EV Digest 6517
Topics covered in this issue include:
1) Re: Voltage Sag, Peukerts Effect
by Ian Hooper <[EMAIL PROTECTED]>
2) Re: Four LiFePo4 cells from batteryspace can work as a lead-acid
replacement
by "Dmitri" <[EMAIL PROTECTED]>
3) Re: Compressed air as battery?
by Lee Hart <[EMAIL PROTECTED]>
4) Re: LRR tire comparision using Prius was Re: My next EV project, or
Paul goes Datsun
by "ProEV" <[EMAIL PROTECTED]>
5) Re: LRR Tires
by "ProEV" <[EMAIL PROTECTED]>
6) Re: Cooling PM motor on 22
by Lee Hart <[EMAIL PROTECTED]>
7) RE: LRR tire comparision using Prius was Re: My next EV project, or
Paul goes Datsun
by "Shawn Waggoner, FLEAA" <[EMAIL PROTECTED]>
8) Portland Roadster Show Photos up
by John Wayland <[EMAIL PROTECTED]>
9) Re: Chevy Metro Weight
by [EMAIL PROTECTED]
10) Re: Cooling PM motor on 22" mower conversion
by Jeff Major <[EMAIL PROTECTED]>
11) Re: Chevy Metro Weight
by dale henderson <[EMAIL PROTECTED]>
12) 1-Wire Confusion
by Bill Dennis <[EMAIL PROTECTED]>
13) Re: [Evtech] SCR's last orders
by "Matt Kenigson" <[EMAIL PROTECTED]>
14) Re: Chevy Metro Weight
by Andrew Letton <[EMAIL PROTECTED]>
15) Racing Golf Carts WSJ front page
by David Dymaxion <[EMAIL PROTECTED]>
16) Re: Voltage Sag, Peukerts Effect
by "Richard Acuti" <[EMAIL PROTECTED]>
17) Fwd: (ET) Loon Solar Boat Story in Toronto Star
by Rod Hower <[EMAIL PROTECTED]>
18) RE: [Evtech] SCR's last orders
by "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[EMAIL PROTECTED]>
19) Re: Kilovac EV-200 as safety disconnect?
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
20) RE: [Evtech] SCR's last orders
by Lee Hart <[EMAIL PROTECTED]>
21) RE: 1-Wire Confusion
by "Dale Ulan" <[EMAIL PROTECTED]>
22) RE: Chevy Metro Weight
by "Ted Sanders" <[EMAIL PROTECTED]>
23) Re: Cooling PM motor on 22" mower conversion
by Mark Hastings <[EMAIL PROTECTED]>
24) Re: 1-Wire Confusion
by Danny Miller <[EMAIL PROTECTED]>
25) RE: 1-Wire Confusion
by "John G. Lussmyer" <[EMAIL PROTECTED]>
26) Re: Kilovac EV-200 as safety disconnect?
by thomas ward <[EMAIL PROTECTED]>
27) Re: 1-Wire Confusion
by Bill Dennis <[EMAIL PROTECTED]>
28) Re: Fwd: (ET) Loon Solar Boat Story in Toronto Star
by Frank John <[EMAIL PROTECTED]>
29) Re: DC Motor (forklift type motors)
by Jeff Major <[EMAIL PROTECTED]>
30) RE: LRR Tires
by Cor van de Water <[EMAIL PROTECTED]>
--- Begin Message ---
8 of A123's M1 lithium cells in parallel would give you a solid 800
amps for 40 seconds no worries.
Although a 120V pack = 36 in series, and 8 in parallel, would cost
around $3K.. oh well.
On 07/03/2007, at 12:46 AM, Peter VanDerWal wrote:
You are going to either have to use much bigger batteries, reduce your
expectations, or spend BIG bucks on high power LiIon batteries.
Hi there,
I am looking at battery options and was wondering if anyone could
help. I
am
designing a high speed EV and need to pull 600 - 800 amps(800
ideally) for
around 40 seconds. I will be building the EV on a tight student
budget..
so
cant afford really expensive batteries - I have been looking at
the SVR
14Ah
sealed AGM lead acids.
Firstly, I am not sure what coefficient(k) to use in Peukerts eqn
Cp = I^k
*
t .If i use 1.1, i can theroetically pull 658 amps for 40
seconds.. but if
i
use k = 1.2, i can only pull 383 amps for 40 seconds! Can anyone
recommend
what value of k i should be using and what is a realistic figure
for the
current i can pull?
Secondly, i was wondering if anyone could advise me on voltage
sag. When
pulling these sorts of high currents, what can i expect the peak
voltage
to
be on a 120V system? half or more? Do you get voltage sag with
other types
of batteries i.e. Lithiums and Nimh's? some comparisons would be
great!
Kind Regards
Scott Littledike
--- End Message ---
--- Begin Message ---
Just use these http://www.thunder-sky.com/products_en.asp?fid=66&fid2=70 for
EV
Why bother with 18650s.
