More Instruments - Temp and KMs

Just some minor enhancements that will really help the driver.

The odometer (though in kilometers) had a feature that forced it to stop advancing when it hit 99,999.9 KM.  After disassembling the speedometer it only took a little push to move the counter past 99,999 back to zero.  Well today it worked just perfectly.  There was still 40 year old grease on the gears but I added some fresh just for good luck.  I guess this starts the official counter of electric miles (or kilometers for those who can't do fractions).

Also, with about 5 lines of code, a 2.2K resistor and a 2N2222 transistor, it was trivial to connect the dashboard Arduino to the Smith Temperature Gauge.  Using the

• Pin 9 PWM to drive the base of  transistor through the resistor
• connecting the emitter to ground
• the collector the gauge's input (the original temp sensor input from the non-existent engine)

... the system worked.  The other connector on the gauge was connected to +12V, once it was discovered the voltage stabilizer was not working well.  The spade was lose which caused intermittent behavior.

Here is a shot of the odometer and temp gauge in full operation.  The gauge is currently set to show 70C as "N" (mid-scale) so that should provide a quick indication for the driver if the motor is heating up.

A voltage gauge is on order to replace the oil pressure gauge on the right side of the speedo.  This will monitor the 12V system to make sure it is operating properly.

25 Miles

A long test drive

Today was a day of test drives.  The first was a speed test.  While cleaning up some wiring I realized that the accelerator cable may not be pulling the controllers sensor fully, so I lowered the effective top of range to 70% of full scale.  Well it made a difference and the motor is now spinning near 4300 rpm in neutral.  Which is very close to the theoretical limit of 50 rpm/V with a 85V battery.  Given, this I wanted to see what Jane would do in 4th gear, so we headed to the one stretch of nearby road with a 45 mph speed-limit which is outside the city limits.  On the level straight-away, Jane hit 53 mph and was humming along.  There may have been a few more mph available, but at about 50 mph, I noticed that the front wheels are out-of-balance and started to shimmy a bit.

Well, after a top-off-charge, we headed out again, this time with a goal of testing range and the fuel gauge.

The image shown above is the screen shot from the GPS Essentials program which shows 25.2 miles covered with a max speed of 35 mph.   The max speed is only captured while the screen is on.  It looks like in 2nd gear, Jane will do about 37 mph, which for city driving is perfect. 

The fuel gauge showed 15% remaining which calculates out to 41 AH consumed (out of the 60 AH available in the battery).   Using the 80% available capacity, this works out to a range of 29.6 miles on a full tank (with a 10% reserve still there to protect the battery).  The batteries were not showing any signs of being depleted.  Only one near the end did the low-voltage alarm trigger during a very steep hill climb.  It cleared as soon as the load was reduced.

The other interesting calculation is 41 AH x 84V / 25.2 miles = 137 WH/mile or 7.2 miles/KWH.  This works out to about 250 miles/gallon (MPGe) using the conversion factor of 1 MPGE = 0.0292 miles/KWH.  This does not take into account the efficiency of the charger which would lower this by about 40%.  You wouldn't think the charger would have to be taken into account....  I have not done the math to see if spending more on an efficient charger would save enough electricity to justify the added cost.

To take this one more step... At $4.00/gallon, Jane with the gas engine hit about 42 mpg or about 9.5 cents per mile for gas.  Based on Oregon electricity prices at 11.5 cents/KWH... the electrical cost comes in at about $0.115/7.2 miles or 1.6 cents/mile.  Even factoring in 60% efficiency 2.25 cents/mile.  The battery pack adds about 4 cents per mile so this brings the total cost of the electric mile to about 6.25 cents (a 30% savings from the gas model of 9.5 cents/mile).

Finally, accurate current measurements

Getting to the "truth"

With a borrowed Fluke 600A DC amp meter, I now have accurate current measurements for the charging system.

1. The charger's current reading is within 0.1 amps of what the Fluke reports for current going into the batteries.
2. The charger pulls 10.1A @ 240V or close to 2,450W.  The fan adds another 0.4 amps.
3. The 12V battery charger pulls about 0.5A @ 240V
4. The 12V power supply draws approximately 0.1A but is probably in the noise.

Impact

1. The current monitor (fuel gauge) Arduino is calibrated to the charger.  This should be now less than 5% off.
2. The fuel gauge is set to never exceed 100%, so it should "zero-out to full" near the end of every charge cycle, as long as the cycle runs to completion.  By ignoring the charging efficiency of the LiFePO4 cells, the fuel gauge should hit 100% about 1%-2% before the batteries are full.
3. The charger's efficiency is about 55%-60% based on power-in (240V x 10.1A = 2425W) divided by power-out (~90V x 16A = 1440W; the charger is rated at 1500W).  The charger spec states that charging should take 1.41x the battery capacity / 16A.  Not a surprise this ties out to the 60% efficiency, though it is spec'ed at 85%-95% efficient.  Maybe at the higher voltages it can achieve this.
4. The best news is the overall energy efficiency of the car is coming in where predicted.
1. 4000 KWH of usable capacity (80% of the pack)
2. Today I drove close to 12 miles using 48% of the pack.  This included several hill climbs and normal traffic driving. 
3. This leads to about a 25 mile range with 20% reserve. or 160 KWH/mile.
5. At work, there is CharePoint charger which reports KWH used, so next I'll try to calibrate against that with the data above.  Mostly it is good just to have an accurate fuel gauge

The Non-Fan - Cooling the ME0913

The Fan or lack there of....

