EV Digest 4348
Topics covered in this issue include:
1) Re: Motor Machine Shop Idea
by "Andre' Blanchard" <[EMAIL PROTECTED]>
2) RE: RPM Counters
by "Bill Dennis" <[EMAIL PROTECTED]>
3) RE: AC drive system on eBay
by "Karl Nichols" <[EMAIL PROTECTED]>
4) Re: An update regarding my JeepEV
by "Rich Rudman" <[EMAIL PROTECTED]>
5) Re: An update regarding my JeepEV
by Otmar <[EMAIL PROTECTED]>
6) Re: Shocking Information
by [EMAIL PROTECTED]
7) Re: Motor Machine Shop Idea
by David Dymaxion <[EMAIL PROTECTED]>
8) RE: SCR controllers?
by "Roger Stockton" <[EMAIL PROTECTED]>
9) RE: Home made charge question
by "Roger Stockton" <[EMAIL PROTECTED]>
10) Re: RPM Counters
by David Dymaxion <[EMAIL PROTECTED]>
11) RE: An update regarding my JeepEV
by "Roger Stockton" <[EMAIL PROTECTED]>
12) Two motors, Two controllers Single POT?
by Mark Hastings <[EMAIL PROTECTED]>
13) TS Cells and Temperature
by "Bill Dennis" <[EMAIL PROTECTED]>
14) Re: SCR controller (misunderstood), &6V(sam's club)
by Lee Hart <[EMAIL PROTECTED]>
15) Re: Isolated chargers
by Lee Hart <[EMAIL PROTECTED]>
16) RE: SCR controller (misunderstood), &6V(sam's club)
by "Bill Dennis" <[EMAIL PROTECTED]>
17) Re: Isolated chargers
by Christopher Zach <[EMAIL PROTECTED]>
18) Charging and Peukert effect question
by Nick <[EMAIL PROTECTED]>
19) Re: Two motors, Two controllers Single POT?
by Lee Hart <[EMAIL PROTECTED]>
20) RE: An EV Made From Leftovers
by "Roger Stockton" <[EMAIL PROTECTED]>
21) Re: SCR controller (misunderstood), &6V(sam's club)
by Lee Hart <[EMAIL PROTECTED]>
22) "eBay hype" or innovation?
by [EMAIL PROTECTED]
23) RE: SCR controllers?
by mike golub <[EMAIL PROTECTED]>
24) Battery box
by TiM M <[EMAIL PROTECTED]>
25) RE: Charging and Peukert effect question
by "Roger Stockton" <[EMAIL PROTECTED]>
26) Re: Two motors, Two controllers Single POT?
by "ProEV" <[EMAIL PROTECTED]>
27) British Electric Land Speed Attempt Fails
by David Dymaxion <[EMAIL PROTECTED]>
28) newbie intro
by tom koehler <[EMAIL PROTECTED]>
--- Begin Message ---
Do a web search for "portable machine tools".
All kinds of special tools for making in place repairs on large equipment.
Here is one company with new stuff.
http://www.cpmt.com/company.php
And here is some interesting older stuff.
http://shopswarf.orcon.net.nz/opmtndex.html
__________
Andre' B.
At 11:08 AM 5/9/2005, you wrote:
Credit for the basic idea goes to Steve Clunn
(http://www.grassrootsev.com).
Steve's neat idea is to put a commercial taperlock hub on the
electric motor, spin it with the electric motor, and machine it to
the perfect size using the electric motor as the lathe. This also
guarantees a perfectly concentric hub, which generally means a more
on-center and balanced flywheel installation.
It's more work then you might guess to wrestle the electric motor
onto the lathe, get the working height right, get it centered, etc.
I was suddenly struck with the idea, why not bolt a mini machine shop
to the face of the motor?
You could get a Sherline or similar x-y (from a lathe or milling
machine), and bolt it to a frame that bolted to the face of the
electric motor. The electric motor would spin the taperlock, and the
x-y would accurately move the cutting tool. A refinement to the idea
would be to make the mounting adjustable, to allow adjustment to
align relative to the motor shaft axis.
You may even be able to machine your own flywheel this way, or one
piece flywheel/taperlock combo.
This is too much trouble for the home hobbyist doing a single
conversion, but could be handy for an EV parts business.
__________________________________
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--- End Message ---
--- Begin Message ---
I wanted it for two purposes, Lee:
1) Overspeed detection
2) Determining shift points for a clutchless transmission -- e.g., turn on
a LED when it's next/previous gear speeds match.
