EV Digest 6980
Topics covered in this issue include:
1) PVC Glue
by Bill Dennis <[EMAIL PROTECTED]>
2) Re: PVC Glue
by rice <[EMAIL PROTECTED]>
3) Re: PVC Glue
by Michael Barkley <[EMAIL PROTECTED]>
4) Re: EV air conditioning, how to connect motor?
by Victor Tikhonov <[EMAIL PROTECTED]>
5) Re: PVC Glue
by "Roland Wiench" <[EMAIL PROTECTED]>
6) Re: PVC Glue
by "John A. Evans - N0HJ" <[EMAIL PROTECTED]>
7) Re: A battery test algorithm that I recently came up with
by "Joseph T. " <[EMAIL PROTECTED]>
8) Re: Would you build if you could buy?
by "Michael Perry" <[EMAIL PROTECTED]>
9) Re: A battery test algorithm that I recently came up with
by "Joe Smalley" <[EMAIL PROTECTED]>
10) Re: PVC Glue
by "Michael Perry" <[EMAIL PROTECTED]>
11) Re: PVC Glue
by Thomas Ward <[EMAIL PROTECTED]>
12) RE: Zombie Rips into the 11s !!!!
by "Pestka, Dennis J" <[EMAIL PROTECTED]>
13) article: evDaytona: electric motocycle with turgid windscreen
by Paul Wujek <[EMAIL PROTECTED]>
14) Re: Flooded Nicads?
by Tom Gocze <[EMAIL PROTECTED]>
15) Re: article: evDaytona: electric motocycle with turgid windscreen
by lyle sloan <[EMAIL PROTECTED]>
16) Re: Wheel alignment Or How to significantly reduce rolling
resistance!
by Markus Lorch <[EMAIL PROTECTED]>
17) Re: Wheel alignment Or How to significantly reduce rolling
resistance!
by "Peter VanDerWal" <[EMAIL PROTECTED]>
--- Begin Message ---
I've got a few PVC body parts to which I need to affix some metal
L-brackets, which will then get bolted to the frame. One suggestion I
got was to use Gorilla Glue. Does anyone have any other recommendation
for a good glue or mastic to attach the L-brackets to the PVC?
Thanks.
Bill Dennis
--- End Message ---
--- Begin Message ---
Bill Dennis wrote:
I've got a few PVC body parts to which I need to affix some metal
L-brackets, which will then get bolted to the frame. One suggestion I
got was to use Gorilla Glue. Does anyone have any other
recommendation for a good glue or mastic to attach the L-brackets to
the PVC?
Thanks.
Bill Dennis
JB Weld
--- End Message ---
--- Begin Message ---
Could you sandwich the L-Brackets between the main PVC
part, and another cutout piece of PVC that mimicks the
shape of the main PVC part? Then use JB Weld to
adhere all three items as one.
M. Barkley
www.texomaev.com
http://www.austinev.org/evalbum/1135
--- End Message ---
--- Begin Message ---
With existing vehicle A/C solution you only substitute external pulley
drive with motor drive. Everything else stay the same, not requiring
re-engineering. Not that it's a rocket science but why bother if
you can reuse most of the well designed system?
With window unit you need to install whole setup - radiators,
evaporators, valves, hoses and all that stuff. Mounts, brackets, etc.
Not undoable but more work involved. Not to mention that stock
system components are already sized for the job in *this* car.
I kept most of the stock stuff in place, just moved
compressor itself. Very simple mod.
But I may agree if you create A/C from scratch in the vehicle
which never had it in a first place, window unit may be
somewhat self-contained OK solution.
Victor
Danny Miller wrote:
Frankly, I think you guys are going the wrong way with these solutions.
If you have a 120V nom pack, you can take apart a 15,000 or so BTU
windor air conditioner unit.
The compressor and motor are integrated, which at first seems terrible
since the motor is AC, but that motor is way smaller and cheaper,
largely because it is cooled by the freon running through it. Far, far
more practical design for the application.
Really if you have a 120VDC pack or more, driving a 120V AC motor is
hardly rocket science. This is a fairly simple inverter circuit as
things go, it should be able to handle somewhat higher pack voltages by
just reducing the duty cycle of the waveform but I'm not sure how much
higher. It's only 15 amps or so and the inverter only needs to switch
at 60Hz so switching losses are generally easy to manage. I might be
interested in doing this design.
A DC/DC converter could certainly accomodate higher or lower voltages,
though it's more complicated than just a 60Hz inverter. Well, the
buck/boost ratio isn't that great and that always makes these converters
easier to pull off.
These guys who pop up periodically who want to build their own EV
controller, this is the direction to send them in.
Danny
Victor Tikhonov wrote:
When I've done this - almost 10 years ago - I used 180V
6.7A Leeson PM DC motor running straight off of 120VDC nom
pack (~130V actual) It was consuming about 5.5A at that voltage
which translates to 715W which is less than 1hp. But CRX compressor
is tiny and efficient, so may not take that much power.
Starting current surge must of been 20-25A or so, but I never
bothered to measure.
