# [EVDL] DC v. AC



## EVDL List (Jul 27, 2007)

Ive been doing some research into EVs and understand fairly well now the 
issues involved with DC based systems but I've been struggling to find 
much info on AC systems - other than books which state AC to be the 
superior choice for the future, then carry on talking about how to do it 
with DC.

As a first timer Im a little unsure whether to invest in an AC system or 
a DC system, am I right in thinking that with AC I can get the same 
performance with a lower voltage -i.e less batteries?

Furthermore is the normal approach with AC to keep the voltage to the 
motor constant and vary speed by changing the frequency?

Andrew

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Andrew,

No, AC systems usually use higher voltage, not lower voltage. This is
a design choice for the motor designer, though, not something inherent
to the technology.

A good AC system will vary voltage, frequency, and phase to control
current to get as high efficiency as possible. The voltage and speed
are still usually proportional, though.

With an AC system, you will spend more money for the same performance,
but you will get slightly higher efficiency and regenerative braking.
DC systems are widely available and relatively inexpensive due to the
forklift industry; there's no equivalent AC motor source that we can
take advantage of.

-Morgan LaMoore



> Andrew Wood <[email protected]> wrote:
> > Ive been doing some research into EVs and understand fairly well now the
> > issues involved with DC based systems but I've been struggling to find
> > much info on AC systems - other than books which state AC to be the
> ...


----------



## EVDL List (Jul 27, 2007)

Thanks Morgan

I guess DC is the best choice then.


What Im looking at using is:

FB1-4001A motor
Trojan 27TMH 12v batteries (10 to give 120v)

I was looking at a Zilla controller but they seem to have stopped making 
them so Im opting for a Curtis instead.

Would this be reasonable?

Regards
Andrew


Morgan LaMoore wrote:
> Andrew,
>
> No, AC systems usually use higher voltage, not lower voltage. This is
> a design choice for the motor designer, though, not something inherent
> to the technology.
>
> A good AC system will vary voltage, frequency, and phase to control
> current to get as high efficiency as possible. The voltage and speed
> are still usually proportional, though.
>
> With an AC system, you will spend more money for the same performance,
> but you will get slightly higher efficiency and regenerative braking.
> DC systems are widely available and relatively inexpensive due to the
> forklift industry; there's no equivalent AC motor source that we can
> take advantage of.
>
> -Morgan LaMoore
>
>


> Andrew Wood <[email protected]> wrote:
> >
> >> Ive been doing some research into EVs and understand fairly well now the
> >> issues involved with DC based systems but I've been struggling to find
> ...


----------



## EVDL List (Jul 27, 2007)

I am thinking that you would be much happier with the logitech 120 - 156
volt controller. There are 3 models to choose from I am planning to use the
750 Amp unit ( part # CT2411 at evparts.com) for an upcoming 120 volt
project.
Best of luck on your project -Thos



> Andrew Wood <[email protected]> wrote:
> 
> > Thanks Morgan
> >
> ...


----------



## EVDL List (Jul 27, 2007)

> Thos True wrote:
> > I am thinking that you would be much happier with the logitech 120 - 156
> 
> Logisystem?
> ...


----------



## EVDL List (Jul 27, 2007)

> On 1 May 2009 at 22:27, Andrew Wood wrote:
> 
> > What Im looking at using is:
> >
> ...


----------



## EVDL List (Jul 27, 2007)

I stand corrected. Over the last several years, we have used one of their
controllers on our wild(e) golf cart, and I had been under the impression
that it was called a logitech. After going back to the site, I see my goof.
Thank you for noticing! -Thos



> Willie McKemie <[email protected]> wrote:
> 
> > On Fri, May 01, 2009 at 06:38:03PM -0700, Thos True wrote:
> > > I am thinking that you would be much happier with the logitech 120 - 156
> ...


----------



## EVDL List (Jul 27, 2007)

So 6v batteries are better than 12v then?

Id like to buy from Trojan because I know I can get those easily in the 
UK, but looking on the golf cart section of their website
(http://www.trojanbattery.com/Products/GolfCart.aspx) there is a lot to 
choose from is one particularly better than the others?

Im spoilt for choice with all these parts to choose from!

Andrew



> EVDL Administrator wrote:
> > On 1 May 2009 at 22:27, Andrew Wood wrote:
> >
> >
> ...


