EV Digest 2598
Topics covered in this issue include:
1) Re: EVLN(FPL raises Electricity prices as fuel goes up)
by "a.k. howard" <[EMAIL PROTECTED]>
2) Re: Drag Racing north bay
by "Richard Furniss" <[EMAIL PROTECTED]>
3) Re: LiIons orientation info
by Victor Tikhonov <[EMAIL PROTECTED]>
4) Re: BMS
by Victor Tikhonov <[EMAIL PROTECTED]>
5) Re: Wide power band for Lawrence's cycle
by "Lawrence Rhodes" <[EMAIL PROTECTED]>
6) Re: [Fwd: Re: Battery Management and Regulators]
by Victor Tikhonov <[EMAIL PROTECTED]>
7) Re: Battery Management System ideas
by Victor Tikhonov <[EMAIL PROTECTED]>
8) RE: Battery Management System ideas
by [EMAIL PROTECTED]
9) Re: pick-up truck dimensions?
by Seth Murray <[EMAIL PROTECTED]>
10) Re: EV speed record
by David Dymaxion <[EMAIL PROTECTED]>
11) Re: EV speed record
by "Roderick Wilde" <[EMAIL PROTECTED]>
12) Re: BMS in general and my plans.
by Victor Tikhonov <[EMAIL PROTECTED]>
13) RE: Battery Management and Regulators - evtech list
by "Walker, Lesley R" <[EMAIL PROTECTED]>
14) Re: BMS - getting...
by Victor Tikhonov <[EMAIL PROTECTED]>
15) AC drives (was Re: EV For Sale)
by Victor Tikhonov <[EMAIL PROTECTED]>
16) Re: pick-up truck dimensions?
by "Thomas Shay" <[EMAIL PROTECTED]>
17) EV1s waiting
by "Alan Shedd" <[EMAIL PROTECTED]>
18) Heaters
by Seth Murray <[EMAIL PROTECTED]>
--- Begin Message ---
From: [EMAIL PROTECTED]
Reply-To: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
CC: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED],
[EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED]
Subject: Re: EVLN(FPL raises Electricity prices as fuel goes up)
Date: Mon, 17 Feb 2003 21:23:43 -0400
I thought Florida had a large nuclear power plant.
What happened to all that cheap nuclear power ?
Florida's 2003 electric rates are still less than CT and MA
(both about 9 cents /kwhr).
FPL has two large nuclear stations.
Per the FPL website, their electricity came from the following sources.
Gas 33%
Nuclear 24%
Oil 18%
Purchased electricity 18%
Coal 7%
Source: http://www.fpl.com/about/profile/contents/fpl_facts.shtml#P105_1732
Hope this helps. Regards, A.K. Howard. Unincorporated Clark County, Nevada.
Board Member, Las Vegas EV Association.
_________________________________________________________________
Protect your PC - get McAfee.com VirusScan Online
http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
--- End Message ---
--- Begin Message ---
I hope you are planning on bringing the bike to Wicked Watts, April 26th,
It would be fun to see!
www.lasvegasev.com
Richard Furniss
Las Vegas, NV
1986 Mazda EX-7 192v
1981 Lectra Centauri 108v
3 Wheel Trail Master 12v
Board Member, www.lveva.org
Las Vegas Electric Vehicle Association
----- Original Message -----
From: "Brian D. Hall" <[EMAIL PROTECTED]>
To: "ev post" <[EMAIL PROTECTED]>
Sent: Tuesday, February 18, 2003 9:51 AM
Subject: Drag Racing north bay
> I had a Fun day, yesterday, at Infineon Raceway ( Sears Point). The crowd
> was very excited seeing an electric motorcycle competing against the gas
> monsters.My best time was 14.558 sec at 79 mph. Folks there could not
> believe how fast it was, I wanted it to go faster.This would be a new
record
> at a NEDRA event. Current record for this 144 volt motorcycle class is
> 14.702 set by John Bidwell. All I need is to have two time slips in the
same
> day , faster than him to take his place.Sunday February 23 , I will be
there
> ,trying again.
> MY motorcycle is : 144 volts ( 12 hawker 13's), 2 E-tec's in series, DCP
> 1000 amp controller.
> My best 0-60(feet) was 1.89 sec.
>
> Brian D. Hall
> ThunderStruck Motors,
> www.thunderstruck-ev.com
> 707-575-0353
>
>
--- End Message ---
--- Begin Message ---
Joe Smalley wrote:
>
...
> You may have no problems, but it is like taking an umbrella to the ball
> game: If you are prepared, you won't need it. If you are not prepared, you
> won't have the resources to deal with it.
>
> Joe Smalley
> Rural Kitsap County WA
> Fiesta 48 volts
> NEDRA 48 volt street conversion record holder
> [EMAIL PROTECTED]
Yes, exactly the same concerns as with Optimas on side.
