EV Digest 6930
Topics covered in this issue include:
1) RE: charging w/ one battery missing
by Joseph Tahbaz <[EMAIL PROTECTED]>
2) Re: Another thought, quarter mile
by Ian Hooper <[EMAIL PROTECTED]>
3) Re: Boost type controller - curtis vs. zilla?
by Markus Lorch <[EMAIL PROTECTED]>
4) Re: Interna Resistance?
by "Joe Smalley" <[EMAIL PROTECTED]>
5) Re: Another thought, quarter mile
by Victor Tikhonov <[EMAIL PROTECTED]>
6) RE: Understanding Motors II
by Mike Willmon <[EMAIL PROTECTED]>
7) Re: Another thought, quarter mile
by Dan Frederiksen <[EMAIL PROTECTED]>
8) Re: Cheap
by Tony Hwang <[EMAIL PROTECTED]>
9) Tell Toyota to Get With the Program!
by Marc Geller <[EMAIL PROTECTED]>
10) thundersky cells for cheap, prices
by Tony Hwang <[EMAIL PROTECTED]>
11) bruhless motor's
by "owen" <[EMAIL PROTECTED]>
12) Re: Another thought, quarter mile
by Chip Gribben <[EMAIL PROTECTED]>
13) Re: Flexible Stainless Steel interconnects
by Chip Gribben <[EMAIL PROTECTED]>
14) Re: Rolling Resistance - how to measure
by "Rob Hogenmiller" <[EMAIL PROTECTED]>
15) Re: Understanding Motors II
by "Rob Hogenmiller" <[EMAIL PROTECTED]>
16) Re: Understanding Motors II
by "Rob Hogenmiller" <[EMAIL PROTECTED]>
17) RE: Solectria Force Contactor?
by "Beth Silverman" <[EMAIL PROTECTED]>
18) Re: Understanding Motors II
by "Phil Marino" <[EMAIL PROTECTED]>
19) Re: DCDC converter
by "Phil Marino" <[EMAIL PROTECTED]>
20) Re: Rolling Resistance
by Tom Parker <[EMAIL PROTECTED]>
21) Re: Flexible Stainless Steel interconnects
by "Roland Wiench" <[EMAIL PROTECTED]>
22) Re: charging w/ one battery missing
by Tom Parker <[EMAIL PROTECTED]>
23) Re: thundersky cells for cheap, prices
by "Peter VanDerWal" <[EMAIL PROTECTED]>
24) Best Timing Advance for standard EV
by "Mark Hanson" <[EMAIL PROTECTED]>
25) Re: DCDC converter
by [EMAIL PROTECTED]
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I guess they'd have 33kJ of energy per cap, you'd only need ~30 of
them (in theory) - which is much more feasible.
(I can't be bothered integrating the drag & rolling resistance
equations for energy use, but I estimate it'd be in the order of
100kJ, not too significant compared with the kinetic energy.)
Couldn't find 2700Fs anymore but here's some similar ones: http://
www.maxwell.com/ultracapacitors/products/large-cell/bcap3000.asp
5.7 Wh/kg is about 20x less than LiFePO4s, but 14kW/kg is impressive.
Anyone know how much they cost?
-Ian
On 22/06/2007, at 12:11 PM, Bill Dennis wrote:
Ian,
I think that the Maxwell supercaps Victor uses are 2700F at 5V.
Try those number in your calculations instead.
I believe that's what the team at BYU has in their EV1, too.
Bill Dennis
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Peter and Roland,
thanks for your replies.
so what I take from this is that if I watch my personal battery amps
limit via my ammeter mounted on my dash (and reduce load if it gets too
high) I can achieve the same battery current limitting effect with the
Curtis that the Zilla would do for me automatically. I also then have
the same advantage that a higher pack voltage would help in reducing
battery amps (averaged out by the capacitors in the controller) when the
controller is not at full throttle/the motor not at full speed. This of
course goes up to the controller voltage limit, which is a lot lower on
the curtis than it is on the zilla.
Thanks, this helps
Markus
via Peter Gabrielsson schrieb:
<div class="moz-text-flowed" style="font-family: -moz-fixed">The zilla
and curtis essentially do the same thing. Power out always
equal power in (minus some heat losses). So if the motor is drawing
100A with 50V across it, power out equals 100*50 = 5kW. Lets say your
battery voltage is 100V the battery current will therefore be 5kW/100V
= 50A
The advantage the zilla gives you is that you can program it to limit
battery current at a specific value. When the curtis goes to full
throttle the battery current can be the same as the motor current.
On 6/21/07, Markus Lorch <[EMAIL PROTECTED]> wrote:
When reading the archives and other info on the web I find
it several times mentioned that the Zilla controller can
lower my battery amps. (e.g. here
http://www.mail-archive.com/ev@listproc.sjsu.edu/msg07672.html)
I am running a curtis 1221 right now. I wonder if another controller
can do significantly better in reducing battery amps than the Curtis
if I have no problem with the power limitations of the Curtis.