Mike Chancey already provided links to these photos (thanks Mike!):
http://metricmind.com/dc_honda/hood1.jpg
http://metricmind.com/dc_honda/hood2.jpg
http://metricmind.com/dc_honda/ac1.jpg
I had the system constantly on without cycling, which was not such a
good idea, but I kept it on for ~5 min at the time and turn of by hand.
I used DC SSR to control it just by the switch on the dash - very
primitive but took 10 min to wire up, and I had cold. SSR was bolted
to the adapter plate which served as a heat sink for it.
The motor, when ran unloaded, ran at whatever RPM lower voltage
provided, but when it actually was linked to the compressor it
didn't slow down a bit as if there is very light load. That tells me
that mechanical power required was not that much (or the motor was
overkill and didn't even "feel" that load.
Today I'd do this differently, but as far as power required I don't
believe you need much more than 1kW motor to run average car A/C.
In fact 1hp (736W) is adequate for efficient modern compressor,
especially scroll type.
BTW, I don't remember having any difficulty to take the pulley/clutch
off and fit it with rubber spider coupling (lovejoy?) I bought in
Pulvis bearing. Compressor has all bearings to support its shaft,
but that might be the case for ones used in Honda CRX/Civic and not
generic case.
Victor
--
'91 ACRX - something different
Christopher Robison wrote:
On Wed, 2007-06-27 at 12:07 -0500, Danny Miller wrote:
You are underestimating the power requirements of a car A/C
compressor. While it varies by make and model and I have no hard
numbers, car A/C is sized like a huge wall unit, people have said
20K-30K BTU equivalent which would be something like 4 or 5 HP. The
draw varies substantially with temp differential as far as I know- I
saw this powering a 6500 BTU off an inverter, I got 80A @ 12V at
start and it worked up to like 120A eventually.
I've been worried about this too. I may be forced to use a belt for
this reason, so I can reduce the size of the motor pulley, and then just
deal with the underperforming A/C. At the size of my 2HP motor (5 inch
diameter, about 10 inches long, and heavy) I can't imagine a 5HP motor
of the same design.
Doesn't a compressor require a substantial surge power to turn on?
No prob if it's just a mattor of not being within the motor's
continuous rating but if it exceeds the motor's max stall torque
then the system will never get turning in the first place.
If the system is not pressurized, I believe that the compressor will
automatically soft-start as it builds up pressure over the first few
seconds of operation. I believe that building A/C units often have a
timer to prevent the system from being switched on until a suitable
delay has expired, to allow the system to depressurize through the
expansion valve, for this reason. Maybe such a timer would be in order
here too.
--- End Message ---
--- Begin Message ---
Use J-B Weld, the slow type, not the 5 minute type. Rough up both contact
areas and do not touch this area with you fingers. Mix the J-B weld and
apply it to the PVC. Press in the bracket. Smooth the compound compound
with a mirror finish putty knife dip in lacquer thinner. Let dry for 24
hours.
Roland
----- Original Message -----
From: "Bill Dennis" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Sunday, July 01, 2007 8:13 PM
Subject: PVC Glue
> I've got a few PVC body parts to which I need to affix some metal
> L-brackets, which will then get bolted to the frame. One suggestion I
> got was to use Gorilla Glue. Does anyone have any other recommendation
> for a good glue or mastic to attach the L-brackets to the PVC?
>
> Thanks.
>
> Bill Dennis
>
>
--- End Message ---
--- Begin Message ---
And, don't use aluminum to make your brackets - use steel or brass.
I've had trouble with making backpacking alcohol stoves - I'd use JB
weld to glue a nut on the inside of the top of the soda can stove so I
could make a pressurized version. Twice, both times in the field, the
nut came loose from the aluminum.
john
Roland Wiench wrote:
Use J-B Weld, the slow type, not the 5 minute type....
--- End Message ---
--- Begin Message ---
It looks like it should work. Have you tried it? Oh, and I agree with
Peter above, you should assume that the pack voltage will be a little
bit lower throughout the whole trip since chances are you won't have
time for your battery to rest.
On 7/1/07, Peter VanDerWal <[EMAIL PROTECTED]> wrote:
Hmm, one obvious problem. You are assuming that the battery sag voltage
throughout the entire trip will equal the sag of a freshly charged pack.
It might be better to assume the battery will be at 110-115V through the
trip. Worse case the battery performs as calculated, best case it
performs better.
With your calculations it will most likely perform less than calculated.
> Over and over people have asked if a battery is
> suitable for use in an EV application. I have the
> same question, so I came up with this.
>
> Here it goes for lead acid. Determine how many amps
> you pull in your typical cruise mode and what your
> overall sagged pack voltage is.
>
> For my car ...
>
> 220 Watt hr / mile (on the high side)
> at 40 miles / hr
>
> = at cruise 8800 Watts
>
> That is with a 120 V nominal pack, fully charged = 132
> V, under this load about 124 V (hot off the charger).
>
> 8800 / 124 = 70.9 Amps.
>
> My numbers are a little approximate, so lets call it
> an even 70 A on cruise. That's battery amps. Pretty
> typical of a low voltage DC system.
