# [EVDL] range meter or ?



## EVDL List (Jul 27, 2007)

Unless the route can be programmed into the range meter system, via
integrated GPS unit, and all the battery parameters, plus driving/battery
usage history, then a range meter will be an inaccurate beast. However
something that says you have used 3/4 of capacity would be helpful and that
is doable.
My car has an old style fuel gage of the kind used in 1930's gas guzzlers
and I will make sure that "empty" on the gage still gives me a 1/4 capacity.
Since I do not plan on anything more than being 30 miles from home, and my
friends have cell phones getting home will not be a problem. There is also
the tow truck!! Yucky, but still what I had to use with my ICE when the
timing chain broke!
Expecting complex electronics to solve all ones problems is INMNSHO is not a
direction that hobbyists need to pursue. Better to concentrate on the fun
stuff..


-- 
When all else fails, remember failure is the success of knowing what not to
do.
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## EVDL List (Jul 27, 2007)

Why can't a simple module take your current usage and and then
estimate range based on remaining pack capacity? If you are using X
W/hrs per mile and you have Y W/hrs in the pack you have about Z miles
of range.

Isn't it that simple?

DAC



> ron doctors <[email protected]> wrote:
> > Unless the route can be programmed into the range meter system, via
> > integrated GPS unit, and all the battery parameters, plus driving/battery
> > usage history, then a range meter will be an inaccurate beast. However
> ...


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## EVDL List (Jul 27, 2007)

> dave cover <[email protected]> wrote:
> > Why can't a simple module take your current usage and and then
> > estimate range based on remaining pack capacity? If you are using X
> > W/hrs per mile and you have Y W/hrs in the pack you have about Z miles
> ...


----------



## EVDL List (Jul 27, 2007)

Calculating the past power used is relatively easy and relatively accurate.
Calculating future power use is a very nearly a shot in the dark and
therefore not a good indicator of range..
Stephen Chapman



> dave cover <[email protected]> wrote:
> 
> > Why can't a simple module take your current usage and and then
> > estimate range based on remaining pack capacity? If you are using X
> ...


----------



## EVDL List (Jul 27, 2007)

Yes but, if you have your foot into the throttle more to go up hill,
the range estimator should show the you have less range. Remaining
capacity divided by current rate of use. Not rocket surgery.

DAC



> Ben <[email protected]> wrote:
> > On Thu, Jul 1, 2010 at 2:19 PM, dave cover <[email protected]> wrote:
> >> Why can't a simple module take your current usage and and then
> >> estimate range based on remaining pack capacity? If you are using X
> ...


----------



## EVDL List (Jul 27, 2007)

But you don't use "future use." You just take the current rate of use.
That will go up and down as you press or release the throttle. Drive
harder, less range. Drive easier, more range.

DAC



> Stephen Chapman <[email protected]> wrote:
> > Calculating the past power used is relatively easy and relatively accurate.
> > Calculating future power use is a very nearly a shot in the dark and
> > therefore not a good indicator of range..
> ...


----------



## EVDL List (Jul 27, 2007)

LOL, then it is too late. The range meter would only tell you that you were
not going to make it. The apparent range would fluctuate wildly with every
accel/decel, uphill/downhill. What good is that?
Stephen Chapman



> dave cover <[email protected]> wrote:
> 
> > Yes but, if you have your foot into the throttle more to go up hill,
> > the range estimator should show the you have less range. Remaining
> ...


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## EVDL List (Jul 27, 2007)

Range is a function of future use. I have a range indicator as part of the
trip computer in my ice. It can be easily fooled by driving habits and my
rate of gas consumption does not really change that much. The power used by
an EV can easily change by a factor of 4-5.



> dave cover <[email protected]> wrote:
> 
> > But you don't use "future use." You just take the current rate of use.
> > That will go up and down as you press or release the throttle. Drive
> ...


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## EVDL List (Jul 27, 2007)

Well, it's much more complicated than that. Obviously I've been on 
record as saying I don't think it has to be quite as complicated as 
other people have suggested but it's still very close.

