EV Digest 3987
Topics covered in this issue include:
1) RE: Low Rolling Resistance Tires?
by "Chris Tromley" <[EMAIL PROTECTED]>
2) remove
by Justin Mortensen <[EMAIL PROTECTED]>
3) Re: EV Christmas Carol
by Jude Anthony <[EMAIL PROTECTED]>
4) Re: The Amazing Little Hawkers That Refuse to Die!
by Janez Svetlin <[EMAIL PROTECTED]>
5) Re: The Amazing Little Hawkers.
by "Rich Rudman" <[EMAIL PROTECTED]>
6) Re: Range + Golf cart vs. AGM wars
by "Rich Rudman" <[EMAIL PROTECTED]>
7) Re: Ideal motor RPM?
by "Rich Rudman" <[EMAIL PROTECTED]>
8) Re: The Amazing Little Hawkers.
by Reverend Gadget <[EMAIL PROTECTED]>
9) Re: Hybrid options for a pickup
by Jude Anthony <[EMAIL PROTECTED]>
10) Follow-up on Valence Li-Ion batteries in 12V size
by Mark Dodrill <[EMAIL PROTECTED]>
11) RE: Range + Golf cart vs. AGM wars
by "Roger Stockton" <[EMAIL PROTECTED]>
12) RE: The Amazing Little Hawkers.
by "Roger Stockton" <[EMAIL PROTECTED]>
13) RE: The Amazing Little Hawkers.
by "Roger Stockton" <[EMAIL PROTECTED]>
14) RE: The Amazing Little Hawkers.
by "Roger Stockton" <[EMAIL PROTECTED]>
15) Re: EV Christmas Carol
by Lee Hart <[EMAIL PROTECTED]>
16) Re: The Amazing Little Hawkers.
by "Rich Rudman" <[EMAIL PROTECTED]>
--- Begin Message ---
Lynn Adams wrote:
> I just purchased a set of Toyo Ultra 800. These tires are
> rated at 44 psi and have 100,000 mile advertized life. I
> have not seen any change in my seasonally adjusted range with
> these tires yet. Can'nt say if they are good or bad, but
> will compare over time and let the list know.
I've had a set of these on my ICE '98 Accord for over a year now. They
replaced the original Michelin MX4s. The most striking difference was the
improved ride of the Toyos. The car has Koni shocks, which always increase
ride harshness (in my experience with 5[?] cars). The Toyos are "like
buttah" compared to the Michelins. They seem to be wearing like iron. No
data on ultimate grip or rolling resistance, but response is on par with the
Michelins.
On this car both the Michelins and the Toyos wear *better* at 44 psi. Nice
and even, no wearing out in the middle. At the (lower) recommended
pressures they wear out quicker on the tread edges.
My only complaint with the Toyos is that I've replaced tires twice due to a
gouge through the sidewall. Can't say for sure, but it might have something
to do thin sidewalls to provide that nice, compliant ride. I got mine at
http://www.etires.com . They easily had the best price, but strung me along
on both the replacement orders. Plan on pestering them.
HTH,
Chris
P.S. Etires also carries Nokian, which might be the next LRR-ish tire I
try.
--- End Message ---
--- Begin Message ---
remove
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--- Begin Message ---
Lee, I just finished reading Dickens's classic to my family. I
recognize many of the references, and I have to say you did an excellent
job. Quite amusing, too!
Judebert
David Roden wrote:
I have a formatted html version of this story on evdl.org - it's at
http://www.evdl.org/pages/xmascar.html
It should print nicely in most browsers, if you're so inclined.
I've never put up a public link to it because I haven't gotten permission
from Lee to do so, but I don't think he'll object to me posting it here.
--- End Message ---
--- Begin Message ---
Lee Hart wrote:
> I'm travelling, and depending on my memory, so you could be right. I
> don't have an easy way to calculate how fast you could do 0-60 mph on 54
> kw. (Can anyone help?)
...
> So... if a vehicle only has 54kw, but it can produce this 54kw
> continuously as the vehicle accellerates, how fast can a 2400 lbs
> vehicle accellerate?
work:
W=mv^2/2
m=1344kg (2400lbs)
v=27.8m/s (100kph, 60mph)
***W=518kJ***
time:
T=W/P
P=54kW
***T=9.5s***
If you could get 54 kw to the wheels all the time, the vehicle could
accelerate to 0-60mph in about 10 seconds.
janez
--- End Message ---
--- Begin Message ---
I am going to try to keep this short...
The point of blowing off 100 watts on each Reg, is not a good design point.
Since All the regs don't fire at once, and with the newer control loops, A
fired regs brings the charger amps back REALLY quick. I don't let them bake
before I take charger action anymore.
Still A set of regs inside a battery box that is not made for them is a
real pain.
But as I see it, it's necessary.. and it's the reason that the Hawkers
are not making expected life cycle numbers. The Reg leads don't need to be
a real concern. Just don't mount them dozens of feet away from the
batteries. Don't mount them in a Box on the front bumper and have the
battery under the truck bed. If you have to remote them, build a water proof
box that screws to the battery box, make sure one side has a rather solid
aluminum plate that power resistors can be mounted to. The new MK2Bs has
that nifty second dissipation path, that can do fan control tricks...A CPU
fan inside a crowded Reg box, Can really change the heat carrying issues.
What ever it takes. Individual regulation is the key to the survival of
long series strings.
Anyone who wants to argue this needs to spend a few Midnight hours at the
Manzanita Micro battery lab....I do about 3 nights a week.