>
> So, cruising, I need to pull an average 70 A. I'd
> say, on average 80% of the time is cruise, and the
> other 20% is acceleration / deceleration. On
> acceleration, I pull lets say 350 A. That's the max I
> recently concluded was safe to pull off a golf cart
> batt. My batts are even worse, but for the sake of
> argument lets use 350 A as the benchmark.
>
> Total I need 70 A * 80% + 300 A * 10% + 0* 10%. If I
> graphed this very crudely, that would be a step
> function. For the sake of averages, it works out to
> an average drain rate of 86 A with 70 A typical and
> 350 A peak.
>
> So, this all makes pretty good sense so far. Can my
> battery do it or not?
>
> Here is the test. Put an 86 A load on the battery and
> time how long it takes to get to a loaded voltage of
> 11 V. That's what a typical inverter will do for cut
> off voltage. Lets just say for the sake of argument
> that it takes 32 minutes to get there. 32 min / 60
> min per hour = 0.533 hrs. We were going 40 MPH on
> cruise. So, just round it off and call it 40 MPH.
> The number will be a little high. .533 hrs * 40 MPH =
> 21 miles. I'd say the max range on that car is 20
> miles to 100% DOD and usable is 15 miles. I'm being
> conservative to account for weather and battery aging.
> This is just an example for the sake of argument, not
> actual data from my test.
>
> Can it pull the 350 A? Here is the tough part. You
> need to get the battery to a 20% SOC (80% DOD). Drain
> it until the resting voltage is 12 V. If you drain it
> loaded to 11 V, you may get lucky and it may recover
> somewhere around 12 V. Somehow drain it slow or
> charge it a little to get it to 20% SOC. Then, hit it
> with a 350 A load for 60 sec. Hepefully your 0-60 is
> better than that and you never accelerate hard for
> more than 60 sec. Hills are a whole different issue,
> but that should have come out in the Wh / mile
> calculation. If the battery under load is still above
> 10.5 V aftr 60 sec, you are good to go. Charge it all
> the way back up on a moderately slow charger 6-10 A,
> and it is good to go.
>
> Actual expected cycle life for any given battery in an
> EV application is a whole different story. I don't
> have any way to estimate that other than to ask around
> and see what batteries are recommended as good and
> what are recommended to stay away from.
>
> I am open to comments or corrections if I have made
> any bad assumptions.
>
> I wish I would have done this test on one of my
> batteries before I bought a whole pack. Hopefully by
> publishing this, it will save someone some heartache
> of buying a bad EV battery.
>
> Steve
>
>
>
>
>
>
____________________________________________________________________________________
> Pinpoint customers who are looking for what you sell.
> http://searchmarketing.yahoo.com/
>
>
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
--- Begin Message ---
David: I agree with your thinking.
I would be interested in how far/fast one of these could go, w/o gasoline.
>From what I see so far, it's mostly going to be hype, at least as far as the
early entries into this class go. I was surprised to learn that the battery
packs on the average hybrid is so small (compared to the vehicle's curb
weight). Considering the charge ratio on these (to keep the batts alive?)
I'm guessing less than the range to the local grocery store, for most rigs.
Assuming, of course, a person actually uses the plug after the first few
weeks. <vbg>
----- Original Message -----
From: "David Roden" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Friday, June 29, 2007 9:13 PM
Subject: Re: Would you build if you could buy?
> For years I've had conversations with friends who are interested in EVs
> until they find out about the range. Suddenly an EV is a great idea - for
> other people.
>
> Lately I'm finding that the word on PHEVs is getting across. Again, it's
> anecdotal (and the plural of "anecdote" is not "data"), but the idea of
> "drive electric as long as you can, then let the gas engine take over" has
a
> lot of resonance with people I talk to.
>
> Some of this is "greenness," but at least as much is the desire to give
less
> trade to the oil companies, which have a certain kind of image. It's not
> that they expect to save piles of money on an EV or PHEV - just that
they'd
> like to give LESS money to Big Oil.
>
> What they'd pay for this is another question. I'd pay $6-10K extra for a
> PHEV that could do 30 miles at 50 mph in EV mode. However, I think maybe
> $5k is about tops for the average person. That's just a guess, though.
The
> company which plans to market such a vehicle would be well served to
perform
> some solid, statistically valid market research.
>
> David Roden - Akron, Ohio, USA
> EV List Administrator
--- End Message ---
--- Begin Message ---
You made some baseline decisions that will give you misleading answer.
1. You assume that amps move the car. The fact is that watts move the car.
You should be doing a constant power discharge instead of a constant current
discharge. If you use a constant power discharge, the voltage sag takes care
of itself. As the battery discharges, the current draw increases to make up
for the lost terminal voltage.
2. You assume that you want to deplete the battery on cruise and then try to
accelerate. My commute has a stop light or a stop sign about every half
mile. If you assume that half of the lights are green and you have to stop
at all the stop signs, then you need to give the battery a break every
minute and follow up with a simulated acceleration. It is up to you to set
the periodicity of stops, the length of the rest during deceleration, the
acceleration power level, the acceleration duration, and the cruise power to
simulate your use of the vehicle, the vehicle weight, and your power train.