----------



## EVDL List (Jul 27, 2007)

> Andrew Wood <[email protected]> wrote:
> > So 6v batteries are better than 12v then?
> >
> 
> ...


----------



## EVDL List (Jul 27, 2007)

A mini, hence Im limited on space.

Looking at the Amp/hr rating the Trojan batteries appear to be good 
value compared to the others Ive seen on websites such as
everything-ev.com & evparts.com

If DC is the best ,why do the 'big' manufacturers only produce AC systems?

Andrew


Evan Tuer wrote:
>


> Andrew Wood <[email protected]> wrote:
> >
> >> So 6v batteries are better than 12v then?
> >>
> ...


----------



## EVDL List (Jul 27, 2007)

> Andrew Wood <[email protected]> wrote:
> > A mini, hence Im limited on space.
> 
> Hmm, and weight capacity. Quite a few people have attempted mini EVs,
> ...


----------



## EVDL List (Jul 27, 2007)

> Andrew Wood wrote:
> > As a first timer I'm a little unsure whether to invest in an AC
> > system or a DC system, am I right in thinking that with AC I can get
> > the same performance with a lower voltage -- i.e. less batteries?
> ...


----------



## EVDL List (Jul 27, 2007)

> Andrew Wood wrote:
> > So 6v batteries are better than 12v then?
> 
> The 6v batteries *we can get* are better than the 12v batteries *we can
> ...


----------



## EVDL List (Jul 27, 2007)

> Andrew Wood wrote:
> > If DC is the best, why do the 'big' manufacturers only produce AC systems?
> 
> In fact, the 'big' manufacturers produce nothing at all! They've built a
> ...


----------



## EVDL List (Jul 27, 2007)

Lee,

Your emails are dated 2008 ane coming in 100 pages back in my email stack. 
Please correct the time and date on your computer. Your contribution here 
is too important to be buried.

George




On Sat, 31 May 2008 09:18:51 -0400, Lee Hart wrote


> > Andrew Wood wrote:
> > > So 6v batteries are better than 12v then?
> >
> > The 6v batteries *we can get* are better than the 12v batteries *we
> ...


----------



## EVDL List (Jul 27, 2007)

<flamebait>
All motors run on AC
</flamebait>

They are either internally commutated or externally commutated 

The series DC motor comes from the forklift industry(and golf cart). It
makes it more available to us converters. It is designed for low voltage
operation. which is higher amps, but controllers are available.
Mostly we can buy 1 piece at a time from various vendors.
One of the failure modes in such a system is FULL ON. If the chances are
1 in 100,000 and you are selling 500,000 there is a possible /percieved
liability issue.
Brushes are a finicky beast. duty cyle and amps and the air's moisture
make a difference on wear. While it often seems auto companies would
love to have a regular repair item, the variablily is a nightmare for
warentees. Brushes and commutators, limit voltage and rpm.

AC motors are usually 3 phase and sealed. If you are making 1000's of
them, they are cheaper to make. They can easily be water cooled which
opens up packaging options. No brushes opens up the rpm and voltage
choices and means you can run at a higher rpm and gear it down. Which
lowers overall material costs and phase amps. The trade off is a need
for higher volts and much more intelligence in the controller. The
controller must be programmed or matched to the motor. This leads mostly
to a systems approach. You have to buy everything all at once. For
lightweight conversions, the total price difference is not much. The
exception is the higher voltage pack, if done with sealed batteries
needs more management $.

The AC motor controller failure mode is to stop turning, no launching
over someone in a cross walk. (this is again partially perceived because
an error in the software or the controller board can tell the power
section to do it anyway)

To meet what the auto manufactures feel is one of a many requirements,
ie >100 mile range, they want to use lithium-ion(advanced) batteries.
These cells generally like lower amps and higher voltage and they get to
save on all that wire weight and extra handling of the heavy wire. 


I think it is mostly a production scalability issue. If you are making
thousands, you have to sub-contract out the motor or make them yourself,
The AC can be lighter, less copper $$ and less iron $ and made with less
human labor. Big Saving when you are making 1000's.


_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

> George Swartz wrote:
> > Lee,
> >
> > Your emails are dated 2008 ane coming in 100 pages back in my email stack.
> ...