Most people still think that a "fuel" type gauge is advantageous and 
doable. A range gauge is nothing other than a fuel gauge that also tries 
to figure out how far you have to go. It can try to do this by 
calculating how far you have gone so far and extrapolate from there 
based on the current fuel gauge reading. Of course, in an EV the fuel 
gauge almost always lies. This is as opposed to an ICE where the gas 
gauge is likely reasonably accurate. This is the first big complication. 
A potential solution is to keep track of how long it takes to get to the 
20% mark (for lithium cells. Assume I mean LiFePO4 cells when I talk 
about batteries from now on.) Once you get to 20% you look at how many 
Ah you've used. If the pack is getting weaker then this # will steadily 
go down. Unfortunately this requires one to drain the pack quite far. 
But did you ever wonder why people tell you to drain your laptop or 
cellphone battery all of the way and then recharge fully to recalibrate 
the remaining power gauge? The same thing would help to calibrate the 
fuel gauge on a lithium pack. It would have to be done periodically 
especially when it is suspected that the fuel gauge is telling lies. One 
can also try to compensate for temperature but in an EV batteries tend 
to be spread out over a large area and potentially over multiple 
locations. This makes getting temperature readings much more 
complicated. Potentially each cell should have a thermometer. In 
addition, batteries, even lithium ones, suffer from peukert factor and 
thus will not give up the same # of Ah if subjected to differing loads. 
Luckily this effect is small in lithium batteries but it still exists. 
Add that all up and the fuel gauge idea even starts to seem complicated. 
However, I think that a reasonable guess is possible. The big catch is 
that a lithium pack which hasn't been monitored closely enough could 
jump from 30-40% down to 20% all at once when the monitoring system 
detects that it got to a voltage knee.

Now that the likely inaccurate fuel gauge has been covered, what about 
the distance calculation? Well, if the upcoming trip is done on the same 
sort of roads, grade, speed as the first part then the calculation will 
be very easy. It would be simple extrapolation and it would be very 
accurate. Unfortunately life doesn't always work that way. Maybe the 
first part was pretty flat and 45MPH but the upcoming part of your trip 
is very mountainous and 40MPH. This will make the calculation much more 
complicated. The range meter will think you have a lot more range than 
you really do. So what to do? Well, the range meter will have to "cheat" 
and take away range at a much faster rate than you are really traveling. 
At some point hopefully you realize that fact and adjust your plans 
accordingly. The range gauge has to trend the data to see how many amps 
you have been drawing lately in order to get a guess as to how much 
further you can go. This will necessarily jump around a bit if you 
change driving patterns.

In essence, a range gauge is nothing but a very sophisticated crystal 
ball. Even a fuel gauge for an EV is really just a guess.

On 7/1/2010 2:19 PM, dave cover wrote:
> Why can't a simple module take your current usage and and then
> estimate range based on remaining pack capacity? If you are using X
> W/hrs per mile and you have Y W/hrs in the pack you have about Z miles
> of range.
>
> Isn't it that simple?
>
> DAC
>
>


> ron doctors<[email protected]> wrote:
> >> Unless the route can be programmed into the range meter system, via
> >> integrated GPS unit, and all the battery parameters, plus driving/battery
> >> usage history, then a range meter will be an inaccurate beast. However
> ...


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## EVDL List (Jul 27, 2007)

I like the 30 mile round trip example. 15 miles downhill and your "range"
meter is probably indicating 60 miles left at the turnaround. Now a mile
into the uphill section you may be indicating 5 miles left. What good is
that?



> Stephen Chapman <[email protected]> wrote:
> 
> > Range is a function of future use. I have a range indicator as part of the
> > trip computer in my ice. It can be easily fooled by driving habits and my
> ...


----------



## EVDL List (Jul 27, 2007)

> dave cover <[email protected]> wrote:
> 
> > Why can't a simple module take your current usage and and then
> > estimate range based on remaining pack capacity? If you are using X
> ...


----------



## EVDL List (Jul 27, 2007)

> Collin Kidder <[email protected]> wrote:
> This is as opposed to an ICE where the gas
> gauge is likely reasonably accurate.