----- Original Message -----
From: "Tony Hwang" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, March 06, 2007 4:30 AM
Subject: Four LiFePo4 cells from batteryspace can work as a lead-acid
replacement
Did some testing with a potential replacement for lead-acid 12V starter
batteries, using lithium iron phosphate (Li-Fe-Po4) cells from
batteryspace. Charged and discharged a string of 4 18650 LiFe cells as
a lead-acid cell.
It seems like the lithium phosphates can be used as lead-acid cells!
The LiFePo4 cells don't fully charge, and don't fully discharge when
treated as a lead-acid, but at a loss of under 150mAh (on a 1300mAh
cell). It leaves about 90mAh capacity left, and less than 50mAh or so
undercharged. I think the amount of undercharge will vary by which
lead-acid charger you are using. (I'm using a Schulze isl 6-330D
charger, which charges LiFe cells BTW) This will actually increase cell
life by undercharging them, so I think it's ok. To maximize life of a
lead-acid cell, you're only supposed to use 50% of it's capacity
anyways. The PC680 is rated for 17Ah at the 20 hour rate, and I was
able to only get slightly more than 9Ah at a 6.8A discharge rate.
So I'm still probably going to add a shunt type regulator to prevent
overcharging, though. Anyways, these can potentially be used for a motive
pack, wired up in series, since these cells are rated for 10C discharge. I
put the CBA charts up on my blog http://evconvert.blogspot.com/.
- Tony
--- End Message ---
--- Begin Message ---
From: mike young
> I don't care i just wanna have an air car and an EV in my
> driveway-maybe I can get to town and back with it just on
> a 120 psi charge from my craftsman compressor and blow my
> air horn on the way past the gas stations
Hey, then go for it! As long as the distance to town isn't too bad, it will
work. Just don't expect a range as good as an electric car.
If nothing else, how about converting a bicycle into an air/human powered
hybrid? It scales the whole project down to a manageable size and cost. And if
you run out of air, you can always pedal home!
--
Lee Hart
--- End Message ---
--- Begin Message ---
Hi Peter,
Just curious, did you calculate the distance the tire travels based on
measured circumference, or radius?
I cheated a little. Everybody seems to be publishing revolutions per mile,
so I just used that. Here is an example:
http://www.tirerack.com/tires/Spec.jsp?make=Michelin&model=Energy+MXV4+S8&tirePageLocQty=
Look at the far right colum. I think it is there to help fiquire out how off
a speedometer will get.
For racing, (as opposed to me personally just playing around with the
Prius), we set the tire pressure to our planned 'hot' pressure and use a
tire tape to measure the circumference at the center of the wheel and use
that measurement for all our DAQ calculations.
Radius would seem to me to be a more accurate measurement, and would
change based on tire pressure.
I am not sure how this would work but it does illistrate a potential
inaccuracy of our (ProEV's) standard method. If you measure the radius at
the sidewall you will get a different measurement than if you mmeasure the
radius at the center of the tire. There seems to be a small crown to the
tire when inflated and off the ground.
I would think the most accurate way to calculate the distance the tire
travels is to bring it to operating temperature and pressure, mark a point
on the side of the tire and roll the car. Mark the ground where the mark on
the side of the tire touches the ground the first time and mark the ground
again where the mark on the tire touches the ground a second time. Measure
the distance between the two marks on the ground.
Cliff
www.ProEV.com
--- End Message ---
--- Begin Message ---
Hi Brian,
Please drive more slowly next time!
Now that is something I just do not seem to be able to master<G>.
Cliff
www.ProEV.com
--- End Message ---
--- Begin Message ---
From: Mark Hastings
> As at least a short term solution to my 1 acre problem
> I found a 22" self propolled mower buried in a pile of
> junk. I cleaned it up and got a new blade. Put this motor
> on it http://tinyurl.com/gyt5s
> I have two 33 amphour AGMs on it. 48lbs of lead.
> The motor gets really warm though. There are no slots
> for cooling nor do I think I'd want any since after
> just a fwe minutes the deck was covered with grass.
For years I used an electric push mower. The motor was air cooled with a big
centrifugal blower (about 6" diameter x 1" thick) on its shaft, between the
blade and bottom deck. The motor had holes in both end plates. The blower
pulled air in the top (brush end) of the motor, down through it, out the holes
in the blade end, and dumped it into the mowing compartment.
Grass clippings are fairly large; there was just a plastic mesh filter on the
top of the motor to keep them out (looked like the urethane foam used to for
chair cushions, packing fragile things in boxes, etc.)
--
Lee Hart
--- End Message ---
--- Begin Message ---
<snip>
I would think the most accurate way to calculate the distance the tire
travels is to bring it to operating temperature and pressure, mark a point
on the side of the tire and roll the car. Mark the ground where the mark on
the side of the tire touches the ground the first time and mark the ground
again where the mark on the tire touches the ground a second time. Measure
the distance between the two marks on the ground.
Cliff
www.ProEV.com
</snip>
We have used this method several times and is an accurate way getting the
actual circumference of the tire, on the car/bike. The only thing different
we do is try push the vehicle far enough in a straight line to get 10
revolutions and mark all them plus the overall length. This way we get the
individual rotations as well as being able to average the distance.