3. If you are using a DC Controller, you can allow a 12 volt battery to sag
to 6 volts during the acceleration portion of the test. If you are using an
AC controller, you need to cut the test off at 11 volts if your controller
is programmed that way. The DC test should be cut off during the cruise
portion when the battery reaches 10.5 volts.
4. You need to monitor the temperature of the battery. Some of them get so
hot, they melt their posts. Try to keep them under 100F.
5. Batteries need some break in time. You will get disappointing results if
you run this test on batteries straight off the pallet. Run them up and down
about three times at about a five hour rate until they give consistent
results. Some give consistent results on the second cycle. Some need ten
cycles to become consistent.
Joe Smalley
Rural Kitsap County WA
Former owner of 48 Volt Fiesta
NEDRA 48 volt street conversion record holder
[EMAIL PROTECTED]
----- Original Message -----
From: "Steve Powers" <[EMAIL PROTECTED]>
To: "ev" <ev@listproc.sjsu.edu>
Sent: Sunday, July 01, 2007 5:24 PM
Subject: A battery test algorithm that I recently came up with
> Over and over people have asked if a battery is
> suitable for use in an EV application. I have the
> same question, so I came up with this.
>
> Here it goes for lead acid. Determine how many amps
> you pull in your typical cruise mode and what your
> overall sagged pack voltage is.
>
> For my car ...
>
> 220 Watt hr / mile (on the high side)
> at 40 miles / hr
>
> = at cruise 8800 Watts
>
> That is with a 120 V nominal pack, fully charged = 132
> V, under this load about 124 V (hot off the charger).
>
> 8800 / 124 = 70.9 Amps.
>
> My numbers are a little approximate, so lets call it
> an even 70 A on cruise. That's battery amps. Pretty
> typical of a low voltage DC system.
>
> So, cruising, I need to pull an average 70 A. I'd
> say, on average 80% of the time is cruise, and the
> other 20% is acceleration / deceleration. On
> acceleration, I pull lets say 350 A. That's the max I
> recently concluded was safe to pull off a golf cart
> batt. My batts are even worse, but for the sake of
> argument lets use 350 A as the benchmark.
>
> Total I need 70 A * 80% + 300 A * 10% + 0* 10%. If I
> graphed this very crudely, that would be a step
> function. For the sake of averages, it works out to
> an average drain rate of 86 A with 70 A typical and
> 350 A peak.
>
> So, this all makes pretty good sense so far. Can my
> battery do it or not?
>
> Here is the test. Put an 86 A load on the battery and
> time how long it takes to get to a loaded voltage of
> 11 V. That's what a typical inverter will do for cut
> off voltage. Lets just say for the sake of argument
> that it takes 32 minutes to get there. 32 min / 60
> min per hour = 0.533 hrs. We were going 40 MPH on
> cruise. So, just round it off and call it 40 MPH.
> The number will be a little high. .533 hrs * 40 MPH =
> 21 miles. I'd say the max range on that car is 20
> miles to 100% DOD and usable is 15 miles. I'm being
> conservative to account for weather and battery aging.
> This is just an example for the sake of argument, not
> actual data from my test.
>
> Can it pull the 350 A? Here is the tough part. You
> need to get the battery to a 20% SOC (80% DOD). Drain
> it until the resting voltage is 12 V. If you drain it
> loaded to 11 V, you may get lucky and it may recover
> somewhere around 12 V. Somehow drain it slow or
> charge it a little to get it to 20% SOC. Then, hit it
> with a 350 A load for 60 sec. Hepefully your 0-60 is
> better than that and you never accelerate hard for
> more than 60 sec. Hills are a whole different issue,
> but that should have come out in the Wh / mile
> calculation. If the battery under load is still above
> 10.5 V aftr 60 sec, you are good to go. Charge it all
> the way back up on a moderately slow charger 6-10 A,
> and it is good to go.
>
> Actual expected cycle life for any given battery in an
> EV application is a whole different story. I don't
> have any way to estimate that other than to ask around
> and see what batteries are recommended as good and
> what are recommended to stay away from.
>
> I am open to comments or corrections if I have made
> any bad assumptions.
>
> I wish I would have done this test on one of my
> batteries before I bought a whole pack. Hopefully by
> publishing this, it will save someone some heartache
> of buying a bad EV battery.
>
> Steve
>
>
>
>
>
>
____________________________________________________________________________
________
> Pinpoint customers who are looking for what you sell.
> http://searchmarketing.yahoo.com/
>
--- End Message ---
--- Begin Message ---
As a thought... whatever adhesive you use, try also a mechanical bond to the
PVC... if at all possible. PVC can be difficult to bond.
----- Original Message -----
From: "Bill Dennis" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Sunday, July 01, 2007 7:13 PM
Subject: PVC Glue
> I've got a few PVC body parts to which I need to affix some metal
> L-brackets, which will then get bolted to the frame. One suggestion I
> got was to use Gorilla Glue. Does anyone have any other recommendation
> for a good glue or mastic to attach the L-brackets to the PVC?
