EkaLore uses “Back Of The Envelope” as a short-cut analytical technique to test conclusions, use guesses that are “good enough”, and provide a simplified (at a risk) view of a marketspace. Today, we’re going to look at a BOTE that “everybody knows” and test the usefulness of BOTE. The concept we’re going to test is that EV’s like Tesla are more reliable because they have fewer parts.
Internal combustion engine (ICE) vehicles are commonly thought to have about 30,000 parts (NADA). “Everyone knows” that electric vehicles (EVs) have fewer parts in their bill-of-materials. After all they don’t need engines/transmissions, complicated braking mechanics, and fluid-cooling/heating systems, not to mention lots of other pieces.
Guesses at the number of assembled parts in an EV (like Tesla) should be in the range of 2,000-3,000 assembled pieces. Therefore, the allegation that an ICE will cost more to maintain also comes from the assumption that fewer piece parts mean simpler maintenance, and lower costs. Is it true that ICE’s will have total costs of ownership higher than EV’s based on assembled parts counts?
The BOTE framework would seem to be a useful shortcut to comparing ICE’s and EVs. A closer look reveals may contradict that simple way of thinking. A battery pack has a LOT of individual batteries and may actually have more individual pieces than a simple engine – where people shortcut the thinking as batteries are all the same part whereas an ICE engine has hordes of different parts. In fact, for the Tesla 18650 battery packs the assembly combines 16 modules of 444 batteries for a total of 7,104 batteries. Another configuration uses 516 cells per module for a total of 8,256 batteries. The newest model Y 4680 battery packs only use about 1,000 batteries. Does the BOTE of 30,000 versus 2-3,000 lead a correct conclusion?
A BOTE is useful as shortcut as long as there is enough detail included to properly test the conclusions.
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