Shawn Waggoner
Florida EAA
561-543-9223
www.floridaeaa.org
--- End Message ---
--- Begin Message ---
Hello to All,
Just a quick note to let everyone know that a few of the many photos I
took from this past weekend's car show, are up at the Plasma Boy Racing
web page. Look for a post all about the fun, excitement, and exhaustion
of this EVent a bit later.
See Ya....John Wayland
http://www.plasmaboyracing.com
--- End Message ---
--- Begin Message ---
Hi Michael,
The '95 and newer Metros were a little heavier and had larger brakes, wheels,
and tires; and a little heavier suspension and chassis to accomodate the
added weight. They also had air bags.
The earlier models, while a bit lighter because of the smaller components,
were a little shy when it came to braking after adding several hundred pounds
of
batteries.
I drive a '93 converted as electric. The Metro makes a very nice conversion
because of its light weight, and I think with your '95 you'll be pleased to
have the larger wheels/tires/brakes.
<BR><BR><BR>**************************************<BR> AOL now offers free
email to everyone. Find out more about what's free from AOL at
http://www.aol.com.
--- End Message ---
--- Begin Message ---
Hi Mark,
Cooling this motor is a problem unless you can force air thru it. That gets
messy on a mower deck. Blowing air over the outside frame will help, but does
not do an effective job of getting heat out of the armature and comm.
A buddy used this motor on a 22 inch deck. He fairs pretty well. Has a
smaller yard. You might consider hs appraoch. Reduce the load. He runs at 18
volts. This slows the blade speed. But he claims still is a good cut. 18/24
= 3/4 speed. Probably half power (like a fan load). This reduces the heat in
the motor a bunch.
BTW he uses NiCad pack I helped him make from D cells. Two in parallel. I
think they are about 4.5 amp-hr cells for 9 amp-hr total. Gets him the whole
yard on one charge. Like I said, a smaller yard. In the city. He and his
nieghbors really like the quiet cut. Made a charger from a Vicor converter off
eBay.
Jeff
Mark Hastings <[EMAIL PROTECTED]> wrote:
As at least a short term solution to my 1 acre problem
I found a 22" self propolled mower buried in a pile of
junk.
I cleaned it up and got a new blade.
Put this motor on it (which I got somewhere else)
http://tinyurl.com/gyt5s
HP 1.54 Voltage 24 DC Amps 4.5 no load
RPM 3,200 Duty intermittent
Built as motor for cordless electric lawnmowers
I have two 33 amphour AGMs on it. 48lbs of lead.
I didn't hook up the self propelled and at first
didn't disconnect the gears in the wheels either. I
was much relieved when I realized that and with all 4
wheels actually turning it wasn't that hard to push.
The motor gets really warm though. There are no slots
for cooling nor do I think I'd want any since after
just a fwe minutes the deck was covered with grass. I
have a metal deck but it doesn't seem to be
transferring any of the heat down.
I'm wondering if there is any way to effectively cool
it down?
33amp hours is almost twice the juice the black and
decker cordless have. And I'm thinking of getting two
more batteries to make a quick change pack. I do have
a Etek which I could stick on it. That woudl be
entirely overkill though and I'm trying to find a nice
30"+ walk behind mower for that.
---------------------------------
Need a quick answer? Get one in minutes from people who know. Ask your question
on Yahoo! Answers.
--- End Message ---
--- Begin Message ---
what kind of motor/controller/trans/batteries are you planning on?
mike golub <[EMAIL PROTECTED]> wrote: Hello
I recently purchased a 1998 Chevy Metro.
GM dropped the "Geo" name in that year.
It seems to be a little heavier. I haven't found the
weight on the car, but some books say 1895 pounds, not
exactly the 1600 pounds, I was hoping for.
I can't get the car to scale, because it doesn't run.
Does anyone know what years of the Geo Metro were the
lightest?
And are there any improvements that are worth the
weight?
Maybe better crash protection?
Thanks a lot!
Michael Golub
Fairbanks, AK
http://community.uaf.edu/~ffmig/home.htm
____________________________________________________________________________________
Have a burning question?
Go to www.Answers.yahoo.com and get answers from real people who know.
Albuquerque, NM
http://geocities.com/hendersonmotorcycles/blog.html
http://www.austinev.org/evalbum/1000
http://geocities.com/solarcookingman
---------------------------------
TV dinner still cooling?
Check out "Tonight's Picks" on Yahoo! TV.
--- End Message ---
--- Begin Message ---
I've been looking at some of the Dallas 1-Wire devices that monitor
Li-ion cells, for example:
http://datasheets.maxim-ic.com/en/ds/DS2760.pdf -- but two things
confuse me. Referring to Figure 2 on page 5:
1) The chip can come configured with a 25mOhm sense resistor between VSS
(Cell minus) and SNS (Pack minus). What keeps large amounts of current
from flowing through this resistor?
2) When you hook the DQ (Data) lines of multiple of chips together from
different cells, to what common are the DQ lines referenced? Or do they
need to go through opto-isolators?
Thanks.
Bill Dennis
--- End Message ---
--- Begin Message ---
Okay, I read up on SCRs, Thyristors, and Rectifiers on Wikipedia but
I still don't understand what they're for. How do you use SCRs in an
EV?
