# [EVDL] Range: 156Volts vs 312 volts



## EVDL List (Jul 27, 2007)

> David Nelson wrote:
> > I'm trying to understand a little better the components which affect
> > range.
> 
> ...


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## EVDL List (Jul 27, 2007)

David said
"Maybe a better
comparison might be 25 T-145s for a 150v pack to 22 T-1275s for a 264
volt pack (1800lbs vs 1804lbs)? "

This is is a very interesting question and similar to one that I worked on
recently. I found Uve's Battery page to be a great tool for looking at this
question. The factory battery ratings are at the 20 hr rate and we need to
discharge at a much faster ( 1/2 hr rate ) for an EV. Here are the numbers
that I came up with using your 2 batteries listed above. 
See http://www.geocities.com/CapeCanaveral/lab/8679/battery.html

T 145 6 volt battery 150 volt pack. qty 25
Peukert Exponent = 1.179 ( lower is better )
Amp Hr at 1/2 hr rate = 142
150 volt * 142 amp hr = 21,300 watt hr
21,300 divide by 350 watt hr per mile = 60.8 mile range ( 100% DOD )

T 1275 12 volt 264 volt pack. qty 22
Peukert Exponent = 1.252 
Amp Hr at 1/2 hr rate = 74
264 volt * 74 amp hr = 19,536 watt hr
19,536 divide by 350 watt hr per mile = 55.8 mile range 

They are pretty close, but the 6 volt option looks like slightly better
range. I talked to the Trojan customer service about this question also and
they told me that the 6 volt battery had more plates per cell and would thus
handle a fast discharge rate better. 

They also said the warranty on the 6 volt battery is 36 months and the 12
volt is only 30 months. I asked about failure rate and they said the 6 volt
battery has a better record on reliability and the warranty reflects that. 

My guess is that the higher voltage pack would have better acceleration and
top speed. The lower voltage pack would have better range. Maybe others with
more experience could comment on that. 

Hope that helps,
Kyle 
http://www.evalbum.com/1414
http://www.zevutah.com/




> David Nelson-5 wrote:
> >
> > I'm trying to understand a little better the components which affect
> > range. Suppose I convert my S10 pickup and use a Zilla HV controller.
> ...


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## EVDL List (Jul 27, 2007)

All other things being equal, the best predictor of range is battery mass as 
a percentage of vehicle weight. Your proposed batteries are nearly equal in 
mass, and they'll most likely deliver very similar range.

A few notes -

AGM batteries may deliver somewhat better range where you expect to 
discharge the battery in appreciably less than an hour. This would be the 
case if you plan to race the EV, or if ast acceleration is more important to 
you than range. (Now that I look at that paragraph it seems contradictory - 
AGMs will deliver better range if you don't care about range. Hmmm. ;-)

AGM batteries usually have a higher cost per mile (or km), sometimes MUCH 
higher. I'm sure the numbers have changed, but about 7-8 years ago, I 
calculated the per-mile cost of Optima batteries at about seven (!) times 
that of flooded golf car batteries (that is, 600% higher). Today lead 
prices are very high so that's a bigger part of batteries' cost, and that 
seems to have diminished the spread a bit. The cost difference may also be 
lower for Universal batteries, which are made in China and thus perhaps 
cheaper than some other brands (however I get the impression that they're 
not a first line battery with the quality of, say, Hawkers, so I'd want to 
test a few for cycle life before assuming anything). In any case, for some 
people, the convenience of not watering or cleaning is worth a difference 
of even 600%. (Not for me, however. ;-)

There are fewer choices in higher voltage DC controllers.

OTOH, most common AC EV drives are designed for higher voltages.

David Roden
EVDL Administrator
http://www.evdl.org/


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## EVDL List (Jul 27, 2007)

Lee,
I know we've had this thread before (over and over!), and I agree that for the most part range equates to weight, but if you double the pack voltage so that you are drawing one-half the current from the traction pack (for the same power), you should get a few more amp-hours, no? Maybe I should restudy Peukert's law! And now that I think about it, you are burning up less energy in waste heat in the connections. I do enjoy the lower current that the 192 volt pack of Orbs provides the RX-7 at highway speeds, unlike the S10...