How accurate would the gauge in an ICE be if you only had a 2 or 3
gallon fuel tank?

I think the issues are similar independent of the fuel used.

I'm not expecting it to predict the future, just a best guess based on
known facts; current use, remaining capacity. I shouldn't be
disappointed if it tells me I have X miles of range when I'm driving
mildly and then I don't get it because I started driving like a
maniac. I would be the idiot, not the gauge.

It's not a miracle device, just a driving aid. There are reasonable
devices already working in ICE's, why not in an EV. Think about the
old fuel economy gauges. They weren't much more than a vacuum gauge.
If you drove conservatively, vacuum stayed high, you would probably be
getting better gas mileage, and the gauge showed that. If you romped
on it the vacuum was low and the gauge showed that you were getting
low economy. It wasn't predicting the future, it was just showing you
a best guess based on the current conditions.

Why can't a simple device count amp hours in your pack and estimate
instantaneous remaining range based on how you are driving? Why is
this complicated?

DAC



> Collin Kidder <[email protected]> wrote:
> > Well, it's much more complicated than that. Obviously I've been on
> > record as saying I don't think it has to be quite as complicated as
> > other people have suggested but it's still very close.
> ...


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## EVDL List (Jul 27, 2007)

Sorry, that analogy just does not work for me. Laptop power consumption
does not frequently change by a factor of 4-5 and if the laptop powers
itself down unexpectedly, no tow truck has to be called. 

All the same, if you think it will work, "more power to you".

Stephen Chapman



> Dave Hale <[email protected]> wrote:
> 
> > On Thu, Jul 1, 2010 at 11:19 AM, dave cover <[email protected]> wrote:
> >
> ...


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## EVDL List (Jul 27, 2007)

The calculation is easy, it is the value of the answer that is in question.
The old vacuum gauges are analgous to an ampere gauge, indicating roughly
the instantaneous rate of power consumption.

If my ice trip computer only had 1 gallon of gas on which to base its
calculation, it would be totally worthless instead of only mildly
inaccurate. One gallon of gas is roughly equivalent to the energy carried
by most EV conversions. As it is, my trip computer gets to average its
calculation over the consumption of 15 gallons of gasoline.
Stephen Chapman



> dave cover <[email protected]> wrote:
> 
> > > Collin Kidder <[email protected]> wrote:
> > > This is as opposed to an ICE where the gas
> ...


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## EVDL List (Jul 27, 2007)

> dave cover wrote:
> >> Collin Kidder <[email protected]> wrote:
> >> This is as opposed to an ICE where the gas
> >> gauge is likely reasonably accurate.
> ...


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## EVDL List (Jul 27, 2007)

----- Original Message ----- 
From: "Dave Hale" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Thursday, July 01, 2010 12:11 PM
Subject: Re: [EVDL] range meter or ?




> dave cover <[email protected]> wrote:
> 
> Why can't a simple module take your current usage and and then
> estimate range based on remaining pack capacity? If you are using X W/hrs
> ...


----------



## EVDL List (Jul 27, 2007)

> Collin Kidder <[email protected]> wrote:
> Gasoline has a coefficient of expansion but it does
> not change volume by as much as a battery pack can change with
> temperature. Additionally, peukert factor has no liquid analog. It would
> be as if stepping hard on the gas magically made some of the gasoline in
> the tank "disappear" without having been burnt. And, the loss of pack

Not to prolong the discussion, but I think there is a correlation
here. Maybe it applies more to carburated cars than fuel injected.
But, if you romp on a gas car your mileage will go down. If you drive
conservatively, your mileage will be greater. If not, how does the
whole hypermiling thing work. The way you drive affects how many
miles you will get to the gallon. The way you drive also affects how
many miles you can get for a given number of amphours in your pack.



> Collin Kidder <[email protected]> wrote:
> > On 7/1/2010 3:20 PM, dave cover wrote:
> >>> Collin Kidder<[email protected]> wrote:
> >>> This is as opposed to an ICE where the gas
> ...