We got the windloader and the Monster charger both under software
control, last night, I can drag a pack down at 10Kw, and fill it at 36kw,
and track both cycles, with Reg fedback control. After more blown up stuff,
I am again seeing the benefits of a couple days of hard work. We had a
breaker open... while the oldest weakest charger was being driven at ....
%130 of rated power. Ooops! I think it's time the old Rev 3 PCB set gets up
graded to Rev 7.... Yea it's been awhile...
----- Original Message -----
From: "Christopher Zach" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, December 29, 2004 12:59 PM
Subject: Re: The Amazing Little Hawkers.
> > Like DUHHHH!!
> > with Rudman Regs of course!!! Hooked back to the chargers. And in this
case
> > also back to the control PC and software.
> > That's why I have been busting Butt to get Regs on the monster
charger...
> > With 36,000 watts on hand... and over 200 amps of charger to make that
> > happen, The Regs are a rather important part of insane charge levels
Backed
> > with
> > safety control gear to keep the lead from getting sprayed about.
>
> I love Rudman regs, but they simply ain't going to fit in my pack.
> Finding a place to dump (50 batts*2amps*whatever volts regging) is a bit
> of a problem. I could put them outside the pack, but then you run into
> wire losses causing them to be inaccurate. Waah.
>
> > Believe ME, it's not just one battery that gets slammed it's about 4,
and
> > they can be different batteries at different times of the cycle.
>
> Yup. I was using the word "one" to keep it simple. About 6 batteries
> were shot beyond repair in my pack.
>
> > With infinte amps.... the voltage regualtion point will be almost
instant.
> > Then you have the whole cycle in tapering back amps to maintain the
given
> > pack voltage, interupted only by single batteries that can't take the
full
> > amps. Or said another way, The pack will have a voltage controlled taper
> > slope, that the charger will follow, and if a single Battery, protected
with
> > a Reg can't keep that battery regulated to 14.8, Then the taper back
slope
> > will get steeper to allow the reg to bring it's battery back into line.
When
> > we did the 80 amps(20Kw) cycle we got 9 amphours back in before we hit
the
> > main pack voltage limit of 191 volts, then seconds later the Regs went
wild,
> > and the amps dropped. The total amp hours returned was just under 25.
>
> *nod* true. I've been doing a mini-experiment with the Elec-Trak and
> it's charger and I can see these things happen with the floodeds using
> my battery monitor light. Next project is I'm going to run the Elec-trak
> on Hawkers for a bit. May sound odd, but two strings should be a model
> of the currents (both discharge and charge) that the Prizm is seeing.
>
> > What you need to do is dump in as many amps as you can until the voltage
> > comes up, Then drop back to the 2.5 amps. We find that keeping the 20
amps
> > on while in taper back is where the Damage occurs. Once the pack hits
full
> > voltage THEN you need regs. Once the total amps drops below the
recombiner
> > max limits then Regs are also not needed. In theory... In practice Keep
the
> > regs on since the combiners still can't keep 2 amps at 16 volts from
> > gassing...
>
> *nod* Good point.
>
> > What???. As I said earlier... you don't need the high rate. On being
> > corrected, is seams that a C/3 rate is all that is recomended. The Why,
has
> > not been stated, it's just that the cycle life is a bit greater if you
do
> > charge them a bit faster. Do the Bulk at 20 amps and the taper at 2.5.
> > Unbalenced string???
>
> Right. Roger and Hawker keep going on about the C/3 being an absolute
> minimum. It's possible the cycle life is a bit greater, but the tradeoff
> is that if you don't have a Rudman designed system you're probably going
> to wind up baking le batteries.
>
> Unbalanced string refers to the slim possibility that one string will be
> pulling almost no current, while the other will pull all the current. I
> suppose, but I doubt it would be a 99%-1% split. Then again I haven't
> tested that; need to put 2 ammeters on the Elec-Trak when I test.
>
> > Yup and .8 will do that! IF you have(had) a good battery, and lots of
time.
>
> Lots of time? Well, if the amount of time to make the nipples pop (that
> sounds bad but accurate) is under 8 hours, then it doesn't make a diff
> since the charger shuts off anyway at that point.
>
> > OK.... 10K$ a pack, and a monthly service agreement of $250, You will
need
> > to have the Ev attached to the charger at all times you are not using
it.
> > And I need a IP address to do daily status checks.
> > You want turn Key? total hands off, that just means that someody else
has to
> > do it for you. And that costs.
>
> *nod* Now for the real question: I can spend 2.5k a battery pack and
> nuke it every 6k miles. For 10k I can buy 4 packs, nuke away and get 30k
> miles. Can a super-managed 10k pack get more than 30k miles?
>
> There is the truth that dropping the pack is terrible. And yes, it is.
> Really terrible. However thru it all there is a cost/benefit to
> everything. Even battery life. That's why even if I had a NiMH pack with
> 5 times the life if it costs >10k it's not a bargain if I exclude the
> annoyance costs.
>
> > don't feel alone, alot of us want to keep our EVs running for longer and
> > have cheaper up keep on our packs.
>
> Thank you. That's really the goal here, learning as much as possible.
> It's interesting without a doubt.
>
> > Cheap is flooded and a watering schedule... Easy is a AGM and a set of
Regs,
> > and a darn good charger. But...it's not cheap.
>
> Life is a set of trade-offs. I could go with BB600 batteries, but from
> those who have it sounds like watering 250-500 batteries every month
> could drive you bonkers. Floodeds are cheap without a doubt, but they
> have all that acid stuff. AGMs are clean and high power and fit
> everywhere in your car and don't take up passenger space, but they go
> foom a lot.
