EV Digest 6924
Topics covered in this issue include:
1) RE: Motor speed
by Mike Willmon <[EMAIL PROTECTED]>
2) Cheap "balancer" for A123 pack
by Tony Hwang <[EMAIL PROTECTED]>
3) Re: Cheap "balancer" for A123 pack
by Marcin Ciosek <[EMAIL PROTECTED]>
4) Re: Improving hillclimbing without mudering the pack?
by "jerryd" <[EMAIL PROTECTED]>
5) Re: Improving hillclimbing without mudering the pack?
by Thomas Ward <[EMAIL PROTECTED]>
6) DCDC converter and balancer in one? switch between 12V cells
by Tony Hwang <[EMAIL PROTECTED]>
7) Re: Internal Resistance? - Now- cable resistance
by "Phil Marino" <[EMAIL PROTECTED]>
8) RE: Internal Resistance? Peukert's Exponent? Voltage Sag?!?!
by "Phil Marino" <[EMAIL PROTECTED]>
9) Re: Heater efficiency (was: EV parts ordered! - ?questions?)
by "TrotFox Greyfoot" <[EMAIL PROTECTED]>
10) Re: Motor speed
by "Phil Marino" <[EMAIL PROTECTED]>
11) RE: Clutch, Keepin' it. Ruland shaft coupler
by "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
12) RE: 55mph
by "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
13) RE: Cheap "balancer" for A123 pack
by "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
14) RE: DCDC converter and balancer in one? switch between 12V cells
by "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
15) Re: DCDC converter
by [EMAIL PROTECTED]
16) RE: 55mph
by "Phil Marino" <[EMAIL PROTECTED]>
17) RE: DCDC converter and balancer in one? switch between 12V cells
by "Phil Marino" <[EMAIL PROTECTED]>
18) Improving hillclimbing without mudering the pack?
by Jeff Shanab <[EMAIL PROTECTED]>
19) Re: Motor speed
by "Rob Hogenmiller" <[EMAIL PROTECTED]>
20) RE: 55mph
by "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
21) Re: DCDC converter
by [EMAIL PROTECTED]
--- Begin Message ---
I pull my RPM reading off the tach sensor mounted to the end of the auxiliary
shaft on the WarP9 motor. If you look at the
picture on my EVAlbum page (the one with the under-the-hood shot)
http://www.austinev.org/evalbum/756 you can see the black thing
on the octagonal plate on the front of my motor. Thats the tach sensor the
Zilla uses to read RPM right from the motor shaft.
I forgot to put in my last post that you can see some acceleration simulations
for my 192V setup with typical limits you would
come up against in several lower power configurations. It also notes speeds at
certain RPM's. If you know what gear I'm in you
can calculate the speed knowing the RPM. http://home.gci.net/~saintbernard/
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Rob Hogenmiller
> Sent: Wednesday, June 20, 2007 7:57 PM
> To: ev@listproc.sjsu.edu
> Subject: Re: Motor speed
>
>
> When you type 3500rpm for an electric motor, where is that determined at?
>
> By/at the shaft circumference point, inside the motor, or some other
> location?
>
> God bless
>
--- End Message ---
--- Begin Message ---
Hi all,
I'm trying to make an A123 pack for an eBike type application, and wonder if
this shunt regulator balancer would work.
A 1 watt 3.6V zener, plus a 1W 1.6ohm resistor in series with each battery.
Basically when the voltage across each sell is over 3.6V, it will bleed across
the zener. It would regulate during charge also. I don't expect the voltage
across a cell during charging to get over 4V, so assuming 4V, the current
through the regulator would be:
4-3.6 = 0.4V 0.4V / 1.6ohm = 0.25amps, which is fine for the zener diode
(3.6V * 0.25 amps = .9 Watts), and more than fine for the resistor.
My question is, would this work, and would this be enough to balance say, a 8
series, 8 parallel pack? I know, not much Ah, but man it would be capable of
being really fast. :)
I figure even if it doesn't get completely balanced during charging, after
charging, the overcharged cells would discharge through the regulators (I've
seen A123 packs up to 3.9V after being overcharged).
- Tony
--- End Message ---
--- Begin Message ---
Tony,
recently I bough 1900 LiFP cells (not from A123 but it doesn't matter) and the
voltage difference between highest and lowest value was 7mV !!
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%). That's my opinion. 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.
Marcin
--- End Message ---
--- Begin Message ---
Hi Markus and All,
----- Original Message Follows -----
From: Markus Lorch <[EMAIL PROTECTED]>
To: Electric Vehicle Discussion List <ev@listproc.sjsu.edu>
Subject: Improving hillclimbing without mudering the pack?
Date: Thu, 21 Jun 2007 10:10:34 +0200
>Hi there,
>
>after first experiences with my Tavria EV I wonder how I
>could improve hillclimbing ability without mudering the
>pack by drawing lots of amps.
That's going to be hard as hill climbing takes
power, thus amps.