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## EVDL List (Jul 27, 2007)

> Peukert factor has no liquid analog. It would be as if stepping hard
> on the gas magically made some of the gasoline in the tank
> "disappear" without having been burnt.

No, that's not how it works. A liquid analog of the Peukert effect would 
be if your gas tank was full of sponges. All the gas is there, but the 
sponges limit how fast you can get it out.

At low fuel delivery rates, it all comes out fine. But the higher the 
delivery rate, the less of it you can get out before it seems to run 
"dry". If you punched a big hole in the tank and tried to get it all out 
quickly, the first half tank or so comes out quickly; but then the flow 
slows down to a trickle. You have to wait hours to get it all and the 
flow to finally stop.

Same with a battery. If you discharge it quickly, it may appear to be 
dead when you've taken half the amphours out of it. But if you wait, it 
appears to recharge itself. Or if you continue discharging it at a lower 
rate, it keeps working. Either way, you'll still get all the amphours 
out if you wait long enough.

The Peukert effect is present with all types of batteries. It's just the 
most noticeable with lead-acids.
-- 
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377	| There is a crack in everything
leeahart earthlink.net	| That's how the light gets in -- Leonard Cohen

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## EVDL List (Jul 27, 2007)

I thought the pukert effect was a "non linear change in internal resistance" and as such more power also gets dissipated as heat and
hince not available for use.

Is the energy lost to heating just a minor side effect?


>> Peukert factor has no liquid analog. It would be as if stepping hard
>> on the gas magically made some of the gasoline in the tank
>> "disappear" without having been burnt.
> 
> No, that's not how it works. A liquid analog of the Peukert effect would be if your gas tank was full of sponges. All the gas is there, but the sponges limit how fast you can get it out.
> 
> At low fuel delivery rates, it all comes out fine. But the higher the delivery rate, the less of it you can get out before it seems to run "dry". If you punched a big hole in the tank and tried to get it all out quickly, the first half tank or so comes out quickly; but then the flow slows down to a trickle. You have to wait hours to get it all and the flow to finally stop.
> 
> Same with a battery. If you discharge it quickly, it may appear to be dead when you've taken half the amphours out of it. But if you wait, it appears to recharge itself. Or if you continue discharging it at a lower rate, it keeps working. Either way, you'll still get all the amphours out if you wait long enough.
> 
> The Peukert effect is present with all types of batteries. It's just the most noticeable with lead-acids.
> -- 
> Lee A. Hart | Ring the bells that still can ring
> 814 8th Ave N | Forget the perfect offering
> Sartell MN 56377 | There is a crack in everything
> leeahart earthlink.net | That's how the light gets in -- Leonard Cohen


----------



## EVDL List (Jul 27, 2007)

> dave cover wrote:
> >> Why can't a simple device count amp hours in your pack and estimate
> >> instantaneous remaining range based on how you are driving? Why is
> >> this complicated?
> ...


----------



## EVDL List (Jul 27, 2007)

> dave cover wrote:
> 
> > Why can't a simple device count amp hours in your pack and estimate
> > instantaneous remaining range based on how you are driving? Why is
> ...


----------



## EVDL List (Jul 27, 2007)

Something hit me while I was driving around today (a thought, not an object)...

There have been EV's that have a huge capacity and a huge weight and load, with the driver *really* caring not only about remaining charge but saving the traction pack from further damage during discharge, and have been around for something like 100 years.

Submarines! Specifically the diesel electric fleet types from WWII, certainly evolved by that time into some kind of reliable (if not panicked) service.

How did they judge remaining SOC? They must have had some rules.

What did they do for speed control? No active electronics, for sure.

What did they do if they took their flooded PbA's to 0%? Got a tow?

Some online research can probably reveal these answers, but I just wanted to toss out there the idea that the things we're interested in today have been dealt with before.

Best Regards,

- Gene

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Lee Hart
Sent: Thursday, July 01, 2010 3:49 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] range meter or ?

> Peukert factor has no liquid analog. It would be as if stepping hard
> on the gas magically made some of the gasoline in the tank
> "disappear" without having been burnt.