David,
I have a 144 volt '89 extended cab S10, and it would be difficult to get more than 24 floodies in one, especially if you are going to have nice poly boxes (and maybe an inch of insulation). My truck would do 50-60 miles with 24 T-145's, but that is pushing the range of a lead brick! Although I got 20,000 miles out of that pack with deep discharges, you won't get that out of AGM's. Not to mention the additional cost of a charging system for sealed AGM's. Also, you mentioned a Zilla, and the 1K will work well in your lead brick.
Suck Amps,
BB

>Date: Sun, 11 May 2008 09:08:15 -0500
>From: Lee Hart 
>


> >David Nelson wrote:
> >> I'm trying to understand a little better the components which affect
> >> range.
> >
> ...


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## EVDL List (Jul 27, 2007)

> Lee,
> I know we've had this thread before (over and over!), and I agree that for
> the most part range equates to weight, but if you double the pack voltage
> so that you are drawing one-half the current from the traction pack (for
> the same power), you should get a few more amp-hours, no?

No.

If you have the same number of batteries and wire them as buddy pairs for
156 or a single straight string for 312, then the individual batteries see
EXACTLY the same amps for a given total power output.

Yes you need twice as many amps at 156V, but the current gets split in
half across each battery in the pair.

If you are using a single string of large batts for 156V or a single
string of smaller batts for 312V, then (for a given weight) the large
batts will have about twice the capacity as the small bats and even though
they will see twice the current, the ratio of amps to amphour rating is
the same.



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## EVDL List (Jul 27, 2007)

> Zevutah wrote:
> 
> > David said
> > "Maybe a better
> ...


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## EVDL List (Jul 27, 2007)

>
> Lee,
> I know we've had this thread before (over and over!), and I agree that for the most part range equates to weight, but if you double the pack voltage so that you are drawing one-half the current from the traction pack (for the same power), you should get a few more amp-hours, no?


I would say only if amphours is kept constant. And then of course the
pack weights twice as much. For the same weight you are now pulling
twice the C-rate of the battery. This is at least how the battery sees it.

I have a 288V pack and part of getting that within a weight I could
manage was using AGM's. Excide Orbitals. But to be honest, I believe the
15% or so the orbital design wastes in air space is, well, a waste. SO
my pack ended up less than 1/2 an equivilent volume of 6 volters would
have been. I am looking at trying Deka Dominators or hawkers, But
lithium is my goal.

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## EVDL List (Jul 27, 2007)

> T 145 6 volt battery 150 volt pack. qty 25 Peukert Exponent =
> 1.179 ( lower is better ) Amp Hr at 1/2 hr rate = 142 150
> volt * 142 amp hr = 21,300 watt hr 21,300 divide by 350 watt
> hr per mile = 60.8 mile range ( 100% DOD )

Well, I suppose that is true if you travel at 120 mph, since that's the
only way you can travel 60 miles while discharging the batteries in only
30 minutes (1/2 hr rate)

Plus, it's VERY important to note that the Peukert formula is just an
approximation of what to expect, it is NOT a perfect fit.
It is /somewhat/ accurate if you calculate the Peukert exponent with rates
that a similar to the rate you are trying to estimate.

I.e. if you use the 10 hr discharge rate and the 20 hr discharge rate to
calculate the Peukert exponent, and then try to use this to calculate the
1/2 hr discharge rate, the results will likely be very different from
reality.


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## EVDL List (Jul 27, 2007)

On Sun, 11 May 2008 09:08:15 -0500


> Lee Hart <[email protected]> wrote:
> 
> 
> > An AC system will cost 2-3 times more, and give you 10-20% more range.
> ...


