Wash and Wear

Wipers and Washers

For a bit of a distraction this weekend, I dove into the windscreen wipers and washers.  The wipers were operational, but very slow.  The washer was an unknown situation.

First was the washer motor.  It is shown below behind the washer bottle.  The motor was pulling current but would not spin.   It was simple to disassemble, just a few tabs to bend back.  It didn't look too bad inside for a 40 year electric motor that has been exposed to moisture its whole life.  The motor was frozen but a little persuasion and it spun free.  A few drops of lithium grease on the shaft and it was humming away.  The pump is in decent shape and just needed a little cleanup of the o-ring.

The washer bottle was another story.  It had a 4" crack on the back side where it slides into the mounting bracket.  Well, a little fiber-glass patch work and it was water tight and probably stronger than the original plastic.  Reasssembled the system system and water sprayed out of both nozzles.  Two issues still:

• The spray jets are positioned right under the wiper arms and thus very little water gets to the windscreen unless the wipers are going.    
• There is no switch to activate the washers.  The wire is behind the dash, but it is not clear where the switch is or was.  Some Minis have the washer switch on the turn-indicator stalk, but Jane's stalk is already full with high-beams and the horn.  A new switch will have to be added to the dash

Black Washer Motor behind yellowish washer reservoir. 

The Wiper motor shown here was mostly just gummed up.  After opening it, cleaning out the 40 year old grease (it wasn't very greasy anymore) and trying to clean-off as much exterior grime as possible, it now spins great with two speeds and automatic parking.  The park switch was a bit sensitive to how the connectors were attached, but after a small adjustment of the inner switch connection, the parking function works as expected.  There is a plunger that is pushed from the motor shaft that separates a contact in park-switch when the motor is in the parked position, stopping its rotation.  One interesting observation about the wiper motor.  The cover holds the permanent magnets and is not marked.  It has two possible orientations, 180 degrees apart.  In one orientation, the motor would spin the drive gear counter-clockwise.  In the other, clockwise (the proper direction).  Of course, it took two tries to figure this out.

Battery Monitoring

The battery monitor has advanced quite a bit.  Shown here is the four CellLog 8M based monitor.  The CellLogs are mounted on a board from ElectricPorsche.ca.  Robin at Electric Porsche has designed this board which was a perfect fit for Jane's needs.  It now monitors all 26 cells and activates a loud piezo buzzer if any of the cells are out of range.  I currently have them set at 2.50V - 3.55V as the normal range.  The looping wiring on the right side is setup to assure that if a CellLog fails or a wire comes loose, the alarm will sound.  The CellLogs keep the 4 relays closed when on and not-alarming.  If a CellLog goes off or alarms, it ceases to maintain the closed relay and the buzzer is sounded.    This system mounted in the boot, on the boot lid, so it folds down quite nicely for easy viewing.  Also, I moved the 600A contactor back to the boot today so that it would not be exposed to the elements under the hood.  Was able to use the electric fuel-pumps power to activate the contactor when the 12V system is turned on with the ignition key.  Just one of the many clean-up things that needed to be taken care of.

Charging update:  With the CellLogs operating now, I have turned down the charger to an 86V terminating voltage, which is 3.3V per cell.  The charger is designed to switch to constant voltage at that point until the current drops to about 1 amp.  This is not the fastest way to charge.  When the charger was set to 91V, a few of the cells would exceed the 3.55V alarm voltage before the pack reach 91V (26 x 3.5V).  Wanting to be conservative, I opted for a slower charge at a lower constant voltage, which should be easier on the cells.  After a couple of charge cycles with this new setup, all of the cells are staying within 30 mV of each other.  LiFePO4 batteries have very steep voltage curves when they near the end of the charge cycle, so as the few slightly fuller cells got near the end of the charge, they would shoot up the voltage curve triggering the out-of-range alarm while the rest were still taking in the last few amp-hours.

Springs

New Springs on the rear

Replaced the rear, very dead rubber cones with new springs today.  The springs are called the SRP-200 (Red, firm).  I started in the back, since most say it is simpler.  However, removing the old springs from the struts turned into a 2 hour job of cutting, chopping, heating, grinding, sawing and a few other choice actions.

This is what Jane's struts looked like.  The top one has the remnants of the old rubber spring.  The bottom one has had it cut away with a angle grinder.

Here are the new springs.  (C-SRP200 from SRacer).