>
>Here the specs of my car:
>- 90V via 15 6V batteries, Varta 160Ah gel
>- series wound, 12kw S2 (60min) motor, about 8", 3500rpm at
>90V - vehicle weight 2500 lb (so a bit over 1/3rd is
>battery weight) - curtis 1221R 375A peak controller
These are notorious for not putting out much power
for any amount of time. You may need a new controller.
>- top speed about 50 mph
Do you have a transmission? If so what gear do you
use for hillclimbing? You should always keep the motor at as
high rpm as you can to not lug, overheat it which is what it
is doing it seems. What motor rpm are you using hill
climbing?
>
>I have lots of smaller hills with inclines of typically up
>to 7%. I was told to keep battery amps below 120A to
>insure long battery life. I am right now trying to keep
>them at least below 160A as a compromise but EVen at this
>rate the hillclimbing is more a hillcreeping.
Even gels should put out more amps than that. I hear
Varta's make good EV batts if picked for the right app. It's
unlikely your controller could damage them over than running
them too low.
Most hills
>that I worry about are about 2 miles long. In city driving
>is not an issue with up to 160A, but on regular streets
>where EVery body wants to go 65 I am not comfortable with
>going 25 when there is a hill.
What kind of amps does in use on a flat road at what
speed??
Even at 160A my motor heats
>up pretty good once I was going a couple of miles. My
>first temp sensor is set to 140deg C and turns on the
>forced air fan.
Way too high!! It shouldn't be over 180F and should
be under 150F. Your fan should come on early rather than
late. If you hit hills just as you start driving, it should
alway be on always or at least on a 100F thermostat/switch.
You want to cool it between hillclimbs, ect as it takes a
while.
I hear the fan almost after every hill. I
>think I could improve by running the fan from the start.
>After a careful trip of 20mi I can touch my motor for
>about 3-4 secs. I guess case temp is around 60 deg C.
About right. The hand has a hard time on 130F.
Motor specs?
Tire pressure?
Gear lubes??
>
>I know I could put in a larger controller, but wouldn't
>that just aggravate the problem as I would draw even more
>battery amps to get higher power? So I am looking at
>alternatives to just drawing a lot of amps.
Gearing!!! Downshift!!
>
>Here are my thoughts:
>- increasing voltage for hills via two contactors and three
>12V 100Ah batteries that will be switched in instead of
>the controller and then drive in 2nd. The first contactor
>would disconnect the curtis controller, the other hook the
>motor directly to the combined battery with 126V once the
>curtis is disconnected. Main contactor would act as safety.
That will lead to too high amps breaking things!
Better would be say a 60vdc pack for this, starting on the
Curtis, then switching to a high amp battery bank.
>
>- adding capacitors (fed from higher voltage batteries) to
>smooth battery current and provide for peak loads e.g.
>during accelleration
Not your problem. Not enough silcon is. Or you
could go to a completely Contactor controller for real amps
and since the battery is doubled in low voltage mode, you
can get probably 450-500 amps safely!!
>
>- lighten the pack and go with 12V SLA 100Ah (according to
>an old post from Lee Hart this could make things worse, as
>I will be drawing similar currents from much smaller
>batteries)
>
>- go higher voltage, e.g. 120V and buy a new controller.
>
>- look for NiCad batteries from SAFT to replace lead
>batteries, but I read these don't like more than 250A.
>OTOH, BB600s are higher amperage but not easy to get and
>heavier.
I assume you are in Europe so BB600's might be hard
to find though airbases may have them and they have to be
replaced long before they would be even used!! SAFT's I hear
are available as surplus from Euro EV's that have been
parted out. But not good at over 250 amps I hear but 2
strings gives you 500 amps.
Jerry Dycus
>
>- currently not an option: use LiPoly or A123 high current
>cells due to price
>
>
>Thanks
>
>Markus
>
>- 90V Tavria EV
>- 36V Elec-Trac E20
>
>
--- End Message ---
--- Begin Message ---
jerryd wrote:
I assume you are in Europe so BB600's might be hard
to find though airbases may have them and they have to be
replaced long before they would be even used!! SAFT's I hear
are available as surplus from Euro EV's that have been
parted out. But not good at over 250 amps I hear but 2
strings gives you 500 amps.
Nicads can be found, I picked up 36V of 80Ah 1 hour rated Jungners for
200 pounds last year and 12V of Alcad LP230s (low discrage batteries).
Apparently the Alcads were originally from the railways, the Jungners
from the Thames Barrier backup winches. I think the guy I bought them
off had them from Colemans in Sunderland, UK.
Saft STM100s can be found fairly easily in France, I found 10KWh for
1,000 pounds off a guy in Bordeaux, he advertised a van for breaking on
Phillipe Borges forum, I forget the URL.
--- End Message ---
--- Begin Message ---
I have an idea that I've been throwing around, would it be possible to make a
DCDC converter for say a 300V pack that outputs 12V by switching between each
of the 25 12V batteries in the 300V pack?
It would probably need a capacitor to keep the voltage steady during the
"switching", but it would stay on one 12V battery for say, 1 second, then very
quickly switch to the next one. For batteries with lower voltages, it can stay
on for say 0.5 seconds, while batteries with high voltages could be connected
for 2 seconds.