Victor
--- End Message ---
--- Begin Message ---
[EMAIL PROTECTED] wrote:
>
> In a message dated 15/02/03 01:47:27 GMT Standard Time, [EMAIL PROTECTED]
> writes:
>
> > Deep discharges - they discharged it to 0V and kept it this way
> > for 10 minutes. No sign of degradation. They overcharged other cell
> > at 22'C with C/3 current to 4.63V and kept charging for 2.8 hours.
>
> ...and the effect on the performance of this expensive piece of chemistry
> that we have put our hard earned cash into was?
These were safety tests. Effect was - no explosions, no fire, no cracked
case or stuff like that. Performance, like with any abused beyond normal
ratings battery, will degrade, this is expected.
>
> The old hands on this list can recall quite a number of battricide events on
> this list. Manually controlled chargers not shutting down, supposedly 'smart'
> chargers not doing what they are supposed to, stretching the range (it'll be
> ok just this once!) and reversing a cell at a couple of hundred amps. The
> list could go on. I've seen two Optimas open under 90 amp loads due to
> previous abuse. Both of these batteries gave rated capacity (1 hour) during
> testing.
When discussing batteries performance, it is assumed other hardware
(BMS, chargers) work as suppose to. Id it doesn't, no battery give
any promised performance.
> You can make quite a strong argument for a BMS for lead acid packs to improve
> performance, extend life, and prevent potentially dangerous situations.
This kind of contradicts your previous statement that BMS may not
work as suppose to.
> Paul Compton
> BVS technical officer www.bvs.org.uk
> www.sciroccoev.co.uk
--- End Message ---
--- Begin Message ---
I am considering this for the golfcart but I am not willing to do this on
the motorcycle. It will reduce range. I might consider going for torque
and a higher ratio though. Lawrence Rhodes....
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, February 18, 2003 9:32 AM
Subject: Wide power band for Lawrence's cycle
> Lawrence,
>
>
> It sounds like what you're after is a way to get some more torque off the
line,
> and still keep high MPH on the road?
>
> How about keeping the gearing high(numerically) for low end torque, and
adding
> field weakening at top speed. I've read plenty about this, but I'm
sticking
> with PM motors, which complicates field weakening a bit. It should be
easy to
> experiment with. Just strap a hunk of wire across the field winding with
a
> contactor. Start with a high resistance, that will only divert a small
amount
> of current from the field. Decrease the resistance as you feel it's
working
> for you. Too low a field current and you'll have big big problems. Maybe
even
> a safety so field weakening is only engaged at WOT.
>
>
> Good luck,
>
> Darin Gilbert
> Bad Fish Racing
>
--- End Message ---
--- Begin Message ---
Rich Rudman wrote:
>
> -------- Original Message --------
> Subject: Re: Battery Management and Regulators
> Date: Sat, 15 Feb 2003 21:42:28 -0800
> From: Rich Rudman <[EMAIL PROTECTED]>
> To: [EMAIL PROTECTED]
>
> Let me make this clear... If this is just a custom load of a Mk2 Rudman
> Reg, It
> will be available next week.
It's dumb regulation type (does nothing until 4.2V, so the cells
will be sitting at 4.2 different times), but it will work.
> We know from Victor and others that 4.200 should be the
> limit
> for charging a Li battery. We don't know where it drops off the voltage
> cliff
> and is considered depleted.
2.75V (from manufacturer)
> We also don't know how low we can still drive the Regbuss Optos to.
> So...We should have Reg driven charger cut back, but I don't know if we
> can have a valid Low Batt signal When the Li battery is less than 2.5
> volts.
You should never allow it to be less than ~2.8V
>
> For right now the Mk2s should be able to do the cell by cell voltage
> regulation. The RegBuss allows a single battery to halt a PFC driven
> over charge event. These are Feature 1 and Feature 2.
Rich, if you only limiting max, it's not quite "regulation".
Again, for cheaper BMS it will be adequate.
> Oh yea the cost for the Li ready Mk2s will be the same as for the 12
> volt Lead Acid Regs. Same thing, different value parts.
>
> Can somebody answer the what the Low voltage threshold for a single Lion
> battery is???
Make it 2.8V, but this has nothing to do with reg. Regs cannot
prevent over discharge unless talk to the controller as you drive.
> Mark, I am doing just what you said you needed, as fast as we can.
> Plans??? have PCBs and schematics, and part lists. And hopefully fully
> loaded hardware very soon.
>
> Rich Rudman
> Manzanita Micro
>
> Joe Smalley wrote:
--- End Message ---
--- Begin Message ---
Dave Davidson wrote:
>
> I think you will also want to be able to control the charger. The regulator
> will have to pass enough current to keep the cell from overvolting. You
> will probably want to throttle back the charger when the first cell reaches
> 4.2 volts, and let the other cells gradually come up. This way your
> regulator won't have to pass as much current, nor will you fool the charger
> into thinking it's still pushing current into your pack when it's really
> being bypassed. Keep me posted on your progress.
>
> Dave Davidson
>
The little trouble with this approach is from the time the first
cell hits 4.2V to the time last one does, several hours may pass.
THis means first cell will be at 4.2V all that time while last one
barely reach 4.2 and you shut off (or throttle back) the charger.
