SOC-Meter Kit Hardware, Display, and Issues

[garygid]

A remaining-range estimator based on long-past driving history or averages ... is mostly an almst-useless "Guess-o-Meter".

However, a rapid-response estimator based on your actual, present consumption would be illuminating to many. If I can find the energy uses, and correlate SOC with remaining useful energy ...
Like, assume 100% SOC is ... maybe 24 kWh, and
motor, A/C & heater, and "other" drawing YY power ...
and your present speed ...
Then I might try that.

Or, try to find and use the Nav-Screen Miles/kWh?

 

[TonyWilliams]

A remaining-range estimator based on long-past driving history or averages ... is mostly an almst-useless "Guess-o-Meter".

However, a rapid-response estimator based on your actual, present consumption would be illuminating to many. If I can find the energy uses, and correlate SOC with remaining useful energy ...
Like, assume 100% SOC is ... maybe 24 kWh, and
motor, A/C & heater, and "other" drawing YY power ...
and your present speed ...
Then I might try that.

Or, try to find and use the Nav-Screen Miles/kWh?

Anything in the future is a wild "Guess-O-Met", including using present miles/KW figures. Every time you accelerate, or go down a hill, the numbers would go all over the place. That's what we already have.

 

[mwalsh]

Saw the results of Gary and Robert's work thus far today. Very impressive!

Sign me up for the simple % SOC meter, in either kit or built form!

 

[TomT]

+10!

Sign me up for the simple % SOC meter, in either kit or built form!

 

[Herm]

A remaining-range estimator based on long-past driving history or averages ... is mostly an almst-useless "Guess-o-Meter".

No it would be very usable.. most people drive in a consistent manner from week to week, just average it over a week and it would be a great improvement on the current one.. if you are coming up to a hill then you will know that the remaining range indicated will be optimistic, but at least you wont be surprised. I expect Nissan to update this at any time, otherwise too many will complain "where did my range go?" when they expand sales.

 

[garygid]

The current driving average used for Remaining Miles calculation is
NOT a week average, or even a last-hour average. It is not just a
last minute average either. There is some indication that the averaging
time is more like several miutes to even as much as 10 or 20 minutes.

If you are always driving at a constant speed/consumption, then a very short term
average does not take into account your recent stops and accelerations.
But, a 30 second average would tell you, if you continue as you have been going
for the last 30 seconds, you will (perhaps) get ... so many miles.

Caught in a slow freeway traffic jam last night (due to an accident ahead),
gave me an estimate of 102 miles this morning, rather than my usual 92 or so.
Did that really help me? No, not really.

If Nissan made the past-performance averaging time user selectable,
it could better satisfy more people, but i any case, trying to use it without
understanding it will often be ... not very helpful.

But, remember that it is based both on an ESTIMATE of remaining energy
AND on an ESTIMATE of what your future energy usage MIGHT be.

 

[garygid]

At the moment there is almost $100 in parts alone, and then some
time required to put the device/kit together. If shipping (and possibly
tax) are required, these might add another 15 to 20 dollars.

I suspect that Boomer will display some pictures in the
SoCal Gathering thread. The demo went well, tried on 3 LEAFs.

More later as it develops.

 

[LEAFfan]

If I can't get the ScanGauge II people to convert my ScanGauge to EV so I can get SOC% and other readings, I'll probably buy one of yours. They told me they would, but they haven't got it yet. I'm going to call them again Monday. Right now, my ScanGauge II is worthless since my wife doesn't want to use it in her car.
Also, I would like to know what 'Other' Kw usage is on the energy screen. The manual only said 'audio, etc.', but the radio, lights, windows, etc. uses the 12V. Would it be the inverter and circulation pumps? It's always the same amount on the energy screen.

 

[evnow]

If I can't get the ScanGauge II people to convert my ScanGauge to EV so I can get SOC% and other readings, I'll probably buy one of yours. They told me they would, but they haven't got it yet. I'm going to call them again Monday.

Tell them to read this thread. They may be looking in the normal CAN bus instead of the EV CAN bus.