What sort of switches would be needed for something like this? I'm thinking
something like a solid state relay? Ideally it would be something that
physically cannot be connected to more than one battery at a time, so that you
wouldn't have the risk of more than 12V out of this DCDC "converter".
- Tony
--- End Message ---
--- Begin Message ---
From: "Joe Smalley" <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: <ev@listproc.sjsu.edu>
Subject: Re: Internal Resistance? Peukert's Exponent? Voltage Sag?!?!
Date: Wed, 20 Jun 2007 21:27:12 -0700
Copper wire is rated in ohms per 1000 feet or milliohms per foot.
You get these values from the manufacturer of the wire.
You don't have to get this information from the particular wire
manufacturer. All copper wire of the same gauge will have the same
resistance.
If it doesn't, it is sub-standard wire - you can find some junk wire from
China on Ebay which is smaller than the spec, So, try to buy wire from a
reputable dealer.
Here is one link that has resistance data for copper wire-
http://www.powerstream.com/Wire_Size.htm
Phil Marino
Joe Smalley
Rural Kitsap County WA
Former owner of 48 Volt Fiesta
NEDRA 48 volt street conversion record holder
[EMAIL PROTECTED]
_________________________________________________________________
Get a preview of Live Earth, the hottest event this summer - only on MSN
http://liveearth.msn.com?source=msntaglineliveearthhm
--- End Message ---
--- Begin Message ---
HI, Joseph
All of your posts are coming through like this. PLEASE figure out how to
set your email client to send PLAIN TEXT only. ( I can't help you with how
to do that)
We would all like to be able to read what you have to say.
Thanks
Phil Marino
From: Joseph Tahbaz <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: <ev@listproc.sjsu.edu>
Subject: RE: Internal Resistance? Peukert's Exponent? Voltage Sag?!?!
Date: Thu, 21 Jun 2007 00:24:16 -0400
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* ---REMAINDER OF MESSAGE TRUNCATED--- *
* This post contains a forbidden message format *
* (such as an attached file, a v-card, HTML formatting) *
* Lists at sjsu.edu only accept PLAIN TEXT *
* If your postings display this message your mail program *
* is not set to send PLAIN TEXT ONLY and needs adjusting *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
_________________________________________________________________
Get a preview of Live Earth, the hottest event this summer - only on MSN
http://liveearth.msn.com?source=msntaglineliveearthhm
--- End Message ---
--- Begin Message ---
Victor,
I suppose...
Trot, the grinning, fox...
On 6/20/07, Victor Tikhonov <[EMAIL PROTECTED]> wrote:
OK, fine, I said *practically* 100%.
The pump takes 4W, heater - 4,000W, so pump consumes 0.1%.
The heater then is 99.9% efficient. Better now?
Victor
TrotFox Greyfoot wrote:
> In regard the heater you offer...
>
> How did you find a water pump that uses no power? } ; ]
>
> In my mind it is less efficient than a ceramic element if it uses
> power for anything other than heating.
>
> Trot, the picky, fox... } ; ]
--
| /\_/\ TrotFox \ Always remember,
| ( o o ) AKA Landon Solomon \ "There is a
| >\_/< [EMAIL PROTECTED] \ third alternative."
--- End Message ---
--- Begin Message ---
Rob - If I understand your question, you're asking - where in the motor
should the RPM be 3500?
The answer is - everywhere. RPM is short for revolutions per minute. Since
the shaft/armature of the motor is a single rigid assembly, it doesn't
matter where you measure it. All parts of it are rotating at the same
speed. ( rotational speed, not linear speed)
Often RPM is measured at the motor shaft ( usually the non-drive end) but
some people measure it with a device which "sees" the fan blades go by.
They will all give the same result. It's a matter of convenience of
installation.
I measure motor RPM with a hall-effect sensor that looks at a notch in the
flywheel. Since the flywheel is keyed to the motor shaft, it gives the
right result. For me, that was a convenient way to do it.
Phil Marino
From: "Rob Hogenmiller" <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: <ev@listproc.sjsu.edu>
Subject: Re: Motor speed
Date: Wed, 20 Jun 2007 22:57:16 -0500
When you type 3500rpm for an electric motor, where is that determined at?
By/at the shaft circumference point, inside the motor, or some other
location?
God bless
----- Original Message ----- From: "Mike Willmon" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 20, 2007 10:21 PM
Subject: RE: Motor speed
Storm,
My WarP9 finds its sweet spot around 3500 RPM, which in 2nd gear happens
to be 35 mph. at 37mph I can feel acceleration start to
taper and seems the perfect shift point to 3rd gear.
Mike
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Jim Husted
Sent: Wednesday, June 20, 2007 6:01 PM
To: ev@listproc.sjsu.edu
Subject: Re: Motor speed
Hey Storm
Actually you don't want to lug the motor and you have
plenty of room and would say it'd be happier at the
3000 to 4000 rpms, you got lots more rpm to play with
8^)
Hope this helps
Jim Husted
Hi-Torque Electric
--- Storm Connors <[EMAIL PROTECTED]> wrote:
> I got the tachometer installed, now the big
> question.