Matt Kenigson
austinev.org/evalbum/882
--- End Message ---
--- Begin Message ---
The short answer is that the older the Sprint/Metro/Swift, the lighter
they were - if you look at just the 3 cylinder models. Not sure on the
weight of a '98 Metro, but I had a '91 that was 1600-something pounds.
I also had an '86 Chevy Sprint (Suzuki-designed 3-cyl predecessor to
Geo) that weighed only 1380 pounds! (My '89 Suzuki Swift GTi (4-cyl
pocket rocket) weighs ~1860 lb.)
HTH,
Andrew
mike golub wrote:
Hello
I recently purchased a 1998 Chevy Metro.
GM dropped the "Geo" name in that year.
It seems to be a little heavier. I haven't found the
weight on the car, but some books say 1895 pounds, not
exactly the 1600 pounds, I was hoping for.
I can't get the car to scale, because it doesn't run.
Does anyone know what years of the Geo Metro were the
lightest?
And are there any improvements that are worth the
weight?
Maybe better crash protection?
Thanks a lot!
Michael Golub
Fairbanks, AK
http://community.uaf.edu/~ffmig/home.htm
____________________________________________________________________________________
Have a burning question?
Go to www.Answers.yahoo.com and get answers from real people who know.
--- End Message ---
--- Begin Message ---
The Wall Street Journal has a front page article about racing golf cars. It is
just a sentence, but there is a mention of people bumping up 36 volt golf carts
to 96 volts. One reason for the increasing popularity is golf carts are cheaper
than other off-road toys.
____________________________________________________________________________________
Have a burning question?
Go to www.Answers.yahoo.com and get answers from real people who know.
--- End Message ---
--- Begin Message ---
This is a timely topic for me. Since I'm running 8v batteries I've been
concerned about treating them right. Currently my ammeter isn't working. I
haven't figured that one out yet.
But- I can provide the following data:
I'm configured as a 128v system using 16 batteries. Deka floodies.
I'm using a Curtis 1221B controller so I can only pull close to 400 amps and
not for long before it cuts back. I think the manual said 2 minutes.
Based on one earlier reply, I shouldn't drag cell voltage any lower than
1.75 vpc. That would be 112v total. (64 cells X 1.75) I do have a
swing-needle volt meter so I can watch the sag while I drive. Another reply
stated 1 vpc. That would be as low as 64v total. I think during hard
acceleration, or hill climbing, the worst sag I've experienced is
95v...maybe 80v once.
The question of the day is: Am I abusing these batteries too much?
Rich A.
Maryland
Date: Tue, 6 Mar 2007 06:08:52 -0800 (PST)
From: Bob Bath <[EMAIL PROTECTED]>
Subject: Re: Voltage Sag, Peukerts Effect
To: [email protected]
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: 8bit
Message-ID: <[EMAIL PROTECTED]>
For lead acid chemistry, you take each cell down to
1.75 VPC. So on a 144V pack, you can assume that on
average, 126V is fairly safe.
Regarding Peukert's, most batteries' numbers are
listed on the web; my floodies at 1.22 or so.
-Just noting that you are on a "student budget", yet
have chosen AGM batteries, which are 2-3x the cost of
floodies, especially once you lay regulators on to
maximize their life. IMHO, that's a contradiction.
- RE: Nickel and Lithium, I don't think you'll find
many on the list using them yet, as they are usually
run in series @ higher voltages, so lower currents.
Higher currents are destructive to many models of this
chemistry. Many of us are sitting on the sidelines,
waiting until someone else tries it so we can learn
from their experiences.
Best to you,
--- Scott Littledike <[EMAIL PROTECTED]>
_________________________________________________________________
Dont miss your chance to WIN 10 hours of private jet travel from Microsoft®
Office Live http://clk.atdmt.com/MRT/go/mcrssaub0540002499mrt/direct/01/
--- End Message ---
--- Begin Message ---
Cool story,
--- [EMAIL PROTECTED] wrote:
> To: [EMAIL PROTECTED]
> From: [EMAIL PROTECTED]
> Date: Tue, 06 Mar 2007 10:46:26 -0500
> Subject: (ET) Loon Solar Boat Story in Toronto Star
>
> Hello,
>
> Just a little shameless self-promotion. if you
> didn't see yesterday's
> business section in the Toronto Star newspaper,
> check out the following
> link:
>
> http://www.thestar.com/article/188158
>
> Monte Gisborne, B.Tech.
> Tamarack Lake Electric Boat Company
> 207 Bayshore Drive, R.R.#3,
> Brechin, Ontario Canada L0K 1B0
> (705) 484-1559
> (416) 432-7067 (cell phone)
> [EMAIL PROTECTED]
> www.tamarackelectricboats.com
>
> Tamarack Lake... Where Water and Electricity Mix!
