Now we are motoring

Well this weekend was one of actual driving the electric Mini.  The motor is mounted, the stabilizer bar connected, the controller, inverter, 18 V supply, throttle and 12 V system are all connected and operational.

So we backed out of the garage.  The electric reverse switch is a wonderful feature.  Just leave the car in 2nd gear and the motor can change direction with a flick of switch.

Heading up the hill.  No Smell, No fumes, No Gas

At the top of hill, it was quick turn-around and then coasting down at about 20 MPH.  A good test of the transmission.  Regeneration is still turned off at this point.  

Then we turned around again and headed back up for another test.  

Observations for the day

1. Electrics are quiet and you can really hear the radio and birds.
2. 25 Volts is only good for about 10 miles an hour on level ground in 2nd.  I figure we are only getting 1000 RPM.  The current meter reports about 300 amps (probably close to 33 ft-lbs of torque).  The original 988 could generate 52 ft-lbs @ 2700 RPM.  With the real batteries, the electric should easily surpass this.
3. Going up and down the block gets a little boring after awhile.  However, with limited battery capacity, it would not be wise to stray too far from home, especially where you can't coast all the way home.

Next steps.... Time to size and purchase the real batteries - Probably 26 LiIon packs... More to come....

In and Out

We pulled the old engine out and actually were able to install the electric in the same day.  It even spins.

Here is a shot of the old oil-leaking gas engine.  The engine lift ($99 from Harbor Freight with $6 shipping) made it fairly easy to lift and move around.  It would have cost more than $6 in gas to drive to the nearest Harbor Freight in Salem.

This is the empty engine compartment.  Lots of clean-up to do.  The Subframe is in good shape.  The real test is whether the electric would fit  You can see the CV joints on the end of the drive shafts, just next to the exhaust manifold, which is now removed.

Here is the electric in place.  It is attached to a Standard rod-change Mini transmission, so the engine mounts can be used with out much modification.

Here is the new engine compartment.  Still lots of wires to cleanup

Here is a video of the wheels actually spinning.  The controller is turned down and only two 12V batteries are attached at this point, so the speed is limited.   The squeal is from the helical gears which need to break-in to mesh better.  Also, there is no oil in the gear box at the moment, so that will help quiet things down.  The thumping sound at low RPM is expected in 3-phase DC motors.  It smooths out with speed.

Next Steps...

• Connect the gas pedal to the controller so we can actually drive
• Buy and install the batteries
• Clean-up the wiring

Minor items before the engine swap

It appears everything is ready for the engine swap.  We just need a good chunk of time to get it done since it will require a rental engine lift.

Today, we swapped out the oil seals for the drive shafts and the rod shifter.  Much easier to do while the engine is out of the car.

This is the where one drive-shaft will connect to the differential.  The others side is identical.

Below, the image shows the shifter (rod on the right) going into the differential housing.  The new oil seal is visible in housing.  With the electric motor, the need to shift will be reduced to only occasionally, so this new seal should last forever.  The electric motor is electrically switchable to reverse.   Based on the current gear ratios and the RPM range of the motor, 2nd gear should suffice for most city driving.  If higher speeds are needed, then 4th gear would have to be engaged, not that Jane should ever really see much above 40 mph.

Painted Roof

The roof had several spots on it where the old paint was bubbling.  After sanding and wire-brushing and filling, here is a shot of the new paint on the roof.  Not perfect, but an improvement from where it was.  Plus, the plan is to put a decal of the Union Jack on the roof, so this should suffice.  Don't be too shocked, the new paint actually has a bit of shine.

Fixed Tail Light

Some older small projects that were done over the weeks

The left rear tail light was missing the separator between brake section and the turn signal section.  So when either light was on, they both glowed.   Using the other side's divider as a template, 5 minutes later a new sheet metal piece was installed and the lights look a lot better.
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The turn indicator would not automatically cancel, leaving the blinker on as we cruised down the street after a turn.  The goal was not to look like a grandmother with the blinker on for 15 minutes.  The white ring (with the screw through it) was just worn out after 40 years and was not quite thick enough to push the cancel bar up as the steering spun around.  A little spacer (the pointed thing) glued on top of the old raised bump provided just enough pressure to push the cancel bar up and turn off the indicator.  Little conveniences like this go a long ways.




Mounting the radio under the dash was a big improvement.  This radio includes USB connectivity so it is quite easy to connect an iPhone to listen to music as we drive around.  The hoses shown in the photo are part of the heater, which thanks to Spring arriving, is no longer needed.  Also, position the radio in front of the passenger, provides some entertainment and keeps it our of reach (aka: distraction) of the driver.

It Spins

After several weeks of designing and awaiting parts, not to mention a broken humerus, the controller is mounted and wired to the transmission.

This shot shows the controller on top of the transmission.  A few details:

• Kelly KHB72701 controller - 700 Amps, 90 Volts opto-isolated controller
• 600 A contactor with protection diode across the contactor coil
• 2K 10W pre-charge resistor across the contractor contacts
• PB-6 with microswitch for throttle control (add to add 3rd wire to potentiometer)
• 2/0 AWG welder wire to carry the power along with 1/2 crimped lugs
• 800A Fuse
• 2 x 2A fuses for controller and the contactor
• 18V and 12V power supplies to isolate the controller (18V) from the contactor (12V) and batteries (24V, eventually 77V)
• A couple of switches to manage the reverse function and contactor power
• Motenergy ME0913 motor with thermistor (KTY84-130) attached with 1K resistor as a voltage divider

After lots of crimping and cutting, we powered up the system, connected two old car batteries and sure enough it spins.  The throttle worked, the reverse switch worked and the motor sounded quite normal.  The transmission is dry at the moment, so we didn't spin it faster than a couple of RPM.