Also, realized that the knuckle joints on the structs were in need to new protective covers during all of this.  The knuckle joint provides rotational flexibility for the strut. Shown here, the top seats in the frame and the strut slides on the post at the bottom.



The front left spring was rather easy to replace.  It required just one trip to Home Depot to get the parts to build a spring compressor.  A 2' piece of 1/2" all-thread, some nuts, a few washers, and for $7, a Mini spring compressor was born.  Worked like a champ.  Removing the upper suspension arm was easy by simple removing the cover plate from the shaft for the arm, taking off the two 3/4 nuts on each end and simply pulling the shaft out.  Took all of 10 minutes.  Once the new spring were compressed, the arm went right back in place.   The front knuckle joints were in good shape, so they just got repacked with grease and sealed-up.

The old rubber spring was a mess but it did separate from the trumpet much better than the rear ones.  A few hits with an old chisel and the spring separated from the trumpet strut.

The right side is going to be trickier since the new electric motor sits right in front of the upper suspension arms shaft cover plate.  Looks like the motor is going to have to be raised out of the way.  

With the new springs in, the front-end sits about 2 inches higher than the rear now.  Makes for an interesting look.  Hi-Los are on order to bring down the front and level the whole car.  A Hi-Lo is just a adjustable strut that can be extended or retracted to raise or lower the suspension.  I guess the reduced weight of the engine missing, does not compress the springs enough to keep things level.

Seeing is believing

LED Dashboard Lights

After an evening drive the other night, we realized that being able to see the speedometer in the dark is useful.  The tiny LLB987 bulbs, which may be 40 years old, just don't put out much light.  Well there are LED equivalents available from www.v12s.com which are perfect.  Not only do they fit well, but they produce a nice white light, much brighter than the old bulbs.

See for yourself.  This photo shows the difference.  The left side bulb was changed to the new LED version, the right is still the old incandescent type.  The fuel gauge may be a bit too bright, but that will be good once it is connected to the battery monitoring system.

Tomorrow, new springs for the suspension which means pulling out the old rubber cone-type (sometimes call donuts) springs and installing heavy duty real steel springs.  This should vastly improve the ride.  Currently, it feels like a bicycle, where every crack, bump and pebble is felt, since the rubber cones are fully compressed and there is no travel available.   No telling how old the current rubber cones are but they are only expected to last 5-7 years and given the lack of compression available, they are well past their life expectancy.

It keeps getting better

Covering some real ground

With the full battery pack and a instrumentation package up and running, we are now going for longer drives.  Yesterday, we covered over 10 miles on a single charge.

The charging system is working great.  Two charges, both tied to the 220V input.  One is the 1500W 91V Lithium Ion charger for the drive battery and the other a 120W 12V charger for the system battery.  Since both are automatic, they shutoff independently when charging is complete.  I have the 220V outlet on a timer just to be safe.

Instrumentation Pack

Here is a the roughed-out instrumentation pack.  This will be mounted behind the dashboard once it is installed.

1) On the left are 4 CellLog8M battery monitors.  These are set to alarm if any of the individual cells go out of range.  Currently I have them set tightly at [3.0V - 3.6V].  Charging is set to 91V which should be 3.5V/cell on average, so any major drift will be detected.  The cells have sagged below 3.0V on a recent hill climb, but recovered to 3.2 very quickly once the road leveled off.  

2) The top-right rectangular LCD is one Arduino Uno which is connected via the CAN Bus to the Kelly Controller.  It monitors: 

• Top Row: RPM, Battery Pack Voltage, Controller Temperature
• Bottom Row: Drive/Reverse, Calculated Speed (Assuming 2nd Gear for now), Motor Amps, Motor Temperature

3)  The lower LCD is another Arduino which is measures battery current through a 600A/75mV shunt.  It is power separately from the drive battery pack via a 12V adapter.  This keeps the battery system isolated from the rest of the car's 12V electrical system.  This Arduino is always on and maintains a running count of the amp-hours consumed.   The shunt is installed at the battery negative terminal to eliminate noise from the motor and to allow for monitoring charge going into the battery from either the charger or from the motor's regeneration braking.

In a quick experiment, after a 5 mile drive, I then connected the charger.  The Amp-Hour counter returned to within 3% of full.  Please note, I have not calibrated the system yet, so this is very promising.  The system is using an Analog Devices AD8210 Shunt monitor to measure the voltage drop across the shunt.  It is wired with a split-supply configuration, so 0 Amps = 2.5V going into the A/D on the Arduino.  This setup should yield about 1A precision on counting amp-hours.  Given the 20% DoD (depth of discharge) limit, this should provide plenty of margin.

