11.  Other Details

This page covers these topics: 

   Blue indicates WIP

 

Aerodynamic Drag Reduction

Feb 2010

For an incremental reduction in aerodynamic drag, here is the main bottom pan in place.

I used ABS sheet with truss/ribs bonded to its top surface for rigidity and mounting aids.  You can see a pair of mounts in the middle(sides), where I took advantage of existing studs that BMW must have planned just for me.  Also, they left me nice panel mount locations on leading edge of this sheet, perfectly suited for this purpose.

I am using the same BMW panel fasteners that hold the stock underside panel up front.  Because of how functional and friendly these BMW panel fasteners are,  I am using them for all my panel mounting locations that will go in in the rear, which will finish cleaning up the air stream below and keep the aux battery pack dry and clean.

Note that the panel in front of the ALU stiffener above (original BMW design) is not in place in this photo but makes a very good seal all the way to the underside of the front bumper.

 

Here is another perspective:  

Working with ABS is a pleasure, I must say.  It can be made very robust very easily with quick bonding of structural elements that you whip out on the table saw or any wood working equipment.  With various sheet thickness and with texture, anything is possible.

 

Water Runoff Management                                                                                                                  

 

Another little detail that I took care of to keep the motor compartment dry.  The cowling below the windshield is where the intake air comes into the interior, it also needs to deal with water that can come in at any time from rain or washing.

I machined this pair of "downspouts" from ABS block to replace the original gray rubber  flap design (image below, bottom right) that simply dribbled water into the engine compartment.

Tubing that slides onto these barbed fittings route the water down and through the new bottom pan to keep the inside of the motor compartment completely dry and clean.

The downspout sleeve (top of image) will be bonded with a permanent squeeze on the O-ring.  

On the other unit, I used a stainless bolt and spreader bar to push on the sleeve and squeeze the rubber O-ring to allow easy removal if access to wiring/plumbing below is ever needed. 

Also made it a bit longer to better clear the wire harness bundle that passes below.

ABS material makes this task easy.  Just had to think up a shape that places the fittings in the best locations while simultaneously considering the machining/material and poof, the assembly magically appears...

 

Vehicle wiring / Control Center                                                                                                          

Here is a look at the quantity of signals that are involved with my electric drive system. 

I didn't hold back; I even embedded wiring for monitoring energy and heat transfer,  for "data mining" to fully understand the system details for further refinements. 

Also included is the LED RGB bus that runs front to back for special lighting purposes.

Next update will have all these wires plugged into their latching headers, on a circuit board that directly replaces the BMW Engine Control Unit.  This allows the use of many embedded resources already wired into the BMW wire harness such as cooling system I/O, driver pedal inputs and ignition key state to name a few. 

 

Update April 20, 2010

Here is what I have spent my time on in the last couple weeks,  confirming things, discovering swapped wires, burning up a few wires...  But all is shaken out now and all but the Air conditioning has been fired up and tested.

The first real world test... I pressure washed the car then opened up the hood to inspect the water presence.    All electrical zones, including this cavity were bone dry, the gutters and drains all worked nicely.

 

 

         

Front Charge Port                                                                                                                November 2009             

Fun with ABS:

This comfortable plug handle was fabricated with ABS which I built around a standard      14-50 220V socket/plug.

This is the charger input port that will be used normally while parked in the garage.  

With this recessed plug design, it is impossible to get your fingers anywhere near metal.

The other end of this plug (out of view) is an adaptor that will allow connection to any source power or plug type.  The power source can be anything from 90VAC to 260VAC, where the charger determines how much current to draw based on that voltage.

These embedded LEDs make it easy to find the charge port in a dark environment, in addition to the cool factor of LEDs...

It will glow for a period of time after stopping/shutting off, then shut off automatically.

I plan to install a door that will keep road grime out of the port, held closed with magnets.

 

Rear Charge Port                                                                                                                        

 

The old fuel tank inlet has been re-commissioned:

BMW made it easy for me here too.  This was only a half day task with the rotary table on the milling machine.  It presses snugly into the rubber lined opening and is anchored from behind with a mount that is perfectly located for this purpose.  Getting a bit repetitive, but Luck happened again...

And with the common plug inserted:

The fit was very close, but I had to machine a slightly larger radius on the corners of this mini electrical box to let it clear the rubber lined ID.  

Easy to see the state of charge, here is the charge complete color:

 

Any color is possible with these RGB mixing LEDs, here are a few examples

 

AC Power Source Select Relay                                                                                                               

 

Here is the finished packaging of the Air Conditioning motor controller, where I happen to be sharing the mounting opportunity for this smaller box that houses the AC select relay.

This turns out to be an ideal location for this function and I had just enough room to clear.  

The inactive port is always electrically disconnected to remove any hazard from exposed metal contacts when the other port that has power coming in.

Here is the installed result:

The two pan head bolts you see on it's top mounting bar are the only HW involved with removal/installation as the lower mount simply drops into a slot/shoulder, seen in upper photo.  I left "service loops" in certain wires to allow strategic access to other functions in the "stack" of hardware.

The inputs to this select relay come directly from the rear charge port, where the simple act of plugging into any voltage will switch the source to that port.

 

Radiator / cooling system                                                                                                               

 

Here is the cooling fluid filler inlet that I machined custom for this situation.

The main issue was to secure a hose barb fitting to this radiator inlet.  The original radiator cap was on a remote reservoir that I am not using so I needed a compact alternative.  As per usual, I had to make it.  The gold cap has an O-ring seal.  The temperature peaks will not be anything like the original ICE type levels, so will need much less accommodation for thermal expansion.

The BMW had this water temp sensor with a nice O-Ring seal that just plugs into a proper size hole so I took advantage.  It plugs right into the original wire harness here where it emerges in the control box shown above, with the original BMW connectors that now plug in to my board instead of the original Engine Control Unit.

The lower radiator plumbing connection, complete with drain cock.  This is what supports the circulation pump:

The circulation pump can be seen in lower left of this view which feeds directly up to the charger which then passes to the Inverter, which will be first in line when driving since the charger is only putting heat into the cooling system when parked and charging.  The next in line is the motor before either going on to the pack base or directly back to the radiator.

It is securely suspended from the radiator output itself. 

The plumbed and wired finished result:

The radiator fan is controlled through the original wiring harness where it emerges at, surprise, the control box, plugging into my board instead of the old ECU.  I send a PWM signal to control the fan speed. 

When charging, the fan speed will be a quiet 20-30% speed only. 

When driving, the fan will not even need to run as the pressure builds as speed is increased automatically.  As the speed diminishes to zero, so does the heat input.

Since I now monitor all temp deltas in the motor, Inverter and radiator,  I know exactly what the speed is necessary and thus use only the energy needed.

 

 June 2010 - Gathering electrical data while driving                                               

Voltage and current waveforms of the Lithium Ion battery pack acquired while commuting to and from work:       (Click for larger images and details)

I added a 12VDC-120VAC power inverter to provide power to the measurement equipment.

 

Interior Control Panel

Best possible use of an ash tray:

Took advantage of this nice little contained package for my master control panel.

I use it to monitor and control certain things manually while the supervisor processor is being finished up.   All this will be fully hands-off when done and possibly re-assigned later.

Now you see it...

Now you don't

 

<Prev (10. Air Cond)                                         Next (12.Range Extender) >