# [EVDL] EV Range question.



## EVDL List (Jul 27, 2007)

If your range is 80 km (50 mi) round trip then you can
convert the tiniest of cars when using Lithium batteries.
If you want to make that trip every day and not murder
your batteries then you need to design for a range double
that size when complletely depleting your batteries, so
you have a chance to keep them towards the good side of
50% discharge.
If you want to do this with lead then you most likely need
a lead-sled which is very optimized in operation and
driven extremely careful - not impossible but also not
very easy to achieve.

Why can't you charge at (or near) work?
I presume that wall outlets are as abundant in AU as
they are in USA or anywhere else around buildings.

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of David Galea
Sent: Tuesday, January 27, 2009 4:55 PM
To: [email protected]
Subject: [EVDL] EV Range question.

I wish to convert a donor car to an EV in the near future to replace my 
ICE car.
The purpose of this EV would be to commute to and from the city for
work.
The commute is 70-80 kms there and back without anyway of charging it at

work.
There is a huge bridge (West-gate bridge in Melbourne, Australia) that I

need to traverse so my choise of motor and batteries require it to catch

up to traffic (80-100km/hr) and accelerate OK. The car will mostly be a 
small car (I really want an aptera!) with seating for two people.

David Galea

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## EVDL List (Jul 27, 2007)

Here's a very basic rule of thumb that will conservatively get you there. 
What you propose is very doable with LiFePo4 batteries - I use THundersky's. 
You can discharge these to 70% DOD very conservatively or 80%DOD - quite
different from the 50% recommended for SLA batteries.

1. Take the current real world MPG of the donar car.
2. Assume 8kwH battery pack per gallon.
3. Design your battery pack for the desired range.

For example, the donar car gets 18 mpg after the fashion you want to drive
it. You want a range of 160 km or 100 miles.

100/18=5.55 gallons of gasoline
5.55 x 8 kwH = 44.44 usable kwH
44.44 x 1.25 = 55.55 kwH

We multiply the 44.44 kwH by 1.25 so that you can use 80% of your total
discharge (instead of 100% which is drain until dead). If you use lead
batteries, the desired figure is 50%.

While rough, this calculation basically uses the vehicles existing
efficiencies with regards to aerodynamics, weight, roling resistance, etc
summed into the current MPG. Actually it works pretty well. There are
actually 32kwH in a gallon of gasoline, but you will rarely see an ICE
vehicle exceed 25% efficiency.

Battery pack size in kwH is basically the voltage of the pack x the AH
rating of the pack. Again, this works with LiFePo4 packs, and essentially
does NOT work with SLA because of peukerts effect, essentially the
difference in what can be drawn from a battery based on the time period over
which it is drawn. In SLA, drawing energy at a faster rate decreases the
total amount you can draw. This effect is still there in LiFePo4 packs, but
is so small as to be negligable in these calculations.

So if you have a 144 volt pack and need 55.55 kwH:

55550/144 = ~386Ah.

Since generally, batteries are available at a specific AH rating, and the
motor and controllers typically work over a wider range up to a point, let's
assume a 180Ah Thundersky.

55550/180 ~ 308 volts. It is somewhat difficult to find DC motors and
controllers to do 308 volts and so this leads you to an AC induction motor
and inverter system to get there.

As you can see, getting a 100 mile range requires what is essentially an
enormous battery package.
These calculations look very different when viewed from a car that truly
gets 25 mpg. And so you see why we tend toward fairly small, fuel efficient
cars and trucks for conversions. Generally speaking, a 30-35kwH pack is
considered enormous and is actually quite difficult to fit into a vehicle.
I use a 20kwH pack and get 75 mile range, but it is in a tiny two seat
Porsche replica that only weighs 2380 lbs, and has great aerodynamics.

You goal is essentially unachievable using lead acid batteries. I have
heard of one case, but it was literally a full sized pickup truck with the
ENTIRE bed filled with batteries. And of course it was enormously heavy.

With LiFePo4s, you might get there with a light Honda or Toyota that had a
pretty spacious trunk and engine compartment. But 100 mile round trip is a
reach - particularly at highway speeds.

We are starting a Mini-Cooper project that could probably do this. The
Cooper gets a true 34-37 mpg on the highway. It does this by having a
fairly aerodynamic profile, and the six speed gertag transmission has all
three of the highest gears essentially operating as overdrive gears. And we
are using an AC induction motor.

In any event, that's how you do the calculations in Lithium land. Your
mileage may vary.
Good luck with your project.

Jack Rickard






> David Galea-3 wrote:
> >
> > I wish to convert a donor car to an EV in the near future to replace my
> > ICE car.
> ...


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## EVDL List (Jul 27, 2007)

Jack,

I like your rule of thumb approach. That's the first time I saw 
someone break it down like that, and it seams quite logical to me.