----------



## EVDL List (Jul 27, 2007)

> On 31 May 2008 at 9:30, Lee Hart wrote:
> 
> > Why did the big auto companies use AC for their EVs? There are many reasons.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

To hop into the discussion myself (a person who has spent the last year 
or two repairing a particular type of AC motor controller and getting 
very intimate with it's features) I think I can add something here.

One of the other reasons AC "controllers" cost more than DC might be 
because the AC "motor controller" does a lot more than just control the 
motor.

Let's compare the GM/Hughes Dolphin motor controller with something like 
a Curtis 1231 controller for DC motors. Both do the following:

Control motor speed from 0 RPM to max
Provide a 50kw peak output

However the Dolphin also does the following additional things.

For the motor:
Monitors the IGBT gate voltage and currents carefully and will shut
down if it detects a problem.

Monitors motor speed and changes torque profile with motor speeds.

Provides motor reversing without outside support

Can provide 3 user-selectable torque curves in "forward" and one in
"reverse" which map well to an ICE car's PRNDL selections

Provides regen as well as brake pot sensors for monitoring how hard
thee brake pedal is being pressed for dynamic regen.

Provides a slight amount of regen to simulate "engine drag" when you
let off the throttle (depending on the virtual "gear" selected)

Monitors temperatures and can run in reduced power mode if needed
(with indicator)

For the "house circuits"
Monitors current in and out of the battery and drives a "Fuel gauge"

Monitors water temperature and can cycle the radiator fan as needed

Monitors overall state and can cycle the water pump as needed

Monitors water, IGBT, and motor temperatures and drives a "water temp
gauge"

For safety's sake
Monitors two separate throttle POTs and will shut down if there is a
correlation error between them.

Monitors a high voltage loop circuit and will shut down if it is
breached (signaling unsafe exposed voltages)

Can monitor a switch to shut down in the event of excessive G forces.

Monitors for isolation faults in the motor and battery pack

Has control over the contactors.

Nifty stuff:
Has a built-in charger for conductive charging
Has a built-in 100 amp DC-DC converter
Has circuitry to pre-charge the HV capacitor rail
Same circuitry to discharge the HV capacitor rail
Full control over the main contactors

As well as a whole in-house processor system to allow fault diagnostics 
and monitoring of the whole car's performance via CAN or RS232 interface 
devices.

That's a lot of extra stuff over the standard Curtis. Now when you start 
getting into Zilla territory many of these things are included. But a 
Zilla 1k+PFC is starting to get into the expensive category.

I would posit that making a simple AC vector motor controller that 
doesn't do any of the neat stuff should not be that expensive anymore. 
There has been a lot of progress in the past 15 years: One can do all of 
the IGBT drive and monitoring functions with a single chip these days. 
You don't need a MACH-220+DSP to handle sequencing and the like, simple 
chips can do the job. But it's the integration of all the other nice 
"stuff" that IMO makes the AC systems nice.

Chris

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

> Evan Tuer wrote:
> >
> > The big manufacturers don't only produce AC systems - the most common
> > production EVs in Europe used brushed DC motors.
> ...