This is shortcoming of any system looking for limiting max voltage
only. If the cells are fairly in balance, the delta time actually may
be minutes.
Victor
--- End Message ---
--- Begin Message ---
What about a stepped approach, where above 3.6v the hold would be for every
.2v? Then system just monitors every 2 or 3 cells to bring them up together.
-Ed T
-----Original Message-----
From: Victor Tikhonov [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, February 18, 2003 2:30 PM
To: [EMAIL PROTECTED]
Subject: Re: Battery Management System ideas
Dave Davidson wrote:
>
> I think you will also want to be able to control the charger. The
regulator
> will have to pass enough current to keep the cell from overvolting. You
> will probably want to throttle back the charger when the first cell
reaches
> 4.2 volts, and let the other cells gradually come up. This way your
> regulator won't have to pass as much current, nor will you fool the
charger
> into thinking it's still pushing current into your pack when it's really
> being bypassed. Keep me posted on your progress.
>
> Dave Davidson
>
The little trouble with this approach is from the time the first
cell hits 4.2V to the time last one does, several hours may pass.
THis means first cell will be at 4.2V all that time while last one
barely reach 4.2 and you shut off (or throttle back) the charger.
This is shortcoming of any system looking for limiting max voltage
only. If the cells are fairly in balance, the delta time actually may
be minutes.
Victor
--- End Message ---
--- Begin Message ---
Hi Alan, just had to comment on this post a bit:
I have helped schools with S-10 and Ranger conversions. I think the
S-10 is
a little easier to convert if you are planning to put the batteries
between
the frame rails. (I think this is the most secure and best looking
method.)
The frame rails have a wider spacing on the S-10 than the Ranger. On
the
Ranger, the leaf springs are to the outside of the frame rails and the
rails
are about 37" outside to outside (on an '83) On the S-10, the leaf
springs
are underneath the frame rails. Also the rear suspension on the Ranger
uses
staggered shocks - the one on the right is angled forward while the
one on
the left is angled to the rear from the axle. Further, the
differential
housing is not centered between the rear wheels so the drive shaft
runs at
an angle from the back of the transmission to the differential.
all true, and why I choose the S-10
We were
able to mount 5 T-145s in the engine compartment, three T-145s turned
long-dimension fore and aft in a box on the left of the driveshaft in
front
of the axle, two on the right side and five more in a box behind the
axle.
This was a long-bed truck and there was more room behind the axle to
install
more batteries but the school limited the voltage to 96 (ed. program
rules).
This arrangement provided good front-rear and side-to-side weight
distribution.
in my shortbed S10, I was able to get 4 batteries on each side of the
driveshaft. another reason to use the S10
On an S-10 conversion, we located 2 T-145s up front. Three each in
boxes on
each side of the drive shaft (inside the rails) in front of the axle
and
eight in a box behind the axle.
I do not recommend this weight distribution because it moves the CG
back which lends to oversteering and sometimes surprising handling in
the snow for someone (like me) who's used to normal rear wheel drive
vehicles. I think it is best to maintain relative F/R weight
distributions. Just my 2 cents worth
Seth
PS - do you have any photos of the truck?
--
QUESTION INTERNAL COMBUSTION
http://users.wpi.edu/~sethm/
http://www.austinev.org/evalbum/387.html
--- End Message ---
--- Begin Message ---
Thanks for the additional info.
Not volunteering to "start" an organization, but I certainly
volunteer to help (like being crew for someone trying for a record
here). BYU has an electric racing team that has run on the Salt
Flats. Maybe the classes could be as simple as "Street legal and
non-street legal." When I get my conversion done I was planning to
run in the 130 mph beginner's class, maybe some NEDRA racers would
like to join me when that happens. Maybe a NEDRA-like organization
could recognize results with official time slips, and the electrics
could run in the modified gasser categories?
--- Roderick Wilde <[EMAIL PROTECTED]> wrote:
> Actually what happened with the SCTA is that they changed horses in
> the
> middle of the stream. The class 1/E record that "Silent Thunder"
> holds was
> for its correct weight by their class system when it set the
> record. Then
> they decided to go with the F.I.A. system of weight classes. A side
> note,
> the worlds quickest electric motorcycle according to the F.I A.
> turned 15
> something seconds in the quarter mile. Give me another break! Ed
> Rannberg
> was turning 12s back in the early 80s. Last year a good friend of
> Ed's sat
> in on the SCTA board meetings to try to get street classes for
> Bonneville
> land speed racing to no avail. The SCTA says that if we build three
> electric
> vehicles in the same non existent class and bring them to
> Bonneville that
> they will consider making a class for them. Let's see now. Invest
> $35000.00
> per vehicle for three vehicles, then transport them across country
> to
> Bonneville, Then it rains and they cancel the event, turn around,
> go home
> and come back again next year just in case you may get to run. Oh,
> and then
> if you are lucky they will make a class the following year so that
> you can
> come back again and try to set a land speed record if the weather
> holds and
> you get to run that is. The SCTA has a totally different mind set
> than the
> NHRA. The NHRA looks at electrics as more customers since they are
> a
> business. In defense of the SCTA, they look at electrics as just
> more work
> for them as they are an all volunteer organization. They do not get
> paid
> more for more work. But I wish they would at least straighten out
> their
> record keeping on their existing electric records. They are a big
> joke and a
> disgrace to electric racing. They make the hard earned records
> meaningless.