>
> And AA battery packs can catch fire. Life's a trade-off. The key is to
> try and maximize what you have, make the improvements that cost the
> least first and yield the highest benefits.
>
> Chris
>
>
> >
> >
> >
>
--- End Message ---
--- Begin Message ---
----- Original Message -----
From: "John Westlund" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, December 29, 2004 5:07 PM
Subject: Re: Range + Golf cart vs. AGM wars
> What could I realistically expect from a 2,600 pound EV with
> a 240V Optima pack and zilla 1k? Rich and Goldie seem to
> suggest 16-18 second 1/4 miles and 0-60 ~ 10, while Blue
> Meanie seems to suggest 0-60 in about 6 and 1/4 mile in the
> 14s. My simulations seem to match closer to your description
> of Blue Meanie's performance, but simulations are often off.
> I know it's all guesswork at this point, but I'd still like
> some idea of what to expect while building this car. It is
> rear wheel drive and has a transmission that can handle the
> torque(Tranny is not stock to the car).
>
Goldie has done 16.7 s with a 1200 amp controller, and only 156 volts of
old Yts.
240 volts and a Zilla, and good traction is 14 second times...
Blue Meanie and Goldie have Very close to the same power limits, I have
front drive John has rear drive,
that's the performance differences. If we both had the same layouts, it
would be a coin toss at every Ev race.
Blue meanie is pretty car, and I respect that. John has also eaten his
tranny, so you won't see John and I duking it out.
I also would not want to disgrace his beautfull master piece with my old
rust bucket....
When John wants to Kick Butt he uses the right tool, and that's the White
Zombie....
John... I see we have contaminated you in just the right way....
I see a fast street racer comin' on Strong.
I like the hand gesture at 90... in 3rd Gear.... and 1400 amps....See
Ya..!
GET the Zilla 2K... and as many AGMs as you can stuff into your EV...
Umm charger?? Regs?????
Oops sorry , I have to lock up the salesman, and keep my Madman racing.
--- End Message ---
--- Begin Message ---
----- Original Message -----
From: "Seth Allen" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, December 28, 2004 5:04 AM
Subject: Re: Ideal motor RPM?
> What I found when I measured was that transmissions get rather
> inefficient at high input shaft speeds and low torques (like highway
> speed cruising). This isn't a revelation, but I was surprised at the
> amount of power they could suck up. Without cutting holes in the side
> of the case to look, it SEEMS like there is a fixed bearing drag, and a
> RPM dependent drag, which I would guess is the moving of the fluid. It
> could be little aliens in the case holding onto the gears, it doesn't
> matter where it comes from, in general, the most efficient operation
> point for the transmission is with as slow an input shaft speed as
> possible, which means the highest gear.
>
> So IF your motor efficiency doesn't drop significantly when you slow it
> down say 1/4 and add 1/3 more torque AND it won't overheat, then top
> gear should help. Ditching any built in fan and swapping out an
> external one for the motor should help with efficiency. And exhaust the
> motor heat onto the transmission to reduce the viscosity of the fluid.
>
> And slowing down helps all the way around.
>
> Seth
I am a little late on this thread.
The AvDC motors like the 3200 to 3600 rpm range. If you keep the amps below
175 this is where the DC motor can reach and exceded the Eff of a AC drive.
BUT... the viscosity drag of the flinging oil.... on a cold day is a real
killer of Hp and range. What I do is I use a low gear to get the oil warm as
fast as I can, but then drop to the lowest RpM I can as soon as I can. This
is in range mode... not Madman mode. On a hot day, I use all the RPM I can
stand for fan cooling, and the lowest amps needed to get the job done.
On cold morings I use 2nd gear going down my hill, It's like free regen,
except that it heat the oil up.... Then the first power run is a lazy pull
to 5500 redline in 2nd, I hold this for about 1/2 a mile, then drop back low
rpm and lazy shifting..
I don't use synth Oil because Goldie bleads it pretty badly....
--- End Message ---
--- Begin Message ---
I have four strings of Hawkers on my EMW, and I have
the banks cross tied, so that each level of batts is
at the same voltage. I don't have regs on them yet, so
I periodically charge each level independently to keep
them in balance. Does anyone else cross tie their
strings? it seems to work well for me, is there a
reason why I shouldn't?
Gadget
--- "David Roden (Akron OH USA)" <[EMAIL PROTECTED]>
wrote:
> On 28 Dec 2004 at 20:58, Chris Zach wrote:
>
> > > I would be concerned that this is too much
> current at too high a voltage
> > > for too long, and will contribute to excessive
> venting and premature
> > > failure of your pack.
> >
> > Hm. How so? Should I back off on the bulk charging
> voltages?
>
> Christopher, reread the thread to date! You've
> missed an important point.
>
> Within reason, you can pretty much whack AGMs with
> any voltage and
> current you want during the bulk phase. In fact, if
> you watch out for excessive
> heat, you can even pump in UNreasonable amounts of
> current - in the
> hundreds of amps.
>
> It's during that last 20% of the charge that you
> need be concerned - and with
> CURRENT more than voltage. Once a given cell is
> above the gassing
> voltage, the more current that you give it, the more
> it gasses. If the gassing
> is slow enough that the recombination reaction can
> keep up with it, all is
> well. But if the current gets too high and the
> gassing exceeds the ability of
> the recombinant reaction to turn the H2 and O2 back
> into water, the gas
> pressure builds up. Then it has to be vented or the
> battery will explode.
