EV1Dash for Palm OS
EV1Dash is a program for Palm OS devices
that will collect data from the EV1 and display it on the
Palm OS device display. The intent is to provide more information
to the driver so that range and performance can be optimized.
Here is one of the displays. There are two other displays.
One replaces the range estimates with amp hour information
and the other shows the stream of bytes in a more raw format.
Frequently Asked Questions
in the EV1
The display shows the following information:
The amps currently being draw or put back into the pack
is shown. Negative numbers indicate amps are being drawn
from the batteries. Positive values indicate recharging
is taking place. It very important to know how many amps
are being drawn when trying to figure out what the maximum
- State of Charge (SOC)
The bar indicates the current state of charge of the pack.
A little game I play is to see what how small I can get
SOC drop to be on my commute to work. Having the SOC in
1% increments helps a lot.
- Power Use Range Estimates
There are 3 power use range bars; one for the instantaneous
use, one for the last kilometer, and one for the whole trip.
To the left, below the bar is the range the pack would contain
if that power setting were maintained. The number on the
right side below the bar is the range remaining in the pack
based on the power setting.
- Trip Distance
Distance used for calculation of range and estimated battery
- Battery Capacity
The calculated battery capacity available to the user when
fully charged. This is based on the amps drawn so far and
the SOC. Optimally you should see 45Ah (53Ah * 85%) here
after the batteries are broken in. If the capacity drops
too low then there may be something wrong with the battery
pack. Remember that capacity is effected by temperature.
Please don't call GM until you are sure the numbers you
are seeing are really abnormal.
- Version 1.7.1 (9/9/2000)
- Very minor change. The application now has
- Version 1.7 (8/11/2000)
- Removed temperature. I could not figure
out what GM was doing to the value which no longer seems reliable
- Version 1.6 (2/17/2000)
- Added preferences form so that battery parameters
can be customized.
- Added help menu and help to forms.
- Additional information is saved when the
program is left for another application.
- New event handling code.
- Temperature and instantaneous range should
now work on the new NiMH cars.
- Version 1.4b3 (7/14/99)
- Another adjustment to the charge time estimates
(probably not enough)
- Fixed some odometer display bugs
- Fractional bar display bug fixed for values
of 45% and below
- Version 1.4b1 (5/25/99)
- Improved charge time estimates
- Fixed some drawing bugs
- Added block receive indicator to raw block
- Version 1.3.4 (5/18/99)
- Removed the bar marks from the SOC display
and added a horizontal bar indicator at the top of the SOC
- Added time to charge information on the
- Version 1.3.3 (3/3/99)
- Removed 3.0 OS font which caused a crash
on older systems.
- Version 1.3.2 (2/20/99)
- Fixed a bug that caused the pilot to go
to sleep if the voltage and amps did not change.
- Version 1.3.1 (2/13/99)
- Fixed a bug in the new block display.
- Version 1.3 (2/10/99)
- Added a new display option that shows all
the data blocks in a tabular format.
- Fixed a recording bug that caused to many
samples to be taken.
- Version 1.2.2 (12/1/98)
- Fixed bug where capacity and ranges did
not show the correct values after 20% change in SOC.
- Version 1.2.1 (11/29/98)
- The freezing problem has been fixed. (I
think. Its certainly improved if nothing else.)
- Drawing of SOC bug fixed. It now refreshes
- New marks were added to the SOC display.
They are somewhat redundant but added to match the cars display
- Automatic trip reset is now an option.
- Out of memory crash fix when recording has
been made. This has not been tested. Please send in reports
on how well it works or doesn't work.
- Version 1.2 (11/21/98)
- Added outside air temperature. Note that
it reads high while charging due to the location of the temperature
- Added extra digit to the power display.
- The initialization spike is now ignored.
- The date was added to the top of the log
- Automatic reset now asks for confirmation
- Bar markers were added to the SOC display.
These show where the real SOC bars map to the SOC display
on the EV1Dash program.
- The SOC digits are larger.
- An optimum power diamond has been added
to the instantaneous range bar. This is the range the car
should get at the current speed on a flat road.
- SOC now shows negative numbers when below
0 user SOC. Useful when below the 3 diamonds and 0 bars.
- Version 1.1 (10/8/98)
- Amp hours updates more frequently while
- Corrected regen and recharge effect on drain.
- Added support for a tap on the range/numeric
display to switch displays.
- Added support for a tap on the SOC to toggle
power adjusted SOC.
- Added small 'P' in upper right corner is
SOC is power adjusted.
- Version 1.0.7 beta (10/2/98)
- Fixed the bug related to range estimates
- Changes the battery capacity calculation
to user capacity instead of full capacity.
- Added options for power adjusted SOC values.
- Added an optional display.
- Added confirmation dialog window for removing
- Version 1.0.6 beta (9/11/98)
- Improved the calculation for the effect
of regen on range and capacity.
- Added additional triggers (odometer and
SOC change) for generating a sample for recording.
- Version 1.0.5 beta (9/6/98)
- Fixed the amp reading on the sample data
- Version 1.0.4 beta (9/4/98)
- Removed the flicker from the values near
the bottom of the screen.