A local machine shop fabricated up a blank disk to replace the fan in the Motenergy ME0913 motor.

This is the original fan in the motor.  Note the blades spin fairly close to the motor housing, which works well when the rotates counterclockwise (CCW, to the left).  In Jane the motor spins clockwise (CW) from the fan-end and thus the blades move no air and only serve to frustrate (restrict) any air that is trying to be pulled through the motor, from the shaft end, which is the direction the original fan attempts to move air..

This is the original fan out of the motor.  The central hub is riveted on and the timing (magnetic) ring is bolted on.  There are no markings on the timing ring, so I marked its position relative to the key slot on the hub.  It took a little persuasion to get the fan off the motor shaft.  There is a 2.5 mm set screw holding the key and hub in place.

The blank aluminum disk is now mounted to the hub using #8 bolts and the timing ring mounted to it with the original bolts.

The disks is now on the motor.  A little high temperature grease was put on the shaft which eased the mounting process and hopefully removal if that is ever necessary in the future.  You will see there is now a nice gap between the disk and the vent holes in the motor housing.  The theory is air will move more freely through the motor and around the spinning disk to the exhaust fan.  The exhaust fan was able to cool the motor quickly when the motor was not spinning but when it was operating, the cooling efficiency really seemed to drop.

Good Results

Hill driving is the best test since it forces the highest current through the motor for an extended time.  I took Jane over to the steepest hill in town and attempted a climb at 20 MPH in 3rd gear.   The motor was already warmed to about 60C.  In the past the temperature would rocket up to 120C about half-way up the hill.   This time under a good load (15KW) it only got to 105C about the time Jane crested the top.  The second test was whether the cooling fan would be able to cool the motor while moving.   This was something that did not happen in the past.  The next 3-4 minutes were driven at lower power (3KW) and the temperature dropped quickly to 85C.  Just the fact the temperature dropped is a vast improvement.  In the past, the only way to see a decrease in temperature was to stop and let the cooling fan run for a few minutes.  Tomorrow, I'll try a more extended run to see if there is a steady-state temperature under normal driving conditions.  Also, the next enhancement is to connect the Arduino that reports the temperature from the Kelly controller to the original Mini engine temperature gauge.  

Controller Supply Voltage and Fan Update

Surging

During the last few test drives, I noticed that the motor tends to have a slight periodic surge when approaching maximum rpm.  It is subtle when cruising at a constant speed, but a slight pulsing or surging could be felt.  This led the following investigation:

1. The Kelly KBH 72710 controller is rated for a supply voltage of 8V-30V.  This is the supply for the controller's functions, not the main drive power which is 85V in Jane, with the controller rated at 90V.
2. The system currently has an adjustable voltage booster to covert the 12V standard car supply upward.    TI LM2577 Link
3. Previously, the booster was set to output 18V to supply the controller.
4. I can't remember why I landed on this but there were  published reports that 12V was insufficient.
5. While reviewing the Kelly datasheet again for the controller, it says that 24V is "preferred".
6. So, a few small turns of the screwdriver and the booster is now set to output 24V.
7. During a test drive today, the surging seems to have stopped.  But it will take a bit more testing to confirm.

Not sure why this was not noted previously but it can only help.  

Cooling

In the next attempt to cool the motor, a local machine shop is fabricating a blank disc to replace the fan in the Motenergy ME0913.  John from Motenergy provided the mechanical drawing for the fan assembly.  The fan carries the hall phase magnets so it is a critical component of the motor and can just be simply removed.  The current theory is the fan, though running in reverse (CCW from the fan end)  from its designed direction (CW from the fan end), is frustrating (impeding) the air flow through the motor.  With the blank disc, there should be no interference or obstruction for the air.  Currently, the cooling system is just on the verge of being sufficient, so if by removing the fan, there can be a 10%-20% gain in flow, the results should provide sufficient headroom.

Dashboard

Work continues on the electronic dashboard.  Here is the latest design:

Boot Up Screen  (Yes, that is an image of Jane Austen)

Sitting Idle

After pulling out from a stop sign

A few highlights:

1. The graph shows power consumption and regeneration in half second intervals.  The bars are color coded to make for quick interpretation.  It will show about the last 30 seconds of data and continuously rotates
2. Watts appear to be the best indicator of system strain and is closest to RPMs for a gas engine.  Thus the real-time motor watt consumption is now shown with the large numerals.  They are set to change color based on the following:
1. Regeneration in effect = Green
2. Less than 12KW (Continuous power limit for the motor) = White
3. 12KW - 18KW =Yellow
4. >18KW = Red - The motor's 1 minute rating is 30KW
5. This is a computed value based on values reported by the controller - Motor Amps ( % of controller rating - 700A) x Battery voltage at the controller x PWM % (pulse width modulator duty cycle)
3. The other values are also color active to help the driver quickly spot an issue.  Much like gas cars, the driver is responsible for managing the system.  This is no different than red-lining a gas engine or ignoring a check-engine light.   The car will let you do it but should warn the driver of the situation.
4. The large "Forward" indicates whether the motor is in Forward or Reverse
5. Warnings and error messages are displayed across the bottom of the screen when needed.