> What is the best speed to aim for with my ADC 9"
> motor
> pushing almost 3500 pounds? I have been keeping it
> between 2000 and 2500 RPM generally. My thinking is
> that if the revs are too low under load, there is
> the potential of overheating. I have red lined it at
> 5000 so as not to break the motor.
>
> What do you think? I have been treating it like an
> ICE
> but don't know if that is right.
>
>
____________________________________________________________________________________
Never miss an email again!
Yahoo! Toolbar alerts you the instant new Mail arrives.
http://tools.search.yahoo.com/toolbar/features/mail/
_________________________________________________________________
Make every IM count. Download Messenger and join the im Initiative now.
Its free. http://im.live.com/messenger/im/home/?source=TAGHM_June07
--- End Message ---
--- Begin Message ---
Those are great!
McMaster Carr also sells couplers. I like their site a little better
because they offer couplers of different types and tell you the torque
rating of each.
www.mcmaster.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Paul
Sent: Wednesday, June 20, 2007 18:48
To: ev@listproc.sjsu.edu
Subject: Re: Clutch, Keepin' it. Ruland shaft coupler
On Jun 19, 2007, at 4:29 PM, [EMAIL PROTECTED] wrote:
> Hello Paul
>
> Could you send a link to the page with Ruland shaft coupler you used?
>
> Thank you
> Don Blazer
The web page at the Ruland site that has the line of couplers I used is:
<http://www.ruland.com/ps_couplings_rigid_clc.asp>.
The coupler I used was:
CLC-18-18-F
Wow, that web site has changed over the last year - it took me a few
minutes to find the current link. Anyway, I had the 1.125 O.D.
transaxle input coupler made out of an VW Bus input to mainshaft
coupler. The splines where correct so the machine work was to machine
the outside down the 1.125 inches and cut the keyway. I haven't removed
the motor since I installed it in early 1999.
Paul "neon" G.
--- End Message ---
--- Begin Message ---
I got this off of a website for MOPARS:
Engine horsepower required to sustain MPH on level ground (HPs):
HPs =
(MPH ÷ 3)
+ (WEIGHT ÷ 1,000 × MPH ÷ 10)
Note: assumes engine HP must be 2 × the HP required at drive wheels.
Example:
What engine HP is required to sustain 75 MPH in a 3,600 pound vehicle?
HPs =
75
÷ 3
+ (3,600 ÷ 1,000 × 75 ÷ 10)
_____________________________
25
+ (3.6 × 7.5)
_______________________________________
52 engine HP
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Peter Gabrielsson
Sent: Thursday, June 21, 2007 2:47
To: ev@listproc.sjsu.edu
Subject: Re: 55mph
The forces you need to overcome are aerodynamic drag plus the rolling
resistance. (This presumes level ground and no wind)
The power required to overcome aerodynamic drag = 0.5rho*Cd*A*V*V*V where rho =
density of air = 1.2 kg/m3, Cd = drag coefficient, A = frontal area of the car
in m^2, V = velocity (55mph = 25m/s)
For my fiat the numbers would be something like: P = 0.5 * 1.2 * 0.4 *
0.6 * 25 * 25 * 25 => 2250W or about 3Hp
The power required to overcome rolling resistance = V * Crr * g * m where V =
velocity, Crr = coefficient of rolling resistance (0.006 -
0.01 for lrr tires), g = gravitational constant (9.81m/s^2), m= mass of car in
kg.
So for a 1200kg (2500lbs) car with marginally low rolling resistance tires the
power needed is 25*0.01*9.81*1200 => 3000W or about 4Hp
Total power needed is thus 3+4 = 7Hp at the wheels. In real life you probably
want twice as much at the motor. (due to wind, slopes & transmission losses)
Someone check for mistakes, it's late ;)
On 6/20/07, Rob Hogenmiller <[EMAIL PROTECTED]> wrote:
> What is the mathematical formula to determine how much HP I will need
> to maintain 55mph.
>
> For i.e.
>
> 5,000lbs vehicle x rolling resistance / 10HP= 50mph would eventually
> produce given a long enough run.
>
> (I know that isn't anywhere close to the true formula ust trying to
> get an
> idea)
>
> God bless
>
>
>
>
--
www.electric-lemon.com
--- End Message ---
--- Begin Message ---
Please educate me if I am wrong but I would think that if you want to
balance your batteries you wouldn't want to drain some down to match the
others but charge the low ones to match the others. Using shunt
regulators will waste valuable charging current won't it? I think Lee
Hart makes a battery balancer that takes the current and shunts it
AROUND the battery but does not run it through a resistor.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Marcin Ciosek
Sent: Thursday, June 21, 2007 5:12
To: ev@listproc.sjsu.edu
Subject: Re: Cheap "balancer" for A123 pack
Tony,
recently I bough 1900 LiFP cells (not from A123 but it doesn't matter)
and the voltage difference between highest and lowest value was 7mV !!
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%). That's my opinion. 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.