No, that's not how it works. A liquid analog of the Peukert effect would
be if your gas tank was full of sponges. All the gas is there, but the
sponges limit how fast you can get it out.

At low fuel delivery rates, it all comes out fine. But the higher the
delivery rate, the less of it you can get out before it seems to run
"dry". If you punched a big hole in the tank and tried to get it all out
quickly, the first half tank or so comes out quickly; but then the flow
slows down to a trickle. You have to wait hours to get it all and the
flow to finally stop.

Same with a battery. If you discharge it quickly, it may appear to be
dead when you've taken half the amphours out of it. But if you wait, it
appears to recharge itself. Or if you continue discharging it at a lower
rate, it keeps working. Either way, you'll still get all the amphours
out if you wait long enough.

The Peukert effect is present with all types of batteries. It's just the
most noticeable with lead-acids.
--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen


_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

I like the idea. Let me know if you get something working.

DAC



> Doug Weathers <[email protected]> wrote:
> >
> > On Jul 1, 2010, at 1:20 PM, dave cover wrote:
> >
> ...


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## EVDL List (Jul 27, 2007)

I to find the crossneedle gauge idea great. I think it will be the kind of gauge you can glance at while driving and get good
meaning from.

My thought was to use the little surplus phone screens and micro controllers and do it in hi-res graphics to get good needle
emulation and also colorization and ability to display text also. or other small LCD screens.

A way to experiment cheaply with different combinations, just draw it on the screen.


Color, backlit, drivable with a micro that has ttl serial

http://yhst-27389313707334.stores.yahoo.net/13secogrlcd.html


The higher pixle tft displays require a bit mroe work to get drawing
http://yhst-27389313707334.stores.yahoo.net/2tftcolcd240.html

>


> dave cover wrote:
> >
> >> Why can't a simple device count amp hours in your pack and estimate
> >> instantaneous remaining range based on how you are driving? Why is
> ...


----------



## EVDL List (Jul 27, 2007)

First of all 2000 to 4000ah cells.
Second of all 25 year lifespan ultra-thick plate with cleanable sump cells
third. THey were floodies, the battery guys laid on their belly on boards above the cells and measured specific gravity.
(In addition to displayed amps and volts.)

multiple battery and motor configurations in addition to gearboxes, probably many many speeds possible.
Less need for accurate speed control than a car anyway.

Little or no terrain  just so many hours at so many knots. a Lot less variation.
Noting of course that 4 knots into a 5knot current is going backwards.



> Something hit me while I was driving around today (a thought, not an object)...
> 
> There have been EV's that have a huge capacity and a huge weight and load, with the driver *really* caring not only about remaining charge but saving the traction pack from further damage during discharge, and have been around for something like 100 years.
> 
> Submarines! Specifically the diesel electric fleet types from WWII, certainly evolved by that time into some kind of reliable (if not panicked) service.
> 
> How did they judge remaining SOC? They must have had some rules.
> 
> What did they do for speed control? No active electronics, for sure.
> 
> What did they do if they took their flooded PbA's to 0%? Got a tow?
> 
> Some online research can probably reveal these answers, but I just wanted to toss out there the idea that the things we're interested in today have been dealt with before.
> 
> Best Regards,
> 
> - Gene


----------



## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> 
> > The cross point meter is a fine indicator. But the key to
> > making it work is the scale you put on it. To make it useful,
> ...


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## EVDL List (Jul 27, 2007)

I have found and I am sure I will get a few people here to back me up that a needle is better for a gage you need to glance at that
gives you a value. In a lot of situations gages are oriented such that the needles all point up if everything is ok. The human eye
can glance at a row of two inch gages and be looking back at the road while the brain processes the 2nd gage was temperature and it
is a bit high.