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## EVDL List (Jul 27, 2007)

> Ralph wrote:
> > FWIW I got my AC kit from Electro Automotive; the cost was about 25% more, not 2-3 times. I went with the Azure Dynamics system as it is air-cooled. It is less expensive than the other AC systems (AC Propulsion and Siemens); those systems really do cost 2-3 times more! I figured since the range **at best** is only 100 miles, that air-cooling won't make that much difference up here on the flats in Minnesota! We have a variety of cooling options if I am plain wrong about that...
> >
> 
> ...


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## EVDL List (Jul 27, 2007)

About 25% more than the cost of the DC conversion kit.


On Mon, 12 May 2008 12:16:58 -0700


> "John G. Lussmyer" <[email protected]> wrote:
> 
> > Ralph wrote:
> > > FWIW I got my AC kit from Electro Automotive; the cost was about 25% more, not 2-3 times. I went with the Azure Dynamics system as it is air-cooled. It is less expensive than the other AC systems (AC Propulsion and Siemens); those systems really do cost 2-3 times more! I figured since the range **at best** is only 100 miles, that air-cooling won't make that much difference up here on the flats in Minnesota! We have a variety of cooling options if I am plain wrong about that...
> ...


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## EVDL List (Jul 27, 2007)

I have a similar situation re elevation. Regen won't buy you anything
if your batteries are fully charged when you leave home. Electric cars
are happier when you live in the valley rather than the mountaintop.


> (I have a 2
> mile drop from my house and a few smaller hills so I'm also thinking
> of the regen) or go with a DC system.
> David D. Nelson
>
>
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>



-- 
http://www.austinev.org/evalbum/1059
http://stormselectric.blogspot.com/
Storm

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## EVDL List (Jul 27, 2007)

On Mon, May 12, 2008 at 1:59 PM, storm connors <[email protected]>


> wrote:
> 
> > I have a similar situation re elevation. Regen won't buy you anything
> > if your batteries are fully charged when you leave home. Electric cars
> ...


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## EVDL List (Jul 27, 2007)

Diesel powered cars have very little compression braking and seem to be
able to descend hills safely.

Considering the limited amount of hill that you can climb, I don't think
you'll have enough downhill to cause any serious problems for the brakes.

I think this is practically a non-issue.

> On Mon, May 12, 2008 at 1:59 PM, storm connors <[email protected]>


> > wrote:
> >
> >> I have a similar situation re elevation. Regen won't buy you anything
> >> if your batteries are fully charged when you leave home. Electric cars
> ...


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## EVDL List (Jul 27, 2007)

----- Original Message ----- 
From: "Peter VanDerWal" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Monday, May 12, 2008 3:28 PM
Subject: Re: [EVDL] Range: 156Volts vs 312 volts


> Diesel powered cars have very little compression braking and seem to be
> able to descend hills safely.

Huh? What? Diseasel cars compression brake just fine! Hell you need a GP 
27 battery to crank the damn things when it's cold! Of course they go down 
hills great in low gear, like throwing out the anchor!

> Considering the limited amount of hill that you can climb, I don't think
> you'll have enough downhill to cause any serious problems for the brakes.
>
> I think this is practically a non-issue.

In hilly CT hasn't been an issue! Out west with MILES of downgrade it 
COULD be an issue, though?

>> On Mon, May 12, 2008 at 1:59 PM, storm connors <[email protected]>


> >> wrote:
> >>
> >>> I have a similar situation re elevation. Regen won't buy you anything
> >>> if your batteries are fully charged when you leave home. Electric cars
> ...


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## EVDL List (Jul 27, 2007)

I really appreciate everyone's responses. It sounds like I need to
keep in mind what I've been reading over the past year or so that no
EV conversion is really ever finished and that I can always build
another one after getting more experience under my belt.

On the cost side of things it looks like I'd be ahead to go with 6v
flooded and a low voltage Zilla. If I read Otmar's web site correctly
that if I needed to go to a higher voltage later I could have him
upgrade my controller.