Controller settings

Now that there is decent current monitoring, we tweaked the Kelly KHB72701 controller settings a bit to see if there is a bit more power available.  During the drives yesterday, The battery current never exceeded 200A and the motor current peaked at about 300A.  The spec on the motor is a max of 420A for 1 minute and the batteries should be capable of 400A-600A for short bursts since they are 60AH packs and there are several reports of people safely pulling 8C-10C.  Batteries are rated in terms of multiples of the AH measurement, so a 8C battery can deliver 8x60AH for a short burst. 

With motor blower providing plenty of cooling, he motor's temp peaked about 55C.

New Settings:  

• Throttle Range 5%-80% (this is a mapping to the mechanical throttle position).
• Max Motor Current 90% (this is of the controller max of 700A --> 455A)
• Max Battery Current 100% (700A)
• Undervoltage (Controller will start to cut back power draw at 110% of this value): 68V (cut-back at 74.8V, or 2.87V)
• Overvoltage (Controller will limit regeneration if voltage exceeds this): 90V
• Throttle Ramp: 4 (How fast it will ramp up acceleration)
• Regeneration: Off 

Off for another test drive to the grocery store....

Starting to see some encouraging signs

First Extended Drive

Today, we headed out on a extended drive.  Not knowing the real efficiency of the car (miles/charge), it is going to take some testing to become comfortable with the nominal range.  The Amp-Hour meter that is currently connected does not retain its values after a power cycle, so it is not a great fuel gauge.  More on that later.....

It was a sunny day here, about 65 degrees, so a perfect day for test drives.  Earlier in the week, I did a 4 mile run around the flat part of the neighborhood and the batteries only required about 30 minutes to recharge fully.  Today, we drove for 8 miles with some hills.  The batteries still read about 85V but since the drop off near the end of the charge is fast, I am hesitant to let them get too low.  Well after a 7.5 mile drive, they took about an hour with the 16A charger to return to 91V (the current target charge level).  This was the previous charge level so it should represent a reasonable replacement energy measurement.

Based on these estimates, the car averaged about 180 Watt-Hours/mile.  Right in the expected range of 150-200.  With a conservative 80% usable capacity, this should equate to 22 miles of range per charge.  A GPS was used to track distance, but a more accurate charge timer is needed to estimate the actual Amp-Hours that are being put into the batteries, or taken out with the a better amp-hour meter.

Here is the boot with the batteries in position.  Not a lot of extra room  The brown and blue wires are the battery monitors which make sure that none of the cells deviate too much.  The next step will be to route these up to the dashboard so the driver can monitor the battery condition.  The large blue connector is the charger connection.  The charger will be mounted to the left of the pack.  The large (red) 12 battery is powering all of the electronics in the car (lights, radio, controller, fans)

Cooling

The motor coil temps, as reported over the CAN bus from the Kelly controller is running between 80C-90C after a couple of miles.  This is well below the limit of 145C but still on the high side.  The internal fan on the motor has two issues:

1. It does move a lot of air - @2,000 RPM, I could barely feel any air leaving the motor.
2. It does not cool when the motor is not spinning. 

A supplemental fan is needed and I found a 12V marine exhaust fan that moves a lot of air.  The challenge is how to duct the fan into the motor in the tiny Mini engine compartment.  I tried a Rube-Goldberg solution today using 4" flexible ducts but there is just not enough room at the end of the motor (where the internal fan draws air) to route the ducts.

The Plan:  Bring in 1" hoses (probably two) into the fan housing on the motor, from the top to push more air through the motor.    The challenge: How to plumb the 4" fan down to a couple of 1" hoses through a manifold.  The air is moved from one end of the motor to the other, horizontally.  There are large vents in the housing on the shaft end, so if enough air can be pushed into the fan end, it should push on through, providing much better cooling.

First test of the Full Battery Pack

We headed out around the block with the new 84V 60AH battery pack.  Starting out in 2nd gear to keep things gentle, Jane climbed our hill with little hesitation.  Next we headed for the short flat stretch of street around the corner and in third gear, she got right up to speed.  Here is a video of us returning home.   You will see the pack mounted in the boot along with the battery monitor leads.

Even under the full hill climb, the pack only sagged to 80V, still close to 3.1V per cell.

Next - Clean up.  Lots of cables and mountings to sort through.   However, it is a great motivator to be able to see it all coming together.  Also, a quick run down the to the non-hilly part of the neighborhood for a real speed test.