Bill Dennis
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Lee Hart
Sent: Monday, May 09, 2005 9:19 AM
To: [email protected]
Subject: Re: RPM Counters
I like to think about problems without preconceived notions of how they
have been solved before. Old solutions may not be a good fit in an EV.
What is the reason to have an RPM counter or tach? What are you going to
do with the information?
If it's an EV conversion, it already has a speedometer and odometer. Is
there a reason to change them?
If you want to know motor rpm, that is strictly a function of mph and
the gear ratio (except with an automatic transmission without a locking
torque converter). So, motor rpm can be computed from the speedometer
and gear you are in.
If all you want is an rpm limiter to prevent overspeeding, then it can
be inferred from the voltage and current fed to the motor. For an AC
motor, frequency is directly proportional to frequency (even for an
induction motor, slip is never more than a few percent). For a PM motor,
voltage is a good indicator of rpm, and gets especially accurate if you
also measure current so you can correct for the motor's effective
resistance. The relationship is more complex for a series motor, but
it's still straightforward to define the particular voltages and
currents that correspond to any given rpm.
--
"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 ---
I found this data on the motors at
http://www.boschrexroth.com/country_units/america/united_states/en/products/
brc/ProductDirectory/CurrentProducts/Motors/2AD/2AD_PRJ2.pdf
Looks like peak RPM is 6000
-----Original Message-----
From: Ryan Stotts [mailto:[EMAIL PROTECTED]
Sent: Sunday, May 08, 2005 9:44 PM
To: [email protected]
Subject: Re: AC drive system on eBay
Karl Nichols wrote:
> I have e-mailed evdoc and found out that it came out of a 30 passenger bus
"motor weighs appox. 600 lbs"
What's this motor red line at?
--- End Message ---
--- Begin Message ---
I doubt that the "external control port" is effecting the timer clock latch
circuit.
In the last week we found another "Surger" maker. But since you are not
having surging issues right now, it may not be important.
My hunch is there might be some outside contamination on the back 6 pins of
the timer adjust solder leads. The upper boards comes out pretty easily, and
you could wash it with warm soapy water, rinse until extremely clean, blow
dry and let sit in a the hot sun for about 1/2 a hour and them reassemble...
If the clock pot is the issue this will cure it..
The blink rate in three steps says you only have 3 clicks on the timer
from zero. Weather the pot is set there or not.....Every decade the timer
completes ups the flash rate. So the steps in blinking are a visual read
back on how much you have left in time. Well that's what you are supposed to
notice....Most just notice the flashing Blue Led or the lack of it.
Rich Rudman
Manzanita Micro
----- Original Message -----
From: "Nick Viera" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Sunday, May 08, 2005 7:34 PM
Subject: Re: An update regarding my JeepEV
> Hi Rich (& all),
>
> Rich Rudman wrote:
> > First the PFC30 is supposed to make 39.5 amps into a 120 volt stack,
> > And for the first 5 minutes, you better see that 39.5 amps. Once the
> > yellow starts flashing, then you should see the amps fall as the
> > unit goes into thermal cut back.
>
> Yes, but my charger goes into thermal limit after about 3-5 minutes of
> operation on a typical hot Texas day. So the majority of my bulk
> charging is done at a lower current.
>
> > Bigger fans and Liquid cooling are the solution. But I can't get much
> > more power through that box as it stands.
>
> I agree, and I'm at some point going to get around to installing a duct
> system to the charger with an extra fan or two to help increase air flow
> to it.
>
> > Once the timer is set you have only the dialed in time effecting how
> > long it will run until it shuts off. There is no state 3. The blink
> > rate of the Blue led speeds up as the time counts down.
>
> I was only noting the timer as being in three different "states" because
> the LED flash rate doesn't change smoothly with respect to time left,
> but instead jumps from/to either "slow", "medium", or "fast" flashing.
>
> > either up the timer setting or just reset the charger and have it
> > time out again. -snip- I just cycle the power, and time it another 30
> > minutes. Since you did not get the amps to taper below 6 amps it
> > needs another cycle or you need to up your timer length.
>
> I too have been turning my charger off/on to reset the timer and force
> it to continue charging into my "fully charged" pack. My concern is that
> I've got the timer set for way _longer_ than what it is actually giving
me.
>
> > Having the timer adj set to 80 minutes and the time out taking only
> > 38 minutes... is problematic. I have seen this happen when the back
> > side of the controller PCB gets some contamination on it. The digital
> > lines from the Digi pot(the timer adjust switch) get crossed and the
> > the timer latch gets the wrong input. Since this is a Cmos input....
> > it doesn't take much.
>
> Hmmm, I wonder then if this is what I'm experiencing with my charger? It
> sounds very likely.
