Hello Electrified Miata and Formula-E-Mazda Fans! This is your weekly update for putting smiles on faces through the power of magnetism and electricity. Last week, we were working on getting the Electrified Miata's large battery plastic covers drilled for mounting. On the Formula-E-Mazda project, we were working on the prototype motor mount assembly. Join us as we make progress on getting both of these vehicles moving quickly and quietly.
Electrified Miata Status:
Two week ago, we needed to get the large battery plastic covers drilled. With some patience, we have both sides drilled with no further audible 'pops' indicating contact between drill bit and battery cell. We also started pack surgery to remove the damaged cell. This allowed us to reveal a sister cell the also has damage and will
need extraction and re-attachment.
With both plastic covers drilled, we now have an accurate count of studs and support washers needed. The support washers have been ordered. On car night, Bruce cut 108 additional studs for large battery on the band saw. Thank you Bruce for cutting again and again and again and again!!!
Meanwhile, Joe has been making progress on the BMS boards. With the code ported for the new processor, Joe focused his efforts on the circuit board layout. Here is the newest design.
Joe submitted the design to JLCBPC for verification and everything was good! Except for the tiny little fact that the voltage reference we use was OUT OF STOCK! Grrrr. Further investigation shows that this non-popular part was unlikely to be re-stocked any time soon. Now we need a different voltage reference part using a different reference voltage, which in turn means using different voltage sense resistors too. Sigh. Stay tuned to see how the second chip-aggedom problem gets resolved. We are very close. I can see the finished packs in my mind.
We had a few 'ah-hah' moments seeing the need for bracing on the motor mounts. The rear wing mounts to the very end of the trans-axle. At speed, the force from the wing will make a lever from the trans-axle mount to front motor mount, as it pushes the rear wheels down Doing so provides nice traction on the rear *if* the force can be applied to the frame. Dave, Brian and Bruce skull sweated and came up with a design to make sure the forces go where we'd like them to. Now we needed to cut the pieces and weld them in place. Time for a trip to Ed's shop!
Before we made the trip, Dave was playing around during lunch. If you've worked with Dave, you'll know he's a pretty focused and centered guy. The centering of the motor with regards to the transaxle was bothering him and so he made some measurements. With Broch's help, he 3D printed a tool to measure the center and found our mount was not quite centered and needed new holes drilled. Dave also found that by rotating the motor 6.5 degrees, we could avoid modifying the inverter where it contacted the frame. The angle change puts the inverter in the stock position avoiding both spacers and extra connections between the inverter and the motor. Yay! With all these changes, we're headed to Ed's shop.
Ed had purchased a 1" cutter for making access holes and it was possible with the new centered configuration, we'd need an access hole. We used the band saw to cut the reinforcement steel pieces. The drill press didn't get much rest either on car night. We drilled all the new holes and things line up perfectly!
Thank you Ed for providing a wonderful place to make our creation come to life! Progress!
Next week on the Electrified Miata, we'll work on replacing the damaged cells, electrically connecting the bus bars, and installing the BMS leads on the large battery. This will be followed by installation of 208 studs. On the Formula-E-Mazda, we'll work on tack welding the motor mount reinforcement bars and taking care of other fitment issues as well as reviewing the battery tray plans. Thanks for reading!
Bill likes cars that understand the 'go fast now' pedal