> That's the hissssssing or ticking sound you hear (or
> would if you could get
> close enough to those buried modules). It means
> your battery is losing
> moisture.
>
> >
> > *nod* The Dolphin seems to have a linear ramp-down
> once the pack voltage
> > goes above 350 or so. At 390 volts it's typically
> under 1 amp total so
> > it's around .5 amps per string. Is that too much,
> or too long?
> >
>
> Again you have missed a crucial point here. No, it
> is NOT around 0.5 amps
> per string. You can't be sure that one amp from
> your charger is dividing
> equally between the parallel strings. It's quite
> possible that 0.99 amps is
> flowing through one string, and 0.01 amps through
> the other. The charger
> should limit the equalization current to no more
> than the value that's
> acceptable for ONE string.
>
> = = = = =
>
> Two packs, going on three. These are expensive
> lessons, aren't they? Been
> there, done that, still learning. IMO, it sure
> would be nice if we could just
> lease and maintain battery boxes with chargers and
> BMSes built into them.
> That way we could pay somebody (presumably
> knowledgable) to ensure that
> the charge algorithms were correct, that the battery
> was always meeting its
> minimum specs, and that it was properly fixed
> if/when it wasn't.
>
>
>
=====
visit my website at www.reverendgadget.com
--- End Message ---
--- Begin Message ---
David Roden (Akron OH USA) wrote:
One interesting strategy might be to use the p'up as a test bed to experiment
with various layouts and control schemes. Then, when you have the design
somewhat stable, try to transfer it to something lighter and more efficient.
You might consider a Honda Civic - perhaps the rear axle from one of the
early-90s 4wd wagons could be adapted to a more recent hatchback or
sedan.
I'm kinda wishing I had gone hybrid on my AWD Wagovan. Unfortunately, I
can tell you from some minor experience that the rear suspension is the
least compatible part between Civic sedans and wagons. The spring perch
is at a different height, so the shocks and springs are different.
My brother has an old Toyota 4x4. He wants to use it for offroading.
He likes electric torque, but not electric range; if there was an easy
way to do regen, I think this hybrid concept would be ideal for his needs.
Judebert
--- End Message ---
--- Begin Message ---
Hello All. I saw the recent posting related to battery types, and
mentioning the Valence company (www.valence.com), and their new Li-Ion
batteries in a "standard" 12v size--they call it their "U-Charge"
product. It really piqued my interest, so I sent them an e-mail
asking for more information. Here is my full e-mail, for everyone's
benefit:
>>> "Mark Dodrill" 12/30/2004 12:36:39 AM >>>
Hi there. I found your web site through some friends of mine, for your
Saphion Li-ion technology batteries. They look very exciting and I wanted
to ask some questions about them to see if they would fit my needs.
1. Is the charger integrated into the battery itself, or is it external?
The picture suggests that it is not integrated into the battery itself.
If it is not internal, is a special charger required to properly charge
these batteries?
**You may use any charger that can charge up to a maximum current per
U-Charge� in parallel (see #3 for values) and up to a constant voltage
in the range of 13.8-14.6V per U-Charge� unit in series.
2. Are there restrictions on how many of these batteries you can put in
series with each other? Is there some maximum number of amps that you can
run through a series string?
**28 U-Charge� batteries in series. See below for max disch. rates
3. What is the maximum number of amps you can pull from the battery
without doing damage to it?
**
U-Charge� Model U1 U24 U27
Capacity 25�C (77�F), C/5 40Ah 100Ah 130Ah
Max 30 sec Pulse Discharge Current 120A 175A 175A
Max Continuous Discharge Current 80A 150A 150A
Optimum Charge Current <=20A <=50A <=65A
Max Charge Current 40A 100A 100A
3. Do you have any curves available for higher discharge rates than 60 amps?
**Please see attached information. Discharge rates up to 60 A
continuous on a U1
which is a 40 Ah battery. There is a comparison made in this slide to
a typical SLA
of the same physical size.
Thanks very much, and I look forward to your reply.
Mark Dodrill
Peter Guggenheim - Business Development Manager - Large Format Energy Solutions
Valence Technology, Inc. - 6504 Bridge Point Pkwy. - Suite 415 -
Austin, TX 78730
512-527-2939 (direct) - 512-415-0756 (cell) - 512-527-2910 (fax) -
http://www.valence.com
*************************
So, a max of 28 batteries in series, which is 336 volts. Hmm, a
high-voltage AC system could keep the max draw down to a reasonable
level.
Looks interesting--I'd encourage others to check it out too. I'll ask
them about pricing to see if these are unobtainium or not. Maybe we
could all chip in $10 or $20 to get a few for Rich or Joe to put to
the test...
--
Mark
--- End Message ---
--- Begin Message ---
John Wayland [mailto:[EMAIL PROTECTED] wrote:
> The straight scoop is, that you can build a dependable EV
> conversion based of golf car batteries that will get you
> from point A to point B, and you can do it affordably, too.
> This conversion will, however, be slow compared to most every
> other vehicle on the road, with similar acceleration to big
> diesel powered work trucks, and oh yes....those early
> 60's VW Beetles.
Careful with the diesel work truck reference John, as you may just find
even White Zombie trounced by one... a friend of mine who specialises in
performance tuning these things recently wrote:
> I drive a Chev truck now with the 6.6 Duramax diesel.
> Performance is good since I got a 12.92 second run at
> 103.5mph in the quarter mile at the Toronto track in
> September. Not too bad for a 7000lb 4wd crew cab short box
> pickup
> It will go 127 miles per hour on GPS before running
> out of gear and still get between 22-24 miles per gallon.
