will.
> As Lee said, the fit is imperical, so the math is done on a
> number only to make outcome to fit empirical test results.
> But the units must be the same on both sides of equasion,
> regardless how close the numerical fit is to reality, and as
> I understand it is not the same.
>
> Two different issues.
Yes; absolutely.
Most of us appear to be in agreement that the units must be the same on
both sides of an equation, and that the equation presented in the CECO
document violates this. We also agree that Peukert's equation describes
an emperical fit to the real-world behaviour of lead acid chemistry.
What is missing at this point is any evidence that the equation in the
CECO document is being used correctly to estimate/predict the battery
behaviour with any accuracy. There is no doubt that CECO has properly
implemented the equation in the E-Meter code, but this doesn't mean the
documentation is correct or accurately describes the algorithm actually
used.
Eric Poulsen has tried to use the equations and algorithm in the CECO
documentation and has thus far been unsuccessful in getting them to
produce sensible results, which suggests that there may be an error in
the documentation since we all agree that the E-Meter does a reasonable
job of estimating battery capacity, and we all agree that Peukert's
equation does a reasonable job of modelling the real-world behaviour of
lead acid batteries.
Given that we can all point to something obviously suspect with the
equations in CECO's documentation, it seems reasonable that we should
assume the documentation is incorrect and therefore examine it
critically for any other errors and/or use versions of Peukert's
equation that do not have the suspect unit manipulation to sanity check
the equations in CECO's documentation. ("We" of course means Eric,
since he is the one particularly interested in implementing his own
version of an E-Meter ;^).
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Speaking of expensive items that sit for most of the time, here in Fort
Pierce there are millions of dollars of boats of all kinds that sit 95% in
port.
BoyntonStu
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Victor Tikhonov
Sent: Thursday, July 07, 2005 5:08 PM
To: [email protected]
Subject: Re: OT: Another idea that probably won't work
David Roden wrote:
> On 6 Jul 2005 at 21:03, Jeff Shanab wrote:
>
>
>>I am not sure this is really off topic, we all must contend with the
>>best way to do the occasional 240 mile trip.
>
>
> If it's only 2-3 times a year, why not rent or borrow an ICE for those
days?
Because people is more individulaistic than practical. A car
has to be MINE, I possess it.
People rent cars or hire taxis if they have no other choice - on trips,
emergency etc, or owning is prohibitively expensive.
Everything else must be in comfort of ownership It is *convenient*
to have a vehicle sitting ready for you at any time.
Doesn't matter that it is sitting doing nothing 364 days of a year
if one can easily afford it.
Like some tools - people may need to lift heally heavy
things 2-3 times per year, but no one rents those folding
hydrolic $200 joists on small metal wheels- every one owns it.
Why not cars.
I believe this is the main reason public transportation is
in so pathetic state here - because word "public" has bad taste
and associations (not nesessairly related to the transportation).
--
Victor
'91 ACRX - something different
--- End Message ---
--- Begin Message ---
Justin, I am curious as to your application.
>From my understanding, ultra caps are only required for batteries in which
are unable to deliver high amounts of current for the intended application.
An example is Victor's work with LiIon cells. He uses ultracaps for higher
current delivery which cannot be obtained by using LiIon cells alone.
Ultracaps would not be required if you were to use a technology such as lead
acid or lithium polymer. I think lithium polymer is somewhat equivalent to
LiIon in terms of price, longevity and power density.
Don
Victoria, BC, Canada
See the New Beetle EV Conversion Web Site at
www.cameronsoftware.com/ev/
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of justin vandeusen
Sent: July 7, 2005 2:31 PM
To: EVLIST
Subject: Supercaps/Ultracaps
I have started looking into Supercaps/Ultracaps for use in my AC conversion.
I read through Victor's site which briefly described the reason to use them
and how to calculate how many to use and the voltage drop across them. I am
looking for more information (as
usual) such as:
1. How are these charged? (I know from experience caps are open to dc but
pass ac) Is the low ESR allowing dc charging or am I way off base here?
2. Equilization. What are some techniques to accomplish this? Will this
require extra circuitry, etc. ?