I.e. does the Zilla work differently than the Curtis. It is my
understanding that the Curtis is a similar type of controller and
also reduces battery amps. Hence buying a Zilla would not give me
an advantage unless I would step to a higher voltage pack.
Am I right?
Markus
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I think you forgot to multiply the resistance of a single battery times the
number of batteries.
In that case you would have:
.0036*12 + .00231 = .04551 ohms
Isc is 144/.04551 = 3164 amps
Pmax for the batteries is 144 / 2 * 3164 / 2 =113.9 kW
The controller limits you to 144 * (1-1000*.04551)*1000 = (144 - 45.51) *
1000 = 98.49 kW
This number needs to be multiplied by the motor and controller efficiencies
to get the mechanical power available.
Joe Smalley
Rural Kitsap County WA
Former owner of 48 Volt Fiesta
NEDRA 48 volt street conversion record holder
[EMAIL PROTECTED]
----- Original Message -----
From: "Joseph Tahbaz" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Thursday, June 21, 2007 5:24 PM
Subject: Interna Resistance?
I previously asked for an equation that puts into account the resistance
losses of an EV. Joe Smalley answered me; thanks Joe. But I can't quite get
the equation right. Can someone check my math? Here's the equation:Battery
short circuit current (Isc)Open Battery Voltage:VocRint: sum or internal
resistance and wiring resistanceIsc = (Voc/Rint)Maximum Power is (Voc / 2 *
Isc / 2)The controller is the power limit if Isc/2 is more than Ic, the
controller's current limit. In that case the equation is:Voc * (1 - Ic *
Rint)
*Ic.------------------------------------------------------------------------
-------Okay, now here's my math. Rint, the combination of internal
resistance (which is 0.036 ohms for me)and the wire resistance (which at
0.000077 ohms per foot times perhaps 30 feet of wire is 0.00231), which
makes about 0.006 ohms of resistance together.0.0036 + 0.00231 = ~ .006So,
with a 144 volt conversion, battery short circuit current is 144/0.006 which
is about 24000. Now, with a Zilla 1k controller the max. amps is 1000, and
24000/2 is more than 1000 amps so I go with the seconds equation. Voc * (1 -
Ic * Rint) *Ic. which is... 144 * (1 - 1000 * 0.004) *
1000This comes out to -863,163... Okay, I'm math stupid. Cansomeone explain
this to me?
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They are 2.5V working voltage, 2.7V - absolute max allowed.
Victor
Bill Dennis wrote:
Ian,
I think that the Maxwell supercaps Victor uses are 2700F at 5V. Try
those number in your calculations instead.
I believe that's what the team at BYU has in their EV1, too.
Bill Dennis
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Rob,
If its a series wound motor you can measure the resistance through both coils
and divide it into the amount of voltage you plan to
drop directly on it from the batteries and you'll get the amount of current
that will go through the motor. The trick is to keep
a good load on it so it doesn't spin up too fast and throw the commutator bars
off the armature. The RPM spec limit is one that
should generally be honored. Unless of course you send it to Jim first for
some bling. Then I hear they have no RPM limit and
are indestructable. Not really, but honor the RPM specs.
Jim Husted wrote: "either that or you think I'm
some freak from Alaska or something (oh hey Mike,
didn't see ya there, hehe)"
Mike wrote: don't worry about poking me in the eye, I have my safety goggles on
;-)
Now like Jim says those huskies will mush on you until they die. So the trick
is to not allow this current to run to them for too
long. Straight juice from a battery to a motor is like injecting adreniline
straight into your heart. A little bit when needed
will work, but too much will kill the husky. Now if you could supercool the
motor while at the same time injecting straight
adreniline then it might just put out super power for a long time. But heat
will build up fast. So if you want to find out how
long you can over amp the motor run it a little harder each time while it
starts out a ambient temperature and see how hot it gets
after 30 seconds, 1 minute 5 minutes etc. If you can't touch it with your hand
then running it longer will surely kill it. (The
other way to tell is if you let the smoke out of it, its probably dead, but
hopefully you'll be checking the heat buildup in a
scientific manner and not let it get that far.)
Anyway, just a few comments.
Mike,
Anchorage, Ak.
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Jim Husted
> Sent: Thursday, June 21, 2007 8:30 PM
> To: ev@listproc.sjsu.edu
> Subject: Re: Understanding Motors II
>
>
> Hey Rob
>
> No it doesn't. Stall that same motor and you're all
> but shorting the batteries so to speak and it'll make
> huge amps and lots of smoke 8^o
>
> Amps equal heat, so the more amps you draw the hotter
> the motor's going to get. The racers take that same
> motor and throw 2000 amps at it, but just for a couple
> sec's or less. The higher the current the shorter the
> duration, that is unless you can cool the motor and
> wisk away the heat (blower motors running air through
> the motor) which extends the duty cycle time.
>
> This is how people get away with using a 7 HP electric
> motor from a forklift as an example. Data tags are
> just points of reference.
>
> I kind of like to say that series wound DC motors are
> like a good sled dog and will die in the harness
> rather than tell you it can't do it, I know I see my
> share of dead huskies, LMAO! What I'm saying is they
> will work themselves to death. Ask to much and well
> they start to look like a marshmellow that's been on
> the campfire a bit to long, only inside out (it's the
> insides that burn)(but don't look to bad from the
> outside) hehe.