> Rear wheel horse power stock was 238HP and 432ftlbs torque
> rear and now is dynoed at 482hp and 910 ftlbs torque. Should
> be able to get 500hp + shortly with a little more tweaking.
> It sure is fun to see the look on everyone faces at the track
> once we ran the truck, they went from laughing at us for
> talking a diesel pickup truck to the strip to total shock.
I had the opportunity to go for a test ride in mid-Dec, now that he is
over the 500Hp mark, and I can honestly state that I would be *thrilled*
with an EV with this level of performance, flooded, AGM, or gerbils in
the battery box! ;^>
> This is not to say that you won't enjoy such
> a vehicle, it can still be fun. You can become one with the
> laid back style of driving that accompanies a modest type
> vehicle, and you can be proud of the way you roll along
> without using any gas!
On this note, I will observe that until just a few years ago I drove a
1970 VW bus with a stock 1600cc dual port (i.e. Beetle) engine, and what
John says about becoming one with the laid back style of driving is
absolutely true! What I found is that I was far more relaxed and
patient in traffic while driving this modestly-powered vehicle than when
I replaced it with much newer, more powerful, etc. car. I don't like
commuting at the best of times, but oddly enough I'd far rather do it in
the old VW than a newer, more powerful car...
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Chris Zach [mailto:[EMAIL PROTECTED] wrote:
> > Your experience suggests that you typically cycle your pack
> > shallowly and that your packs have died prematurely as a
> > result of having been vented...
>
> *nod* That's actually probably the cream of the crust; most of my
> driving is shallow discharge, thus every time it would fly up to 375
> volts, then sit there roasting then of course the 50 minute "finish
> charge" at 390 volts and .1 amps. Quite possible that contributed
> to the roasting.
I am fairly certain that the 50 min "finish" charge bears much of
responsibility for "finishing" off your packs prematurely!
I'm not sure how you arrived at the 50min duration, but assume that you
saw Hawker's note stating that this phase should not last more than
60min under any circumstance and settled on 50min as "safe".
The problem here is that you typically do shallow cycles and the finish
phase duration should be decreased proportionately. The example I
provided was based on a 25% discharge and resulted in a maximum finish
phase duration of about 19min (even less if the Magnacharge runs at more
than 17A in bulk). Also, keep in mind that Hawker warns that for this
algorithm to work properly, the bulk current must be at least C/3 amps;
while there may be disagreement on whether or not the batteries require
this minimum current, there is no doubt that Hawker's caution is that
the phase duration relationships that they specify do *not* hold true if
you reduce the bulk charge rate to lower (e.g. 2.5A Dolphin) levels.
> > No; Hawker specifies constant current to 14.7V/module:
>
> I'll have to look around; somewhere in my life I picked up
> the 375 volts even though I also saw the 14.7 volt numbers.
I think Hawker states that 14.7-15.0V is "acceptable", however, their
examples and graphs are based on the 14.7V value. Being a conservative
type, I would definitely not choose to run at the absolute maximum value
mentioned unless I had tested to convince myself that this was a good
idea.
> > I would be concerned that this is too much current at too high a
> > voltage for too long, and will contribute to excessive venting and
> > premature failure of your pack.
>
> Hm. How so? Should I back off on the bulk charging voltages?
Not necessarily; I was referring to the finish charge only, and the bulk
endpoint voltage is not going to impact the finish charge. I would
reduce the finish current to about 1.3-1.5A so that *if* the current
imbalance between strings is really bad, neither string will ever see
more finish current than is appropriate for a 26Ah module. I would also
reduce the 50min duration of this phase to something more appropriate
for your typical depth of discharge, taking into account your actual
bulk current and Hawker's phase duration calculations. For example, at
a bulk rate of about 17A and a 25% DOD, a finish duration of about 19min
would be more appropriate.
If you remain seriously concerned about the module voltages getting out
of line before the end of the bulk phase, here is what I would try:
- run maximum current up to something "safe" like 2.35-2.40V/cell
(14.1-14.4V/module)
- hold this voltage until the current tapers to some lowish value, e.g.
4A (lower is safer, but with parallel strings and aging batteries you
want the level high enough to ensure it is reachable)
- increase the voltage to 2.45V/cell (14.7V/module) and hold it there
until the current tapers again to a lowish level, or some maximum
timeout occurs
- increase the voltage to 2.5V/cell (15.6V/module) and set the current
limit to 1.3-1.5A; run for a specified duration appropriate for your
typical depth of discharge.
The rationale here is that you charge at a high rate initially to reap
any associated benefits (including reduced charge duration), but stop at
a voltage that is low enough that the odds of any out of line battery
exceeding 14.7V are minimal. You then hold this voltage until the
current tapers to a lowish level, which gives the modules a chance to
fill up more and come into a bit better balance. When you crank up the
voltage to 14.7V, the current will spike briefly and then drop rapidly,
so that even if modules remain out of line they will not see high
current for very long at these elevated voltages (gassing is
proportionate to current x time spend above gassing voltage).
You could try infinite variations on this theme, such as run full
current to 14.1-14.4V/module, then reduce the current to a "safe" level
and continue at this rate until reaching 14.7V/module. Or, just forget
14.7V/module entirely and just charge to 14.4V/module and hold that
until the batteries are full (downside is a longer charge time), then do
the finish charge.
> *nod* The Dolphin seems to have a linear ramp-down once the
> pack voltage goes above 350 or so. At 390 volts it's
> typically under 1 amp total so it's around .5 amps per
> string. Is that too much, or too long?