3. Any other usefull information. What are good mounting practices? Should
these be placed as close to motor as possible or battery? etc....
As always, thanks for the information/help for an EV noobie!
Justin
____________________________________________________
Sell on Yahoo! Auctions - no fees. Bid on great items.
http://auctions.yahoo.com/
--- End Message ---
--- Begin Message ---
> -----Original Message-----
> From: Eric Poulsen [mailto:[EMAIL PROTECTED]
> Sent: July 7, 2005 3:01 PM
> To: [email protected]
> Subject: Re: State of Charge calculations
>
>
>
>
> Roger Stockton wrote:
>
> >Victor Tikhonov [mailto:[EMAIL PROTECTED] wrote:
> >
> >
> >
> >>If I have voltage squarer circuit, I feed 2V in it, i get 4V
> >>out. I feed 3V i get 9V out. It is Vout=Vin^2, bit volts as
> >>units are not squared, expression on the right *does not* get
> >>V*V or V^2 unit.
> >>
> >>
> >
> >But, have you ever seen a voltage squarer circuit? ;^>
> Voltage doubler,
> >tripler, etc. sure, but these are all volts + volts types of things,
> >not volts * volts.
> >
> >
> Here's one:
>
> http://www.ee.washington.edu/stores/DataSheets/linear/ad633.pdf
>
> Just put the same voltage to both inputs.
Nope. The datasheet states that the transfer function of this device
is:
(X1-X2)(Y1-Y2)
W = -------------- + Z
10V
X1, X2, Y1, Y2, W, and Z are in units of volts (V), so a units analysis
is:
(V-V)(V-V) V*V
V = ---------- + V = --- + V = V + V
V V
That is, units of volts are preserved due to the internal division by
10V.
> Well, besides
>
> I^n * Ti = C
>
> you can also do
>
> C / I^n = Ti
>
> To get the time remaining before discharge.
>
> In a practical sense, C is no different from being the effective
> "Peukert's Capacity" of the battery, for the 20C rate.
Nope. You still appear to be missing the fact that amps raised to some
power no longer have units of amps, and therefore C cannot have units of
Ah.
C is a constant for the battery, not just for the C/20 rate, but it
doesn't have units of Ah so you cannot use it in calculations involving
Ah values.
Use the relationship: C1 = C2 * (I2/I1)^(n-1)
to determine the Peukert exponent (n) for your battery.
and then compute the battery's Peukert capacity (Cp = I^n*Ti) for both
pairs C1/I1 and C2/I2 and you should find that Cp is the same in both
cases.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Different league, these boats are demonstration of wealth and
status, not the transportation means. The more expensive -
the better their purpose is served.
Many exotic and collectible cars sit in private displays/garages
100% of the time, yet, there are many people who would like to own it.
We're discussion practical [once-twice per year] transportation means,
ownership vs. rent, not ownership-for-bragging cars/boats.
Victor
Stu or Jan wrote:
Speaking of expensive items that sit for most of the time, here in Fort
Pierce there are millions of dollars of boats of all kinds that sit 95% in
port.
BoyntonStu
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Victor Tikhonov
Sent: Thursday, July 07, 2005 5:08 PM
To: [email protected]
Subject: Re: OT: Another idea that probably won't work
David Roden wrote:
On 6 Jul 2005 at 21:03, Jeff Shanab wrote:
I am not sure this is really off topic, we all must contend with the
best way to do the occasional 240 mile trip.
If it's only 2-3 times a year, why not rent or borrow an ICE for those
days?
Because people is more individulaistic than practical. A car
has to be MINE, I possess it.
People rent cars or hire taxis if they have no other choice - on trips,
emergency etc, or owning is prohibitively expensive.
Everything else must be in comfort of ownership It is *convenient*
to have a vehicle sitting ready for you at any time.
Doesn't matter that it is sitting doing nothing 364 days of a year
if one can easily afford it.
Like some tools - people may need to lift heally heavy
things 2-3 times per year, but no one rents those folding
hydrolic $200 joists on small metal wheels- every one owns it.
Why not cars.