Just out of curiosity, do you figure that 75 miles is about 80% DOD on 
your LiFePO4s? If so, that's about 213 wh/mile. Is that driving 
conservatively?

Thanks,
Roger



> Jack Rickard wrote:
> 
> > I use a 20kwH pack and get 75 mile range, but it is in a tiny two seat
> > Porsche replica that only weighs 2380 lbs, and has great aerodynamics.
> ...


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## EVDL List (Jul 27, 2007)

As I recall, I ended the run with 3.21 v per cell static. The minimum on
these cells is 2.5v and ElitePower recommends not discharging below 2.8v. 
The discharge is quite flat to about 3.0 v and then it falls off the planet. 
So I think 75 is quite conservative at this point.

I am going to call that 80% erring on the side of caution.

As to the driving, it was very specifically NOT conservative. We had tire
pressure of about 34 lbs, and we drove 75 mph probably 1/3 of it. We drove
in very hilly terrain constantly. And as it IS a sports car, I was checking
acceleration at every takeoff. 

I don't really intend to drive a 356 Porsche "conservatively" so we
definitely were not driving gingerly.

Jack Rickard


Roger Heuckeroth wrote:
> 
> Jack,
> 
> I like your rule of thumb approach. That's the first time I saw 
> someone break it down like that, and it seams quite logical to me.
> 
> Just out of curiosity, do you figure that 75 miles is about 80% DOD on 
> your LiFePO4s? If so, that's about 213 wh/mile. Is that driving 
> conservatively?
> 
> Thanks,
> Roger
> 
>


> Jack Rickard wrote:
> >
> >> I use a 20kwH pack and get 75 mile range, but it is in a tiny two seat
> >> Porsche replica that only weighs 2380 lbs, and has great aerodynamics.
> ...


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## EVDL List (Jul 27, 2007)

David:

I misread your message in my previous response. The rules of thumb still
hold true, but I was assuming 80km one way and a 160km roundtrip. That's a
reach. If its 80 km "there and back" this is pretty easy with Lithiums.

Note these rules of thumb simply don't work on lead acid. You don't get the
20ah rate they are usually rated at in an hour or so, and yes, most of the
guys running SLA try to stay at 50% Depth Of Discharge (DOD) to prolong the
cycle life of the cells.

Jack Rickard




> David Galea-3 wrote:
> >
> > I wish to convert a donor car to an EV in the near future to replace my
> > ICE car.
> ...


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## EVDL List (Jul 27, 2007)

How about sag? When you pressed the pack, how did it do?

Dave Cover, looking to "Lithiumize" my Porsche too



> Jack Rickard <[email protected]> wrote:
> 
> >
> > As I recall, I ended the run with 3.21 v per cell static. The minimum on
> ...


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## EVDL List (Jul 27, 2007)

> dave cover wrote:
> > How about sag? When you pressed the pack, how did it do?
> >
> > Dave Cover, looking to "Lithiumize" my Porsche too
> ...


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## EVDL List (Jul 27, 2007)

Lithium batteries in general do not sag much - they retain full voltage 
until right at the end, when they drop very fast!!

Joseph H. Strubhar

Web: www.gremcoinc.com

E-mail: [email protected]


----- Original Message ----- 
From: "Willie McKemie" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Wednesday, January 28, 2009 6:18 AM
Subject: Re: [EVDL] EV Range question.


>


> dave cover wrote:
> >> How about sag? When you pressed the pack, how did it do?
> >>
> >> Dave Cover, looking to "Lithiumize" my Porsche too
> ...


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## EVDL List (Jul 27, 2007)

Quite impressive. Let us know when the E-Vision is working what the 
average W/mile is.



> Jack Rickard wrote:
> 
> >
> > As I recall, I ended the run with 3.21 v per cell static. The
> ...


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## EVDL List (Jul 27, 2007)

Well, I see 300-400 battery amps or so accelerating. My pack usually rests
at 104 or 105 fully charged. I see it as low as 87 volts under those
conditions. I thought it was "pretty dramatic" sag - rather beyond what I
expected.

In fact, I had the lower voltage on the Kelly Controller set at 90 volts. 
When I lowered that to 80, the acceleration improved markedly I was
unknowingly running in limp mode, generally when I was really trying to
accelerate quickly. We're now doing 0-80km in about 7 seconds. Not a
Tesla, but perky.

So I'm seeing 15% sag easily. And I'm 180 Ah wide, so I'm not asking a lot
from the batteries - less than 3C in all cases it would appear.

I have actually built a dummy load out of several huge 5 ohm resistors in
parallel. It has a built in ammeter, voltmeter, and some switches where I
can select 1 to 3 resistors in parallel.. I can put a 13.5 v pack of four
Thunderskys on it and watch it drop from 13.5 to 11.8 volts doing 50 amps. 
This is a 160 Ah battery. I have a couple of bench power supplies that then
let me charge the pack or individual cells. I'll intentionally "unbalance"
this battery to then try various active balancing circuits to bring them
back in. Too much time on my hands I guess...