>
> Anyway as long as you're not the grinch whipping that
> poor dog to climb a mountain carrying some big ass
> sliegh, you should be okay 8^) If you go to "You
> Tube" and type in electric drag cars, you'll see that
> you can whip em a little bit 8^o just be careful to
> not over-whip, LMAO. Anyway just some technical info
> for ya 8^) This is why people use dual motors as they
> get twice the whipping in as they now have two dogs to
> share the load and can make for a faster ride or a
> longer duty cycle. Hopefully this helps you to
> understand a bit more... either that or you think I'm
> some freak from Alaska or something (oh hey Mike,
> didn't see ya there, hehe)
>
> Thought I'd throw a couple FYI's while I was here 8^)
>
> Be careful not to apply to much voltage on an unloaded
> motor as they will over rev and blow their commutators
> and or windings. Use just 12 volts for bench testing.
>
> Never stall a DC motor as it will pit the comm bars
> resulting in brush arcing and premature brush wear.
>
>
>
> Hope this helps
> Jim Husted
> Hi-Torque Electric
>
>
>
> --- Rob Hogenmiller <[EMAIL PROTECTED]> wrote:
>
> > If a motor specs reads it can do 30seconds at
> > 300amps and 100amps continous.
> >
> > Does that mean the most it can ever draw from a
> > battery is 300amps if you
> > connect it straight up to a battery?
> >
> > God bless
> >
> >
> >
> >
> >
>
>
>
>
> ____________________________________________________________________________________
> Finding fabulous fares is fun.
> Let Yahoo! FareChase search your favorite travel sites to find flight and
> hotel bargains.
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doing the math on those, we end up with quite the dragster
just 200kg of those would give you 6800 horses in peak :)
and 4MJ of energy
should get you down range in decent time : )
Dan
Ian Hooper wrote:
I guess they'd have 33kJ of energy per cap, you'd only need ~30 of
them (in theory) - which is much more feasible.
(I can't be bothered integrating the drag & rolling resistance
equations for energy use, but I estimate it'd be in the order of
100kJ, not too significant compared with the kinetic energy.)
Couldn't find 2700Fs anymore but here's some similar ones:
http://www.maxwell.com/ultracapacitors/products/large-cell/bcap3000.asp
5.7 Wh/kg is about 20x less than LiFePO4s, but 14kW/kg is impressive.
Anyone know how much they cost?
-Ian
On 22/06/2007, at 12:11 PM, Bill Dennis wrote:
Ian,
I think that the Maxwell supercaps Victor uses are 2700F at 5V. Try
those number in your calculations instead.
I believe that's what the team at BYU has in their EV1, too.
Bill Dennis
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What are the ZL431 and LM138's? I couldn't find the ZL431, and the LM138 looks
like a voltage regulator? How would you use these as a zener-equivalent?
- Tony
> Assuming you will start from similar point you balancer will do the
> trick as long as zener diodes won't differ too much (usually tolerance
> of of shunt voltage is 5%).
Zener diodes usually have a 5% tolerance, which is too much in this situation.
Also, low voltage zeners have really large variations with current and
temperature. They would be inadequate for per-cell regulation.
Try a zener-equivalent integrated circuit, like a ZL431 or LM138 instead.
> I would add a protection circuit preventing cells from deep
> discharge. If you don't need fancy BMS that would cost (for you
> configuration) 400E this will work fine.
Yes; this is a virtual necessity. Running them down to 2v or so is a one-way
trip!
--
I would not waste my life in friction when it could be turned into momentum. --
Frances Willard
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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To: ev@listproc.sjsu.edu
Subject: Re: DCDC converter
Date: Fri, 22 Jun 2007 09:05:28 -0400
MIME-Version: 1.0
From: [EMAIL PROTECTED]
Content-Type: text/plain; charset="utf-8"; format=flowed
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"Buck" is a switchmode topology term. Perhaps this will help:
http://en.wikipedia.org/wiki/Buck_converter
Ken
-----Original Message-----
From: Dan Frederiksen <[EMAIL PROTECTED]>
To: ev@listproc.sjsu.edu
Sent: Thu, 21 Jun 2007 10:32 pm
Subject: Re: DCDC converter
why not simple buck it? why through a transformer?Â
Â
DanÂ
Â
[EMAIL PROTECTED] wrote:Â
> Yes, it runs on DC. On page 2 directly under "Key Design Points"
tells > how to use the circuit on DC only.Â
>Â
> Note: all isolated switchmode DC-DC converters run on DC and they all
> use a transformer. Non isolated can use an inductor for the same >
purpose. Switchmode means the DC is switched on and off (at 66KHz for >
the DI-124) creating AC for the transformer. Without the AC and >
without the transformer or inductor it would be an analog regulator >
which is horribly inefficient. Generally, the higher the frequency the
> higher the efficiency. That is why the 60Hz line frequency is >
converted to DC so it can then be "switched" to a higher frequency.Â
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