> A solution would be to start a new record keeping organization. Use
> their
> rule books and their track and have your own classes. Similar to
> what we do
> with NEDRA. They do have a good safety record and the rule book
> spells out
> the safety regulations well. Any volunteers out there to start a
> new
> organization?
=====
__________________________________________________
Do you Yahoo!?
Yahoo! Shopping - Send Flowers for Valentine's Day
http://shopping.yahoo.com
--- End Message ---
--- Begin Message ---
David your idea for two basic categories is a great idea and is right on. It
would be the simple way for the SCTA to save face without adding two many
new categories for electrics. Instead of street legal and non I think
Streamliner and Sedan would fit in better with what they already have for
ICE classes. This however wouldn't resolve their other big screw up. Two
almost identical vehicles are shown as having class 2/E and class 3/E
records. They list Ed Rannberg's "Lightning Rod" in class 2 and "White
Lightning" in class 3. They are identical bodies and frames with different
batteries and motors but I believe the weights are very close. It wouldn't
hurt if others started calling the SCTA and asking why the records are
messed up. If enough people call they may eventually respond. This mess up
and their unwillingness to make any sedan or street electric classes is the
main reason I have adamantly opposed NEDRA's involvement with the folks out
in Utah trying to put on an electric Bonneville event. There is however one
electric Bonneville event worth seeing and entering. Land Speed Record
Electric Barstool Racing. Check out: http://www.saltflats.com/barstool.html
for the rules and the following link has some pictures of barstools at
Bonneville and a great short video of indoor racing:
http://www.barstoolracing.net/Jim's_page.htm. Definitely a worthwhile
adventure and fairly low budget. We currently sponsor a world record attempt
barstool running a 671 Gimmie starter motor with a group 31 Optima and a
1000 amp 12 volt controller with bypass.
Roderick
Roderick Wilde, President, EV Parts Inc.
Your Online EV Superstore
www.evparts.com
1-888-EV Parts (387-2787)
Phone: 360-385-7966 Fax: 360-385-7922
PO Box 221, 107 Louisa Street
Port Townsend, WA 98368
----- Original Message -----
From: "David Dymaxion" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, February 18, 2003 3:41 PM
Subject: Re: EV speed record
> Thanks for the additional info.
>
> Not volunteering to "start" an organization, but I certainly
> volunteer to help (like being crew for someone trying for a record
> here). BYU has an electric racing team that has run on the Salt
> Flats. Maybe the classes could be as simple as "Street legal and
> non-street legal." When I get my conversion done I was planning to
> run in the 130 mph beginner's class, maybe some NEDRA racers would
> like to join me when that happens. Maybe a NEDRA-like organization
> could recognize results with official time slips, and the electrics
> could run in the modified gasser categories?
>
> --- Roderick Wilde <[EMAIL PROTECTED]> wrote:
> > Actually what happened with the SCTA is that they changed horses in
> > the
> > middle of the stream. The class 1/E record that "Silent Thunder"
> > holds was
> > for its correct weight by their class system when it set the
> > record. Then
> > they decided to go with the F.I.A. system of weight classes. A side
> > note,
> > the worlds quickest electric motorcycle according to the F.I A.
> > turned 15
> > something seconds in the quarter mile. Give me another break! Ed
> > Rannberg
> > was turning 12s back in the early 80s. Last year a good friend of
> > Ed's sat
> > in on the SCTA board meetings to try to get street classes for
> > Bonneville
> > land speed racing to no avail. The SCTA says that if we build three
> > electric
> > vehicles in the same non existent class and bring them to
> > Bonneville that
> > they will consider making a class for them. Let's see now. Invest
> > $35000.00
> > per vehicle for three vehicles, then transport them across country
> > to
> > Bonneville, Then it rains and they cancel the event, turn around,
> > go home
> > and come back again next year just in case you may get to run. Oh,
> > and then
> > if you are lucky they will make a class the following year so that
> > you can
> > come back again and try to set a land speed record if the weather
> > holds and
> > you get to run that is. The SCTA has a totally different mind set
> > than the
> > NHRA. The NHRA looks at electrics as more customers since they are
> > a
> > business. In defense of the SCTA, they look at electrics as just
> > more work
> > for them as they are an all volunteer organization. They do not get
> > paid
> > more for more work. But I wish they would at least straighten out
> > their
> > record keeping on their existing electric records. They are a big
> > joke and a
> > disgrace to electric racing. They make the hard earned records
> > meaningless.
> > A solution would be to start a new record keeping organization. Use
> > their
> > rule books and their track and have your own classes. Similar to
> > what we do
> > with NEDRA. They do have a good safety record and the rule book
> > spells out
> > the safety regulations well. Any volunteers out there to start a
> > new
> > organization?