After reading about all of the problems people have had, it was a surprise that things worked out of the gate. Though I shouldn't be since this was assembled as the manufacturers suggest.

Next up....

Finish sealing the transmission and put in some transmission fluid to allow it to spin full speed.   Then the planning starts for the engine swap.

Mounting the Electric Motor

Fitting the pieces together

This is the electric motor (ME0913) mounted to the adapter plate mounted to the flywheel housing connected to the gearbox.  Some preliminary measurements indicate that this should fit in the engine compartment without having to make any major modifications, a key goal and reason for selecting this motor.

From the top, you can see the full gear train of the transmission.  The differential is the protruding mechanism at the bottom, nearest my left foot.  The CV joints and axles will connect to that.

A new thrust washer was also needed to tighten up the tolerances on the float for the idler gear (the one the primary gear mates to).   The spec is about 0.003" of float (movement back and forth) and with the new thrush washer, the float is right at 0.002".  Most of the advice on the web is to be very close to 0.003", so this should be just right.  Thrust washers only come in 0.005 increments or so, there is not a lot of options.

The original primary gear is shown right in the center with its retaining bolt holding it to the shaft of the motor.  The shaft adapter (7/8") was turned to press fit into the primary gear with its roughly 1.5" bore along with a 3/16 key.   Then a hole was drilled through the spline of the primary gear to lock it to the shaft adapter with a 3/8" bolt.  We also installed a new oil seal for the primary gear, though there should not be much oil around that gear since it does not have any bearings now.

This is the primary gear.  The splines that were drilled along the top end of the gear.

  

Next steps... cut and drill covers the gear box, then order up the controller

Drivability

In an effort to keep Jane driving during the conversion, the clutch slave cylinder was rebuilt.  The old internal parts looked to be 40 years old and the rubber seals were shot.  This explained why the clutch was so spongy.  Carly noticed immediately how much firmer the clutch feels and how the contact point is much closer to the top of the range of travel.  Also, it doesn't bottom-out any longer and shifts easily with no gear grinding.  It's the small things....

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Controller Thoughts

At this point, I am thinking of using Kelly KBH72701  which is a 72 volt 700 amp BLDC controller.  The biggest question at this point is whether we should go with a 96 volt model to squeak out a few more RPMs.  The maximum RPMs of the motor are determined by the voltage at a rate of approximate 50 RPM/volt.  The ME0913 is rated @ 5,000.  Our overall strategy is not to operate any key component at  or near its limit to extend its life and reliability.

Given then gear ratio and 10" wheels of the Mini, this tables shows the speed of the car in different gears and motor RPMs.

RPMS	1st	2nd	3rd	4th
1000	5	7	12	16
2000	9	15	23	33
3000	14	22	35	49
4000	19	30	46	66
5000	23	37	58	82

Courtesy of Guess-Works

At 72 volts, the motor will top out around 3,500 RPM which in 4th gear will be about 55 MPH.  Probably faster than anyone wants to go in Jane.  The motor torque will be limited by the amperage of the controller.  The motor is spec'ed at 420 AMPs (for 1 minute) and this controller can deliver up to 700A, so there is plenty of headroom.  This will help not overhead the controller.

The motor's torque is computed by Amps x 0.15 (NM/controller amp).  At maximum current (600 battery amps into the controller, this will equate to 90 NM (Stall Torque) or 66 ft-lb.  The 998 motor that was standard in Jane is spec'ed at 52 ft-lb at 2,700 rpm.  If the numbers are accurate, the electric should have 25% more torque than the original engine, and it will be across the whole rpm range, not just at a peak RPM.  The highly coveted 1275 Mini engine is rated at 69 ft-lb @ 3,000 rpm, only 5% more than what is expected from the electric.

Cutting Steel

Electric Motor Mount

After much mechanical "engineering", a scheme has been launched for attaching the electric motor to the gearbox.  Simplicity is the goal and here are some photos.

This is the gearbox and flywheel housing (on the right) mounted.  The gear in the housing is the primary gear that will be attached through a shaft adapter to the electric motor, mounted on the other side.  The adapter is being turned by a local machine shop to fit the primary gear (1.5" bore) and the electric motor shaft (7/8").    The primary gear links to an idler gear which passes motion down to the input gear for the transmission.  I am mixing A and A+ components for the transfer gears, but they are fairly interchangeable except for the idler gears shaft size (3/4").  Luckily, there are bearings that adapt both (1.375" bore in the gearbox).

This is the mounting plate (3/16" steel) for the motor.  The 8 bolts (5/16"x3/4"), located using a piece of acrylic to trace the mounting holes on the flywheel housing, hold this plate to the housing and gearbox.  Next, the mounting holes and shaft hole will be drilled for the motor.

This is the 40HP motor, 38 pounds.  Won't be able to test it for a while.  Must complete the mounting and I am still debating on which controller to use.  More on that later.

Cutting 3/16 steel plating is a slow process using a circular saw with a cut-off blade.  After about 3 cuts, I am now able to cut fairly straight.  A few more covers are needed for the gearbox to go where the block normally would.

This is the Input Gear for the transmission.  It had to be swapped out so the teeth would match those of the idler gear and primary gear.  The classic situation that you change one thing and 3 others have to change.  In this case, the input gear had to be swapped and the idler gear's bearing (shown in the upper right corner of this photo).  Also the input gear's bearing chase on the flywheel cover did't match the bearing which goes on the end of this shaft, so yet another swap-out.  All of these parts are used and so I really can't complain about having to buy a few bearings or adapters.