I believe this is the main reason public transportation is
in so pathetic state here - because word "public" has bad taste
and associations (not nesessairly related to the transportation).
--
Victor
'91 ACRX - something different
--- End Message ---
--- Begin Message ---
Justin's question brings up a question I have about Lithium Ion batteries,
such as the Thundersky versus the LiPoly batteries such as Kokams.
Is the LiIon technology now obsolete for EVs because of Lithium Polymer?
>From reading mail lists and speaking with people about Kokams and TS, I have
the following impressions:
Price per Ah - similar
Energy Density - similar
Safety - I have the perception that LiIon can burn quite badly, yet Li
Polymer cannot.
Discharge Rate - Li Polymer is superior, does not require Ultracaps or extra
PbA batteries for high discharge needs
Weight - similar
Charging - both require over-voltage limiters
Quality - Kokam's seem to have a better reputation than TS
Comments? Corrections? Other impressions? (maybe a reference to a
scientific test?)
Don
Victoria, BC, Canada
See the New Beetle EV Conversion Web Site at
www.cameronsoftware.com/ev/
--- End Message ---
--- Begin Message ---
C'mon Roger, don't drag this thing :-)
...
Nope. You still appear to be missing the fact that amps raised to some
power no longer have units of amps, and therefore C cannot have units of
Ah.
If I multiply 10m room length by 10m width I get area (*different*
"variable) in m^2.
(10m)^2 - note, meters are inside the brackets.
If I say I want to increase the area of my room to make it equal
the square of the area *number* I currently have, I get
10 square meters squared or (10)^2 square meters, (100 m^2) now.
Area remains area. Note, this is because units are outside brackets
now so do not change.
I only scaled value. I could have raised my area 10 meters square
in 1.3 power and get *number* 19.95 and *then* put units next to it.
It is not adding another dimention as width x length.
Same with Ah - you can raise number itself to anything
to make result fit practically obtained, just don't raise
units - you're only scaling the same units.
--
Victor
'91 ACRX - something different
--- End Message ---
--- Begin Message ---
Don Cameron wrote:
Justin, I am curious as to your application.
From my understanding, ultra caps are only required for batteries in which
are unable to deliver high amounts of current for the intended application.
An example is Victor's work with LiIon cells. He uses ultracaps for higher
current delivery which cannot be obtained by using LiIon cells alone.
Correction - current needed for *my* EV cannot be obtained by using
*my current* LiIon pack, because it is undersized and the cells
underperform compared to promised spec.
The statement in general is not true ACP is good ecxampel of use of
LiIons without ultracaps.
If I had 200Ah cells, the current they easily provide would exceed limit
of my inverter, and there would be no point of using ultracaps.
Ultracaps would not be required if you were to use a technology such as lead
acid or lithium polymer. I think lithium polymer is somewhat equivalent to
LiIon in terms of price, longevity and power density.
Yes, and the difference is in liquid ion conducting electrolyte
vs semi-solid (polymer) one.
Victor
Don
Victoria, BC, Canada
See the New Beetle EV Conversion Web Site at
www.cameronsoftware.com/ev/
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of justin vandeusen
Sent: July 7, 2005 2:31 PM
To: EVLIST
Subject: Supercaps/Ultracaps
I have started looking into Supercaps/Ultracaps for use in my AC conversion.
I read through Victor's site which briefly described the reason to use them
and how to calculate how many to use and the voltage drop across them. I am
looking for more information (as
usual) such as:
1. How are these charged? (I know from experience caps are open to dc but
pass ac) Is the low ESR allowing dc charging or am I way off base here?
2. Equilization. What are some techniques to accomplish this? Will this
require extra circuitry, etc. ?
3. Any other usefull information. What are good mounting practices? Should
these be placed as close to motor as possible or battery? etc....
As always, thanks for the information/help for an EV noobie!