>
>
> =====
>
>
> __________________________________________________
> Do you Yahoo!?
> Yahoo! Shopping - Send Flowers for Valentine's Day
> http://shopping.yahoo.com
--- End Message ---
--- Begin Message ---
"[EMAIL PROTECTED]" wrote:
>
> >I'm not disagreeing, but this is just an opinion. Data please.
>
> Cycle life data is expensive and time consuming. I am simply
> restating what the engineers at Li-Ion battery plants have told me. I
> haven't taken data myself.
Please ask them again when they will make non-sealed ones.
> For a fixed length of time, the lowest and highest SOC become more
> diverse as the number of cells increase. The cell environment also become
> more variable as the number of cells increase. Thus, for any selected A-hr
> charge-discharge cycle, the odds of damaging a cell increases as the pack
> size increases.
>
> Remember, you only have to over-charge or over-discharge ONE cell
> to ruin the pack (or set it on fire.)
I remember. And remember, to set one on fire, you have to exceed
rated voltage 4x times, keep pumping 20A after that and wait for few
minutes for the fire. One must almost deliberately do that.
> >The cells are checked by human being often and when any gets out of
> >average by the amount the owner believes is too much, he corrects it.
> >All I know the correction was needed a few times since the pack
> >was installed; the rest of the time the pack was (and is) being
> >closely watched for, but nothing was done to it.
>
> 18 cells is not 90 cells. You will have to do 25 times more work
> to achieve the same result. You have five times as many cells to check and
> you will have to check them five times more often, because they are five
> times more likely to get out of balance. You will wear out the probes on
> your voltmeter.
In statistic class they will tell you that while you do need to check
5 times more cells, but you don't need to do it 5 times more often
unless you want more data.
> >Experience with computer related LiIons biases you and you inadvertainly
> >apply this experience to valved EV sized LiIons.
>
> Unlike AGMs, if Li-Ion cells vent, they are damaged.
When AGMs vent they loose capacity - essentially become useless
i.e. damaged.
> >Computer LiIons as you mentioned almost always have internal chip
> >measuring cell(s) condition and not allowing to charge or
> >drain too much. It uses MOSFETs in series (often two - Nch and Pch)
> >to disconnect the battery, and shunts to measure current.
>
> You aren't monitoring anything in real time.
Yes, *I* am. But the guy whose car ai described, indeed didn't.
> EV packs have it worse.
>
> EV cells can be placed in one enclosure - it's not easy but
> doable and up to the user.
>
> Typically not.
Typically EVer use PbA. Nothing about LiIon is typical, this
is not an argument.
> Computer cells have no thermal management - just monitoring.
> >EV cells can be cooled off, heated, whatever.
>
> You are no proposing that. Also, you are not proposing individual
> thermal management to control imbalance.
I'm not proposing anything, what I will be doing for my conversion
is below. I said a car with 18 cells and no integrated BMS
has worked OK for long time. Do I have to include disclaimer after
each statement that "Do it at your own risk?"
I'm reporting what I saw and know.
Disclaimer: I may be off, may be wrong, may be total moron
in electronics. Now everyone should feel better.
> >Deep discharges - they discharged it to 0V and kept it this way
> >for 10 minutes. No sign of degradation.
>
> No change in cycle life? What about reversal?
C'mon Bill apply common sense. I stated I described safety tests
only because you keep saying cells can catch fire.
Of course normal performance degrades, as for any type of battery,
it was not reported because deliberately abused cells are not
expected to perform equally well as new ones.
> ...
> Voltage reached 18V, temp 88'C
> >and then the cell catched fire and exploded.
>
> This would be what would happen to an unbalanced cell on a long
> downhill regen charge or simply during ordinary charging if no cell
> monitoring were present.
If your charger puts out x Ah, based on current SOC you can
calculate how much time allowed before voltage reaches max
allowable. This is my understanding what was done.
Sorry, I keep forgetting I talk about my situation and my high tech
hardware. I have integrated system where power inverter, charger
and [future] BMS will all talk to each other. As of now,
Siemens inverter takes care of not allowing overcharge during regen
and not allowing over discharge during driving; I don't have to
worry about that. It also takes care of limiting max current from
and into the pack. Brusa charger takes care of not overcharging whole
pack, based on max voltage and tracking Ah in and out.
If you only keep all the cells at the *same* voltage you don't
need to know what this voltage actually is, you need only total.
Primary function of my BMS is to keep cells at the same voltage
at any time you're not driving (optionally - when parked).
For not that smart hardware most of EVers use, owner will
have to deal with these issues. Everyone complains high tech
systems cost too much. Well, all above is exactly why, and
to me ensuring $5k inverter won't cook $15k pack worth it.
Your mileage will vary.
>
> >Well, for 324V pack this means 450V on charge is still safe,
>
> No. You assume equal SOC for all cells. Without a BMS, it is a
> guaranty that cells will NOT be in balance.
Please LISTEN: I never said no BMS. I said no INTEGRATED BMS was done
and worked.
If you want strict answers whether it works, it is different
from whether it's practical or cheap or little work for the Joe Doe.