>
> Thanks.
>
> Bill Dennis
--- End Message ---
--- Begin Message ---
John A. Evans - N0HJ wrote:
> And, don't use aluminum to make your brackets - use steel or brass.
> I've had trouble with making backpacking alcohol stoves - I'd use JB
> weld to glue a nut on the inside of the top of the soda can stove so I
> could make a pressurized version. Twice, both times in the field, the
> nut came loose from the aluminum.
John,
Aluminium is difficult to bond because it oxidises so quickly, stainless
steel is similar.
one way to bond both AL and stainless is to grind the adhesive into the
plate.
I use slow cure epoxy, below is the procedure I follow
1. clean both surfaces with soapy water
2. rinse thoroughly with warm wate
3. thoroughly dry
4. mix the epoxy
5. clean both surfaces with acetone
6. abrade both surfaces
7. very quickly clean both surfaces with acetone
8. spread the epoxy
9. abrade the epoxy into both the surfaces
10. clamp with good pressure
11. heat to a little below the recommended cure temp
12. keep checking to make sure the joint isn't overheating
Always works for me.
the heat is important but most adhesives I have worked with are
exothermic so you need to make sure the reaction doesn't get out of control
cleaning with water is important especially if you have been using
epoxies before, some of the epoxy byproducts don't dissolve well in
typical solvents and are best removed with water.
--- End Message ---
--- Begin Message ---
Fantastic !
Looking forward to seeing what the Lithium's will do.
Dennis
Elsberry, MO
-----Original Message-----
From: Roderick Wilde [mailto:[EMAIL PROTECTED]
Sent: Friday, June 29, 2007 11:42 PM
To: ev@listproc.sjsu.edu
Subject: Zombie Rips into the 11s !!!!
Well all of the hard work and long hours and weeks of preparation have
finally paid off big time. On it's fourth run of the night Tim Brehm
piloted the over zealous Zombie into the elevens and into the record
books with a blistering 11.948 second ET at almost 110 mph. Terminal
speed was 109.75 mph. The powerful Enersys batteries just keep on
putting out more after each run. The sixty foot time was a very
impressive 1.667 so not only is it pulling hard on the far end it is
still launching like a son of a b**ch! The eighth mile was also
impressive with a 7.520 ET at almost 90 mph, 89.48 to be exact. The
11.948 is a new world record as it is backed up with the
12.037 run. John said they will make one more run tonight and then head
home. My most profound congratulations go out to John and Tim and Jim of
course hiding in the shadows somewhere tonight. His motor has held up
well under this new extreme performance. By the way, they never did turn
up the controller past 1000 battery amps and the Enersys batteries will
take 1500.
John is just so conservative you know :-)
Roderick Wilde
"Suck Amps EV Racing"
www.suckamps.com
--- End Message ---
--- Begin Message ---
Electric Triumph Daytona, got $70,000 in your back pocket?:
http://www.engadget.com/2007/07/02/evdaytona-electric-motocycle-with-turgid-windscreen/
--
Paul Wujek ([EMAIL PROTECTED])
--- End Message ---
--- Begin Message ---
I have 96-100 ah UPS nicads in my '95 S10 truck (it is on the EV
Photo List).
Have not run it real hard yet. Got a little over 20 miles driving
50-68 mph on coastal Route 1 in Maine (is a fast road that I happen
to live on!) when I first started using it.
I suspect after I exersize the batts a little that I would eek out
another 5-10 miles driving fast.
Suspect that in town I would do twice that.
Good news is these batteries are pretty bullet proof, unless you do
not water them.
Could probably run a lot faster if I had a controller other than the
1231 that seems to top out at around 300A.
Of course, then I wouldn't go as far ;^)
Tom in Maine
--- End Message ---
--- Begin Message ---
This particular build is already in the EValbum.com
(but you might not have bothered looking), has been
discussed on this list earlier this year, and Jay from
gowheel is a member of this list. If gowheel can sell
one for 70k, more power to them. They have at least
tried to be a part of this community.
--- Paul Wujek wrote:
> Electric Triumph Daytona, got $70,000 in your back
> pocket?:
>
>
http://www.engadget.com/2007/07/02/evdaytona-electric-motocycle-with-turgid-windscreen/
>
> --
> Paul Wujek ([EMAIL PROTECTED])
>
>
____________________________________________________________________________________
Boardwalk for $500? In 2007? Ha! Play Monopoly Here and Now (it's updated for
today's economy) at Yahoo! Games.
http://get.games.yahoo.com/proddesc?gamekey=monopolyherenow
--- End Message ---
--- Begin Message ---
Peter,
If you read my mail, how did you miss the point that the curtis is not
the (main) bottleneck I am concerned about. Its the batteries. I had
read many posts talking about 400 or even 600 battery amps and just now
learned that that is way too much for most 6V 160-200 Ah AGM, flooded,
or gel batteries if one expects a battery life of 100 or more cycles to
80% dod.
The curtis and my current batteries will give me peak 500A, then drop to
450, 400, 350 and will eventually settle at 250A or so if I push it.