I think it is too long, and possibly too much current.
My concern is that it is current x time that you must be concerned with,
and what you've provided isn't enough to know how much of the 50min is
being spent at what voltage (and current). It is possible that the
current drops rapidly and most of the 50min is spent at 390V and 1A,
which is definitely bad.
Assuming the linear ramp down between 350-390V, the Dolphin would still
be pumping a bit over 1.8A into the pack at 14.7V/module, and this is
enough current that reasonable imbalance in the current sharing between
strings could result in one string getting more current (>1.3A) for
longer than it can handle.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Chris Zach [mailto:[EMAIL PROTECTED] wrote:
> How do you know when an individual battery in a string has
> hit the end of the "bulk charge"?
>
> That's the unknown, and I think that's where the problem is.
> If you have a pack of 25 batteries, and battery number 18
> in there is a trifle bit different from it's neighbors, then
> it may hit the end of bulk charge a bit before it's neighbors.
The assumption is that you start with a pack of modules that are
*reasonably* well-balanced, and then charge them properly so that they
remain well-balanced for most of their usable life.
If your batteries are reasonably well-balanced, then you will not have
module voltages getting far out of line before the end of the bulk
phase. The bulk phase typically takes the batteries up to 80-90%
state-of-charge, the higher the charge current, the lower the SOC at the
end of bulk.
If you were to plot the pack (and module) voltages during the charge
cycle, you will notice that the voltage increases more or less linearly
through most of the bulk phase. However, as the bulk phase nears
completion, the voltage(s) rise exponentially. What this means is that
even if a module's voltage gets out of line with the others in the
string, it is not going to spend very much time at all at this level
(and high current) before the transition to constant voltage. A battery
does not vent immediately upon gassing, rather it is a function of how
much time it spends above the gassing voltage and how much current is
being pumped into it.
> Which is why I think one can charge at 2.5amps using the dopey
> Dolphin "safely". The recombiners can keep up with this
> apparently, but they can't keep up with 20 amps.
Don't bet on it ;^> 2.5A will still vent your pack if you hold it long
enough; even 1A (or less) can. I don't think the recombination reaction
can keep up with more than a very low current indefinitely; the higher
rates (like 0.05C specified by Hawker) almost certainly take into
account the amount of head space in the battery for gasses to accumulate
pending recombination and the maximum durations that the current is to
be sustained.
> Also why I ask about lowering the voltage setpoint from
> switching from bulk charge to finish charge rate. That's
> the only window I have in my pack at the moment, and if
> I drop down from 362.50 to 350 say for this I reduce the
> chance of "clipping" a battery.
Absolutely; a sensible question. Pick a number between about 13.5 and
14.7V/module and run full current up to this level, then drop the
current limit to something you are comfortable with and continue the
rest of the way to the 14.7V/module level. If you have your LED
monitors installed, you could pick the initial voltage level and
following current such that you get the quickest recharge without any
module going over-voltage for an excessive time. You would probably
find that you need to charge more gently with a fresh pack as well as
with an old one that is less well-balanced.
> By lowering the bulk current at the start, I also limit the
> damage somewhat if a battery was really weird. Though the
> more I think about it, if one battery goes above 14.7
> while the pack itself is at 14.0 average (350) then maybe
> it's time to drop the pack anyway.
I wouldn't worry about lowering the bulk current at the start. If you
have a module that can't take 20-ish amps at the start of charge without
getting that far out of line, then it needs some one-on-one TLC to get
it back into line, or replacement.
> Except for this "Hawkers *REQUIRE* that you charge at high
> rates during bulk" thing. Why? To what level? Can I charge
> at high rates for 5 minutes of the charge to "blow off the
> electrons" or whatnot then crawl back into my lower-current
> pit of comfort?
Unfortunately, we just don't know. *If* Hawker's reasons are similar to
USBMC's, then perhaps charging at high rates for the first few minutes
of bulk will yield most or all of the benefits; this is something that
you can experiment with - it certainly can't be *worse* for the pack to
give it 5-10min of C/3 at the start of charge than to charge it at 2.5A
with the Dolphin every time.
> *nod* I was assuming that 1 amp (actually .8a IIRC) is safe
> for a 26ah battery so that it won't gas. I can test this
> easily enough; take a Hawker out to the woodshed, remove
> the top (so the cell nipples will pop off if it gasses) and
> charge away using my 1 amp constant voltage/current bench
> power supply. If I can make the nipples pop, I'm gassing.
I can pretty much guarantee that if you hold 1A long enough you will
vent your battery. The only question is how long can you hold it before
venting. Be cautious in drawing any hard conclusions from this testing
since how easily a battery vents will vary depending on how well
balanced the cells are.
If you got really ambitious, you could perform such testing and come up
with a graph of current vs time-to-venting. You might find that the
battery can take 20A for 5min, 5A for 20min, 1.5A for 1hr, 0.5A for 3hrs
and 0.1A indefinitely, or some similar relationship.
> Yes, they are expensive. And I hope this pack lasts longer.
> Even so, 6k miles is not the end of the world; I've read about
> people flattening US battery floodeds in 8k. And it's an AGM
> pack, so it makes for a fast little car.
Something I would seriously consider is replacing the pack with a single
string of larger AGMs, such as Optima YTs, Exide Orbitals, or the Deka
Intimidators. The D34 YTs, for instance would provide about the same
capacity as your present pack (even though you apparently seldom use the
full capacity anyway). Going to a single string makes charging a bit
more predictable and cuts your number of modules in half (a reasonable
cost savings if you were to install regs).