Justin
____________________________________________________
Sell on Yahoo! Auctions - no fees. Bid on great items.
http://auctions.yahoo.com/
--
Victor
'91 ACRX - something different
--- End Message ---
--- Begin Message ---
Don,
Thanks for the reply. For my first conversion I plan
on building a high performance pickup. I am planning
on using hawkers for my first set of batteries, So I
can get into a EV sooner and learn about them by
actual usage. Later (1-2, maybe 3 years max) I would
like to upgrade to tbe best batteries that I can
afford. Not sure what I will end up with at that time,
depends how much cash I can throw into it. I am still
curious about supercap implemntation just in case....
I will make a note of your good point, so I don't ask
this question again in the future. Thanks again!
Justin
--- Don Cameron <[EMAIL PROTECTED]> wrote:
> Justin, I am curious as to your application.
>
> >From my understanding, ultra caps are only required
> for batteries in which
> are unable to deliver high amounts of current for
> the intended application.
> An example is Victor's work with LiIon cells. He
> uses ultracaps for higher
> current delivery which cannot be obtained by using
> LiIon cells alone.
>
> Ultracaps would not be required if you were to use a
> technology such as lead
> acid or lithium polymer. I think lithium polymer is
> somewhat equivalent to
> LiIon in terms of price, longevity and power
> density.
>
> Don
>
>
>
> Victoria, BC, Canada
>
> See the New Beetle EV Conversion Web Site at
> www.cameronsoftware.com/ev/
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On
> Behalf Of justin vandeusen
> Sent: July 7, 2005 2:31 PM
> To: EVLIST
> Subject: Supercaps/Ultracaps
>
> I have started looking into Supercaps/Ultracaps for
> use in my AC conversion.
> I read through Victor's site which briefly described
> the reason to use them
> and how to calculate how many to use and the voltage
> drop across them. I am
> looking for more information (as
> usual) such as:
>
> 1. How are these charged? (I know from experience
> caps are open to dc but
> pass ac) Is the low ESR allowing dc charging or am I
> way off base here?
>
> 2. Equilization. What are some techniques to
> accomplish this? Will this
> require extra circuitry, etc. ?
>
> 3. Any other usefull information. What are good
> mounting practices? Should
> these be placed as close to motor as possible or
> battery? etc....
>
> As always, thanks for the information/help for an EV
> noobie!
>
>
> Justin
>
>
>
> ____________________________________________________
> Sell on Yahoo! Auctions - no fees. Bid on great
> items.
> http://auctions.yahoo.com/
>
>
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
--- End Message ---
--- Begin Message ---
Victor Tikhonov [mailto:[EMAIL PROTECTED] wrote:
> C'mon Roger, don't drag this thing :-)
I won't if you don't ;^>
> If I multiply 10m room length by 10m width I get area (*different*
> "variable) in m^2.
Nope. You must be able to do a units analysis on your calculation and
end up with the same units on both sides. You cannot arbitrarily
associate or dissassociate units (dimensions) from values.
> (10m)^2 - note, meters are inside the brackets.
area (m^2) = length x width
= meters x meters
= m^2
Units are not inside or outside of the brackets; they are inseparably
associated with the length and width values.
> If I say I want to increase the area of my room to make it
> equal the square of the area *number* I currently have, I get
>
> 10 square meters squared or (10)^2 square meters, (100 m^2) now.
>
> Area remains area. Note, this is because units are outside
> brackets now so do not change.
No, it is because you have increased your area by a dimensionless
factor.
If you really did take an area value of 10m^2 and squared it you would
have 100 m^4, which is not area but something else (what exactly, I'm
not sure ;^).
What you really have done is said "my room is presently 10m^2 and if I
made it 10x larger, I would have 10m^2 * 10 = 100 m^2, which happens to
be the square of the present area".
> I only scaled value. I could have raised my area 10 meters
> square in 1.3 power and get *number* 19.95 and *then* put
> units next to it.
You could also add 2 + 2 and get 5, but it still wouldn't be correct.
It is easiest to understand this issue when using integer exponents such
as 2, but it hold just as true for exponents like 1.23.