I'm did a 10 segment LCD with an LM3914 chip to try to develop a monitor
that would be easy to tell at a glance the condition of each 4 cell
"battery" - more in respect to the other cells than to an absolute value. 
It worked quite well with very good granularity at about 0.15 volt per LED
segment. But that left it a little too narrow. So I'm now revising it to
work with two LM3914s and a 20 segment display. This should let me do 10.8
to 13.8 volts in 0.15 volt increments or 11.8 to 13.8 in 0.10 volt
increments. While a bit more expensive, it will fairly accurately portray a
batt from fully charged resting down to 80%DOD under load. 

I'll assemble them into a bank of 16 in an enclosure under the stereo - a
little over 2 inches high and maybe 7.5 inches wide. I'll wire it to the
batteries with ethernet cable. Despite having pack voltage in the cockpit,
which we've thus far avoided, my thinking is that the very light wires in
this will carry the voltage fine, but if a mishap occurs, the wires will act
as fuses. They won't be able to handle enough current to do much damage
before the smoke leaks out of them.

Jack RIckard



Willie McKemie-3 wrote:
> 
>


> dave cover wrote:
> >> How about sag? When you pressed the pack, how did it do?
> >>
> >> Dave Cover, looking to "Lithiumize" my Porsche too
> ...


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## EVDL List (Jul 27, 2007)

> Jack Rickard wrote:
> >
> > Well, I see 300-400 battery amps or so accelerating. My pack usually rests
> > at 104 or 105 fully charged. I see it as low as 87 volts under those
> ...


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## EVDL List (Jul 27, 2007)

Well, looking at your EVALbum it lists TS-LFP260s. Ye Gods and Little
Fishes. The reason you don't have any sag is that you've got enough battery
there to be a power station. 

I am running two parallel strings of TS LFP AH90s.
http://www.evalbum.com/2363. The common talk on the Thundersky forum is that
they don't sag. I think its more a factor of most of the motorcyle guys
just don't have a way to monitor it very well. Under load, they do sag, not
like an SLA but sagging nonetheless. But you would have to draw 500-600
amps to see much with 260 Ah batteries. These cells really can do 10C
briefly and if you stay under 3C they consider you a kind and gentle owner. 
That would be 780 amps for you.

You have a lot heavier car. But, yeah, it should go 100 miles easily. That
would be overkill here but I have two brothers who live in Texas and its not
like here in "The States." Things tend to be a bit spread out down there.

The EVision displays battery pack voltage and amps in digital form and
simultaneously. It also updates more frequently than most meters, or
appears to.

I read your EValbum. Yes, you paid a bit, but I fear that's the price of
occupying the bleeding edge. If it helps, I've got more in a 2 seat Porsche
replica and did it myself. From all I've seen and heard, EVBlue is doing
some very yeoman work on conversions and yours looks pretty good to me. My
only change would be to use 160 AH batteries. Your weight distrubution just
has to be rear heavy. But I don't need 100 miles....

My pack has just been unbelievably well balanced so far. I haven't put that
many miles on it yet. I had experimented with Seiden batteries earlier and
they were very problematical. Particularly on charging. They would charge
normally for awhile and then one cell would take off by itself and zoom to 5
or 6 volts. I had one go to 14v before I caught it. The Thundersky's seem
to share much better and I can't find much variation across the pack under
any realistic charging scenario. 

I have a couple of Thundersky chargers - my favorite will do 0-160v at 32
amps from 240 vac. It has a panel meter and nicely done adjustment knobs,
but no programmability. It's excellent for experiments and supervised
charging, and it does do a CV finish in very orderly fashion. 

The car has a Brusa 511 onboard. It charges from either 120vac or 240vac
and you can program the entire charge scenario with a very usable array of
parameters, time, voltage, amperage, temperature, etc through a number of
phases. It will do 25 amps from 240 vac and about 9.5 amps from 120 vac. 

What are you using to charge a 37 kWh pack?

You should be able to use a 6v charger and a multimeter to get your two
cells up manually - if you can get to them.

Jack Rickard 

Willie McKemie-3 wrote:
> 
>


> Jack Rickard wrote:
> >>
> >> Well, I see 300-400 battery amps or so accelerating. My pack usually
> >> rests
> ...


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## EVDL List (Jul 27, 2007)

> Jack Rickard wrote:
> <snip>
> > little over 2 inches high and maybe 7.5 inches wide. I'll wire it to the
> > batteries with ethernet cable. Despite having pack voltage in the cockpit,
> ...