A LiIon cells in series are similar to a capacitors in series.
Unlike PbA undercharge doesn't seem to damage them, just
like NiCD. Take hundred 1 Farad 5V capacitors and charge them
to different voltages *between 3 and 4 volts* each.
Connect them all in series. Now you can run the load from
this bank until lowest voltage one hits some arbitrary
minimum, you can then charge them all without any BMS with the same
current and duration as your load took and this will restore
initial condition - the same imbalances as you started with,
no measurably worse. As long as you charge -discharge such
that highest voltage cap stay below 5V, you're fine. No cap
will ever get damaged. With ideal caps you'd be able to do
such cycling forever, with less than ideal ones, you have to
manually bring lowest and highest ones closer to each other.
This is similar to how LiIon pack runs in the example above.
Am I suggesting to do it? No.
Am I saying no integrated BMS is OK? Not for me, but it depends.
Does this method above works? Sure.
Do I suggest it's OK to do it for someone? No, Otmar.
What I'm reporting is what someone has done in real life, who is
ahead of all of us, and his experience.
We' re not discussing if it's practical, not how much work
it takes, nor depth of one's pocket.
Bottom line: one has to insure no cell gets beyond rated voltage
limits, SOC and rate of charge/discharge. If (*IF*) you manage to
achieve it without BMS, you don't need BMS.
Practically speaking I have other things to worry about, so
I will make integrated BMS to achieve it in my conversion. Hope
it is clear what I'm trying to convey.
Did I learned anything from the packs I killed? Yes Otmar.
I learned that Powercheqs are not doing what they suppose to
if the wires are extended (which they didn't mentioned
in the manual) and powercheqs indicated that they did the job file.
I wasn't neglecting Optimas. FYI, I'm on my 4th pack since 1996.
Could be worse.
>
> Becoming unbalanced is what batteries do best. When you reverse a
> cell during discharge, it gets hot and vents.
As I said, my inverter won't allow to reverse the cell because
BMS will reduce driving current or shut off the battery if a cell
voltage gets beyond specified limits.
> Do you have a data from the real vehicle
>
> Not on Li-Ion, but I have plenty of lead-acid data. We all do.
Common sense apply, but the data is not.
>
> It is well known that you can overcharge an AGM lead-acid battery
> slightly with no harm done. It is also well known that you can
> over-discharge an AGM lead-acid battery slightly with no harm done. It is
> foolhardy to run a high-voltage AGM pack without a BMS of some sort. The
> pack won't last long without one.
Sure, I agree, without management system it will likely die from
inadvertent mistakes or abuse. A system implemented in hardware
is most practical one for human being, but not the only one possible.
> Since Li-Ion cells are well-known to suffer damage from even
> slight overcharge or over-discharge, it is beyond foolhardy to run a Li-Ion
> pack without a BMS.
>
See above.
> Are you planning to do this? Wouldn't a BMS be cheaper and simpler?
Definition of BMS includes optional thermal management. Since
manufacturer is stating that min performance parameters are guaranteed
over the temp range exceeding realistic environment temp where I live
(-18'C ... +70'C), I will only ensure the temps are about equal, not
some particular degrees number.
> >The "cables" you're talking about are just gauge 4 wires. Remember,
> >you're the one calculated and suggested this for me a while ago?
>
> Do the heat transfer calculation for an infinite copper fin of
> that diameter. Remember, none of the other cells have this added cooling.
Every cell has interconnects. Most of the wire from first
and last cell is still in the box and will not measurably transfer heat.
>
> The end cells are different than the interior batteries. Measure
> them all and you will see.
OK, when I'll be ready I will.
> >All you have to do, Bill, is clamp the max to 4.2V per cell. Just like
> >MK2 do. When last cell is clamped, the charger throttles back.
> >Nothing more complex than that really needed (provided some other
> >conditions like equal temp are met).
>
> But you are proposing NO BMS.
Oh, not again...
> This clamp system would work OK
> unless the capacity of one cell started to fade, then you would have a pack
> fire on the road when it reversed.
Again about fire? Why one cell suddenly start to fade and you don't
know about it? Or fade in 10 minutes?
If it fades because of manufacturer defects, than it happens over weeks
of time. And if you don't have integrated means to detect it, *YOU* are
BMS with voltmeter and must do it, practical or not, it's doable.
If you neglect the pack, which I never suggested to do, you will
reverse and damage cells pretty quickly.
Now, about my BMS:
A module on each cell will compare it's voltage (10 bit A/D'ed) to
the mathematical average voltage of a cell and either boost or drain
it depending on the comparison. Average is delivered via VCO as a
frequency, using IR link, so no buses or any signal carrying
interconnects are needed just to do that.
Initially boost will not be implemented but the means to do it it will
be there. Draining cells may be to resistive load, since most likely
the power is < 1W, but the hardware is there to do lossless draining:
each cell has small isolated step up DC-DC dumping excess to whole
pack, nothing (minus DC-DC efficiency) is lost and no heat produced.