If 10m x 10m = (10m)^2 = 100m^2, and (10m)^3 = 1000m^3, then surely it
is obvious that (10m)^1.23 = 16.98m^1.23. The exponent is applied to
both the value and the units, and parentheses do not change this they
are merely used in the examples above to avoid confusion.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
--- Victor Tikhonov <[EMAIL PROTECTED]> wrote:
> justin vandeusen wrote:
> > I have started looking into Supercaps/Ultracaps
> for
> > use in my AC conversion. I read through Victor's
> site
> > which briefly described the reason to use them and
> how
> > to calculate how many to use and the voltage drop
> > across them. I am looking for more information (as
> > usual) such as:
> >
> > 1. How are these charged?
>
> From a charger :) And from an AC system during
> regen,
> but this depends how do you hook them up - if there
> is
> a DC-DC converter in between (which I doubt it is in
> your case).
>
> What type of battery are you planning? E.g. what
> exactly makes you think you'd benefit from
> ultracaps?
>
I plan on using lead acids to start with (Hawker
Odyssey). Would like to upgrade to lithiums in the
future. Sounds like I wont need them to start off
with. Thats good, less complexity, less wieght, and
less for me to blow up.
> > (I know from experience caps
> > are open to dc but pass ac) Is the low ESR
> allowing dc
> > charging or am I way off base here?
>
> It is all DC in your case, and you need to re-phrase
> it - caps are open to DC and pass any *changes* in
> DC.
> *Changes* of DC is alternating DC value, which by
> definition becomes "AC" and caused by AV
> (alternating
> voltage).
>
> > 2. Equilization. What are some techniques to
> > accomplish this?
>
> Look on Maxwell's site. Passive - resistors ladder
> (as I did)
> or active - similar to a battery equalizing.
>
> Will this require extra circuitry,
> > etc. ?
>
> Of course it will.
> >
> > 3. Any other usefull information. What are good
> > mounting practices? Should these be placed as
> close to
> > motor as possible or battery? etc....
>
> How are you planning to connect
>
> >
> > As always, thanks for the information/help for an
> EV
> > noobie!
> >
> >
Thanks for the reply Victor!
Justin
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
--- End Message ---
--- Begin Message ---
Don Cameron wrote:
Justin's question brings up a question I have about Lithium Ion batteries,
such as the Thundersky versus the LiPoly batteries such as Kokams.
It is better to compare cells in similar form factor - like
18650 LiIons vs 18650 LiP. Jacket packaged flexible Kokam's will have
different characteristics vs TS LiIon partially because of the packaging
form factor and reaction area, heat dissipation, etc.
Is the LiIon technology now obsolete for EVs because of Lithium Polymer?
Dod NiCD obsolate because of NiMH came out? Bith are nickel based...
From reading mail lists and speaking with people about Kokams and TS, I have
the following impressions:
Price per Ah - similar
function of volume
Energy Density - similar
yes
Safety - I have the perception that LiIon can burn quite badly, yet Li
Polymer cannot.
depends on the manufacturer, in general consider the same
Discharge Rate - Li Polymer is superior, does not require Ultracaps or extra
PbA batteries for high discharge needs
No, everything else (other than ion carrier) being equal,
it is the same. *Li* is the one which does the work.
Weight - similar
yes
Charging - both require over-voltage limiters
Yes
Quality - Kokam's seem to have a better reputation than TS
Reputation isn't always reflect the product. TS ruined
it by bad actions and now produces excellent manganese
flavor of their batteries. They are trying to reectify
the situation. But no matter how much superior and cheaper
new cells *really* may be, few will believe TS for a long
time. Try to convince John Lussmyer to try different TS product.
I don't think he's going to bother unless many other will
demonstrate for him it worth it and TS corrected their mistakes.
Comments? Corrections? Other impressions? (maybe a reference to a
scientific test?)
Don
I'd like to hear coments from others too. Or everyone
expects to get free data at my expense? :-)
If you want to know how a battery performs, buy a sample
and test it. I do. Asking on the web is easy, but the answer
may worth nothing too, you know.
--
Victor
'91 ACRX - something different
--- End Message ---
--- Begin Message ---
Roger Stockton wrote:
No, it is because you have increased your area by a dimensionless
factor.
Back to the battery, this is what peukert exponent is - dimentionless
number you raise Ah into, and so get Ah as well.