Marcin
--- End Message ---
--- Begin Message ---
It would cause your battery pack to get waaaay out of balance. If not
equalized every day you would quickly kill your pack. The batteries
used for the DC/DC part would get charged fully and the ones not used
for DC/DC would get overcharged every time.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Tony Hwang
Sent: Thursday, June 21, 2007 6:56
To: ev@listproc.sjsu.edu
Subject: DCDC converter and balancer in one? switch between 12V cells
I have an idea that I've been throwing around, would it be possible to
make a DCDC converter for say a 300V pack that outputs 12V by switching
between each of the 25 12V batteries in the 300V pack?
It would probably need a capacitor to keep the voltage steady during the
"switching", but it would stay on one 12V battery for say, 1 second,
then very quickly switch to the next one. For batteries with lower
voltages, it can stay on for say 0.5 seconds, while batteries with high
voltages could be connected for 2 seconds.
What sort of switches would be needed for something like this? I'm
thinking something like a solid state relay? Ideally it would be
something that physically cannot be connected to more than one battery
at a time, so that you wouldn't have the risk of more than 12V out of
this DCDC "converter".
- Tony
--- End Message ---
--- Begin Message ---
Yes, it runs on DC. On page 2 directly under "Key Design Points" tells
how to use the circuit on DC only.
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.
Ken
-----Original Message-----
From: Dan Frederiksen <[EMAIL PROTECTED]>
To: ev@listproc.sjsu.edu
Sent: Wed, 20 Jun 2007 8:09 pm
Subject: Re: DCDC converter
Thanks guys
the di124 says AC though and although it says that it converts it to DC
first, it then says it feeds it to a transformer which seems odd for
DC. do you think it can be used for DC as well?
Dan
[EMAIL PROTECTED] skrev:
Here are some links to a few products and some elementary application
notes that may be helpful:
http://www.powerint.com/
http://www.powerint.com/psearch/
http://www.powerint.com/PDFFiles/di124.pdf
http://www.national.com/apnotes/BuckSwitchingControllers.html
http://www.national.com/an/AN/AN-558.pdf
http://www.national.com/an/AN/AN-1149.pdf
http://www.national.com/an/AN/AN-1197.pdf
http://www.national.com/an/AN/AN-1246.pdf
http://www.national.com/an/AN/AN-1146.pdf
http://www.national.com/an/AN/AN-1197.pdf
http://www.national.com/ms/PA/PACKAGE_THERMAL_CHARACTERIZATION.pdf
http://www.premiermag.com/pdf/pny.pdf
Ken
-----Original Message-----
From: Dan Frederiksen <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Sent: Tue, 19 Jun 2007 4:53 pm
Subject: Re: DCDC converter, was Doers vs talkers
Yes they might actually work. not sure why I couldn't find those at >
digikey. do you happen to know an online source for them too? > > the
minimum input voltage is a bit high but the graph seems to > indicate
it might work lower. 140v minimum is a bit high in a one size > fits
all controller but maybe if it can work well down to 120. > > The power
is not great so will I need a transistor to drive the big >
transistors? not sure about gate charge and saturation etc yet > > Dan
> > Thomas Ward wrote: >> are these any good to you? >>
http://www.pwrx.com/pwrx/docs/m57184n_715b.pdf >>
http://www.pwrx.com/pwrx/docs/m57182n_315.pdf >> >> Dan Frederiksen
wrote: >>> maybe a range of 100-400V and around 3-500A >>> >>> I've
seen the simple text book circuits but there is of course more > >> to
it. I need to supply the low voltage components from the unknown
100-400v supply >>> efficiently >>> I've looked for switching
voltage regulators components for that but >>> haven't found any >>>
and don't know how to make it discretely >>> >>> Dan > >
________________________________________________________________________
AOL now offers free email to everyone. Find out more about what's >
free from AOL at AOL.com.
=0
________________________________________________________________________
AOL now offers free email to everyone. Find out more about what's free
from AOL at AOL.com.
=0
--- End Message ---
--- Begin Message ---
Jody
This doesn't look like a useful formula to me. It might be close at a
particular speed (similar to a stopped watch being exactly correct twice a
day), but it would give you huge errors at most speeds.
It makes no account of frontal area, Cd, or tire drag coefficient,
Even worse, its says that the required horsepower it proportional to the
speed. Because air drag dominates at high speed, and the power it soaks up
is proportional to the cube of speed, this formula is way off.
For example, it would predict that your car would need twice the power to
travel at 60 MPH compared to 30 MPH. In most cases, you would need closer
to six times the power at double the speed.
If you know the frontal area, Cd, tire RR, and weight, Peter's calculations
should give you very accurate answers. if you don't know them, take your
best guess - and use it anyway.
It would still give you much better answers than the MOPAR version.
Phil
From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: <ev@listproc.sjsu.edu>
Subject: RE: 55mph
Date: Thu, 21 Jun 2007 08:29:37 -0400
I got this off of a website for MOPARS:
Engine horsepower required to sustain MPH on level ground (HPs):
HPs =
(MPH ÷ 3)
+ (WEIGHT ÷ 1,000 × MPH ÷ 10)
Note: assumes engine HP must be 2 × the HP required at drive wheels.
Example:
What engine HP is required to sustain 75 MPH in a 3,600 pound vehicle?