I realise that you have some space constraints in terms of the battery
box size, etc., however, this could be the sort of situation where it
makes financial sense to have a new box fabricated. D34 YTs laid on
their side are not much taller than 26Ah Hawkers, and you wouldn't need
to leave space above the batteries for cabling. Optima also makes the
smaller (41Ah) D51 version, which is just 5 1/16" tall when laid on its
side.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Rich Rudman [mailto:[EMAIL PROTECTED] wrote:
> > How do you know when an individual battery in a string has
> > hit the end of the "bulk charge"?
>
> Like DUHHHH!!
> with Rudman Regs of course!!! Hooked back to the chargers.
> And in this case also back to the control PC and software.
> That's why I have been busting Butt to get Regs on the
> monster charger... With 36,000 watts on hand... and over 200
> amps of charger to make that happen, The Regs are a rather
> important part of insane charge levels Backed with safety
> control gear to keep the lead from getting sprayed about.
Rich is absolutely right that when you start playing with this sort of
power, you need pretty good gear to keep from hurting things *quickly*.
In fact, something like his regs are pretty much required if you want to
achieve the shortest possible recharge times even at more modest charge
levels.
However, once you get to the point of having the regs tied into the
control loop so that the charger knows to cut back, you don't actually
need regs anymore; all you need is voltage sensors. If the module
exceeds the sensor setpoint, the sensor tells the charger to cutback.
When you've got 200A (or even 40A) on tap, the extra cost of equipping
each module with 2.5A of bypass capability is questionable economics
(though it also may disappear into the noise compared to the cost of a
36kW monster charger). Likewise, if the absolute shortest charge time
is not critical to you, then you have the option of more conservative,
longer duration charge algorithms instead of regulators.
> When we did the 80 amps(20Kw) cycle we got 9
> amphours back in before we hit the main pack voltage limit of
> 191 volts, then seconds later the Regs went wild, and the
> amps dropped. The total amp hours returned was just under 25.
Notice that this backs up what I have said about module voltages staying
pretty well behaved until the end of bulk: it wasn't until shortly
*after* the bulk phase ended (at 14.7V/module on a 13 module string)
that the regulators (set to 14.8V/module?) went wild.
> Once the pack hits full voltage THEN you need regs.
Or you need to limit the amount of current the pack sees and how long it
sees it for. For the quickest recharge, use regs.
> Once the total amps drops below the recombiner max
> limits then Regs are also not needed. In theory... In
> practice Keep the regs on since the combiners still can't
> keep 2 amps at 16 volts from gassing...
Ideally, if the regs are left on you would tweak the voltage setpoint up
to 15.6V since the batteries benefit from the voltage being allowed to
rise to such high levels during the finish charge. Once the battery is
over the gassing voltage, it makes little difference with respect to
venting if the voltage is 14.8V or 15.8V.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Jude Anthony wrote:
> Lee, I just finished reading Dickens's classic to my family.
> I recognize many of the references, and I have to say you did
> an excellent job. Quite amusing, too!
Thanks! I'm glad you liked it! Yes, there are *many* references in it to
EVDL members.
--
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!" -- Margaret Mead
--
Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
No Roger I am NOT in flame mode...
But some points.
I have seen 399 Hp at 750 plus from one of those Duramax Trucks.
On a Dyno.... Turbo Tech's Dyno in Tacoma , Wa for real Hp. I helped tie it
to the hardpoints on the Dyno.
Holy S!!! . I don't like GM anything, But the Duramax and the Allison tranny
are my Fav for real hard work.
EV mode... the tow Rig for the Gone Postal trailer is a Duramax.. I have a
couple of thousand miles on it... Love it. I can't swing the payments, Glad
Tom True can...
----- Original Message -----
From: "Roger Stockton" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, December 30, 2004 2:49 PM
Subject: RE: The Amazing Little Hawkers.
.
>
> Rich is absolutely right that when you start playing with this sort of
> power, you need pretty good gear to keep from hurting things *quickly*.
> In fact, something like his regs are pretty much required if you want to
> achieve the shortest possible recharge times even at more modest charge
> levels.
You wann see Madman bouncing around like spit in a griddle??? Light off the
monster charger while I am adding Regs to the pack, Read Regbuss not hooked
up.
Like why are ALL the regs locked into thermal cut off??? OH Cra! shut it
down Joe!!! The fait smell of really hot Reg heat sinks floats through
shop......No damgage... but the regs have over temped and the charger is
being held off until they cool. A locked on Reg will over temp in about 45
seconds.... if you drive a reg to one volt over it's setpoint....with a few
dozen Kws of charger available, this takes.....about 45 seconds...
So... Joe now has the Reg hot line tied into the software for control,
so... we can use software developed curves instead of real time events, we
can back off, stay off, watch things cool attack again but with a LOT less
aggresiveness....So....We are getting some really nifty curves...
The point of this reply.
You certainly DO still need the regs.!! Granted that the feed back can
keep the regs from getting fried... the regs are the tool that lets your
series string have some "Give" to it so the low ones get some charge and the
high ones dumps some charge. Without Reg(of some sort) this effect is very
minimal. Yes.. the recombiners should hold thier own. But..... and this is a
Big Butt, I have never seen the recombiners stay up with even a 2amp
constant over charge. This is WHY the Zivans on the Sparrows kill the
Optima Yts in such a short order. Even at 2 amps Gassing happens. And I
don't care who says they do or don't!!! I see it all the time. I have seen
gassing as low as 15 volts at 500 milliamps. With a new set of Yts, half a
amp will drive them to 17 some odd volts. So....