If you really did take an area value of 10m^2 and squared it you would
have 100 m^4,
> The exponent is applied to
both the value and the units,
No, not in this Ah example, and this is the source of confusion.
Peukert exponent merely scales output, it does *not* applies to the
number and units as in your [I think general, but I may be wrong]
statement.
We both understand. And sinse you asked not to reply,
I promise I won't :-)
Victor
--- End Message ---
--- Begin Message ---
if we take peukert's equation:
I^n*T=C
1amp^1.2*1hour = 1 amp hour
1000 milliamps^1.2*1hour=3981 milliamp hours = 3.981 amp hours
so is it an approximation that just happens to model real world behavior
correctly but only when measuring in amp hours?
--travis
--- End Message ---
--- Begin Message ---
On the bright side, ZipCar is alive and well... I joined just so I could
drive one of the Rav4-EVs (yes, a RAV4 EV near Boston!), but the bulk of
their cars are ICE's so a perfect compliment to an EV owner.
http://www.zipcar.com/
Only in the north east so far, but they are expanding...
David Roden wrote:
If it's only 2-3 times a year, why not rent or borrow an ICE for those days?
What we really need, gang, is station cars. Unfortunately stncar.com seems
to be defunct, which isn't a good sign.
--
Jim Coate
1970's Elec-Trak's
1998 Chevy S-10 NiMH BEV
1997 Chevy S-10 NGV Bi-Fuel
http://www.eeevee.com
--- End Message ---
--- Begin Message ---
Hi don and victor and all
I too am interested in the LI technology I have
purchased a 48 volt 40AHR pack consisting of 4 12v
Valence Technology Saphion U-charge batts/charger and
BMS. As of this writing I have only recieved one of
the batts and the charger when I get the other three
batts, the bms and the vehicle to use them in next
week---hope hope ??? I will beging tests on the whole
pack and let the group know what I find out. I have a
lot of confidence in what i have read but one can
never be sure untill they have them in a vehicle and
on the road
Keith
> I'd like to hear coments from others too. Or
> everyone
> expects to get free data at my expense? :-)
> If you want to know how a battery performs, buy a
> sample
> and test it. I do. Asking on the web is easy, but
> the answer
> may worth nothing too, you know.
>
> --
> Victor
> '91 ACRX - something different
>
>
____________________________________________________
Sell on Yahoo! Auctions no fees. Bid on great items.
http://auctions.yahoo.com/
--- End Message ---
--- Begin Message ---
So what did those batteries cost? And where can you buy them?
Thanks,
Jake Oshins
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of keith vansickle
Sent: Thursday, July 07, 2005 5:24 PM
To: [email protected]
Subject: Re: LiIon vs LiPoly
Hi don and victor and all
I too am interested in the LI technology I have purchased a 48 volt
40AHR pack consisting of 4 12v Valence Technology Saphion U-charge
batts/charger and BMS. As of this writing I have only recieved one of
the batts and the charger when I get the other three batts, the bms and
the vehicle to use them in next week---hope hope ??? I will beging tests
on the whole pack and let the group know what I find out. I have a lot
of confidence in what i have read but one can never be sure untill they
have them in a vehicle and on the road Keith
> I'd like to hear coments from others too. Or everyone expects to get
> free data at my expense? :-) If you want to know how a battery
> performs, buy a sample and test it. I do. Asking on the web is easy,
> but the answer
> may worth nothing too, you know.
>
> --
> Victor
> '91 ACRX - something different
>
>
____________________________________________________
Sell on Yahoo! Auctions - no fees. Bid on great items.
http://auctions.yahoo.com/
--- End Message ---
--- Begin Message ---
Exactly. Except I already have the stud in the actuator-arm. The part I
really need is the socket.
But I've gotten a whole lot of new leads from EVerybody.
Thanks a million!
Marv
PS: Still shaking over the fact that I found something that's NOT in
McMaster-Carr catalog...scary!
> From: Ryan Stotts <[EMAIL PROTECTED]>
> Date: Thu, 7 Jul 2005 12:21:42 -0500
> To: [email protected]
> Subject: Re: Source For Miniature Ball-Joints/Ball-Socket?