HPs =
75
÷ 3
+ (3,600 ÷ 1,000 × 75 ÷ 10)
_____________________________
25
+ (3.6 × 7.5)
_______________________________________
52 engine HP
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Peter Gabrielsson
Sent: Thursday, June 21, 2007 2:47
To: ev@listproc.sjsu.edu
Subject: Re: 55mph
The forces you need to overcome are aerodynamic drag plus the rolling
resistance. (This presumes level ground and no wind)
The power required to overcome aerodynamic drag = 0.5rho*Cd*A*V*V*V where
rho = density of air = 1.2 kg/m3, Cd = drag coefficient, A = frontal area
of the car in m^2, V = velocity (55mph = 25m/s)
For my fiat the numbers would be something like: P = 0.5 * 1.2 * 0.4 *
0.6 * 25 * 25 * 25 => 2250W or about 3Hp
The power required to overcome rolling resistance = V * Crr * g * m where
V = velocity, Crr = coefficient of rolling resistance (0.006 -
0.01 for lrr tires), g = gravitational constant (9.81m/s^2), m= mass of
car in kg.
So for a 1200kg (2500lbs) car with marginally low rolling resistance tires
the power needed is 25*0.01*9.81*1200 => 3000W or about 4Hp
Total power needed is thus 3+4 = 7Hp at the wheels. In real life you
probably want twice as much at the motor. (due to wind, slopes &
transmission losses)
Someone check for mistakes, it's late ;)
On 6/20/07, Rob Hogenmiller <[EMAIL PROTECTED]> wrote:
> What is the mathematical formula to determine how much HP I will need
> to maintain 55mph.
>
> For i.e.
>
> 5,000lbs vehicle x rolling resistance / 10HP= 50mph would eventually
> produce given a long enough run.
>
> (I know that isn't anywhere close to the true formula ust trying to
> get an
> idea)
>
> God bless
>
>
>
>
--
www.electric-lemon.com
_________________________________________________________________
Who's that on the Red Carpet? Play & win glamorous prizes.
http://club.live.com/red_carpet_reveal.aspx?icid=REDCARPET_hotmailtextlink3
--- End Message ---
--- Begin Message ---
I think you missed the key point of Tony's idea. The DC-DC would use ALL of
the traction batteries,
And, it would be smart enough to draw more power from those batteries at a
higher charge level. So, it would act as a balancer that would work all the
time that you are using 12V power.
You would end up with batteries that are closer in balance, not further out
of balance.
I think it's a great idea. You would need a bunch of wiring and relays, etc,
But, you need that for any balancer. This way, you're not wasting any
power as you balance.
Phil
From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: <ev@listproc.sjsu.edu>
Subject: RE: DCDC converter and balancer in one? switch between 12V cells
Date: Thu, 21 Jun 2007 08:41:28 -0400
It would cause your battery pack to get waaaay out of balance. If not
equalized every day you would quickly kill your pack. The batteries
used for the DC/DC part would get charged fully and the ones not used
for DC/DC would get overcharged every time.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Tony Hwang
Sent: Thursday, June 21, 2007 6:56
To: ev@listproc.sjsu.edu
Subject: DCDC converter and balancer in one? switch between 12V cells
I have an idea that I've been throwing around, would it be possible to
make a DCDC converter for say a 300V pack that outputs 12V by switching
between each of the 25 12V batteries in the 300V pack?
It would probably need a capacitor to keep the voltage steady during the
"switching", but it would stay on one 12V battery for say, 1 second,
then very quickly switch to the next one. For batteries with lower
voltages, it can stay on for say 0.5 seconds, while batteries with high
voltages could be connected for 2 seconds.
What sort of switches would be needed for something like this? I'm
thinking something like a solid state relay? Ideally it would be
something that physically cannot be connected to more than one battery
at a time, so that you wouldn't have the risk of more than 12V out of
this DCDC "converter".
- Tony
_________________________________________________________________
Make every IM count. Download Messenger and join the im Initiative now.
Its free. http://im.live.com/messenger/im/home/?source=TAGHM_June07
--- End Message ---
--- Begin Message ---
Sounds like you are on the right track. The only way to get more power
out of a given motor at a fixed amp is to spin it faster and let the
gears translate that added rpm into added torque. The only way to spin a
given motor faster is to raise the voltage.
I believe you have two other options
1) get a second motor and do the series parallel switch. This is
like an electric transmission. Double the torque at half the max RPM,
but that may make a particular gear possible. But only if the motor is
the limit.
2) I think Lee mentioned once on this list how to use a curtis on a
higher system voltage thru a retactor circuit. I'd say check the
archives, But I couldn't find it. Going to a higher system voltage and
keeping the controller this way and using the lower gear sounds like a
good idea.
--- End Message ---
--- Begin Message ---
How can that be?
If you measure the rpms at 3500 on a 1inch shaft motor.
And you now put a 2 inch shaft on the same motor still turning at the same
speed, the revolutions per minute will have changed because where your
measuring now takes it twice as to make one revolution.
So unless I'm incorrect it does make a difference where it's measured.