As for an AC system I like the idea of having regen, not so much for
any range I might gain, but for braking. I know that I wouldn't get
too much regen buffer in a full pack but there should be a little,
especially if my Gizmo is any indication (SepEx motor, T-875s). I
don't need much but I do occasionally have a 0.5mi steep down hill
with a stop at the bottom. The reality is that if this were too much I
could take the long way around. As Peter said below:


> Peter VanDerWal <[email protected]> wrote:
> > Diesel powered cars have very little compression braking and seem to be
> > able to descend hills safely.
> >
> ...


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## EVDL List (Jul 27, 2007)

> Peter VanDerWal <[email protected]> wrote:
> 
> > Considering the limited amount of hill that you can climb, I don't think
> > you'll have enough downhill to cause any serious problems for the brakes.
> ...


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## EVDL List (Jul 27, 2007)

I don't know if going downhill in a car that now has no engine breaking and
is probably over the design weight of the brakes on the car would be
considered a non issue, of course the first trip down the hill will be the
deciding factor. I do like the idea of the resistor across the motor for
engine braking but would you not have to put some voltage to the field to
get it to work?

Mark Grasser


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Peter VanDerWal
Sent: Monday, May 12, 2008 3:29 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Range: 156Volts vs 312 volts

Diesel powered cars have very little compression braking and seem to be
able to descend hills safely.

Considering the limited amount of hill that you can climb, I don't think
you'll have enough downhill to cause any serious problems for the brakes.

I think this is practically a non-issue.

> On Mon, May 12, 2008 at 1:59 PM, storm connors <[email protected]>


> > wrote:
> >
> >> I have a similar situation re elevation. Regen won't buy you anything
> >> if your batteries are fully charged when you leave home. Electric cars
> ...


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## EVDL List (Jul 27, 2007)

> Zeke Yewdall wrote:
> > Schools
> > busses for use in the mountains here are required to have an electric
> > retarder on the driveshaft in case the brakes fail (I think a bus full of
> ...


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## EVDL List (Jul 27, 2007)

True.... It must have been a situation where the engine failed so they lost
engine braking, then the brakes overheated and stopped functioning.

Z

On Tue, May 13, 2008 at 7:26 AM, Karl Bellve <[email protected]>


> wrote:
> 
> > Zeke Yewdall
> 
> ...


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## EVDL List (Jul 27, 2007)

My old CableForm controller had resistance braking. It consist of another 
main contactor and a resistor in series with that contactor. As the 
accelerator was de-press, the main contactor would open and this resistance 
braking contactor would close if I had a control switch on, which it allow 
to do so.

A DC series motor with compensating fields normally become a generator when 
a mechanical force is use to turn it. The problem here, is when you put in 
100 percent battery power to become a motor, it will only become a 75 
percent generator, because you lose about 25 percent by iron saturation.

The DC series type motor is connected to a large 300 amp diode which is 
place in the direction that battery current cannot flow from the battery to 
the motor. It is same type of diode that is across the main contactor which 
is call a free wheel diode.

There is several ways that the energy can be use from the main motor during 
the coast down time. One is where the resistance braking contactor is 
connected directly to a very large resistor that will accept any level of 
voltage and provide some load to the motor which slows the EV.

One way, which is call rheostatic braking. This involves disconnecting the 
motor from the supply, reversing the field connections relative to the 
armature and connecting a resistance across the motor. The then acts as a 
series generator supplying the resistance load.

Another method which was tested on my EV, which was use to help slow the 
7850 lb EV on a very steep 2 mile hill, is to reversed the two main lines 
coming off the motor and connected to a very large resistor to limit the 
current while still connected to the supply source. The motor now tends to 
run in the opposite direction of the vehicle motion.

The second method was more effective which is call plug braking than the 
resistance only braking. It gave greater torque, but current is drawn from 
the battery. We had to use a 30 inch long resistor that was 15 inches 
square that was 0.5 ohm with tapes at 0.16 and 0.32 ohms. It was hang off 
the front of the EV, and would glow red which would slow the EV from 90 mph 
down to 60 mph.