>
> Marvin Campbell wrote:
>
>> Anybody have a source for these? I see them in throttle linkage app's all
>> the time (my Chevy truck had them on the throttle-body- plastic, of course).
>
> Did they look like these?
>
> http://www.holley.com/data/products/pictures/large20-2.jpg
>
> http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=728&prmenbr=361
--- End Message ---
--- Begin Message ---
No, everything else (other than ion carrier) being equal,
it is the same. *Li* is the one which does the work.
Valence li ion cells use a different cathode material which results in lower
voltage per cell - hence a little less power/energy stored per
weight/volume - but greater safety. It also works out conveniently that 4
Valence cells are close to a 12V battery voltage (instead of being too high
or using 3 cells, then too low) and then can be packaged as 12V batteries
in conventional sizes (U1, 24, 27) easy to integrate. I believe these
batteries are great for EV use and look forward to using them in a plug-in
hybrid Prius. (The first of many such conversions I hope to do for others
as well.)
Reputation isn't always reflect the product. TS ruined
it by bad actions and now produces excellent manganese
flavor of their batteries. They are trying to reectify
the situation. But no matter how much superior and cheaper
new cells *really* may be, few will believe TS for a long
time. Try to convince John Lussmyer to try different TS product.
I don't think he's going to bother unless many other will
demonstrate for him it worth it and TS corrected their mistakes.
I'd like to hear coments from others too. Or everyone
expects to get free data at my expense? :-)
--
Victor
'91 ACRX - something different
I have received 4 shipments of TS 100 and 200 A-Hr cells over 1.5 years,
Spring 2003 to Fall 2004. The 3 first shipments are combined together in
one vehicle, the Skoda pickup. So far I have had good results, hundreds of
cycles, no noticeable deterioration, and no failures, including after a deep
discharge. I had excellent service from them also with delivery better than
promised and phone calls if any shipping trouble occurred, even at my end.
By the way, the idea of combining 28 of the 100 Amp-Hr TS cells with 8
DCS-75 AGM group 24 size batteries to make a 96V hybrid pack (a nice
improvement over 84V GC!) in a simple way (contactor closed for charging and
driving, open and battery packs separated when sitting) is working out very
well for the Skoda hatchback. The hybrid pack is lower cost than all
lithium, provides lots of pep and is still 300 pounds lighter than the 84V
golf cart pack it replaced, with better top speed and range. Contrary to
the Skoda pickup, for this vehicle it is the TS cells that are helping the
AGM batteries, and keep them charged during pauses or lower demand time
periods. There are still no regulators on these 28 TS cells and that has
not been a problem since this arrangement does not charge them past about
4V/cell. ( Although I will likely add regulators eventually) So this
arrangement is simple, fits in about the same space (but less high) compared
with a conventional GCbattery pack, less maintenance, is "relatively" cheap
and works well.
My 2 battery types worth...
Best Regards,
Doug
--- End Message ---
--- Begin Message ---
Marvin Campbell wrote:
> Exactly. Except I already have the stud in the actuator-arm. The part I
> really need is the socket.
Like the part that is on the end of the shocks used for trunks, hoods
and hatchbacks?
http://www.rsjparts.com/catalog/images/hatchshock2.jpg
I've never seen a separate fitting like that for sale.
--- End Message ---
--- Begin Message ---
Uh, 12 feet squared or (12 squared) feet, one is 144 sq feet or an
area measurement and the other is a measure of length. it is a simple
typographic convention that is the issue. The parenthesis were just in
the wrong place . The equations on the web sites have no parenthesis .
fixed
Cp = (10 )1.25Amps x 20 hr = 355.6 Ahr
like this site shows radioactive decay C= C0 (1/2)^n
http://www.geneng.mtu.edu/courses/1001/current/en1001.b06.p.solve.web.pdf
I agree units must match, we were required(and it is good practice) to
work all equations thru with units only, if the units worked then we ran
numbers. The other side to this philophy is when it is obvious, the
extra parenthisis can be dropped. Hince the web-sites.
--- End Message ---