>
> _______________________________________________
> Elec-trak mailing list
> [EMAIL PROTECTED]
>
https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak
>
--- End Message ---
--- Begin Message ---
SCRs are basically fast switches. If you apply +5VDC to the gate the
SCR will conduct. If you are using DC they will remain on until either
you reverse the current through the anode to cathode path or cut off the
current flow completely. However, if you apply AC to the anode to
cathode path, you will have to maintain +5V on the gate or the SCR will
turn off when the current reaches the zero point.
Jody
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Matt Kenigson
Sent: Tuesday, March 06, 2007 11:32
To: [email protected]
Subject: Re: [Evtech] SCR's last orders
Okay, I read up on SCRs, Thyristors, and Rectifiers on Wikipedia but I
still don't understand what they're for. How do you use SCRs in an EV?
Matt Kenigson
austinev.org/evalbum/882
--- End Message ---
--- Begin Message ---
I used a Kilovac rated to break a 144vdc pack. It didn't make it. Good
thing my Heinemann relay was up to the task. I'm now using two Albrights.
Cost should not be an issue here. Lawrence Rhodes......
----- Original Message -----
From: "Ben Apollonio" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, March 05, 2007 8:17 PM
Subject: Kilovac EV-200 as safety disconnect?
> How reliable is the Kilovac EV-200 as a safety disconnect breaking a
> 192V pack of Optima YT's shorted across an ADC 9" (i.e. inductive
> load)? I am using an older T-Rex 1000 and I'm concerned about the
> consequences of my controller failing ON (as in, still powering the
> motor). I will have a pair of contactors in series, and I prefer the
> EV-200's for their low cost over the EV-250's and bubbas. I know
> better than to reuse the contactors after I've opened them under that
> kind of load, so it's not a repeated reliability thing so much as a
> one-time thing. But will they even be up to carrying the continuous
> current of my EV? I'd hate to deform them such that they didn't open
> when I needed.
>
> I plan on having a fuse too, but I'm really concerned about having a
> disconnect I can initiate. The Heinemann breakers look good, except
> they're only rated at 160VDC.
>
> If you think that no, they won't work, what alternatives can you
> suggest?
>
> Thanks!
> -Ben
>
--- End Message ---
--- Begin Message ---
From: "Dewey, Jody R
> SCRs are basically fast switches. If you apply +5VDC to the gate the
> SCR will conduct.
5v is too much voltage! You'd kill it!
The gate-to-cathode input of an SCR behaves like the base-to-emitter junction
of an NPN transistor, i.e. like a forward-biased diode. Depending on the size
of the SCR, you need 0.2ma to 300ma at 0.5v to 1.5v for 1 microsecond or so to
switch it on. Once on, the gate no longer does anything.
Behalf Of Matt Kenigson
> Okay, I read up on SCRs, Thyristors, and Rectifiers on Wikipedia
> but I still don't understand what they're for. How do you use SCRs
> in an EV?
Like Jody said, they are fast switches. You can use them wherever you need to
switch something on/off. Because they are solid state devices, they don't wear
out and so can be switched thousands of times per second for years. It's not
uncommon to find 30-year-old SCR controllers and chargers that still work today.
--
Lee Hart
--- End Message ---
--- Begin Message ---
1) The chip can come configured with a 25mOhm sense resistor between VSS
(Cell minus) and SNS (Pack minus). What keeps large amounts of current
from flowing through this resistor?
All of the cell's current is supposed to go through this resistor. That's
how it senses cell current. It has the same function as a shunt for an
ammeter. You need to size it accordingly from a current handling standpoint.
You don't want it to blow up cuz it'll blow the chip up too.
2) When you hook the DQ (Data) lines of multiple of chips together from
different cells, to what common are the DQ lines referenced? Or do they
need to go through opto-isolators?
You would need to isolate each one for cells in series. Since it's
bidirectional, you would need two optoisolators per chip - one from the
processor to the DQ line, and the other going back. Make sure you use fast
enough optos here. In theory, cells in parallel may be referenced to the
common ground (SNS or VSS is ok), BUT that would fall apart with a
series-parallel mix.
-Dale
--- End Message ---
--- Begin Message ---
go to http.www.carsplusplus.com
They have car specs beginning in 1970
Beano -- 1981 Ford Escort EV
Ted Sanders
From: mike golub <[EMAIL PROTECTED]>
Reply-To: [email protected]
To: [email protected]
Subject: Chevy Metro Weight
Date: Tue, 6 Mar 2007 05:41:29 -0800 (PST)
Hello
I recently purchased a 1998 Chevy Metro.
GM dropped the "Geo" name in that year.
It seems to be a little heavier. I haven't found the
weight on the car, but some books say 1895 pounds, not
exactly the 1600 pounds, I was hoping for.
I can't get the car to scale, because it doesn't run.
Does anyone know what years of the Geo Metro were the
lightest?
And are there any improvements that are worth the
weight?
Maybe better crash protection?
Thanks a lot!
Michael Golub
Fairbanks, AK
http://community.uaf.edu/~ffmig/home.htm
____________________________________________________________________________________
Have a burning question?
Go to www.Answers.yahoo.com and get answers from real people who know.