For the boost HF transformers with tiny rectifiers will deliver
boosting energy; at the same time (in this case) frequency is used
as an information carrier about average.
Individual cells have temp sensors. Indication via LEDs and common
"idiot light" just saying attention needed. Modules memorize the
error condition and LED flashing patterns indicate the cells needing
attention.
Once this work and demand for boost/drain (value, timing, recovery
timing, sample averaging, etc.) will be settled, a bus for main
display will be added; most likely IR link. Average voltage is
present (as frequency) for sampling at any time, so no polling
individually addressed uPs needed, they will transmit fast in a
ring arrangement and display will indicate deviations from the
average rather than actual voltage (which will also be displayed).
As the temp approach predefined limit, max drive current will be
gradually reduced not to exceed it. Same with charging.
Modules keep balancing at any SOC, during bulk charge too, so all
the cells will reach 4.2V max at the same time. Each time a cell
needed a boost or drain it is counted and stored in memory and used
for self learning - a cell consistently requiring boost near
finishing charge will get periodic boosts in the beginning even
though its voltage is not lower than average (yet).
So each module learns how its cell compares to average and
proactively makes it to behave this way. When the bus is
in place, history data can be downloaded for analysis, or
vice versa, individual adjustment coefficients can be uploaded
to some modules to compensate for different things. This is
all in software which is subcontracted out and first version
should be ready this week. Developed and simulated in C, compiled
for 16F816 PIC.
THe battery box is force vented so the temperatures of individual
cells will be close. Equalizing temps with running water is probably
not necessary, but such add on option is thought out, this depends
on how much temp gradient across the box do I see.
Status: most of the hardware is on the prototype boards.
Precision VCO (PLL based) works. It's linear to 1%. Couple of
my cells will be tested as soon as software is ready. Actual
module will have 10-15 components on it.
VCO is fed from precision voltage divider for whole pack,
this is thermal compensated and non-linearity is taken care of
by look up tables stored in modules' memory.
Plan: deliberately make imbalance and adjust parameters so that
cells get equalized by the time they reach max 4.2V (or sooner).
Any suggestions welcome.
Victor
--- End Message ---
--- Begin Message ---
Lawrence Harris wrote:
> This discussion and development would be a great thread for the evtech
> mailing list once/if you get into the nitty gritty details of
> the project.
I'd love to eavesdrop - how does one subscribe to the evtech list?
I found it once but couldn't see how to subscribe.
--
Lesley Walker
EDS New Zealand
[EMAIL PROTECTED]
"The secret to getting ahead is getting started. The secret to
getting started is breaking your complex overwhelming tasks
into smaller manageable tasks, and simply starting on the
first one." --- Mark Twain
--- End Message ---
--- Begin Message ---
Otmar wrote:
>
> Victor, I wonder if you've learned anything from all the batteries
> you've killed?
...If you can't make a set of Optimas last over
> 500 cycles, then I would strongly advise against experimenting with a
> much more expensive lithium pack.
I'll swallow this comment.
As of 500 cycles on the Optimas I can manage that. At this point I
have no need to - my Optima pack will survive without
balancing efforts until I replace it with LiIon one (about 100
more cycles) all I need. I'll have to recycle YTs then, so don't
want to put much effort in balancing now. This is not to say
I underestimate importance of it. I just want to do it this way and
have resources to do it. Yes, this is not typical.
> It is well known that it is impractical to manually balance AGM
> packs. Many of us have tried and realize that at one time or another,
> the rest of our life interferes with doing it well.
Sure, if you don't do it well, "human BMS" is not for you then.
You talk from the side customer point of view since produce
hardware for others. This is understandable.
I've read on this list couple of people actually enjoy going
over their floodies and check electrolyte level. You won't convince
them they need those automated fill up caps. But this is impractical
or boring for the most of us, myself included, I agree.
However, it WORKS.
> From what I've
> heard it's more important to protect lithium ion packs. Manual
> balancing is a possibility, but only if the vehicle has a battery
> monitoring system to halt any activity which would shorten the life
> of the batteries. When the vehicle is stopped and won't run, then at
> least you can be sure that the user will balance the back in a timely
> manner.
100% agreed.
> As for the question of MOSFETS on each cell, this is just ridiculous.
> There is a simple way to do this.
Yes, this is what I said - using MOSFETs is impossible in an EV.
This is, however, what's used in laptop's and portable gadgets' LiIons.
> My personal belief is that this level of integration has been lacking
> in both the EV conversions, and the early production cars. This is
> something which we can fix. I am slowly working toward it with my
> products. When we finally have the BMS controlling both the charger
> and the controller, then we should be heading toward read battery
> system reliability.
>
> -Otmar-
> http://www.CafeElectric.com
> Mailto:[EMAIL PROTECTED]
The only draw back is lack of standardization - by implementing
what you're describing you force a customer to buy your controller
and your charger if he wants them to talk to your BMS.
If every controller and charger you come up with had common
interface (like CAN, existing for years), than diverse variety
of hardware can be integrated easily.
