Hello Electrified Miata and Formula-Mazda-E Fans! Last week's goals on the Electrified Miata were to remove the nuts from all the studs on the large battery and install the bottom cover. We'll also work on getting the 5th and final battery assembled. For the Formula-Mazda-E, we'll be ordering material for the next phase - building the battery trays. Join us on the journey to convert these vehicles and improve the fun factor when driving them!
Electrified Miata news:
On the largest battery, (see video) all the studs were installed, so it was time to de-nutify (I'm sure that's a word i.e. removing hundreds of nuts from the studs). Surprisingly, that didn't take all that long. With the nuts taken off and the spacers installed, the bottom cover could be test fitted. After increasing the size of the drilled holes by 4 number sizes, that cover fit without using a hammer! (See Joe K, sometime I can work without a hammer, ;)) Day by day I added washers and started the nuts onto the threads. I saved the final tightening for car night.
With the fourth battery in good shape, I wanted to get the fifth battery prepared for the difficult task of drilling the plastic covers. For the fifth battery, I need to take two smaller batteries and combine them physically and electrically into one. The two smaller batteries each contained 10 cells in parallel string and 20 cells in series. The smaller configuration was great for running the Leaf on the bench, each pack giving me 72 volts at 100 amps. (an individual cell can safely discharge 10 amps). Two cells
had to be added to each parallel string because I need 220 amps to run the Leaf full out in the car. However, since the smaller packs had been used for testing, their state of charge was different from uncharged new batteries.
After some experimentation, I found charging the cells for approximately three and half hours, I would reach the same state of charge as the rest of the pack. Since I needed 40 charged cells, this procedure took 35 hours before I could insert the newly charged cells into the pack. I made some custom wood clamps at Ed's shop to assist in the physical joining process of the two smaller batteries. Thank you Ed for having such a great place to be able to make what's needed!
Car night came quickly this week! The two tasks for the night were final assembly on battery number 4 and figure out how to drill the plastic covers for battery #5 with the studs still in the pack. Bruce, Brian and Eric started working on the problem of how to drill all the holes in the plastic covers with the studs in place. You can seen them checking the alignment in all three directions.
Unfortunately, the original holes were hand drilled and subject to enough error that a simple pattern wouldn't work. A solution was found, but more on that next week.
Dave got busy tightening the forth battery and making the studs uniform length. Here Dave is modifying the stud length the quick way, using an angle grinder with a flap wheel. Who said sparks and batteries don't mix! (see video)
I've saved some exciting news for last! Issac Stephenson has joined our team and initially will help out with documenting our project through pictures and video. We also will work on producing YouTube video's for parts of the project with motion, like computer assisted rev matched shifting. Thank you Isaac for joining this effort and providing pictures and video this week!
On any long project, additional inspiration is needed at times. For me, it usually comes from seeing the other guys on my team, working hard to make the project happen. This week, Bruce, Eric, and myself got a welcomed boost, in the form of a ride in a Tesla Model 3 performance. Isaac offered a ride after the work was done. I have driven a P100D (thanks Kurtis Klein!), but hadn't ridden in a Performance 3, so I was curious. The Performance 3 didn't disappoint! Hard hitting acceleration and a very smooth feel overall. While the first version of the Electrified Miata won't be *that* fast, I can imagine the fun of shifting gears with an electric motor. Thank you Isaac for providing inspiration in the long battery assembly phase of this project. Hoping I don't blow up the Miata transmission too quickly with excessive torque.. ;) Shifting will be so much fun!
Formula Mazda E news:
Racing is built on the ability to adapt to the current conditions. Moisture, heat, other drivers, rules, etc. are always changing. To deal with all of this, we need to carefully consider all the details we can before we reach the track. In this case, time was used to verify battery specifics before submitting the order for the most important part of an electric race car besides the driver.
Next week for the Formula Mazda E, we'll be ordering the batteries and associated hardware. For the Electrified Miata, we'll continue working on the fifth and final battery. I intend on finishing the electrical part so all that will be left is putting the covers on and waiting on our BMS parts. While waiting on our BMS parts, we'll start working on the computer assisted rev matched shifting. As always, thanks for reading!
Bill likes cars that understand the 'go fast now' pedal