_________________________________________________________________
With tax season right around the corner, make sure to follow these few
simple tips.
http://articles.moneycentral.msn.com/Taxes/PreparationTips/PreparationTips.aspx?icid=HMFebtagline
--- End Message ---
--- Begin Message ---
Before going out and buying the new batteries I had
actually tested it on 18 volts with my string trimmer
batteries and it seemd to cut ok given the size pack.
It would bog down of course being the batteries were
so tiny but it would cut pretty good.
It seems that if I slow down the RPMS and get an equal
cut at the same walking speed I could potentially get
more range in addition to less heating of the motor.
On my way home going to get an empmeter to see what
i'm pulling. I might be able to use a little scooter
controller to find the best RPM and still use easily
chargeable 12v that I already purchased.
--- Jeff Major <[EMAIL PROTECTED]> wrote:
> Hi Mark,
>
> Cooling this motor is a problem unless you can
> force air thru it. That gets messy on a mower deck.
> Blowing air over the outside frame will help, but
> does not do an effective job of getting heat out of
> the armature and comm.
>
> A buddy used this motor on a 22 inch deck. He
> fairs pretty well. Has a smaller yard. You might
> consider hs appraoch. Reduce the load. He runs at
> 18 volts. This slows the blade speed. But he
> claims still is a good cut. 18/24 = 3/4 speed.
> Probably half power (like a fan load). This reduces
> the heat in the motor a bunch.
>
> BTW he uses NiCad pack I helped him make from D
> cells. Two in parallel. I think they are about 4.5
> amp-hr cells for 9 amp-hr total. Gets him the whole
> yard on one charge. Like I said, a smaller yard.
> In the city. He and his nieghbors really like the
> quiet cut. Made a charger from a Vicor converter
> off eBay.
>
> Jeff
>
> Mark Hastings <[EMAIL PROTECTED]> wrote:
> As at least a short term solution to my 1 acre
> problem
> I found a 22" self propolled mower buried in a pile
> of
> junk.
> I cleaned it up and got a new blade.
> Put this motor on it (which I got somewhere else)
> http://tinyurl.com/gyt5s
> HP 1.54 Voltage 24 DC Amps 4.5 no load
> RPM 3,200 Duty intermittent
> Built as motor for cordless electric lawnmowers
>
> I have two 33 amphour AGMs on it. 48lbs of lead.
> I didn't hook up the self propelled and at first
> didn't disconnect the gears in the wheels either. I
> was much relieved when I realized that and with all
> 4
> wheels actually turning it wasn't that hard to push.
> The motor gets really warm though. There are no
> slots
> for cooling nor do I think I'd want any since after
> just a fwe minutes the deck was covered with grass.
> I
> have a metal deck but it doesn't seem to be
> transferring any of the heat down.
> I'm wondering if there is any way to effectively
> cool
> it down?
> 33amp hours is almost twice the juice the black and
> decker cordless have. And I'm thinking of getting
> two
> more batteries to make a quick change pack. I do
> have
> a Etek which I could stick on it. That woudl be
> entirely overkill though and I'm trying to find a
> nice
> 30"+ walk behind mower for that.
>
>
>
>
> ---------------------------------
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> who know. Ask your question on Yahoo! Answers.
>
>
--- End Message ---
--- Begin Message ---
Bill Dennis wrote:
I've been looking at some of the Dallas 1-Wire devices that monitor
Li-ion cells, for example:
http://datasheets.maxim-ic.com/en/ds/DS2760.pdf -- but two things
confuse me. Referring to Figure 2 on page 5:
1) The chip can come configured with a 25mOhm sense resistor between
VSS (Cell minus) and SNS (Pack minus). What keeps large amounts of
current from flowing through this resistor?
It's a shunt, current is supposed to flow through it. Like all shunts,
they make heat and thus have a very specific current rating. Going with
a lower shunt value will allow larger currents but "fool" the IC into
seeing a current as smaller than it actually is.
2) When you hook the DQ (Data) lines of multiple of chips together
from different cells, to what common are the DQ lines referenced? Or
do they need to go through opto-isolators?
Device VSS. It is not really possible to optoisolate a 1-wire either,
since 1-Wire is bidirectional. See, say we try to make a
"bidirectional" opto by using one opto to pull side B low when side A is
low, and another to pull side A low when side B is low. That's just
latching feedback, once one side goes low then both sides will stay low
forever. Actually there's a way around this problem by making a type of
current sense input instead of a voltage, but it's not all that simple
and often not all that practical. For example, say instead of pulling
it to a normal logical low, you only pull it low to 0.25V (something
below the Vlow threshold of the device) with the opto. Now if the
1-Wire device actually pulls that wire low, it'll pull the pin to 0v so
if the voltage is below 0.25V you turn on the opto to pull down the
other side of the bus. But like I say this requires a number of components.
Danny
--- End Message ---
--- Begin Message ---
At 08:42 AM 3/6/2007, Dale Ulan wrote:
2) When you hook the DQ (Data) lines of multiple of chips together from
different cells, to what common are the DQ lines referenced? Or do they
need to go through opto-isolators?
