Hello Electrified Miata Fans! This week has been filled with the ups and downs involved doing fun things! Join us on the journey to make vehicles go quicker, quieter, and more efficiently through the science of electricity.
There was HUGE progress this week on the BMS. Joe blasted through the 621 pages 'data sheet' for the new processor and re-coded and verified every subsystem involved in our BMS.
BMS Technical mode on:
This involved the Analog Digital Converter, Pulse Width Modulation, timers, Serial port logic (this processor handles half duplex, so coding changes here), Sleep modes, the boot loader, compiler and linker tools, eeprom storage, fuse setups and programmers. (and I'm sure I missed some details)
BMS Technical mode off and translation:
There was a ton of details to be addressed in that 621 page data-sheet involving a specialized language for processor geeks.
Joe got our BMS code to run after jumping over and around a few hurdles. Currently, Joe is investigating why low power mode isn't as low as it used to be. According to the data sheet, we should be able to match or maybe even better our previous processor, around 40 micro-amps, but right now we're at 400 micro-amps. When the power problem is resolved, Joe will shift his focus to modifying the BMS board to use this processor. Many thanks and awesome progress Joe!
While Joe was working on the BMS, I was drilling holes to mount our large battery pack cover. The longer drill bit had arrived and I was anxious to get this big battery under cover because 115 volts at 220 amps makes me nervous exposed to my skin.
Drilling approximately 600 holes is an ultra boring task, punctuated with brief moments of terror if you are unlucky. I was 1/6 of the way through with the holes when I managed to nick one of the cells with the drill, resulting in an immediate drill tip deformation and loud audible POP! After cursing steadily for a few minutes, I was grateful for no fire! The pack will need surgery to extract the damaged cell and I'll need to consult with the team about ways to make this operation safer. Sigh... Drilling through the pack to get fastening stud alignment correct was working so much better than the older method of position, mark, remove, and re-install. I was feeling quite depressed about the battery problem when car night arrived. I even had those fleeting melancholy thoughts of giving up on this style of battery pack. There must be a better way!
We have been making progress on our second project, the Formuala-E-Mazda. Dave and Broch Evans came over to Ed's along with Bruce and we proceeded to work on the Leaf & trans-axle mount. Bruce and Broch met earlier in the week and welded mount once the Leaf side was drilled. For car night, we worked on locating and drilling the holes for the trans-axle side. We also cleaned up the holes to allow a socket to access the blind holes on the Leaf side.
As you can see, the drill bit got smoking hot and we switched to using an end mill cutter to complete the job. Here's Dave playing 'Etch-A-Sketch' with the mill to making circular shapes a socket will fit through.
Car night magically lessened the depression about batteries and we made good progress on the Formula-E-Mazda project. Besides the battery pack problem I'm having delays with parts coming from DigiKey. According to the salesperson, they are experiencing extremely high volume right now. The order for the speed sensor was submitted on March 11th, while the order for the Pi real time clock (RTC) was submitted on the 15th. No parts are on back-order. I received my (RTC) parts (yay!), but not the speed sensor or the capacitor for Brian's plasma cutter. :( Digikey did upgrade shipping on my delayed order.
Next weeks activities will be testing the RTC module, booting our Pi Pico board and finishing the mounts on the Formula-E-Mazda project.
As always, thanks for reading Hope everyone is staying well
and having fun!
Bill likes cars that understand the 'go fast now' pedal