>
> Also, do you remember the problems I was having with my charger at first
> (the real bad surging it was doing), which ended up being caused by that
> integrated circuit? I believe the IC was for a remote function or
> something, and I ended up removing it and inserting a jumpered DIP
> socket in it's place to bypass the IC, as per your advice. Although
> doing so fixed my charger's surging problems, maybe this modification
> has been causing this weirdness with the timer all along? Or maybe my
> jumper has become loose? Could that cause problems with the timer?
>
> I can take the cover off my charger and check this out, but I don't like
> to open up the charger without talking to you first. ;-)
>
> Thanks,
> --
> -Nick
> http://Go.DriveEV.com/
> 1988 Jeep Cherokee 4x4 EV
> ---------------------------
>
--- End Message ---
--- Begin Message ---
At 10:11 AM -0700 5-9-05, Rich Rudman wrote:
The blink rate in three steps says you only have 3 clicks on the timer
from zero. Weather the pot is set there or not.....
Maybe it's only set at three clicks?
On mine there is no clear indication of where zero is or what click it's at.
I'd suggest turning it a few clicks clockwise and see if the time changes.
--
-Otmar-
http://www.CafeElectric.com/ Home of the Zilla.
http://www.evcl.com/914 My electric 914
--- End Message ---
--- Begin Message ---
When I was in Radar school in 1960 there was one that started out with ":
Microfarad took milliamp for a ride on his megacycle."
Larry Cronk 72
Datsun ELEC TK
--- End Message ---
--- Begin Message ---
Thanks for the links, neat machines! I should have figured I wouldn't
be the first person to think up such an idea. Using the electric
motor double duty as the lathe provides some economy in our case.
--- Andre' Blanchard <[EMAIL PROTECTED]> wrote:
> Do a web search for "portable machine tools".
> All kinds of special tools for making in place repairs on large
> equipment.
>
> Here is one company with new stuff.
> http://www.cpmt.com/company.php
>
> And here is some interesting older stuff.
> http://shopswarf.orcon.net.nz/opmtndex.html
> __________
> Andre' B.
>
>
> At 11:08 AM 5/9/2005, you wrote:
> >Credit for the basic idea goes to Steve Clunn
> >(http://www.grassrootsev.com).
> >
> >Steve's neat idea is to put a commercial taperlock hub on the
> >electric motor, spin it with the electric motor, and machine it to
> >the perfect size using the electric motor as the lathe. This also
> >guarantees a perfectly concentric hub, which generally means a
> more
> >on-center and balanced flywheel installation.
> >
> >It's more work then you might guess to wrestle the electric motor
> >onto the lathe, get the working height right, get it centered,
> etc.
> >
> >I was suddenly struck with the idea, why not bolt a mini machine
> shop
> >to the face of the motor?
> >
> >You could get a Sherline or similar x-y (from a lathe or milling
> >machine), and bolt it to a frame that bolted to the face of the
> >electric motor. The electric motor would spin the taperlock, and
> the
> >x-y would accurately move the cutting tool. A refinement to the
> idea
> >would be to make the mounting adjustable, to allow adjustment to
> >align relative to the motor shaft axis.
> >
> >You may even be able to machine your own flywheel this way, or one
> >piece flywheel/taperlock combo.
> >
> >This is too much trouble for the home hobbyist doing a single
> >conversion, but could be handy for an EV parts business.
> >
> >
> >
> >
> >
> >
> >__________________________________
> >Yahoo! Mail Mobile
> >Take Yahoo! Mail with you! Check email on your mobile phone.
> >http://mobile.yahoo.com/learn/mail
>
>
Discover Yahoo!
Use Yahoo! to plan a weekend, have fun online and more. Check it out!
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--- End Message ---
--- Begin Message ---
John Wayland [mailto:[EMAIL PROTECTED] wrote:
> mike golub wrote:
>
> > Is it worth using a SCR motor controller, if you are
> > just starting to get involved with your first ev
> > project, and you don't want to spend too much money?
>
> Sure, as long as you can put up with its limited power
> delivery and noisy operation. Forklifts, though very
> powerful, operate on gear reduction and only have to run at
> low speeds, so they can get by on 10-18 kw of traction power.
Rather than using a surplus forklift controller, look for a GE EV1 SCR
controller someone has removed from an older conversion (like a Jet
Industries 007). These typically ran 120V systems and had a 500 or 550A
currnet limit. With a stiff pack, this is 66kW (upwards of 80HP).
These controllers were rated for a maximum battery pack of 144V and the
EV1 typically runs down to 1/2 its rated voltage, so one of these ought
ot be happy when fed anything from about 60-144V.