You would need to isolate each one for cells in series. Since it's
bidirectional, you would need two optoisolators per chip - one from the
processor to the DQ line, and the other going back. Make sure you use fast
enough optos here. In theory, cells in parallel may be referenced to the
common ground (SNS or VSS is ok), BUT that would fall apart with a
series-parallel mix.
And last I knew, nobody had come up with a workable system for
isolating 1-wire devices on the 1-wire bus.
(An Opto in each direction just will NOT work.)
--
John G. Lussmyer mailto:[EMAIL PROTECTED]
Dragons soar and Tigers prowl while I dream....
http://www.CasaDelGato.com
--- End Message ---
--- Begin Message ---
Lawrence
what model of Kilovac did you use?
What do you mean by "it didn't make it". Can you give
more details. I don't know much about breakers and was
thinking of using kilovac ev200s.
thanks
Tom Ward
--- Lawrence Rhodes <[EMAIL PROTECTED]>
wrote:
> I used a Kilovac rated to break a 144vdc pack. It
> didn't make it. Good
> thing my Heinemann relay was up to the task. I'm
> now using two Albrights.
> Cost should not be an issue here. Lawrence
> Rhodes......
> ----- Original Message -----
> From: "Ben Apollonio" <[EMAIL PROTECTED]>
> To: <[email protected]>
> Sent: Monday, March 05, 2007 8:17 PM
> Subject: Kilovac EV-200 as safety disconnect?
>
>
> > How reliable is the Kilovac EV-200 as a safety
> disconnect breaking a
> > 192V pack of Optima YT's shorted across an ADC 9"
> (i.e. inductive
> > load)? I am using an older T-Rex 1000 and I'm
> concerned about the
> > consequences of my controller failing ON (as in,
> still powering the
> > motor). I will have a pair of contactors in
> series, and I prefer the
> > EV-200's for their low cost over the EV-250's and
> bubbas. I know
> > better than to reuse the contactors after I've
> opened them under that
> > kind of load, so it's not a repeated reliability
> thing so much as a
> > one-time thing. But will they even be up to
> carrying the continuous
> > current of my EV? I'd hate to deform them such
> that they didn't open
> > when I needed.
> >
> > I plan on having a fuse too, but I'm really
> concerned about having a
> > disconnect I can initiate. The Heinemann breakers
> look good, except
> > they're only rated at 160VDC.
> >
> > If you think that no, they won't work, what
> alternatives can you
> > suggest?
> >
> > Thanks!
> > -Ben
> >
>
>
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--- End Message ---
--- Begin Message ---
Okay, my understanding is getting closer, but all still isn't quite clear.
1) I understand the shunt concept. So if you want to measure up to 400A
instead of 2A, you use the chip configured for external sense resistor,
and use a .16mOhm resistor (losing some accuracy?). And perhaps I'm
misreading the diagram for "Pack -"; does this just mean "toward pack
minus" instead of "pack minus" (i.e., it means the positive terminal of
the next cell in series)?
2) I'm still confused about device VSS. With two cells in series, are
you saying that how does it work when DQ of the first slave chip is
referenced to VSS of cell 1, and DQ of the second slave chip is
referenced to VSS of cell 2? To what is the master referenced?
Thanks.
Bill Dennis
Danny Miller wrote:
Bill Dennis wrote:
I've been looking at some of the Dallas 1-Wire devices that monitor
Li-ion cells, for example:
http://datasheets.maxim-ic.com/en/ds/DS2760.pdf -- but two things
confuse me. Referring to Figure 2 on page 5:
1) The chip can come configured with a 25mOhm sense resistor between
VSS (Cell minus) and SNS (Pack minus). What keeps large amounts of
current from flowing through this resistor?
It's a shunt, current is supposed to flow through it. Like all
shunts, they make heat and thus have a very specific current rating.
Going with a lower shunt value will allow larger currents but "fool"
the IC into seeing a current as smaller than it actually is.
2) When you hook the DQ (Data) lines of multiple of chips together
from different cells, to what common are the DQ lines referenced? Or
do they need to go through opto-isolators?
Device VSS. It is not really possible to optoisolate a 1-wire either,
since 1-Wire is bidirectional. See, say we try to make a
"bidirectional" opto by using one opto to pull side B low when side A
is low, and another to pull side A low when side B is low. That's
just latching feedback, once one side goes low then both sides will
stay low forever. Actually there's a way around this problem by
making a type of current sense input instead of a voltage, but it's
not all that simple and often not all that practical. For example,
say instead of pulling it to a normal logical low, you only pull it
low to 0.25V (something below the Vlow threshold of the device) with
the opto. Now if the 1-Wire device actually pulls that wire low,
it'll pull the pin to 0v so if the voltage is below 0.25V you turn on
the opto to pull down the other side of the bus. But like I say this
requires a number of components.
Danny
--- End Message ---
--- Begin Message ---
Good luck Tamarack! I read about this in a sailing mag somewhere. It'd be
great to be able to lease an electric boat someday to travel the Trent-Severn
waterway.