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## EVDL List (Jul 27, 2007)

> Josh Wyatt wrote:
> > Jack Rickard wrote:
> > <snip>
> >> little over 2 inches high and maybe 7.5 inches wide. I'll wire it to the
> ...


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## EVDL List (Jul 27, 2007)

> Josh Wyatt wrote:
> > I would *stringly advise against* the use of ethernet cable for any
> > situation like this. Ethernet cable is made as cheaply as possible
> > with insulation which will generate serious toxins as it burns.
> ...


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## EVDL List (Jul 27, 2007)

I blunderstood you the first time. I kind of disogree, and I've been using
egernet for a long time. I've done quite a bit of bad POE and that's how I
know just what it will do. No, I'm not going to installulate 16 1/4 amp
fuses for this. More complexityization and something else to breakify
and/or developerize voltage drops.

The wire will smokify quite easily. And I've already inhalulated too much
of it. It's a convertible, not a submarine. If there's a short, these
batteries want to dump 100 amps. The wires ARE teh fuses. 

Oops. I meant THE not TEH.

Jack Rickard




> Josh Wyatt wrote:
> >
> >
> 
> ...


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## EVDL List (Jul 27, 2007)

I blunderstood you the first time. I kind of disogree, and I've been using
egernet for a long time. I've done quite a bit of bad POE and that's how I
know just what it will do. No, I'm not going to installulate 16 1/4 amp
fuses for this. More complexityization and something else to breakify
and/or developerize voltage drops.

The wire will smokify quite easily. And I've already inhalulated too much
of it. It's a convertible, not a submarine. If there's a short, these
batteries want to dump 100 amps. The wires ARE teh fuses. 

Oops. I meant THE not TEH.

Jack Rickard




> Josh Wyatt wrote:
> >
> >
> 
> ...


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## EVDL List (Jul 27, 2007)

As far as I know,
Plenum rated is being tested for its
smoke generating capabilities and
must be below a certain threshold of
blocking vision.
One of the reasons that typically very
light colors are used in Plenum rated
products.
But they certainly do smoke, just not
so much and not so fast... 


Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Rick Beebe
Sent: Friday, January 30, 2009 2:03 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] EV Range question.



> Josh Wyatt wrote:
> > I would *stringly advise against* the use of ethernet cable for any
> > situation like this. Ethernet cable is made as cheaply as possible
> > with insulation which will generate serious toxins as it burns.
> ...


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## EVDL List (Jul 27, 2007)

It's like fat chicks and mopeds. I may be caught using it but I wouldn't 
tell anyone 

Although data transmission is around 3 volts, typical line voltage on an 
analog phone is 48 volt and around 45ma. Ringing voltage can go as high as 
100 volts Ac. I've also used it many times to run 48 volt powered speakers. 
Also, IP phones get power through a POE network switch on the brown pr of a 
CAT5 cable. High power POE switches advertise being able to deliver up to 1 
amp for 24 phones. If I remember right Mitel phones are 15 watt each.

Solid core is not a good idea because of the vibration in a car. Plenum 
cable won't survive the temperature in a car for long and it breaks down 
rather quickly when exposed to the sun. PVC is recommended when running it 
outside. The entire reason for PVC v/s Plenum cable is because of the toxins 
put off when PVC catches fire. But... PVC is OK and passes most building 
codes as long as it isn't used in air return ceilings (drop tiles). Because 
PVC is more durable it is actually suggested for use in conduits.

One trouble is that the insulation on individual pair is exceptionally thin. 
It won't take much of a pinch or kink to short it out. In fact, although 
they are commonly used, tie wraps pulled to tight can short out a pair in a 
network cable. I see and fix it all the time.

So if I was going to do it, I'd use PVC and stranded and make sure I don't 
kink it or try to tie wrap it up to tight. Use grommets between panels and 
basically don't pinch it or tell anyone I did it.

Stub





> Rick Beebe wrote:
> > Josh Wyatt wrote:
> >> I would *stringly advise against* the use of ethernet cable for any
> >> situation like this. Ethernet cable is made as cheaply as possible
> ...


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## EVDL List (Jul 27, 2007)

> Jack Rickard wrote:
> >
> > What are you using to charge a 37 kWh pack?
> 
> ...


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## EVDL List (Jul 27, 2007)

Well, Stranded and higher voltage ethernet cable is actually quiet common.
For the toxicity part, plenum cable has two requirements

1) "Plenum cable must not burn easily"
2) "Plenum cable must not emit toxic fumes when exposed to extreme heat "

PS Hint: When you are making your own cables and are useing the stranded 
cable, the ends you crimp are different.

The last time I read the imprint on the ethernet cable it said 300V. But 
every manufacturer is diff.
Remember, it must be safe to run it along power cables.



> > Jack Rickard wrote:
> > <snip>
> >> little over 2 inches high and maybe 7.5 inches wide. I'll wire it
> >> to the
> ...


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