Where I am coming from.
We had a bunch of plastic molding machines at the company I used to work for and after years of analog gages, they went to all
digital. Then they realized that gages are really nice to have so they simulated them on a screen. For temperature, digital was a
better display. I could glance at the readout from 20 feet away and read the temp and the led that let me know it was on/off.
Temperature moves slowly. For the hydraulic pressures the analog gage was much better than a digital gage but the screen offered
more than one mode. Simulate the analog gage and/or graph the pressure or velocity over time for each shot. It also offered
temperature deviation over time. These new modes a screen provides, that of history(seeing more than one reading at various points
in time) was very useful.
I am not sure how this would translate into an EV gage, but with such a screen, i'd say it opens up not just multiple paradigms,
but one's we haven't yet thought of. perhaps each acceleration is drawn as a series of lines scrolling up the screen and fading to a
vanishing point thus creating a live contour map.

It also means a change to a display is less expensive. it isolates or abstracts measurement from display. The display could be just
a display. Sitting on a bus that listens to traffic from chargers, bms's motor controllers and remote sensors. Then a common display
could work on a different charger with just a change in software. Maybe you have 2 battery strings? or super caps?

I have thought beyond this a bit. I had always wanted to start a car company and one way to significantly lower cost I though was to
get rid of the typical instrument cluster that is custom and just replace it with a good screen.





> > Lee Hart wrote:
> >
> >> > The cross point meter is a fine indicator. But the key to
> >> > making it work is the scale you put on it. To make it useful,
> ...


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## EVDL List (Jul 27, 2007)

> Jeff Shanab wrote:
> > a needle is better for a gauge you need to read at a glance...
> 
> Agreed. It takes less mental arithmetic to read an empty-full pointer
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> 
> [I wrote:]
> 
> ...


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## EVDL List (Jul 27, 2007)

Roger, using only one needle type guage considerably reduces the available
data for driver information. My Brother had a second guage (In the 1950's)
that Dad called an "Economiser" to show how much of the ICE available power
we were throttling in. It measured Vacuum and therefore related to furl
consumption via carburetor.Perhaps comparable to an Ammeter in an EV. Hence
my suggestion for an analog indication of driver technique perhaps an
Ammeter, and a "SOC" (Or its crude approximation a Voltmeter.) and of course
a "Odometer" for speed and distance. (Incidentally In 1978 I learned the
actual piece cost for the "Works" inside an Odometer driven by a flexible
shaft was only thirteen cents for a Chevrolet.)
Regards,
Dennis Miles

On Mon, Jul 5, 2010 at 11:47 PM, Roger Stockton <[email protected]>wrot=
e:



> > Lee Hart wrote:
> >
> > [I wrote:]
> >
> ...


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## EVDL List (Jul 27, 2007)

> Roger Stockton <[email protected]> wrote:
> 
> > Basically tell the driver "drive so the needle stays off of 'E'" ;^>
> >
> ...


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## EVDL List (Jul 27, 2007)

> Roger Stockton wrote:
> >> The type of indication is independent of the technology used to
> >> drive it.
> 
> ...


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## EVDL List (Jul 27, 2007)

I've been messing with a car pc and fusion brain board with Programmable touch screen. I'm using the cross-point idea but with two overlapping bar meters one moving down the other moving up. The bars are opaque so where the meet is noticeably darker.

Stub 
Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: Lee Hart <[email protected]>
Sender: [email protected]
Date: Tue, 06 Jul 2010 09:30:23 
To: Electric Vehicle Discussion List<[email protected]>
Reply-To: Electric Vehicle Discussion List <[email protected]>
Subject: Re: [EVDL] range meter or ?



> Roger Stockton wrote:
> >> The type of indication is independent of the technology used to
> >> drive it.
> 
> ...


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## EVDL List (Jul 27, 2007)

> Lee Hart wrote:
> 
> > They will often choose a display based on fashion; but that
> > doesn't make it a good display - just a pretty one.
> ...


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## EVDL List (Jul 27, 2007)

> > Lee Hart wrote:
> >
> >> > They will often choose a display based on fashion; but that
> >> > doesn't make it a good display - just a pretty one.
> ...


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## EVDL List (Jul 27, 2007)

> Jeff Shanab wrote:
> > There are some new display technologies out there that may be of use. The
> > digital paper is now avail in small screen sizes and it can be viewed in direct
> > sunlight and uses no power to continue displaying results, only when the info is
> ...


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