Thoughts on Tesla : Part 1

Quite late to the party but in this series I’ll share and try to elaborate my thoughts on Tesla. In Part 1, I’ll discuss my personal thoughts on Tesla’s approach to the EV market and in Parts 2 and 3 I’ll try dive into the two aspects that I found most interesting – safety and battery control.

Part 1 – Thoughts on Tesla

My first impression of Tesla was of disbelief – how could a startup even attempt to disrupt the automobile industry let alone try and spearhead the paradigm shift into EVs? Promises, offers for pre-orders, and delivery delays made everything very… sketchy. But after some experience with EV battery development, I now realize Tesla’s brilliance, which I’ll try to organize to serve as a reminder and a message to my future self as a lesson learned.

Battery first approach

In an EV, the battery is quite frankly the determining factor behind acceleration and mileage. ICE components made of metal alloys are robust and durable, able to withstand much of the physical rigors that the vehicle undergoes on a day to day basis. By contrast, batteries – to be honest, electrochemical reactions in general – are incredibly sensitive and prone to accelerated degradation unless operated in optimum environments throughout the entirety of the battery life. Considering automobiles operate from Alaska to Death Valley… this really isn’t good news for EVs.

But based on its patents, Tesla realized this from the start of EV development.

Tesla took great care to develop temperature control schemes (ex. cooling jackets that maximize contact with cells), made sure to develop protocols that heat up the battery temperature prior to fast charging and/or low temperature charging, surrounded each cell with insulation materials to prevent thermal propagation between cells, and developed BMS schemes that collect data to monitor all the thousands of 18650 cells even from the beginning.

Basically, Tesla made sure the entire vehicle design centered around their cylindrical cell-based skateboard style battery pack rather than shoving a square peg (battery) into a round hole (ICE vehicles). And this was possible because Tesla was starting from scratch without any pre-constructed factory lines, internal processes, or conflicts of interests. This contrasts with automobile companies where much of its efforts were hampered due to tip-toeing around existing ICE framework. (In addition to the fact that EV expansion means cannibalizing ICE models for automobile companies while it meant new growth for Tesla). This is how the 300 mile range and the marketing masterpiece of the million mile battery was backed up by actual data.

For any system, the weakest link needs to be fortified and taken care of - similarly, for the EV to succeed, I believe there needs to be a restructuring of priorities in the automobile industry to be more battery-centric. To take from JFK’s famous quote – The Vehicle should ask not what the battery can do for it, but what it can do for the battery.

Make do with what is available

Looking at the issues related to Tesla cars with respect to vehicle finishing (i.e. sunroof being blown off, lack of interior quality, etc.) Tesla seems to have had to simply make do with what is available for the given price range. Considering it had to invest in brand new factories and develop a functioning battery pack system… I think it’s quite understandable the lack of general quality compared to conventional ICEs.

The biggest example is the 18650 sized elephant in the room – the adoption of cylindrical cells in stead of developing a dedicated large format cell. 18650 cell has been around since 1994 and therefore has a solid mass production history with a proven track record in high power, power tool applications. So that meant it could handle the sudden power output required for automobiles. The next point for contention was capacity i.e. driving range - by connecting 7,104 18650-type cells in 6s74p x 16 modules, Tesla was able to develop a battery pack with ~85kWh of energy (this was upgraded to 100kWh pack by re-configuring battery pack structure to hole 8,256 cells).

The circuitry and BMS must have been insane but this is a case of making do with what is available – the limiting factor for EV mass production was cell development and Tesla overcame that. However, this meant that the BMS had to carefully monitor each cell, which will no doubt be expensive to incorporate into the battery pack and difficult to develop a dedicated BMS for, which leads to the last point…

Value engineering with engineering intent is crucial

To conduct value engineering, a complete understanding of what is being value engineered is required. Looking at Tesla’s patents (specifically US7602145B2, which will be referenced more in depth in Part 3) it becomes obvious Tesla had tested how to first monitor each cell as a separate entity and gradually moved onto optimizing protocol to ensure that a similar level of cell management was possible even when monitoring a brick of cells. This gradual, data-backed change in protocol no doubt decreased production costs and software development costs significantly.

Another more recent example is in the tab-less 48600 cells where the removal of battery tabs not only function as a VE in fabrication process, but in effect improves the contact between the jelly roll and the terminal. This increase in contact area is crucial for homogenous current distribution, thermal management, and lowering parts contribution to resistance - all improving cycle life and power output, and reducing the frequency of cooling jacket activation.

In summary of Part 1…

The disruptive and innovative nature of Tesla needs to be remembered. The understanding that the core component of EVs is the battery, carrying that understanding to actual EV design, and keeping that same understanding when conducting VE to become more price competitive – this thought flow hints at the existence of a clear long-term road map composed of manageable short-term goals.

It is in-line with my personal mantra – engineering decisions must not be made with political or business intent as its primary driving force.