Today, I use a 7kw invertor-alternator that is connected to the main motor 
pilot shaft, that is connected by a electric clutch. It can provide over 
100 amps of power to all my accessories at the REGEN time.

Roland





We had to use a very large resistance that was hung off the front of the EV. 
This resistor is a 0.50 ohm resistor that had two center taps of 0.16 and 
0.32 ohms.

The size of this resistor is about 30 inches long and 15 by 15 inches wide 
stainless steel plates. This resistor is normally use for a test load bank.






----- Original Message ----- 
From: "Mark Grasser" <[email protected]>
To: <[email protected]>; "'Electric Vehicle Discussion List'" 
<[email protected]>
Sent: Tuesday, May 13, 2008 6:38 AM
Subject: Re: [EVDL] Range: 156Volts vs 312 volts


> I don't know if going downhill in a car that now has no engine breaking 
> and
> is probably over the design weight of the brakes on the car would be
> considered a non issue, of course the first trip down the hill will be the
> deciding factor. I do like the idea of the resistor across the motor for
> engine braking but would you not have to put some voltage to the field to
> get it to work?
>
> Mark Grasser
>
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On 
> Behalf
> Of Peter VanDerWal
> Sent: Monday, May 12, 2008 3:29 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Range: 156Volts vs 312 volts
>
> Diesel powered cars have very little compression braking and seem to be
> able to descend hills safely.
>
> Considering the limited amount of hill that you can climb, I don't think
> you'll have enough downhill to cause any serious problems for the brakes.
>
> I think this is practically a non-issue.
>
> > On Mon, May 12, 2008 at 1:59 PM, storm connors <[email protected]>


> > > wrote:
> > >
> > >> I have a similar situation re elevation. Regen won't buy you anything
> > >> if your batteries are fully charged when you leave home. Electric cars
> ...


----------



## EVDL List (Jul 27, 2007)

> David Nelson wrote:
> 
> > On the cost side of things it looks like I'd be ahead to go
> > with 6v flooded and a low voltage Zilla. If I read Otmar's
> ...


----------



## EVDL List (Jul 27, 2007)

> Mark Grasser wrote:
> 
> > I don't know if going downhill in a car that now has no
> > engine breaking and is probably over the design weight of the
> ...


----------



## EVDL List (Jul 27, 2007)

Roger,
I would have to disagree with you. Just an easy example, go down a small
hill near you in drive then go back to the top and go down in neutral.
Anyone with any knowledge of hill descending knows to split the decal work
between the brakes and the engine.

Mark Grasser


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Roger Stockton
Sent: Tuesday, May 13, 2008 1:49 PM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Range: 156Volts vs 312 volts



> Mark Grasser wrote:
> 
> > I don't know if going downhill in a car that now has no
> > engine breaking and is probably over the design weight of the
> ...


----------



## EVDL List (Jul 27, 2007)

> Mark Grasser wrote:
> 
> >I do like the idea of the resistor across the motor for engine braking,
> >but would you not have to put some voltage to the field to get it to work?
> ...


----------



## EVDL List (Jul 27, 2007)

> Mark Grasser wrote:
> 
> > I would have to disagree with you.
> 
> ...


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## EVDL List (Jul 27, 2007)

> I do not believe that compression braking is required to safely slow or
> stop any modern passenger car,
>
> I hope you never drive up Pikes peak then.......

Z
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## EVDL List (Jul 27, 2007)

----- Original Message ----- 
From: "Zeke Yewdall" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Tuesday, May 13, 2008 6:16 PM
Subject: Re: [EVDL] Range: 156Volts vs 312 volts


>> I do not believe that compression braking is required to safely slow or
>> stop any modern passenger car,
>>
>> I hope you never drive up Pikes peak then.......

Hell! It's DOWN Pikes Peek, ya gotta worry!

Bob, 01 Prius, been there.

> Z
> _______________________________________________
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## EVDL List (Jul 27, 2007)

> [email protected] wrote:
> > Mark Grasser wrote:
> >
> >> I do like the idea of the resistor across the motor for engine braking,
> ...


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