----------



## EVDL List (Jul 27, 2007)

T24gU2F0LCBNYXkgMiwgMjAwOSBhdCA5OjM4IFBNLCBNZXRyaWMgTWluZCA8YWNAbWV0cmljbWlu
ZC5jb20+IHdyb3RlOgo+IEV2YW4gVHVlciB3cm90ZToKPj4KPj4gVGhlIGJpZyBtYW51ZmFjdHVy
ZXJzIGRvbid0IG9ubHkgcHJvZHVjZSBBQyBzeXN0ZW1zIC0gdGhlIG1vc3QgY29tbW9uCj4+IHBy
b2R1Y3Rpb24gRVZzIGluIEV1cm9wZSB1c2VkIGJydXNoZWQgREMgbW90b3JzLgo+Cj4gSWYgeW91
J3JlIHRhbGtpbmcgYWJvdXQgb24tcm9hZCBFVnMgKG5vdCB3aGVlbCBjaGFpcnMgZm9yayBsaWZ0
cyBnb2xmCj4gY2FydHMgYW5kIHN1Y2gpLCB0aGlzIHN0YXRlbWVudCBpcyBub3QgYWNjdXJhdGUu
IFRoaXMgd291bGQgYmUgdGhlIGNhc2UKPiBtYXkgYmUgMzAgeWVhcnMgYWdvLCBidXQgbm90IHRv
ZGF5LgoKVmljdG9yLCB0aGVyZSdzIHRlbnMgb2YgdGhvdXNhbmRzIG9mIFBTQSByb2FkIEVWcyBt
YWRlLCBJIG93biBzZXZlcmFsCm15c2VsZi4gIFRoZSBsYXN0IG9uZXMgd2VyZSBwcm9kdWNlZCBv
bmx5IHRocmVlIG9yIGZvdXIgeWVhcnMgYWdvLgpUZWxsIG1lIHRoZSBBQyB2ZWhpY2xlIHdoaWNo
IGlzIG1vcmUgY29tbW9uIHRoYW4gdGhhdD8KCj4KPj4gSG93ZXZlciwgdGltZSBtb3ZlcyBvbiBh
bmQgYSBtb2Rlcm4gRVYgd291bGQgZGVmaW5pdGVseSB1c2UgYW4gQUMgb3IKPj4gQkxEQyBzeXN0
ZW0gdGhlc2UgZGF5cywgYXMgdGhlcmUgYXJlIG1hbnkgwqBhZHZhbnRhZ2VzIGFuZCB0aGUgcHJp
Y2UKPj4gZGlmZmVyZW5jZSBvZiB0aGUgY29udHJvbGxlciBpcyBkZWNyZWFzaW5nIGFzIGVsZWN0
cm9uaWMgY29tcG9uZW50cwo+PiBnZXQgY2hlYXBlciBhbmQgbW9yZSBwb3dlcmZ1bC4KPgo+IFll
cywgdGltZSBoYXZlIG1vdmVkIG9uIGFscmVhZHkuIElJUkMsIG9ubHkgUGV1Z2VvdCAxMDYgd2Fz
IGhpZ2ggdm9sdW1lCj4gcHJvZHVjdGlvbiBFViB0aGF0IHVzZWQgU2VwRXggREMgc3lzdGVtLgoK
QW5kIFNheG8sIEJlcmxpbmdvIC8gUGFydG5lciwgQ2xpby4uCgpCdXQgd2UgYXJlIGFncmVlZCAt
IERDIGlzIHByZXR0eSBtdWNoIGNvbnNpZ25lZCB0byBoaXN0b3J5IGZvciByb2FkIGNhcnMgbm93
LgoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KR2VuZXJh
bCBFVkRMIHN1cHBvcnQ6IGh0dHA6Ly9ldmRsLm9yZy9oZWxwLwpVc2FnZSBndWlkZWxpbmVzOiBo
dHRwOi8vZXZkbC5vcmcvaGVscC9pbmRleC5odG1sI2NvbnYKQXJjaGl2ZXM6IGh0dHA6Ly9ldmRs
Lm9yZy9hcmNoaXZlLwpTdWJzY3JpcHRpb24gb3B0aW9uczogaHR0cDovL2xpc3RzLnNqc3UuZWR1
L21haWxtYW4vbGlzdGluZm8vZXYKCg==


----------



## EVDL List (Jul 27, 2007)

Nice summary!



> Christopher Zach wrote:
> > To hop into the discussion myself (a person who has spent the last year
> > or two repairing a particular type of AC motor controller and getting
> > very intimate with it's features) I think I can add something here.
> ...


----------



## EVDL List (Jul 27, 2007)

On Sat, 2009-05-02 at 12:08 +0100, Andrew Wood wrote:
> A mini, hence Im limited on space.

A real Mini, or the BMW MINI? I'm converting the former. See
http://carrott.org/blog &
http://carrott.org/cgi-bin/twiki/view/ElectricMini/WebHome

As others have said, a Mini is a challenge to convert. The MGVW is
1050kg, mine started out at 720kg with a full tank of fuel. When I'm
done it will be at about 750kg. See
http://carrott.org/blog/archives/78-Weights-Measures.html

The mini gearbox is really not an easy thing to use, I ended up
replacing mine with a Mitsubishi gearbox.

> Looking at the Amp/hr rating the Trojan batteries appear to be good 
> value compared to the others Ive seen on websites such as
> everything-ev.com & evparts.com

I really wouldn't try to do a mini with lead batteries, unless you're
going to be happy with very short range. For reference, my car does
about 30km of mixed highway & suburban speeds per charge with a 50kg
Thundersky Lithium Iron Phosphate battery. I'm going tripple the size of
the battery shortly.

