Hello Electrified Miata and Formula-Mazda-E 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 repaired and bus bars installed, BMS leads attached and installation of the studs. On the Formula-Mazda-E project, we were working on tack welding the motor mount reinforcement bars and taking care of other fitment issues as well as reviewing the battery tray plans. Join us as we make progress on getting both of these vehicles moving quickly and quietly.
The large battery pack both damaged cells were replaced. Lucky for me this pack has never been charged, so replacing cells consists of un-soldering, cutting a tiny bit of plastic, without cutting the cell, and reversing the processes. This process is not without it's dangers, since cutting into the cell can cause them to catch fire, and I'm quite sensitive to that having seen it first hand. After replacing the damaged cells, I installed the 44 little jumpers to connect the pack to the bus bars. Twenty two parallel connections of 14 gauge copper per side to allow 220 amps to exit the pack without significant heating. Unfortunately, that's all the progress on the batteries this week.
However, Joe made great progress on the BMS. As you may recall from last week, Joe had finished the design and submitted the board to JLCPCB for a cost estimate and verification. The estimate listed the voltage reference as out of stock. After some research, Joe consulted with John Guy (Thanks John, we owe you a few beers!) and decided to use the microprocessor's internal voltage reference. This actually reduces the parts count but makes the software a little more complicated. The temperature readings will need a compensation factor which will depend on the current voltage of the pack. Luckily, the new microprocessor has plenty of code space and Joe is great at coding. Here is the final picture of the board. Thirty of these boards have been ordered.
I've just realized this project has reached the turning point where all the parts strewn around my shop and office will start to coalesce into a drive-able car! I can move from the parts collecting phase into the parts assembly phase. That is a major milestone and feels good to have finally gotten this far.
Car night arrived and Dave and Broch had everything ready for tack welding. Thanks to Arm, we had a TIG welding machine there. Thanks to Brian we had someone who was familiar with a TIG welder.
Brian tack welded the front plate mount. Then we worked on fitting left side motor mount. Here, Dave is cutting the bar stock to achieve the proper angles.
The Leaf motor we've been using to test fit everything had been in a front end collision and suffered some damage to the front motor mount. Now that the majority of the fitting has been done, we'll be swapping motors for one that has both good coolant ports and all the mounting holes are intact. With things are tacked in place, Bruce will do the final welds with a MIG welder, including some hole filling, so we can complete this part of the job.
Only one person can be welding, so what were the rest of us to do? Hmmmm, this looks like fun!
With this picture on my phone, I just had to text my wife and ask her we "needed" one of these. She replied 'Yes, 2 & 1 in purple'. I love my wife! She supports me with all these crazy projects. Thank you Teresa for being the fun and supportive mate!
Next week for the Electrified Miata project, we'll be installing the BMS leads, and installing 208 studs by hand (can you say boring but with an element of danger fore the careless?). On the Formula-Mazda-E, we'll be finish welding the motor mount, filing in holes and drilling the two blind back motor mount holes. Once those are done, we'll be able to do the last reinforcement support, and move on to battery trays and motor couplings. Due to weekend activities, I'll update y'all on Monday next week. Thanks for reading!