Thats good for in city and I could live with that on the highway, hower
I was told to stay around 120-160A if I do not want to buy batteries on
a yearly basis.
I have been reading many mails about people having 250-300Wh/mile
performance with even heavy cars doing 40mph (just one today) but that
figure seems to be only for flat roads, maybe including infrequent
accelleration and deceleration. I also get there if I drive carefully,
let it slow down significantly on hills and do not take the charger and
equalization inefficiency into account. I did not fully realize how much
more power hills take and how slow an EV really gets when it hits a
hill. (even though my first car was a 45hp VW fox)
I also don't see a good way around the power limitation currently. I can
go to 12V AGM batteries (e.g. Optimas) that cost a fortune, have
significantly less capacity, but would deliver the needed amperage
better, however I was also told that their cycle life is as well
significantly shortened by high-amp discharge. I could go to a 120V pack
but that would not reduce amperage a lot, maybe 25%. According to an old
post from Lee Hart the smaller the battery the lower the amperage drawn
should be for similar life expectancy. His mail was about 6V vs. 12V
batteries.
Now I am not sure if the difference in technology from flooded or gel to
AGM turns this rule of thumb upside down, if not then going from a 160Ah
to a 55Ah with a current reduction of only 25% (90 to 120V step up)
seems counterproductive.
Now I could buy a higher voltage controller but that doesn't seem to
solve the issue as the batteries will also have to have less capacity in
order to fit more in the car. The car right now has the "right" battery
to overall vehicle weight ratio according to an old rule of thumb found
on this list (a bit more than 1/3rd of the weight are batteries).
I followed the current AGM vs. Gel debate very closely and it seems to
indicate that AGMs can cope with the higher currents (I guess about 3*C)
but other posts about aging YT packs etc. let me doubt this. Also
another EV driver told me his long time experience is that also AGMs
should not be driven past 1C e.g. 90A for a 90Ah battery to get
something like 200 cycles to 80% out of them.
Flooded batteries that I just was quoted also specify 200 cycles to 80%.
That would be something like 10 000 miles with my car, which is way too
low for the battery price. Most calculations I've seen by other EV
owners claim that the cost of batteries plus the cost of electricity is
less or similar per mile than the cost of gas. Now if I can only go 10k
miles with a pack then the price of the pack at roughly 2500 USD will be
25ct per mile, or 25 USD per 100 miles. Thats way more than the price of
gas just for the batteries. Even with double the battery life its more
expensive compare to the (expensive) USD 6.50 / Gal gas price (e.g. at
30mpg (typical 10 year old VW rabbit) that would be about USD 21 for 100
miles for gas. Now if I compare that to USD 25 for the batteries plus
electricity of 40 kwh/100 miles (0.24USD/kwh) then thats 35 USD per 100
miles in my EV compared to 21 USD for the gas rabbit.
Now this is not an apples to apples comparison as the stock 75Hp Rabbit
goes much faster and is more comfortable (heavier) than my EV. OTOH the
electricity for my EV is from water and sun power, so no pollution
there. I already did decide that I will trade the comfort and power of
the Rabbit for the clean EV, but this was under the assumption that
running costs are about equal. I need to add insurance and licensing
savings as well as emissions inspections and other maintenance into the
equation to be roughly equal in cost.
Back to batteries: it seems to me that either one drives his batteries
to at least 2x-3x the safe (longlife) discharge rate or it is impossible
to move a lead battery EV with regular traffic on highways and in hilly
terrain. With these discharge rates batteries are used up relatively and
hence the cost is high.
I am looking forward to a SAFT 100Ah NiCD pack that I try to acquire. I
may go to 120V if somebody can tell me for sure is that my curtis can
cope with this voltage (it says 84V on the plate, 120V nominal would be
what 140V peak?). The batteries should be good to 300A so I am told
which would be twice the power I have now at about half the weight (If I
keep the voltage the same I can lighten the pack as I should be able to
get as far with less capacity due to the lack of the peukerts effect and
as I can drive them until empty).
Peter, so I guess my mistake was to read too many good news and not
enough bad news and as (almost) everybody on this list is pro-ev I guess
the view of the reality is a bit skewed. I book my on-road EV experience
under "reality-check", having learned that it is hard to not too hinder
traffic too much when there is an incline with 350A*85V=40hp and
virtually impossible to go any decent speed uphill with 160A*90V=20HP,
the safe discharge rate of my 160Ah batteries.
Markus
Peter VanDerWal schrieb:
If you have been reading the list for years, how did you miss the point
about 450 amp curtis having barely adequate performance? And that is with
a 120V pack, couple low amps with a low voltage pack you have have to
expect low performance.
Series wound motors are great performers, but they can't make power out of
thin air. Your controller and battery pack are good for 37 hp maximum,
that is about 30% less power than the original ICE.