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Andrew,

You also may want to consider an open source DC controller. There is 
a group on Ecomodder currently working diligently on an open source 
144V, 500A controller that can be assembled for less than $500. Its 
still in the testing phases, but if your not in a super hurry for it, 
and have some basic electronics skills, this may be an option for 
you. See:

http://ecomodder.com/forum/showthread.php/paul-sabrinas-cheap-144v-motor-controller-6404.html

Good Luck!
Roger



> Thos True wrote:
> 
> > I am thinking that you would be much happier with the logitech 120 -
> > 156
> ...


----------



## EVDL List (Jul 27, 2007)

Is this one of the newer Minis, or a classic Mini?

DC is not the best. DC is the most affordable. For a Mini, you could 
look at a AC package by HPG. They are limited to 96V and 40 HP peak 
and 12 HP continuous, but that may be enough for a mini. They cost 
around $4,300 for motor and controller. That's currently the least 
expensive AC option that I know about.

See
http://www.evparts.com/prod-MT5610.htm

or

http://www.thunderstruck-ev.com/AC_drive_performance.htm

Roger



> Andrew Wood wrote:
> 
> > A mini, hence Im limited on space.
> >
> ...


----------



## EVDL List (Jul 27, 2007)

I would agree with this. This package is pretty small, but it would
probably suit that car very well.. and it' is smaller and lighter motor as
well, and with a pack of lithium batteries, you could get quite good
performance without exceeding the GVWR.

Z



> Roger Heuckeroth <[email protected]>wrote:
> 
> > Is this one of the newer Minis, or a classic Mini?
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Andrew Wood asked (in part):
> If DC is the best ,why do the 'big' manufacturers only produce
> AC systems?


As someone else answered, DC is less expensive for the conversion 
market. My answer to why the manufacturers prefer AC has very little to 
do with technology, but one of liability. If a controller fails in a DC 
system you generally get either dead or uncontrollable full throttle 
(really BAD). If a controller fails in an AC system, almost universally 
you get dead or a reduction of power. The legal department would have a 
cow over a failure mode that leaves the car at full throttle.


-- 
73
-------------------------------------
Jim Walls - K6CCC
[email protected]
Ofc: 818-548-4804
http://home.earthlink.net/~k6ccc
AMSAT Member 32537 - WSWSS Member 395

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

> Jim Walls wrote:
> > As someone else answered, DC is less expensive for the conversion
> > market. My answer to why the manufacturers prefer AC has very little to
> > do with technology, but one of liability. If a controller fails in a DC
> ...


----------



## EVDL List (Jul 27, 2007)

From: Jim Walls
>My answer to why the manufacturers prefer AC has very little to 
>do with technology, but one of liability. If a controller fails in a DC 
>system you generally get either dead or uncontrollable full throttle 
>(really BAD). If a controller fails in an AC system, almost universally 
>you get dead or a reduction of power. The legal department would have a 
>cow over a failure mode that leaves the car at full throttle.

When a failure leads to a bad outcome, you don't just hope it will never happen, or avoid the technology completely. Example: Cars might crash. Are the only options to a) ignore the risk, or b) never drive?

Of course not! Instead, we design safer cars. We figure out what might go wrong, and provide ways to deal with it. We make cars that are less likely to crash, and if they do, the occupants are more likely to survive.

The same is true for EV design. If a failure leads to a runaway motor, you design in ways to prevent such a failure, or to reduce the hazard if it does occur.

If you let the corporate lawyers and accountants make all the decisions, nothing new would ever be done. They would tell you to never *ever* go first.

--
Those who say it cannot be done should not interrupt the one who is
doing it. -- Chinese proverb
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

> Lee Hart <[email protected]> wrote:
> 
> >
> > If you let the corporate lawyers and accountants make all the decisions, nothing new would ever be done. They would tell you to never *ever* go first.
> ...


----------



## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> > From: Jim Walls
> >> My answer to why the manufacturers prefer AC has very little to do
> >> with technology, but one of liability. If a controller fails in a
> ...