They also have built-in bypass contactor control logic, which you can
use to improve efficiency and allow silent operation.
> Unlike the
> totally irritating non-varying 2 khz squeal of the Curtis
> controllers, the SCR 'growl' is lower in frequency, varies,
> and is more 'entertaining' than irritating.
Absolutely! It also disappeared above about 20mph in the Omni
conversion I used to own (96V, GE EV1, 7" Prestolite).
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
Lee Hart [mailto:[EMAIL PROTECTED] wrote:
> Philip Marino wrote:
> > I've read that the batteries are better off if you add some
> > capacitance (a few big electrolytics) to the output of this kind of
> > charger (right after the bridge). Is this really true?
>
> No. 99% of all battery chargers have little or no filter
> capacitors. The ones that do have them to protect the charger
> -- the batteries themselves don't care.
I'll use one of Lee's own "it depends" here ;^>
What Lee says may be true for flooded lead acid, however, sealed lead
acid batteries most definitely do care about the ripple current and
voltage. Several manufacturers specify an upper bound on the amount of
ripple the charger is allowed to subject the battery to.
Among other things, ripple on the output of a battery charger causes
unnecessary heating in the battery.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
You are right, in a sense tachs are redundant. For instance, why both
with one in a single gear direct drive EV like the EV1? My parents'
1961 VW bug had little tic marks on the speedo indicating max speed
in each gear (I have seen this on motorcyles, too).
For racing, the tach's consistent user interface of "This needle
angle means shift now!" is helpful. This "racer image" to help sell
cars is probably the biggest reason many cars have tachs in them.
Tachs can make nice debugging devices, though, for instance to check
if your clutch is slipping, or if the locking torque converter is
actually working. For a RWD, I thought it would be a neat for
traction control. If rpm and speed (off a nondriven wheel) mismatch
too much, cut back on the current.
--- Lee Hart <[EMAIL PROTECTED]> wrote:
> I like to think about problems without preconceived notions of how
> they
> have been solved before. Old solutions may not be a good fit in an
> EV.
>
> What is the reason to have an RPM counter or tach? What are you
> going to
> do with the information?
>
> If it's an EV conversion, it already has a speedometer and
> odometer. Is
> there a reason to change them?
>
> If you want to know motor rpm, that is strictly a function of mph
> and
> the gear ratio (except with an automatic transmission without a
> locking
> torque converter). So, motor rpm can be computed from the
> speedometer
> and gear you are in.
>
> If all you want is an rpm limiter to prevent overspeeding, then it
> can
> be inferred from the voltage and current fed to the motor. For an
> AC
> motor, frequency is directly proportional to frequency (even for an
> induction motor, slip is never more than a few percent). For a PM
> motor,
> voltage is a good indicator of rpm, and gets especially accurate if
> you
> also measure current so you can correct for the motor's effective
> resistance. The relationship is more complex for a series motor,
> but
> it's still straightforward to define the particular voltages and
> currents that correspond to any given rpm.
> --
> "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
>
>
Yahoo! Mail
Stay connected, organized, and protected. Take the tour:
http://tour.mail.yahoo.com/mailtour.html
--- End Message ---
--- Begin Message ---
Nick Viera [mailto:[EMAIL PROTECTED] wrote:
> My pack was pretty low as I drove about 14 miles (I know,
> I know, very lame range). Here's what I noticed:
>
> 4:30pm Start charging - Constant Current
> 5:45pm Switches to Constant Voltage, timer phase 1
> (blue LED blinking slow, ~29 Amps still going into pack)
> 6:08pm Constant Voltage, timer phase 2
> (blue LED blinking faster, ~14 Amps still going into pack)
> 6:17pm Constant Voltage, timer phase 3
> (blue LED blinking fastest, ~6 Amps still going into pack)
> 6:23pm ~6 Amps still going into the pack, and the
> timer times-out
> (blue LED lit solid, charger shuts off).
Charger timer discrepancy aside, the rest of this charge cycle looks
pretty odd.
You say the pack started off pretty deeply discharged, yet bulk lasted
only 1.25hr @ ~29A, which is just 36.25Ah returned to the pack. The odd
thing here is that bulk (the initial constant current phase) should
return about 80% of the Ah removed from the pack and your pack of 8VGCs
ought to have a capacity of *significantly* more than 45Ah. What do you
have the charge voltage set to, and what did you actually observe?
The constant voltage portion of the charge will not necessarily take
longer than the bulk portion. The current should taper fairly quickly
on a healthy pack. The pack is not necessarily fully charged at the end
of this phase, even if the current does taper off to the target level of
a few amps (about 3-5A).