 

[garygid]

During running, all the 12v needs are provided by the Traction Battery,
via its HV DC to 12v DC converter, which also charges the 12v battery if needed.
So, in that sense, all the 12v energy needs are included in "Other".

Try turning on the high beam headlights while watching the "Other" energy gauge?

Only when the car is OFF (or in accessory modes, I think) are the 12v energy needs
provided by the 12v battery. Does this energy usage show on the "Other" display?

Again, try the high beams when in Accessory Mode, watching the Energy Other gauge.

 

[evnow]

At the moment there is almost $100 in part alone, and then some
time required to put the device together. If shipping (and possibly
tax) are required, these might add another 15 to 20 dollars.

I just need the part list and simple instructions. I'll take out my soldering iron and dust it.

Part list is more or less available in the thread (if I go back and look) - instructions are a little more difficult to find.

 

[garygid]

ALL at your own risk, and there might even be mistakes below!!!

I will work on more detailed instructions when we get the parts better settled, but here is a start:

1. The only "difficult" part. I used a milling machine and still made a small mistake. Make a rectangular hole in the project box to just-fit the LED display. I use the screw-on "lid" as the back of the finished SOC-Meter, with the slot for the display centered around the moulding dimple in the "bottom" of the box (will become the "front" of the finished project). A snug-fit for the display tends to hold it in place better.

2. Make a U-shaped notch in the exposed edge of the left end of the box, suitable for the OBD cable to enter the box, but be held quite snugly in the notch when the "lid" is screwed on. Remember, making the notch wider and deeper is easy, but making it smaller is ... more difficult.

3. A hole in the left side for the On/Off switch, possibly also needed/used for mounting a 7808 regulator and heat-sink.

4. Wire 4 connections from the 16-wire OBD cable to the female 9-pin "D" connector (that will plug into one end of the AVR-CAN board). Wire the "12v" OBD power connection through the power switch and 7808 regulator.

5. Use the just-constructed cable to provide power to the AVR-CAN board, and "flash" the SOC-Meter program (version 4.09 or later) into the AT90CAN128-16's memory. You will either need help or special "JTAG" programming equipment and software for Atmel uP parts. I think I have located an inexpensive part, but I have not yet gotten it to work.

6. CAREFULLY wire 3 pins on the AVR-CAN EXT2 connector to 3 holes on the display board. Best to cover the ends on the EXT2 connector with shrink-wrap.

7. Carefully test the device, before putting it into the box. Correct any mistakes as needed.

8. Carefully Assemble the parts into the box, with the JTAG and "D" sockets facing the lid. Screw on the "back" of the Project Box.

9. Plug into your LEAF's OBD connector, enjoy, and either unplug or switch it OFF when not using it. I suggest using the miniature toggle switch to power Off the SOC-Meter when it is not in use.

----------
Parts:
(Due to typical shipping costs, buying single quantities might be somewhat inefficient.)

1. The 16 MHz Olimex AVR-CAN Development board, about $55 from http://www.Mouser.com or http://www.SparkFun.com ... NOT the slower 8 MHz AVR-CAN-H? board from ??Kit (about $49).

2. Plastic box from http://www.AllElectronics.com ... part MB-132, (ABS Project Box 3.97" x 2.12" x 1.72"), about $3.

3. OBD cable, suggest the right-angle 16-wire cable from http://www.obd2cables.com ... about $11 for #142601 (on sale), or $13 for #144507. Both seem to have basically the same specs: OBD, right angle, male, 16-pin, 16-wires, and a 6-foot cable length. I have ordered both of these, but I am not sure of the differences, and I have not yet received/used/tested either of them.

4. One female 9-pin "D" connector, with solder pins, no cover needed.

5. One LED display, 7-segment, 4-digit "serial" input, in Red, Yellow, Green, or Blue. For about $14 from http://www.SparkFun.com ... Part Number ??

6. A miniature toggle switch for the Power On/Off, a 7808 regulator chip, a suitable heat-sink, and probably a 0.33uF 20v capacitor for the 7808's input side.