The Dashboard Continues

Rev 2 of the Dashboard

After a lot of cutting, sanding and re-doing, the dash is in but not covered.  Next step is to find some appropriate material to cover the rails and dash.  Next step is to create the center binnacle frame but that may mean pulling the binnacle forward to make is in-plane with the rest of the dash.

The before condition

Driver side

Passenger side with new glove box door

The new speakers  make a world of difference.  The glove box is not built yet, just the door is in place with the magnetic catch.  Having the stereo by the driver is also much easier than the old position in front of the passenger.  The Arduino is mounted in a portrait orientation since this was the only way it would fit with the defroster vent running right behind the dash.    The stereo barely clears the same duct.  There is still the question about adding the red and green status lights to help grab the driver's attention.

Minor Arduino enhancements this weekend:

1. Limit the screen update frequency to no faster than once every 3/4 of a second.  These seems more than fast enough and provides sufficient time to perform all of the queries to the controller between updates.
2. The system now reads the status of the accelerator switch to determine if the system is in regen mode.  If there is controller current and PWM values and the accelerator switch is off, then it must be in Regen.  With this information, the power reading on the display turns "Green" to indicate regen.  It is White normally, Yellow above 12,000W and Red above 18,000 watts.
3. Added a rolling column graph to show power over time. This is not terribly useful but it does provide a quick glimpse to see how much power was used for a recent hill climb or acceleration.  It shows about 20 bars each representing 3/4 of second.  With the limit screen real estate available for this, it is not very high resolution but the bars change color in a similar manner to the power indicator in #2 above, to speed interpretation.  The whole graph is about 200x50 pixels.

Testing

Completed another extended drive today, 15 miles with hills and one 45 mph stretch.  Everything worked well, no real issues.  The motor heated up to around 100C during heavy loads but cooled off to 80C as soon as the load was reduced or the car was stopped at a red-light.  With the ChargePoint charger at work now, it be easier to assess actual energy efficiency since the charger will report total KWH provided during a charging session.  

Here is a ChargePoint screen shot from a quick charge last week.  This is reporting about 1.1 KWH, which is a 25% of the 4 KWH usable battery capacity. Took about 40 minutes.  This also included the recharging of the 12V accessory battery which has 100W charger.  Their Android app is also very handy since it reports real time charge status like time and power.  Makes it easy to know when the charge is complete.

ChargePoint Data Reporting - Shows actual KWH used to recharge

New Dashboard

A Real Dashboard

Jane came with a fairly limited dashboard (instruments + storage + decorative features to hide in inner workings).  It has the 3-gauge binnacle with the speedometer (w/ fuel gauge), temp and oil pressure gauges.  Besides that, there were two shelves (Vinyl covered cardboard) on the left and right which had limited value except to gather junk.  The blue vinyl never fit that well.

This weekends project was to build a real dashboard and here is the current state.    You can see the Arduino display positioned where the driver can see it through the steering wheel.  This new wood panel will be covered in some durable material along with the top and bottom rails.  the panel mounted with two brackets which connect with wing-bolts to the supporting structure holding the lower rail.  The side vents are going to be capped and only the main blower will be available fresh air intake.

The plan is to have matching panels on each side and a nice wrap-around for the binnacle.   All matching and all wrapped.  The radio will be moved to the driver side just, to the left of the Arduino.  The passenger side is getting a small glove-box.  The final addition will be two 4" speakers for the stereo, probably close to where the vents were originally place.  This will improve the sound quality since Jane currently only has two speakers in the rear deck. Also, the USB for the stereo and the Arduino will be routed to the Glove Box for easy access

It only took a few minutes to add the bonnet hold-down latches.  Picked these up from 7ent.com : Bonnet Hook Kit.  They fit great and provide a very secure yet easy latching.  Much better than the quarter turn screws that were in the holes shown.  A little patch work and those holes will be gone.

While inside the dashboard, the battery monitoring Arduino is getting moved to the boot.  Two benefits - The current monitor AD8210 will be closer to the shunt (1 foot vs. about 7 feet of wire) and there will be no need to bring the battery voltage (84V) into the cabin for the adapter to power this Arduino.  This Arduino must be isolated from the main 12V supply which is why it is powered of the main battery pack, no the 12V accessory battery.    However moving this naturally threw off the calibration so that will be tomorrow's task.  Now only the battery alarm and fuel gauge signals are being routed through the cabin to the dash, a better and safer design.