To fully charge flooded lead acid batteries, you need to return about
107-120% of the Ah removed, but only about 100% is typically returned by
the end of absorption (the constant voltage phase). If you don't
continue charging beyond this point, you will find your battery capacity
declining slowly from one charge cycle to the next.
Usually, the last bit of charge is performed by holding the current
constant at the 3-5A finish rate (to minimise gassing, etc.) for some
additional amount of time. If the PFCxx charger doesn't have the
ability to do this, then you will need to set the timer for a long
enough duration to allow charging to continue for an acceptable amount
of time *after* the current tapers to the desired level. That is, if it
typically takes about 1hr for the current to taper, you may need to set
the timer to 2-3hrs to ensure that the pack has a shot at getting fully
charged.
It is still something of a crapshoot since the charger is going to
continue in the constant voltage mode, which means the current may
continue to taper and so the amount of overcharge provided will be
variable and unpredictable compared to a constant current finish phase.
Cheers,
Roger.
--- End Message ---
--- Begin Message ---
I am going to use two PM Etek motors for my scooter/trike project and would
really like to have contactorless reverse and regen which comes with the
millipak 4Q. I wrote sevcon a while back so was hoping someone here had some
previous experience.
Can I use a single pot or a single linear accelerator that they sell to control
both controller to make sure they have the same input? My intention is to
remove another possible difference from the Dual scheme I have going. I'm
somewhat concerned the two motors and two controllers will fight eachother, or
just not fully reach their potential, but with two input I fear disaster. Is
there an off the shelf controller that will do contactorless reverse and regen
with roughly 600+ amps at 48 volts? Plan B is an altrax 650amp running them
both but then I have to add contactors for reverse and lose regen.
Mark Hastings
--- End Message ---
--- Begin Message ---
If I park my EV outside in the cold all day while at work, do I need to keep
the TS cells warm the whole time, or can I just let them get cold and then
warm them up at some period of time before they're needed? In other words,
does getting cold when not in use deplete capacity, or is capacity depleted
only when cold cells are actually used? Thanks.
Bill Dennis
--- End Message ---
--- Begin Message ---
mike golub wrote:
> I'm not in the mood to make anything so complicated.
> My experience with electronics is that most of the
> time they give you a circuit to make, it them blows
> up, and then they tell you what you did wrong.
A good description! A few-page construction article only covers about
10% of what you need to know. The author assumes you already know the
rest. If you don't, your chances to get it to work right the first time
are pretty slim!
> My orginal question was [are] there some off the shelf SCR
> controllers that could be used?
Yes. The GE EV1 that Rod Hower mentioned is a good example. Thousands
were built and still to be found surplus. Cableform also built some very
good ones. In most cases, you just treat them as a 'black box'. Hook it
up, and it works.
> the 6Volt golf cart batteries at Sam's Club are $48.13, with a 12
> month policy. They say EXIDE on them, and they are 110 Amps in 75
> minutes...
Yes, they will be just fine for a modest EV.
> I figure if I get 18 of them would give me 113.4 volts (6.3v per
> battery)
No; assume 6v per battery. 18 will give you a 108v nominal system.
> and could be charged with my 120vac through a bridge. I'm only
> getting 117VAC at my house.
Charging a 108v pack from a 117vac outlet with nothing but a bridge
rectifier is called a "bad boy" charger. It sort-of works. Your cords
and connectors will get hot; cheap ones will melt and fail. The charging
current is unpredictable -- a deeply discharged pack will trip your
circuit breaker, and the current may still be too high into a
fully-charged pack (more than 5 amps at 135vdc).
As a minimum, you should add a series inductor or variac or buck-boost
transformer wired to buck the AC voltage down a bit. Any of these will
let you control your charging current to avoid breaking things. Also,
add a timer that automatically shuts if off in case you forget.
> In regards to my batteries freezing up here at -40
> degrees. A local engineering professor, is more
> worried about overheating in an insulated box.
No, you won't overheat them under "normal" EV usage circumstances. A
normal EV is driven ~1 hour a day at an average current of ~100 amps,
and then charges ~10 hours a day at an average current of ~10 amps. The
other 13 hours a day it is just sitting, letting the batteries cool back
down to ambient temperature.
> Obviously I'll need to have some sort of fan.
Only in hot climates, or when you drive and charge a lot more than the
"normal" amount (see above).
> He also said that there is an internal resistance. Does anyone
> know what that value is?