7. Small diameter shrink tubing, about 3 inches long to cover exposed power and signal connections.

8. Some small gauge stranded hook-up wire, and some double-sided foam tape might help in mounting the LED Display.

-----------
Tools: Soldering iron, solder, small Philips screwdriver, something to cut and strip small gauge wire, a small pair of scissors, and something to "cut" the plastic project box.

 

[evnow]

Thanks Gary. This looks good.

To add to the parts we need an AVR programmer.

I should have made clear in my post that I was actually looking for steps on flashing the AVR (and configuring it to display to the LED).

May be we should start a separate thread on how to flash & program the AVR board.

 

[garygid]

SOC-Meter Internal Wiring (firmware v4.09), not necessarily final:

Edited: To add a 7808 voltage regulator on the "12v" (really 14v) input.

Use this information entirely at your OWN risk, it might contain errors.

If you are not sufficiently competent to do this wiring, get help.

-------------------------
Wire the OBD cable to the female 9-pin "D":

(IMPORTANT: The 12 unused OBD wires must be treated in such
a way that they cannot short with each other, or with anyting else.)

1. Power: OBD pin 16 (always-on 12v) to the Power switch, through a suitably-mounted 7808 regulator, to "D" pin 9
(Note: Something like a 0.33uF 20v capacitor should be added across the input to the 7808 regulator.)
2. Ground: OBD pin 5 to the 7808 regulator's ground, and then to "D" pin 3
3. EV-CAN High Line: OBD pin 13 to "D" pin 7
4. EV-CAN Low Line: OBD pin 12 to "D" pin 2

-------------------------
Wiring the serial-input LED Display to the AVR-CAN's EXT2 connector's pins.

(CAREFUL: Cover each connection with shrink-wrap or equivalent protection
to prevent the shorting of these connections to each other, or to anything else.)

Note: Since these wires will be flexed when the unit is assembled,
the use of stranded rather then solid wire is suggested.

1. Ground: EXT2 pin 8 to the LED's "GND" hole.
2. Power: EXT2 pin 6 to the LED's "VCC" hole.
3. Transmitted Serial Data: EXT2 pin 23 to the LED's "RX" hole.

Good Luck.
Better to ask questions than blow out your LEAF!

 

[evnow]

Anyone wants to try a low power display ? E-Paper with breakout board is $40. They have libraries for Arduino. Ofcource, you can't see it at night ;-)

http://www.sparkfun.com/products/10150

 

[garygid]

Looks like the 5v regulator on the AVR-CAN is running a bit hot with the "automotive 12v" (might be 14v) power input.

So, we intend to add a 7808 regulator (and possibly a "heat-sink") to the input line between the Power Switch (gets +V from OBD pin 16) and pin 9 on the "D" connector.

I edited the parts list and wiring instructions (above) to note this addition.

 

[garygid]

SOC-Meter Options:

1. We might add an optional push-button to cycle the display through several display modes.

Examples might be to display:
1. SOC in percent (of 281 raw, the default mode)
2. SOC raw data
3. alternate each second between SOC percent and SOC raw
4. Show the 4 tire pressures (if/when we find them)
NOTE: That info might be on the Car-CAN buss, not the EV-CAN buss, so a double-pole input-selector switch might be needed.
5. Internal Speed
6. Four battery temperatures
7. actual "instantaneous" miles/kWh
8. what else ??

 

[TonyWilliams]

SOC-Meter Options:

1. We might add an optional push-button to cycle the display through several display modes.

8. what else ??

Range.

 

[evnow]

Range.

Yes - if we can get the miles driven, m/kwh till now, we can give calculate a range. I think we can come up with better algorithms than Nissan - even without elaborate topography and nav data.

 

[lincomatic]

Range.

Yes - if we can get the miles driven, m/kwh till now, we can give calculate a range. I think we can come up with better algorithms than Nissan - even without elaborate topography and nav data.

Yes, miles driven would be great. I'd love to be able to integrate with an EVSE to automatically calc actual miles/KWh at the wall.