- Fixed the odometer problem that occured
for odometer values over 65535 Km.
- Reversed the direction of the amp bar.
- Added power to charging screen.
- Changed the recorded information to include
odometer and speed. The fields were also changed.
- The state of recording is now remembered.
- There is still a bug that causes data to
be invalid after charging.
- Version 1.0.3 beta
- Changed the display to show Amps in much
larger font. SOC font is also larger in this version.
- State is remembered when the program is
- Separate display added for charging.
- Kilometer to miles conversion is more accurate
and closer to the EV1 conversion. It still might be off a
little at the higher mileage.
- Version 1.0.2 beta
- Fixed a bug where the trip distance was
incorrect after the trip reset if the Pilot was not receiving
- Version 1.0.1 beta
- Added carriage return to the data transfer
for PC users (I'm a Mac user)
- Added trip distance to the display.
- Made an automatic trip reset when its detected
that the cars SOC has changed more than 2% since the last
time the PalmPilot was connected.
- Estimated battery capacity is now saved
on trip reset as well as when switch applications if the more
than 30% SOC has been use on that trip.
- Estimated SOC is now displayed after 20%
change in SOC instead of 10%.
- Battery model has been updated to use
accurate test data on the EV1 batteries!
- Version 1.0 beta
- Initial release.
- Peukert's constant is not accurate and needs
adjusting. This effects the estimated battery capacity.
- OC correction equation needs to be determined.
- Range and SOC display is not correct when
SOC is below 0%. I'm not sure what it should be but whatever
it should be its not that way now.
Frequently Asked Questions
- How can I avoid using so many batteries for
Try the Nickel Metal Hydride batteries which are rechargeable.
I got mine from Radio Shack. They give me 6 or more hours of continuous
operation and can then be recharged. The voltage is a little different
than the alkaline batteries that are expected in the PalmPilot
so the capacity gauge on the pilot is off a little but other than
that they last a long time and can be reused.
- Can I plug the OBD II connector into another
The plugs are the same but the pinouts are different. The plugs
I provide, at least for now, have pairs of pins shorted for mechanical
strength. That works out fine for the EV1 but not for most OBD
II systems which use more pins than the EV1.
- How do I get records off of the PalmPilot?
After recording data in the EV1Dash program that data can be downloaded
to another computer through the serial port of each. To download
place the Palm device into its cradle which should be connected
to a PC, Mac, or some other computer with a serial port. Start
a terminal emulation program on the other computer and open the
serial port at 19200, 1 stop bit, no parity, 8 data bits. Start
a stream capture to a file. Then go to the EV1Dash program and
pick the Transfer menu item. All the records will be send to the
other computer and saved in the file you specified. When transferring
is done close the file and quit the program. Thats it.
- How do I run the EV1Analysis program?
The first thing to do is download and install Java. After that
run the EV1 Analysis program. Using the File:Open menu item select
the file downloaded from the EV1Dash program on the Palm organizer.
Depending on the speed of the computer and the length of the file
it may take some time to complete the screen drawing. Be patient.
- When does the estimated capacity change?
The intial value of the estimated capacity is what ever the last
value was or 45Ah if none have been saved yet. After a change
of 20% SOC (not power adjusted SOC) the estimated capacity is
calculated and displayed. After a change of 30% the value is saved
as the starting value for the next trip. The value can be reset
back to 45Ah using the Reset Capacity menu item.
- Sometimes the estimated capacity changes
alot while I drive?
The estimated capacity is just that, an estimate. It is based
on amps used and the SOC. Depending on a number of factors (random?)
the SOC may not be completely accurate. I've seen it off by as
much as 10% around the 50% SOC mark. This often causes the estimated
capacity to start out low and climb to a higher value and then
drop off again as the SOC drops below 50%. This error is due to
the SOC calculation algorithm of the EV1. Maybe someday I'll figure
out what it is and correct the error but for now its something
we'll have to live with.
- In the numeric display what does "drain"
The "drain" is the same as the "Net Ah" except that the amps are
scaled according to the effect they have on the charge (Peukert
like). If you hold a steady 25 Amps the net Ah and the drain will
be exactly the same. If you pull more than 25 Amps the drain starts
to become larger than the net Ah. If you get real aggressive the
difference gets even larger. The drain is more indicative of how
much you are really effecting the battery capacity. If you are
moderately careful you should be able to keep the drain within
15% of the net amps. If you are really pressing for a record you
want to be under 10%. That's a lot harder to do though.
- What is the "SOC Power Adjustment" option
under the Display menu?
The "SOC Power Adjustment" corrects for the drop in voltage as
the SOC changes. It used to be on all the time but I made it an
option so you can see what the EV1 thinks the SOC is. If you don't
compensate for the voltage sag of the batteries as the charge
runs out you find that the second half of the battery charge does
not get you as far as the first half. The effect is about 6% overall.
If you want a more accurate picture of the SOC by how far you
can go then leave the "SOC Power Adjustment" on. That's with the
little dot next to it.