For 6v golf cart batteries, it is about 5 milliohms (0.005 ohms) when
fully charged. This value rises as the battery is discharged, as the
temperature drops, and as the battery ages. So, you can use 10 milliohms
as a typical number.
This means (for your professor friend) that a battery box with 18 golf
cart batteries has a total resistance of about R=0.18 ohms. If your EV
draws about I=100 amps at cruise (about right for your project), then
the heat being generated in the battery box is about P = I^2 x R = 100^2
x 0.18 = 1800 watts. For 1 hour's driving, that's 1.8 kwh x 3414 btu/kwh
6145 btu.
Now, 1 btu raises the temperature of 1 pound of water by 1 deg.F.
Batteries aren't all water, and they aren't perfectly insulated; so
their temperature actually goes up maybe twice this amount. Given that
these batteries weigh over 1100 lbs, 6145 btu will raise their
temperature about 2 x 6145/1100 = 12 deg.F after your drive.
Charging will add a few more deg.F. But then you have 13 hours for them
to cool back down. Thus, you aren't likely to have a problem.
I used twelve 6v golf cart batteries in my EV, in boxes insulated with
about 1" of styrafoam, and fiberglass batts for insulation on top (to
allow airflow for venting). Commuting to work every day in the winter,
the batteries stayed about 20-30 deg.F warmer than ambient. Here in
Minnesota, that means they were around 50-60 deg.F in winter (a little
cooelr than optimal, but acceptable without heaters).
In the summer, I left the top fiberglass batts off for better cooling.
Then the batteries ran 5-10 deg.F warmer than ambient. Here in
Minnesota, that means 80-100 deg.F, which is still acceptable without a
fan.
Also note that with insulation, the batteries have so much thermal mass
that it will take a week or so for them to "move" to a new temperature.
So, they do not respond to day/night temperature cycles.
--
"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 ---
Christopher Zach wrote:
> If I wanted to charge 10 batteries at once that were connected in
> series, could I just use a single 120 volt AC source, and a charge
> circuit that involved a transformer on each mini-charger and a seperate
> DC power supply to each battery?
>
> Thus each charger would be 100% isolated from any other, correct? (any
> monitor signals would be buffered by optoisolators)
Yes, you can use 10 individual chargers with isolated outputs. It's been
done, and it work reasonably well IF the individual chargers are
sufficiently reliable. But if you try it with "cheap junk" grade
chargers, then having 10 of them means your "system" is 10 times more
likely to fail. And when one charger fails, you may drive off with 9
charged and 1 dead battery. The dead one is going to do something
drastic!
--
"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
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Lee Hart wrote:
>Charging will add a few more deg.F. But then you have 13 hours for them to
>cool back down. Thus, you aren't likely to have a problem.
Lee, regarding Nicads and TS cells: given the same amperage on charge and
discharge, will the cells heat the same amount? For TS cells, for example,
if I drive them at an average of 60A, then bring them home and charge them
at 60A, will the amount of heat generated be the same?
Thanks.
Bill Dennis
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Yes, you can use 10 individual chargers with isolated outputs. It's been
done, and it work reasonably well IF the individual chargers are
sufficiently reliable.
*nod* I'm actually starting to work on the Prius Prismatic batteries as
a possible replacement for Hawkers. First step is to build some sort of
a charging system that can handle NiMH without blowing them sky-high.
Phase 1 is to have them power the Elec-Trak in place of six T105's
(reduced range)
I'm leaning towards building around the TI DV2004 charge controller; it
looks reasonable, handles the dt/dv, peak, and -DV charge cycles, can
top off/bulk, etc. Basically built for NiMH battery charging. Problem is
I don't know if I can make it work for 300+ volts, so the plan is to try
and use two chargers in series, one for each 18 (ok, 21) volts of a 36
volt pack. Cycle the packs thru the parallel strings (4 to start with)
with relays (for now) as the charge current is going to be under 3 amps.
I might be able to catch failure with a lockout circuit.
Chip specs at:
http://focus.ti.com/docs/toolsw/folders/print/dv2004s1.html
Chris
But if you try it with "cheap junk" grade
chargers, then having 10 of them means your "system" is 10 times more
likely to fail. And when one charger fails, you may drive off with 9
charged and 1 dead battery. The dead one is going to do something
drastic!
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I am confused:
I have T-105 (equivalent) batteries in my truck...
Warning: all of these figures are very approximate, and just used for
this example!
If I have a constant discharge rate of say 100 amps, I should get about
110-120ah out of my batteries.
On the other hand, if I discharge at about 10 amps, I should get about
220 ah out of these batteries.
In both cases, the batteries are discharged to about 100 percent of
capacity.