Hopefully it is enough to keep you happy. Have fun and try not to murder
your batteries ;-)
Cheers.
have been driving round in my 90V Tavria for the last two weeks every
chance I got. I installed and Amp and Voltmeter and closely monitored
current and voltage. Also monitored my weakest block. Point was I was a
bit dissappointed with the performance. Reading all your emails for
several years now about the great acceleration of a DC series wound
motor etc. (I have a 120lb 8" series motor mated to a manual gear box
with a curtis 1221R and a 90V pack in a small car - 2500lbs)
If I floor it right from the start there is an OK accelleration but at
the cost of 450A which, as I was told, will murder my batteries in no
time. I am creeping up hills with 20mph (always in the smallest gear I
have) and still drawing 200A. I could go faster but am afraid my
batteries will not like it. And the 50psi pressure in the tires lets me
feel every little rock. So much for my physics lesson.
Now the good news. I found out one reason for the low performance when
looking at my new front tires after only 100miles were on them. They
looked like I would corner the car at high speeds all the time. When
comparing the wheels I noted that they aint pointing in the same
direction. Well sort of. The steering was off about 1 inch. Adjusting
the steering meant removing all front batteries incl. the front battery
rack. So, trying not to hurt my back, I spend yesterday evening doing
just that and adjusting the wheels. Oh wonder, it now rolls much easier.
I can push it with little effort.
Hill climbing and accelleration still needs Amps like heck but I can see
and feel a clear difference in Amps drawn going a steady speed. Probably
a 15% improvement. So, I guess I learned my lesson and will pay more
attention to such details like wheel alignment :) This is all not such a
big deal with my Elec-Traks. I guess they would just happily plow along
with slightly misaligned front wheels (especially with the heavy garden
tiller on the rear)
Markus
--- End Message ---
--- Begin Message ---
The batteries are limiting your top end performance, but the controller is
limiting your low end performance AND your top end performance.
Poor low end performance is much more noticeable (and annoying) than poor
top end performance.
A 450 amp Curtis controller can only source 450 amps in the motor loop,
regardless of the battery current. A 550 amp controller will perform
almost 25% better at the low end where you notice performance the most.
Note: at the low end, your motor loop can be 550 amps while the battery
current is only at 100 amps.
Switching to a 120V pack is a 33% percent increase in voltage and will
allow a corresponding reduction in battery current for the same
performance, will allow you to keep your controller in current limit
(stronger acceleration) for 33% longer.
Having 25% more power for 33% longer (higher speed) will make a noticeable
improvement in performance.
12V AGMs like Optima YTs shrug off 550 amp draws, even when at 50% DoD.
If you are limited in weight or space the YTs, especially the group 31s,
would be a better option if you want better performance. Something to
consider when it comes time to replace the pack.
> Peter,
>
> If you read my mail, how did you miss the point that the curtis is not
> the (main) bottleneck I am concerned about. Its the batteries. I had
> read many posts talking about 400 or even 600 battery amps and just now
> learned that that is way too much for most 6V 160-200 Ah AGM, flooded,
> or gel batteries if one expects a battery life of 100 or more cycles to
> 80% dod.
> The curtis and my current batteries will give me peak 500A, then drop to
> 450, 400, 350 and will eventually settle at 250A or so if I push it.
> Thats good for in city and I could live with that on the highway, hower
> I was told to stay around 120-160A if I do not want to buy batteries on
> a yearly basis.
> I have been reading many mails about people having 250-300Wh/mile
> performance with even heavy cars doing 40mph (just one today) but that
> figure seems to be only for flat roads, maybe including infrequent
> accelleration and deceleration. I also get there if I drive carefully,
> let it slow down significantly on hills and do not take the charger and
> equalization inefficiency into account. I did not fully realize how much
> more power hills take and how slow an EV really gets when it hits a
> hill. (even though my first car was a 45hp VW fox)
>
> I also don't see a good way around the power limitation currently. I can
> go to 12V AGM batteries (e.g. Optimas) that cost a fortune, have
> significantly less capacity, but would deliver the needed amperage
> better, however I was also told that their cycle life is as well
> significantly shortened by high-amp discharge. I could go to a 120V pack
> but that would not reduce amperage a lot, maybe 25%. According to an old
> post from Lee Hart the smaller the battery the lower the amperage drawn
> should be for similar life expectancy. His mail was about 6V vs. 12V
> batteries.
> Now I am not sure if the difference in technology from flooded or gel to
> AGM turns this rule of thumb upside down, if not then going from a 160Ah
> to a 55Ah with a current reduction of only 25% (90 to 120V step up)
> seems counterproductive.
>
> Now I could buy a higher voltage controller but that doesn't seem to
> solve the issue as the batteries will also have to have less capacity in
> order to fit more in the car. The car right now has the "right" battery
> to overall vehicle weight ratio according to an old rule of thumb found
> on this list (a bit more than 1/3rd of the weight are batteries).
>
> I followed the current AGM vs. Gel debate very closely and it seems to
> indicate that AGMs can cope with the higher currents (I guess about 3*C)
> but other posts about aging YT packs etc. let me doubt this. Also
> another EV driver told me his long time experience is that also AGMs
> should not be driven past 1C e.g. 90A for a 90Ah battery to get
> something like 200 cycles to 80% out of them.
>
> Flooded batteries that I just was quoted also specify 200 cycles to 80%.