God bless
----- Original Message -----
From: "Phil Marino" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Thursday, June 21, 2007 7:10 AM
Subject: Re: Motor speed
Rob - If I understand your question, you're asking - where in the motor
should the RPM be 3500?
The answer is - everywhere. RPM is short for revolutions per minute.
Since the shaft/armature of the motor is a single rigid assembly, it
doesn't matter where you measure it. All parts of it are rotating at the
same speed. ( rotational speed, not linear speed)
Often RPM is measured at the motor shaft ( usually the non-drive end) but
some people measure it with a device which "sees" the fan blades go by.
They will all give the same result. It's a matter of convenience of
installation.
I measure motor RPM with a hall-effect sensor that looks at a notch in the
flywheel. Since the flywheel is keyed to the motor shaft, it gives the
right result. For me, that was a convenient way to do it.
Phil Marino
From: "Rob Hogenmiller" <[EMAIL PROTECTED]>
Reply-To: ev@listproc.sjsu.edu
To: <ev@listproc.sjsu.edu>
Subject: Re: Motor speed
Date: Wed, 20 Jun 2007 22:57:16 -0500
When you type 3500rpm for an electric motor, where is that determined at?
By/at the shaft circumference point, inside the motor, or some other
location?
God bless
----- Original Message ----- From: "Mike Willmon" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 20, 2007 10:21 PM
Subject: RE: Motor speed
Storm,
My WarP9 finds its sweet spot around 3500 RPM, which in 2nd gear happens
to be 35 mph. at 37mph I can feel acceleration start to
taper and seems the perfect shift point to 3rd gear.
Mike
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Jim Husted
Sent: Wednesday, June 20, 2007 6:01 PM
To: ev@listproc.sjsu.edu
Subject: Re: Motor speed
Hey Storm
Actually you don't want to lug the motor and you have
plenty of room and would say it'd be happier at the
3000 to 4000 rpms, you got lots more rpm to play with
8^)
Hope this helps
Jim Husted
Hi-Torque Electric
--- Storm Connors <[EMAIL PROTECTED]> wrote:
> I got the tachometer installed, now the big
> question.
> What is the best speed to aim for with my ADC 9"
> motor
> pushing almost 3500 pounds? I have been keeping it
> between 2000 and 2500 RPM generally. My thinking is
> that if the revs are too low under load, there is
> the potential of overheating. I have red lined it at
> 5000 so as not to break the motor.
>
> What do you think? I have been treating it like an
> ICE
> but don't know if that is right.
>
>
____________________________________________________________________________________
Never miss an email again!
Yahoo! Toolbar alerts you the instant new Mail arrives.
http://tools.search.yahoo.com/toolbar/features/mail/
_________________________________________________________________
Make every IM count. Download Messenger and join the i'm Initiative now.
It's free. http://im.live.com/messenger/im/home/?source=TAGHM_June07
--- End Message ---
--- Begin Message ---
A lot of people don't have that kind of data though. I don't know the Cd of my
Nissan or the tire drag coefficient. I do however have the ability to use that
general calculation.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Phil Marino
Sent: Thursday, June 21, 2007 8:55
To: ev@listproc.sjsu.edu
Subject: RE: 55mph
Jody
This doesn't look like a useful formula to me. It might be close at a
particular speed (similar to a stopped watch being exactly correct twice a
day), but it would give you huge errors at most speeds.
It makes no account of frontal area, Cd, or tire drag coefficient,
Even worse, its says that the required horsepower it proportional to the speed.
Because air drag dominates at high speed, and the power it soaks up is
proportional to the cube of speed, this formula is way off.
For example, it would predict that your car would need twice the power to
travel at 60 MPH compared to 30 MPH. In most cases, you would need closer to
six times the power at double the speed.
If you know the frontal area, Cd, tire RR, and weight, Peter's calculations
should give you very accurate answers. if you don't know them, take your best
guess - and use it anyway.
It would still give you much better answers than the MOPAR version.
Phil
>From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
>Reply-To: ev@listproc.sjsu.edu
>To: <ev@listproc.sjsu.edu>
>Subject: RE: 55mph
>Date: Thu, 21 Jun 2007 08:29:37 -0400
>
>I got this off of a website for MOPARS:
>
>Engine horsepower required to sustain MPH on level ground (HPs):
>
>
> HPs =
> (MPH ÷ 3)
> + (WEIGHT ÷ 1,000 × MPH ÷ 10)
>
>
>Note: assumes engine HP must be 2 × the HP required at drive wheels.
>Example:
>What engine HP is required to sustain 75 MPH in a 3,600 pound vehicle?