Battery Time

The batteries arrived and this opens an entirely new chapter in design and learning.  Not only is there the mechanical design elements of assembling and installing the battery pack, there are the safety challenges. Compared to gasoline, I believe batteries are safer and easier to work with, but society's false sense of security with gasoline causes some initial concerns.

The batteries of choice for Jane are the CALB CA60FI.  These were introduced last year and the reviews are all very positive.  These were sourced from Shift-EV in Albany Oregon.  Kirk is a true expert on EV conversions.





The chemistry is LiFePO4 (Lithium Iron Phosphate) and these offer 60AH  at 3.2V nominal.  The pack will consist of 26 of these in series providing a nominal pack voltage of 83V.  At a 80% depth of discharge assumption, these cells will provide 48AH @ 83V or just shy of 4 KWH.  The Kelly Controller is limited to 90V input voltage, so  this provide a little margin, but should still be sufficient voltage for the motor to achieve 3,600 RPM under load.   Based on the best gear ratio calculations, in 4th gear, Jane will cruise comfortably at 55 MPH.  3rd Gear will yield 45 MPH.  More than fast enough for this car and any city driving.  There is an option final drive gear (3.44:1 --> 2.76:1) which will pull in another 13 MPH at the electric red-line.

Pack weight=26 x 4.45 lbs = 116 lbs.

If you want to see the detailed calculations, here is a spreadsheet (Called Vehicle Calculations) with the best-guesses for performance.

Charger

Another major component for the battery pack is the charger.  We selected an automatic, adjustable voltage charger from BatterySpace which provides 16A and 1,500 Watts since there is still much debate over the best charging process to maximize longevity of the battery pack.  The first charge cycle completed successfully set at 91V and the charger performed as expected, shutting off when the pack reached terminal voltage.  This is plugged into a 6 hour mechanical timer and a 220V 30A outlet in the garage.  It will get mounted in Jane's boot and eventually a simple cord is all that will have to be plugged in to "fill her up".
This charger will fully charge an 80% depleted pack in about 5 hours.  The CALB cells can take a faster charge, but there are cascading effects from increasing the charger power such as more heat, more battery wear-n-tear, larger cables and bigger power sources.

Battery Monitor

And the final critical element of the battery pack is the monitoring system.  With LiFePO4 batteries, maintaining them within the proper voltage range is critical to prevent damage.  There are many opinions on how best to do this but it is clear that the tighter the range of voltages, the less stress on the pack.  Initially, the system will be set to keep the cells between 3.0V (discharged)  and 3.5V (charging), though others say the window can be slightly larger.  Battery Management Systems range in price up to thousands of dollars, depending of the size and number of cells in the pack.  Since the battery is the most expensive element of the EV drive train, it makes sense to monitor and manage it diligently.

For Jane's initial BMS system, passive cell monitors will be used to report and alarm if a cell goes outside of the target range.  The driver will have to respond appropriately based on the situation and severity of the deviation.  Not terribly different than the check-engine or over-temperature light on a gas car.  A driver can choose to ignore it but damage may occur.


The CellLog 8M is a clever device.  It provides monitoring for up to 8 cells and alarm capability for High Voltage, Low Voltage or if there is too much variation between the cells.  It will take 4 of these to monitor the 26 cells (2x6 and 2x7).  There is an minor annoyance with these devices in that they draw less power from cells 7 and 8, causing those to discharge at a slightly slower rate than the first 6 cells.  Given Jane's configuration, this will only impact 2 cells which may need to be balanced periodically to bring them back in line with the rest of the pack.  The four CellLogs will be mounted in a cluster on the dashboard so the driver can quickly see all 26 cell voltage values if an alarm occurs.

The last component in the monitoring system is the AH meter from Elite Power (600A 90V Combo Meter).  This will act as a fuel gauge and provide a count of the Amp-Hours (AH) drawn from the batteries. Using a 600A 75mv shunt on the negative side of the battery, this meter will count the actual cumulative power (AH) fed into the controller.   With LiFePO4 batteries, voltage is not a good indicator of State-of-Charge (how much energy is still available from the cell), so using AH counting will provide the most accurate fuel gauge.  It will take some verification and experimenting to map AH to overall state-of-charge.    More on that to follow...


Elite Power Meter

Shunt

Finally, the EVALBUM page is up for Jane.  Not all of the details yet, but a great gateway to other electric vehicles.   Be sure to check it out....   http://www.evalbum.com/4768