----- Original Message ----
From: Rod Hower <[EMAIL PROTECTED]>
To: [email protected]
Sent: Tuesday, March 6, 2007 12:02:28 PM
Subject: Fwd: (ET) Loon Solar Boat Story in Toronto Star
Cool story,
--- [EMAIL PROTECTED] wrote:
> To: [EMAIL PROTECTED]
> From: [EMAIL PROTECTED]
> Date: Tue, 06 Mar 2007 10:46:26 -0500
> Subject: (ET) Loon Solar Boat Story in Toronto Star
>
> Hello,
>
> Just a little shameless self-promotion. if you
> didn't see yesterday's
> business section in the Toronto Star newspaper,
> check out the following
> link:
>
> http://www.thestar.com/article/188158
>
> Monte Gisborne, B.Tech.
> Tamarack Lake Electric Boat Company
> 207 Bayshore Drive, R.R.#3,
> Brechin, Ontario Canada L0K 1B0
> (705) 484-1559
> (416) 432-7067 (cell phone)
> [EMAIL PROTECTED]
> www.tamarackelectricboats.com
>
> Tamarack Lake... Where Water and Electricity Mix!
>
> _______________________________________________
> Elec-trak mailing list
> [EMAIL PROTECTED]
>
https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak
>
____________________________________________________________________________________
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--- End Message ---
--- Begin Message ---
Hey James,
Maybe they do things differently down under. But the interpole machines I
know are not as you describe. I doubt anyone on the list is planning to put
interpoles in their motor, but just in case.
Interpoles are narrow pieces of iron or steel located midway between the main
poles in the frame of the motor. They are typically as long as the stack and
about as wide at the tip as one armature tooth. The coil around the interpole
is called a comm coil, as opposed to a field coil or armature coil. These comm
coils carry full armature current (like series field coils) but are in the
armature circuit and not the field circuit. So they have to be connected in
series with the armature (brushes) between A1 and A2, inside the motor. Then,
when S1 and S2 are reversed to reverse motor rotation, the comm coil polarity
does not reverse and stays proper relative to the armature. This also
maintains proper comm coil strength if field weakening is used across S1 and S2.
Probably more than was needed to know. Sorry.
Jeff
James Massey <[EMAIL PROTECTED]> wrote:
<<snip>>
Some motors designed for higher voltages have interpole windings - skinny
field windings that are in circuit (in series with the rest of the field
windings) for one direction and not in circuit in the other direction (in a
forklift).
Other motors are compound or shunt wound, but they are not common for
traction motors as they are usually used for constant speed applications.
Think that covers it, Jim?
Regards
[Technik] James
---------------------------------
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--- End Message ---
--- Begin Message ---
Going from 0.01 to 0.007 rolling resistance coefficient, I'd expect
the mpg to go up at lower resistance - did you mean to say: change from 48
to 52 MPG?
Note that a new tire (after the initial effects of the first few hundred
miles) has
a thicker thread of softer rubber than an old worn-down tire.
This not only impacts radius, but also rolling resistance (the thread
consumes energy
in the compression/decompression and shape-change while rolling)
Old worn-down tires may not be the safest, but they are the best for
mileage!
Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Phil Marino
Sent: Tuesday, March 06, 2007 4:45 AM
To: [email protected]
Subject: RE: LRR Tires
>From: "Brian M. Sutin" <[EMAIL PROTECTED]>
>Reply-To: [email protected]
>To: EV List <[email protected]>
>Subject: LRR Tires
>Date: Mon, 5 Mar 2007 22:44:19 -0800
>
> > The 2005 Prius was being driven the same route regularly and over a
> > long period of time so it was possible to get a pretty steady
> > average. The
>route
> > was mainly 70 MPH highway and the Prius was getting 48 MPG with the
>tires at
> > 40 PSI. Over time, same route, same driver, the mileage began to
> > improve reaching 50 MPG at 50,000 miles. As this point the tires
> > were worn to
>the
> > point of needing replacement.
>
>MPG at 70 MPH is so massively dominated by wind resistance over rolling
>resistance that the experimental results are pretty meaningless for
>rolling resistance. As you concluded, they say a lot about calibrating
>the tire diameter. A better experiment would not exceed 40 MPH.
>Please drive more slowly next time!
The air drag is dominant at 70 MPH for the Prius, but I wouldn't call it
massively dominant.
My calculations ( based on frontal area of 2.16 Meters squared, CD = 0.26,
road weight = 3065 #, and tire RR = 0.01) result in the following drags at
70 MPH:
Air drag = 77 #
Tire RR drag = 31 #
So, a change in tire RR could very well show up in his measured MPG.
For instance a change from 0.010 RR to 0.007 RR tires ( a moderate change)
would drop the total drag by 8.5 % . If MPG and drag were proportionally
related, that would result in a change from 48 MPG to 44 MPG. In reality,
the change in MPG would probably be less than that, since some engine
losses are independent of drag.
I agree with you, though, that driving at slower speeds would make tire drag
comparisons more meaningful.
Phil
>
>Brian
>Alfa Romeo Electric Conversion
>http://www.skewray.com/alfa/
>
>--
>Brian M. Sutin, Ph.D. Space System Engineering and Optical Design
>Skewray Research/316 W Green St/Claremont CA 91711 USA/(909) 621-3122
>
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--- End Message ---