----------



## EVDL List (Jul 27, 2007)

Actually, on the MES system anyway, it is so programmable that you set 
the max rpms that will allow a shift from fwd to rev or vice versa. 
When I made my shifter I spent a while with springs and notches so that 
the shifter couldn't be bumped into reverse while driving but it's not 
even necessary - I can knock it into reverse while coasting fwd and it 
doesn't care. It just rolls until it hits the programmed rpm and I hit 
the pedal and then it gently reverses direction. The DC punch is fun 
(and you can't beat the cost), but the AC system is really smooth all 
the way around and has a nice pull thru the rpms. It's almost too 
programmable though - still tweaking the 300 + parameters 8<{

Gary Krysztopik
www.ZWheelz.com
www.aceaa.org
San Antonio, TX



> As a side note on this: One of the things recently that amazed me about
> the Dolphin is that the wires going in for the PRNDL have 3 bits for the
> state of the shifter and a fourth bit for PARITY.
>
> Thus if one of the wires gets shorted or opened, the Dolphin will
> respond with a parity fault and go into "park" (disable motor).
>
> Now *that* is proper thinking. Because it would be crummy for a short to
> put the car into reverse at 70mph *
>
> This is what makers of AC controllers seem to think about. Parity on key
> signal lines. That's pretty cool. 
> 
>
> Chris
> (on an AC powered car, this would simply slow the car down *quickly* as
> it would basically turn the forward velocity into max regen. Still, I'd
> rather coast to a stop.)
>
>
> 

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

> Roger Heuckeroth wrote:
> > Is this one of the newer Minis, or a classic Mini?
> >
> > DC is not the best. DC is the most affordable. For a Mini, you could
> ...


----------



## EVDL List (Jul 27, 2007)

Keep in mind that the duty cycle used to define continuous may not be the
same as for a typical EV. I do not know what they use -- 30 minute, 1 hour,
3 hour? A typical electrical circuit is not defined as continuous unless
it is more than 3 hours. I think that motors are usually 1 hour... but I do
not know for sure, or for this motor in particular. An EV is unlikely to
keep up highway speed for more than an hour -- so... who knows.

>From what I hear this motor can keep a geo metro at 65mph easily, but I
don't know for how long.

Z



> Tom Parker <[email protected]> wrote:
> 
> > On Sun, 2009-05-03 at 07:37 -0400, Roger Heuckeroth wrote:
> > > Is this one of the newer Minis, or a classic Mini?
> ...


----------



## EVDL List (Jul 27, 2007)

Tom, what batteries, make, type, voltage are you using for that?



> Tom Parker wrote:
> >
> >
> > I can do about 85km/h
> ...


----------



## EVDL List (Jul 27, 2007)

At the moment I have 36 Thunder Sky LFP40AHA 3.2v Lithium Iron Phosphate
cells manufactured in mid 2008 (two aluminium posts, newer ones have one
copper, one aluminium). I'm limiting my battery current to 200A, the
battery sags to about 95V at this current. When I'm finished I'll have
about 100 cells.

I haven't yet paid any attention to optimising the interconnections, I
believe the resistance can be usefully reduced by cleaning the posts and
using thicker straps. They were supplied with quite thin copper straps,
it might be better to replace them with aluminium to reduce long term
corrosion problems.

You can see more about my car at
http://carrott.org/cgi-bin/twiki/view/ElectricMini/

On Wed, 2009-05-06 at 19:16 +0100, Andrew Wood wrote:
> Tom, what batteries, make, type, voltage are you using for that?
> 
> Tom Parker wrote:
> >
> >
> > I can do about 85km/h
> > on the flat in my classic Mini. I haven't tried to optimise my rolling
> > resistance yet. I've got 20kW peak which is more than enough around
> > town, 40kW peak would be great.
> >
> > Soon I'll enlarge my battery and have more power.
> >
> > _______________________________________________
> > General EVDL support: http://evdl.org/help/
> > Usage guidelines: http://evdl.org/help/index.html#conv
> > Archives: http://evdl.org/archive/
> > Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
> >
> >
> > ______________________________________________________________________
> > This email has been scanned by the MessageLabs Email Security System.
> > For more information please visit http://www.messagelabs.com/email 
> > ______________________________________________________________________
> > 
> 
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
> 

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Keep the interconnects copper, Tom - aluminum will corrode worse, and the 
copper is MUCH better at transferring energy.