PFC-20 reg bus is great only if you have Rich's regs and Rich's
charger. Not to diminish this achievement, but this is minimalist
implementation to do just enough for one function with one piece
of hardware - PFC charger. It's a step forward because before
most of us had nothing. But the protocol, if exist, is obscure,
no other charger can take advantage of it. Same with
motor controller market - most have no standardized means to
talk to anything else (like BMS), including your Zillas as
I understand.
I realize it is cheaper and so far adequate, and this is fine
with me. As always, people get what they want and paid for.
Victor
--- End Message ---
--- Begin Message ---
Christopher Zach wrote:
>
> This brings up a question: As an owner of an AC drive EV I have to wonder
> why everyone thinks that AC is the greatest thing since sliced bread?
...
>
> What makes AC such a holy grail to have?
>
> Chris
To name a few other than obvious regen and light wiring you mentioned:
Lack of brushes with all the stuff associated with it (timing),
Easy electric reverse, no extra contactors
Linear torque (acceleration) over wide RPM range
Practically fail safe (no full on fail mode)
Saves brake pads/disks (because of regen), no need to upgrade,
this applies to SepEx DC systems with regen as well)
Water cooling option (there are no water cooled DC motors; anyone?
Possibility to have one gear covering all driving range so no
clutch needed (like ACP CRX, not the best solution though);
two gears will do it easily
Usually programmability of inverters allow optimal parameters
for given motor to be entered.
If you ask about high end systems, I can name a few more.
Victor
--- End Message ---
--- Begin Message ---
Be careful about putting battery behind the rear axles. There's risk
of oversteer and loss of control when the center of gravity is too
far back. Every expert will tell you that heavy loads in a pickup
should be placed as far forward as possible. Eight T-145s in a box
behind the rear axle is really asking for trouble.
If the center of gravity is too far back and the truck tends to oversteer,
wider
wheels and tires, more air in the rear tires and stiffer rear springs can
cure
the oversteer and restore safe handling at least to the extent that a
heavily
loaded pickup can be safe.
My Ranger had 17 T-105s in the pickup box with none behind the axle
centerline and three under the hood. It needed two leaves added to each
rear spring to restore the rear ride height. Front/rear weights were 1640
and 2240lbs with no driver or passenger. It did oversteer until I put
wider wheels and tires on the rear.
Tom Shay
----- Original Message -----
From: "Alan Shedd" <[EMAIL PROTECTED]>
To: "EVL" <[EMAIL PROTECTED]>
Sent: Monday, February 17, 2003 7:11 PM
Subject: Re: pick-up truck dimensions?
>
> I have helped schools with S-10 and Ranger conversions. I think the S-10
is
> a little easier to convert if you are planning to put the batteries
between
> the frame rails. (I think this is the most secure and best looking
method.)
> The frame rails have a wider spacing on the S-10 than the Ranger. On the
> Ranger, the leaf springs are to the outside of the frame rails and the
rails
> are about 37" outside to outside (on an '83) On the S-10, the leaf
springs
> are underneath the frame rails. Also the rear suspension on the Ranger
uses
> staggered shocks - the one on the right is angled forward while the one on
> the left is angled to the rear from the axle. Further, the differential
> housing is not centered between the rear wheels so the drive shaft runs at
> an angle from the back of the transmission to the differential. We were
> able to mount 5 T-145s in the engine compartment, three T-145s turned
> long-dimension fore and aft in a box on the left of the driveshaft in
front
> of the axle, two on the right side and five more in a box behind the axle.
> This was a long-bed truck and there was more room behind the axle to
install
> more batteries but the school limited the voltage to 96 (ed. program
rules).
> This arrangement provided good front-rear and side-to-side weight
> distribution.
>
> On an S-10 conversion, we located 2 T-145s up front. Three each in boxes
on
> each side of the drive shaft (inside the rails) in front of the axle and
> eight in a box behind the axle. I have several photos, dimensions, and
can
> put you in touch with people at each school who can run out and measure
> things you have questions about.
--- End Message ---
--- Begin Message ---
Attached are two photos of some of the EV1's that have been reclaimed from
leases and are waiting in Atlanta for the truck to carry them to their final
parking spot. I know much has been said on the list about the waste of
resources, how many of us would love to give one of these a good home, and
how unfortunate the auto industry's stance is on battery-electric vehicles.
Many people in Atlanta used these cars as their daily transportation. I
know they will miss them. I will miss seeing one occasionally go by on the
road. There's not much else to say. What the auto industry cannot or
will not accomplish is left for us to do. Keep your EVs running and keep
working toward your goals.
-Alan
* LP8.2: HTML/Attachments detected, removed from message *
--- End Message ---
--- Begin Message ---
Hi All -
It seems that the standard electric heater core that everyone uses is
only rated up to 120 volts, and I want heat at 192 volts. Is there any
way I can rewire it for a higher voltage operation (it has a lot of
connections...) or do I need to consider putting two in series or
possibly another heater element? thanks
Seth
--
QUESTION INTERNAL COMBUSTION
http://users.wpi.edu/~sethm/
http://www.austinev.org/evalbum/387.html
--- End Message ---