My question is:
When I recharge them, am I going to put ~220ah back into the batteries
in both cases, or am I going to only put 110-120ah back in after the
100amp discharge and 220ah after the 10amp discharge? I realize that in
either case I will have to put somewhat more amp hours back into the
battery than I took out, but that's beside the point (I think).
I guess I am wondering where the extra amp hours are going when the
Peukert effect kicks in.
Nick
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Mark Hastings wrote:
> I am going to use two PM Etek motors for my scooter/trike project
> and would really like to have contactorless reverse and regen which
> comes with the millipak 4Q...
>
> Can I use a single pot or a single linear accelerator that they sell
> to control both controllers
Why do you want to have two controllers? Just use one.
> ...with roughly 600+ amps at 48 volts?
How long do you expect an Etek to see that 600+ amps? That's a *lot* for
this motor!
--
"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
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Mike Chancey [mailto:[EMAIL PROTECTED] wrote:
> My concern is the controller, the Jet was 120 Volt system
> while the Rabbit was only setup for 108 Volts. Will the
> controller be happy at the reduced voltage?
Yes. (Even in the 120V '007, the main contactor used a 108V coil...
check the wiring carefully and you'll discover a couple watt resistor in
series with the contactor coil.)
The EV1 controllers were designed to run down to 1/2 the nominal pack
voltage.
> The intended use is just a local use vehicle, no high speeds
> or excessive range demands, 45 mph and 25 miles is more than
> enough. I suspect this combo should be able to do much better
> than that. Any other opinions?
The challenge may be the range. The EV1 subjects the batteries to high
peak currents even when the average draw is modest, so range tends to be
less than with a more modern high frequency controller. Driving
technique can help (try to keep the controller near max throttle so that
the on-time is maximised and ripple current minimised). Additional
inductance in series with the motor can help (look for a 'reactor' out
of a large welder; a good source may be David Chapman on this list).
Taking advantage of the controller's built-in bypass contactor control
logic can also help. The controller can only achieve about 90% duty
cycle, but if you install a bypass contactor it will use that to achieve
100%, during which time there is no battery current ripple and the
controller is able to cool off.
Cheers,
Roger.
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Bill Dennis wrote:
> Lee, regarding Nicads and TS cells: Given the same amperage on charge
> and discharge, will the cells heat the same amount?
How much a battery heats up during discharge is almost entirely due to
its internal resistance. There are no easy answers; it varies
considerably. In general, nicads have lower internal resistance.
Lead-acids, nimh, and lithiums all have a huge range of values; you can
find examples of very low resistance and very high resistance cells for
both types. So, you have to look at the specific cells to answer.
During charging, battery heating depends both on internal resistance and
how much overcharging is needed (for gassing, equalization, and other
reactions). Nicads need a considerable amount of overcharging, and so
generate the most waste heat from charging. Nimh, which are very
similar, are also high. Lead-acids don't start to heat until they are
almost fully charged. Lithiums are never overcharged, so you don't get
any additional waste heat from overcharging. However, they normally have
a per-cell batter management systems which burns up excess charging
power as heat, and this heat is dumped right at the the battery; so the
effect is much the same.
--
"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
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More pulse charging or something new? Found this on eBay, but I'd be suspect of
any "battery revival" technology:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7514789483
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anyone out there have a EV1 for sale?
--- Roger Stockton <[EMAIL PROTECTED]> wrote:
> John Wayland [mailto:[EMAIL PROTECTED] wrote:
>
> > mike golub wrote:
> >
> > > Is it worth using a SCR motor controller, if you
> are
> > > just starting to get involved with your first ev
> > > project, and you don't want to spend too much
> money?
> >
> > Sure, as long as you can put up with its limited
> power
> > delivery and noisy operation. Forklifts, though
> very
> > powerful, operate on gear reduction and only have
> to run at
> > low speeds, so they can get by on 10-18 kw of
> traction power.
>
> Rather than using a surplus forklift controller,
> look for a GE EV1 SCR
> controller someone has removed from an older
> conversion (like a Jet
> Industries 007). These typically ran 120V systems
> and had a 500 or 550A
> currnet limit. With a stiff pack, this is 66kW
> (upwards of 80HP).
>
> These controllers were rated for a maximum battery
> pack of 144V and the
> EV1 typically runs down to 1/2 its rated voltage, so
> one of these ought
> ot be happy when fed anything from about 60-144V.
>
> They also have built-in bypass contactor control
> logic, which you can
> use to improve efficiency and allow silent
> operation.
>
> > Unlike the
> > totally irritating non-varying 2 khz squeal of the
> Curtis
> > controllers, the SCR 'growl' is lower in
> frequency, varies,
> > and is more 'entertaining' than irritating.