>
>
>
> HPs =
> 75
> ÷ 3
> + (3,600 ÷ 1,000 × 75 ÷ 10)
> _____________________________
> 25
> + (3.6 × 7.5)
> _______________________________________
> 52 engine HP
>
>
>-----Original Message-----
>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
>Behalf Of Peter Gabrielsson
>Sent: Thursday, June 21, 2007 2:47
>To: ev@listproc.sjsu.edu
>Subject: Re: 55mph
>
>The forces you need to overcome are aerodynamic drag plus the rolling
>resistance. (This presumes level ground and no wind)
>
>The power required to overcome aerodynamic drag = 0.5rho*Cd*A*V*V*V
>where rho = density of air = 1.2 kg/m3, Cd = drag coefficient, A =
>frontal area of the car in m^2, V = velocity (55mph = 25m/s)
>
>For my fiat the numbers would be something like: P = 0.5 * 1.2 * 0.4 *
>0.6 * 25 * 25 * 25 => 2250W or about 3Hp
>
>The power required to overcome rolling resistance = V * Crr * g * m
>where V = velocity, Crr = coefficient of rolling resistance (0.006 -
>0.01 for lrr tires), g = gravitational constant (9.81m/s^2), m= mass
>of car in kg.
>
>So for a 1200kg (2500lbs) car with marginally low rolling resistance
>tires the power needed is 25*0.01*9.81*1200 => 3000W or about 4Hp
>
>Total power needed is thus 3+4 = 7Hp at the wheels. In real life you
>probably want twice as much at the motor. (due to wind, slopes &
>transmission losses)
>
>Someone check for mistakes, it's late ;)
>
>
>
>
>On 6/20/07, Rob Hogenmiller <[EMAIL PROTECTED]> wrote:
> > What is the mathematical formula to determine how much HP I will
> > need to maintain 55mph.
> >
> > For i.e.
> >
> > 5,000lbs vehicle x rolling resistance / 10HP= 50mph would eventually
> > produce given a long enough run.
> >
> > (I know that isn't anywhere close to the true formula ust trying to
> > get an
> > idea)
> >
> > God bless
> >
> >
> >
> >
>
>
>--
>www.electric-lemon.com
>
_________________________________________________________________
Who's that on the Red Carpet? Play & win glamorous prizes.
http://club.live.com/red_carpet_reveal.aspx?icid=REDCARPET_hotmailtextlink3
--- End Message ---
--- Begin Message ---
Forgot to mention, here is an application note that may help:
http://www.national.com/an/AN/AN-556.pdf
Ken
-----Original Message-----
From: [EMAIL PROTECTED]
To: ev@listproc.sjsu.edu
Sent: Thu, 21 Jun 2007 7:47 am
Subject: Re: DCDC converter
Yes, it runs on DC. On page 2 directly under "Key Design Points" tells
how to use the circuit on DC only.
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.
Ken
-----Original Message-----
From: Dan Frederiksen <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Sent: Wed, 20 Jun 2007 8:09 pm
Subject: Re: DCDC converter
Thanks guys
the di124 says AC though and although it says that it converts it to DC
first, it then says it feeds it to a transformer which seems odd for
DC. do you think it can be used for DC as well?
Dan
[EMAIL PROTECTED] skrev:
Here are some links to a few products and some elementary application
notes that may be helpful:
http://www.powerint.com/
http://www.powerint.com/psearch/
http://www.powerint.com/PDFFiles/di124.pdf
http://www.national.com/apnotes/BuckSwitchingControllers.html
http://www.national.com/an/AN/AN-558.pdf
http://www.national.com/an/AN/AN-1149.pdf
http://www.national.com/an/AN/AN-1197.pdf
http://www.national.com/an/AN/AN-1246.pdf
http://www.national.com/an/AN/AN-1146.pdf
http://www.national.com/an/AN/AN-1197.pdf
http://www.national.com/ms/PA/PACKAGE_THERMAL_CHARACTERIZATION.pdf
http://www.premiermag.com/pdf/pny.pdf
Ken
-----Original Message-----
From: Dan Frederiksen <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Sent: Tue, 19 Jun 2007 4:53 pm
Subject: Re: DCDC converter, was Doers vs talkers
Yes they might actually work. not sure why I couldn't find those at >
digikey. do you happen to know an online source for them too? > > the
minimum input voltage is a bit high but the graph seems to > indicate
it might work lower. 140v minimum is a bit high in a one size > fits
all controller but maybe if it can work well down to 120. > > The power
is not great so will I need a transistor to drive the big >
transistors? not sure about gate charge and saturation etc yet > > Dan
> > Thomas Ward wrote: >> are these any good to you? >>
http://www.pwrx.com/pwrx/docs/m57184n_715b.pdf >>
http://www.pwrx.com/pwrx/docs/m57182n_315.pdf >> >> Dan Frederiksen
wrote: >>> maybe a range of 100-400V and around 3-500A >>> >>> I've
seen the simple text book circuits but there is of course more > >> to
it. I need to supply the low voltage components from the unknown
100-400v supply >>> efficiently >>> I've looked for switching
voltage regulators components for that but >>> haven't found any >>>
and don't know how to make it discretely >>> >>> Dan > >
________________________________________________________________________
AOL now offers free email to everyone. Find out more about what's >
free from AOL at AOL.com.
=0
________________________________________________________________________
AOL now offers free email to everyone. Find out more about what's free
from AOL at AOL.com.
=0
________________________________________________________________________
AOL now offers free email to everyone. Find out more about what's free
from AOL at AOL.com.
=0
--- End Message ---