You still need Regs..
>
> However, once you get to the point of having the regs tied into the
> control loop so that the charger knows to cut back, you don't actually
> need regs anymore; all you need is voltage sensors. If the module
> exceeds the sensor setpoint, the sensor tells the charger to cutback.
> When you've got 200A (or even 40A) on tap, the extra cost of equipping
> each module with 2.5A of bypass capability is questionable economics
> (though it also may disappear into the noise compared to the cost of a
> 36kW monster charger). Likewise, if the absolute shortest charge time
> is not critical to you, then you have the option of more conservative,
> longer duration charge algorithms instead of regulators.
>
Umm I tried this, knowing what you know Roger.... I killed the Yt pack in my
Fiero in less than 18 months... Alway had a voltage controlled charger,
Never ran it dead, filled often just to top off.
DEAD in 18 months, less than 1/2 range and 1/2 the pack got recycled when
any single Yt could not make %30 Cap.
DEAD
DEAD.
Goldie..... run hard...every Woodburn. Left uncharged for months....
numerous burn outs, fail Regs, funky Kludged Regs and chargers....
Always had Regs....Mk0, Mk1, Mk2, Mk2B.... every style I have made she has
had them and been my test mule for them.
I still have 6 Yt factory prototypes on board, the rest are Sparrow
throwaways from John Lussmeyer's Sparrow. All make (made) at least 240 watt
hours(new is 280 to 320) When I installed them.
I still have 10 mile range in warm weather. I can use 3.25 Kwhr If I am
carfull.
Abuse and Regs, out lived little if any abuse, and no regs.
That's a pretty good test of my $1000 bill.
> > When we did the 80 amps(20Kw) cycle we got 9
> > amphours back in before we hit the main pack voltage limit of
> > 191 volts, then seconds later the Regs went wild, and the
> > amps dropped. The total amp hours returned was just under 25.
>
> Notice that this backs up what I have said about module voltages staying
> pretty well behaved until the end of bulk: it wasn't until shortly
> *after* the bulk phase ended (at 14.7V/module on a 13 module string)
> that the regulators (set to 14.8V/module?) went wild.
Pretty much true.. the subtilety is... the event that Wreaks batteries is
when, as the end of Bulk is nearing, a single battery fills and it's voltage
jumps, and the total voltage is still below the peak, This is when a single
battery can still see the entire full power current of the charger, This is
when you can see 20 volts and acid spryaing....This can be a fleeting event,
since the entire stack is coming up pretty fast... But it's the most
unprotected time. It's also why you need to yank the charger back really
hard to prevent. Since just a few amps back can keep the "jumpers" in line.
We are messing with a %50 decay at first hit and a 10% attack.. this is all
very fluid at the present time.... and I should think about potential
confidential Info issues. It's that subtile....
>
> > Once the pack hits full voltage THEN you need regs.
>
> Or you need to limit the amount of current the pack sees and how long it
> sees it for. For the quickest recharge, use regs.
>
Limit pack current, Umm that's a time penalty... and a it becomes a Wild ASS
guess...
Also the abuse of the regs depends on the history of the pack... DOD, temps,
selfdischarge.... how hard it was just pulled down, and Moon phase.... And
what sign it's under.....etc.
The biggie.. is how unequalized is the pack??? has it been pushed to Equal,
or pulled farther apart???? You need some knowledge of the past to predict
the future...OR....Regs and live in the present.
> > Once the total amps drops below the recombiner max
> > limits then Regs are also not needed. In theory... In
> > practice Keep the regs on since the combiners still can't
> > keep 2 amps at 16 volts from gassing...
>
> Ideally, if the regs are left on you would tweak the voltage setpoint up
> to 15.6V since the batteries benefit from the voltage being allowed to
> rise to such high levels during the finish charge. Once the battery is
> over the gassing voltage, it makes little difference with respect to
> venting if the voltage is 14.8V or 15.8V.
>
> Cheers,
>
> Roger.
First the Mk2b Regs have a "equalize" mode that kicks the Reg voltage up 1.5
volts.. just for this need. NO we don't use it much.... Yes it's being
looked at as yet another input for the monster charger to scan.
14.8 or 15.8 as a venting limit. I would sure expect the the extra volt
would certainly push a gassing batteries internal pressure MUCH higher.
Though if the Amps are the same, the Coulombic generation of gasses is the
same. I would not want my batteries to be in this situation....at all. 14.8
and NO gassing....
As Ryan is finding out ...maybe we should drop the end voltage for Orbitals
down to 14.6, instead of the Optima Yellow Top tried and true 14.8 volts.
Orbs do seam to vent at a lower voltage. The regs on my Orbs seamed to get
crasy about 277, Even when my Regs are set to 14.8(*19)= 281. 284 lit all
the regs hard on!. 281 was a quite flicker from about 1/2 the pack. 277, an
not a reg fired.
Yes they are getting pretty well equalized. That's 5 full cycles on all 19
batteries. The software terminated at 1 amp of current.
But as we came out of Bulk, there was about 5 minutes of Reg hell. The DOD
was only 2.5 amphours on this stroke. I expect to do a %100 DOD on Sunday...
That will be 10Kw to the first to hit 10 volts.
That will be a nice test. 10 Kw down, and 20Kw up. HeLLO there!! WAKE UP!!!
Thank you......
I gotta go damage my hearing.... and haul speakers around again... Sleep?...
not for many hours yet....
>
--- End Message ---