>
> Absolutely! It also disappeared above about 20mph
> in the Omni
> conversion I used to own (96V, GE EV1, 7"
> Prestolite).
>
> Cheers,
>
> Roger.
>
>
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Well, I melted a post off one my tired old batteries.
It's time to replace them and their cables. I'm adding
batteries so I'm going to have to replace the battery
box. It's in the truck bed so it's a pretty easy
redesign. What I need to know is how much room to add
for clearence expansion? Do lead acid batteries swell
much, and if they do is it a bad thing to restrict it?
TiM McCann
'61 Electrc Corvair Rampside
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
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Nick [mailto:[EMAIL PROTECTED] wrote:
> If I have a constant discharge rate of say 100 amps, I should
> get about 110-120ah out of my batteries.
> On the other hand, if I discharge at about 10 amps, I should
> get about 220 ah out of these batteries.
> In both cases, the batteries are discharged to about 100 percent of
> capacity.
> My question is:
> When I recharge them, am I going to put ~220ah back into the
> batteries in both cases, or am I going to only put 110-120ah back
> in after the 100amp discharge and 220ah after the 10amp discharge?
You only return about 110% of what you removed. If you discharge at a
high rate and only get 100Ah, then you will only have to return about
110Ah to fully charge the battery. If you discharge at a low rate and
get 220Ah, then you'll return about 240Ah.
> I guess I am wondering where the extra amp hours are
> going when the Peukert effect kicks in.
The "extra" Ah, that is the 120Ah that you don't get out at the high
rate, are still in the battery. Mostly; you do lose some of them to
heat due to the I^2R losses at the high discharge rates.
Cheers,
Roger.
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Mark,
We are running two Siemens controllers off a single pot. It does not seem to
be a problem. The Kw-hr meter for each controller shows the two to be using
very close to the same amount of power, usually within .01 kw-hrs. It is
important to be careful about running the throttle wires in such a way that
they are not exposed to different amounts of interference otherwise the
power can be unbalanced.
Our separate motors drive the front and rear wheels rather than right and
left, so unbalance throttle input would affect us less.
Hope this helps
Cliff
www.ProEV.com
----- Original Message -----
From: "Mark Hastings" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, May 09, 2005 2:30 PM
Subject: Two motors, Two controllers Single POT?
I am going to use two PM Etek motors for my scooter/trike project and would
really like to have contactorless reverse and regen which comes with the
millipak 4Q. I wrote sevcon a while back so was hoping someone here had
some previous experience.
Can I use a single pot or a single linear accelerator that they sell to
control both controller to make sure they have the same input? My
intention is to remove another possible difference from the Dual scheme I
have going. I'm somewhat concerned the two motors and two controllers will
fight eachother, or just not fully reach their potential, but with two
input I fear disaster. Is there an off the shelf controller that will do
contactorless reverse and regen with roughly 600+ amps at 48 volts? Plan B
is an altrax 650amp running them both but then I have to add contactors
for reverse and lose regen.
Mark Hastings
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--- Begin Message ---
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--- Begin Message ---
Greetings, folks. My name is tom koehler, and I live in northeastern
Minnesota. I've been doing a lot of thinking about an electric car
conversion project, and have decided to act. I know that there is much
to learn, and will be going over the ev archives as much as I can. My
first reference book is "Build Your Own Electric Vehicle" by Bob Brant.
Though it is about 10 years old, I'm hoping it will still be a good
starting point for me. If you have other favorite references, please
let me know, if you will.
I've looked for reference to a list of FAQ's for this group, but so far
have failed to find such a reference. Is there such a list?
My ruminations so far, for my project are as follows: the donor car
would be my '93 2-door Explorer. (is physically sound and good
condition) My intention is to convert it to front wheel drive,
connecting the drive motor directly to the transfer case. The transfer
case has two "speeds" 1:1 and 2:1. Most usage will be in town, so the
2:1 gear should suffice. When I do decide to take this vehicle out of
town, I believe the 1:1 gear should work out. There's no serious
hill-climbing ability needed. Replace the conventional rear axle and
differential with a "straight" axle from another front wheel drive
vehicle. The contemplated system would be 120 volts DC.
I've a fairly thick hide, so please do not worry about bruising my
tender ego with your remarks and feedback. I'm going back into lurk
mode again, for awhile. Got to continue working on my list of questions.
Thanks for your time.
tom koehler
I will find a way, or make one.
(attributed to Hannibal, crossing the Alps
with his elephants in the Second Punic War,
22 centuries ago)
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