> That would be something like 10 000 miles with my car, which is way too
> low for the battery price. Most calculations I've seen by other EV
> owners claim that the cost of batteries plus the cost of electricity is
> less or similar per mile than the cost of gas. Now if I can only go 10k
> miles with a pack then the price of the pack at roughly 2500 USD will be
> 25ct per mile, or 25 USD per 100 miles. Thats way more than the price of
> gas just for the batteries. Even with double the battery life its more
> expensive compare to the (expensive) USD 6.50 / Gal gas price (e.g. at
> 30mpg (typical 10 year old VW rabbit) that would be about USD 21 for 100
> miles for gas. Now if I compare that to USD 25 for the batteries plus
> electricity of 40 kwh/100 miles (0.24USD/kwh) then thats 35 USD per 100
> miles in my EV compared to 21 USD for the gas rabbit.
> Now this is not an apples to apples comparison as the stock 75Hp Rabbit
> goes much faster and is more comfortable (heavier) than my EV. OTOH the
> electricity for my EV is from water and sun power, so no pollution
> there. I already did decide that I will trade the comfort and power of
> the Rabbit for the clean EV, but this was under the assumption that
> running costs are about equal. I need to add insurance and licensing
> savings as well as emissions inspections and other maintenance into the
> equation to be roughly equal in cost.
>
> Back to batteries: it seems to me that either one drives his batteries
> to at least 2x-3x the safe (longlife) discharge rate or it is impossible
> to move a lead battery EV with regular traffic on highways and in hilly
> terrain. With these discharge rates batteries are used up relatively and
> hence the cost is high.
>
> I am looking forward to a SAFT 100Ah NiCD pack that I try to acquire. I
> may go to 120V if somebody can tell me for sure is that my curtis can
> cope with this voltage (it says 84V on the plate, 120V nominal would be
> what 140V peak?). The batteries should be good to 300A so I am told
> which would be twice the power I have now at about half the weight (If I
> keep the voltage the same I can lighten the pack as I should be able to
> get as far with less capacity due to the lack of the peukerts effect and
> as I can drive them until empty).
>
>
> Peter, so I guess my mistake was to read too many good news and not
> enough bad news and as (almost) everybody on this list is pro-ev I guess
> the view of the reality is a bit skewed. I book my on-road EV experience
> under "reality-check", having learned that it is hard to not too hinder
> traffic too much when there is an incline with 350A*85V=40hp and
> virtually impossible to go any decent speed uphill with 160A*90V=20HP,
> the safe discharge rate of my 160Ah batteries.
>
> Markus
>
>
> Peter VanDerWal schrieb:
>> If you have been reading the list for years, how did you miss the point
>> about 450 amp curtis having barely adequate performance? And that is
>> with
>> a 120V pack, couple low amps with a low voltage pack you have have to
>> expect low performance.
>> Series wound motors are great performers, but they can't make power out
>> of
>> thin air. Your controller and battery pack are good for 37 hp maximum,
>> that is about 30% less power than the original ICE.
>>
>> Hopefully it is enough to keep you happy. Have fun and try not to
>> murder
>> your batteries ;-)
>>
>> Cheers.
>>
>>> have been driving round in my 90V Tavria for the last two weeks every
>>> chance I got. I installed and Amp and Voltmeter and closely monitored
>>> current and voltage. Also monitored my weakest block. Point was I was a
>>> bit dissappointed with the performance. Reading all your emails for
>>> several years now about the great acceleration of a DC series wound
>>> motor etc. (I have a 120lb 8" series motor mated to a manual gear box
>>> with a curtis 1221R and a 90V pack in a small car - 2500lbs)
>>> If I floor it right from the start there is an OK accelleration but at
>>> the cost of 450A which, as I was told, will murder my batteries in no
>>> time. I am creeping up hills with 20mph (always in the smallest gear I
>>> have) and still drawing 200A. I could go faster but am afraid my
>>> batteries will not like it. And the 50psi pressure in the tires lets me
>>> feel every little rock. So much for my physics lesson.
>>>
>>> Now the good news. I found out one reason for the low performance when
>>> looking at my new front tires after only 100miles were on them. They
>>> looked like I would corner the car at high speeds all the time. When
>>> comparing the wheels I noted that they aint pointing in the same
>>> direction. Well sort of. The steering was off about 1 inch. Adjusting
>>> the steering meant removing all front batteries incl. the front battery
>>> rack. So, trying not to hurt my back, I spend yesterday evening doing
>>> just that and adjusting the wheels. Oh wonder, it now rolls much
>>> easier.
>>> I can push it with little effort.
>>>
>>> Hill climbing and accelleration still needs Amps like heck but I can
>>> see
>>> and feel a clear difference in Amps drawn going a steady speed.
>>> Probably
>>> a 15% improvement. So, I guess I learned my lesson and will pay more
>>> attention to such details like wheel alignment :) This is all not such
>>> a
>>> big deal with my Elec-Traks. I guess they would just happily plow along
>>> with slightly misaligned front wheels (especially with the heavy garden
>>> tiller on the rear)
>>>
>>> Markus
>>>
>>>
>>
>>
>
>
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