Joseph H. Strubhar

Web: www.gremcoinc.com

E-mail: [email protected]


----- Original Message ----- 
From: "Tom Parker" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Friday, May 08, 2009 3:15 AM
Subject: Re: [EVDL] DC v. AC


> At the moment I have 36 Thunder Sky LFP40AHA 3.2v Lithium Iron Phosphate
> cells manufactured in mid 2008 (two aluminium posts, newer ones have one
> copper, one aluminium). I'm limiting my battery current to 200A, the
> battery sags to about 95V at this current. When I'm finished I'll have
> about 100 cells.
>
> I haven't yet paid any attention to optimising the interconnections, I
> believe the resistance can be usefully reduced by cleaning the posts and
> using thicker straps. They were supplied with quite thin copper straps,
> it might be better to replace them with aluminium to reduce long term
> corrosion problems.
>
> You can see more about my car at
> http://carrott.org/cgi-bin/twiki/view/ElectricMini/
>
> On Wed, 2009-05-06 at 19:16 +0100, Andrew Wood wrote:
>> Tom, what batteries, make, type, voltage are you using for that?
>>
>> Tom Parker wrote:
>> >
>> >
>> > I can do about 85km/h
>> > on the flat in my classic Mini. I haven't tried to optimise my rolling
>> > resistance yet. I've got 20kW peak which is more than enough around
>> > town, 40kW peak would be great.
>> >
>> > Soon I'll enlarge my battery and have more power.
>> >
>> > _______________________________________________
>> > General EVDL support: http://evdl.org/help/
>> > Usage guidelines: http://evdl.org/help/index.html#conv
>> > Archives: http://evdl.org/archive/
>> > Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>> >
>> >
>> > ______________________________________________________________________
>> > This email has been scanned by the MessageLabs Email Security System.
>> > For more information please visit http://www.messagelabs.com/email
>> > ______________________________________________________________________
>> >
>>
>> _______________________________________________
>> General EVDL support: http://evdl.org/help/
>> Usage guidelines: http://evdl.org/help/index.html#conv
>> Archives: http://evdl.org/archive/
>> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>>
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>


--------------------------------------------------------------------------------



No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.325 / Virus Database: 270.12.21/2102 - Release Date: 05/07/09 
05:57:00

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

> joe wrote:
> > Keep the interconnects copper, Tom - aluminum will corrode worse, and
> > the copper is MUCH better at transferring energy.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

there is a special salve that u have to use on aluminum wire when
doing house wireing.
Louis in central BC
----- Original Message ----- 
From: "Lee Hart" <[email protected]>
.
> 
> However, aluminum is a pretty good conductor. It's almost as good as 
> copper, and actually has *less* resistance per pound (important when low 
> vehicle weight is the goal)
> -- 
> Ring the bells that still can ring
> Forget the perfect offering
> There is a crack in everything
> That's how the light gets in -- Leonard Cohen
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
> 
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
> 
>

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

I see on your website you say

"I hope they turn out to be a good investment as Thunder Sky don't 
have the best reputation."

How have you found them? Any problems?



> Tom Parker wrote:
> 
> > At the moment I have 36 Thunder Sky LFP40AHA 3.2v Lithium Iron
> > Phosphate
> ...


----------



## EVDL List (Jul 27, 2007)

> joe wrote:
> > Keep the interconnects copper, Tom - aluminum will corrode worse, and the
> > copper is MUCH better at transferring energy.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

On Sat, 2009-05-09 at 14:39 +0100, Andrew Wood wrote:
> I see on your website you say
> 
> "I hope they turn out to be a good investment as Thunder Sky don't 
> have the best reputation."
> 
> How have you found them? Any problems?

No problems so far, but I really haven't put them to any significant
use.

I've exercised 36 of the cells and taken 27Ah (from a 40Ah cell). I
really need to finish the car and get the rest of the battery installed!

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

My cells are have seen 16 months use (Oct 2007 build date) and 14'000
lifetime AH drawn. 
I havent witnessed any corrosion issues yet.
Im using the supplied TS interconnects (which I assume are copper)

Matt

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Tom Parker
Sent: Monday, 11 May 2009 7:07 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] DC v. AC



> joe wrote:
> > Keep the interconnects copper, Tom - aluminum will corrode worse, and
> > the copper is MUCH better at transferring energy.
> 
> ...


----------

