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Batteries

Published on February 10th, 2018 | by Steve Hanley

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Are NMC Prismatic Cells & CCS About To Blow Tesla & Its Superchargers Out Of The Water?

February 10th, 2018 by  


Seeking Alpha is the stock analysts site Tesla fans love to hate. Most of its commentary about electric cars predicts Tesla is on the brink of bankruptcy and Elon Musk is not as smart at the average bear. So far, few of the gloomy predictions from skeptics on the site have come true, but that hasn’t stopped Seeking Alpha from being the darling of Tesla short sellers.

But just as bread needs a little leavening to rise, a dash of contrarianism is often useful to see things clearly in the business world. This past week, Seeking Alpha published a story claiming that Tesla’s vaunted Supercharger system is about to change from a moat keeping competitors out into a prison wall trapping Tesla inside. That rather startling conclusion arises from one sentence in a tweet about the Jaguar I-Pace, which is currently undergoing cold weather testing.

Seems pretty innocuous, doesn’t it? But not to Seeking Alpha analyst Simon Mac. As a former Model S owner, he is well familiar with the charging phenomenon known as tapering. “Jaguar’s tweet has profound implications in this regard — it implies the Jaguar must be able to charge at a near constant 100kW across the important 0-80% range. By contrast, a Tesla can charge at its 120kW for only a small range of specific levels of charge. Once a Tesla battery reaches a state of charge of around 30%, the charge rate drops below that of its British rival, and the Supercharger rate continues to drop off as the battery’s state of charge increases. In other words, the first 30% for a Tesla is zippy, but things then slow to a walk, and finally a crawl.”

Mac says battery chemistry has a lot to do with tapering. “Here’s the simple truth: The pouch prismatic cells using NMC chemistry offer a superior charging experience to Tesla’s cylindrical cells using NCA chemistry. So, Jaguar’s more desirable charging curve is not magic. It’s exactly what one would expect by doubling the size of the battery used in cars [like the Renault Zoe, Nissan LEAF, and BMW i3] with similar cell types. Tesla is alone in its choice of cylindrical cells based on NCA rather than NMC chemistry. And in Europe (and China), at least, that’s shaping up to be a very real disadvantage.”

Mac explains the difference in user experience this way. With a Tesla, when you charge is often dictated by your state of charge. If you want to stop an hour into a long trip for a coffee, your Tesla battery still has a nearly full state of charge. Because of tapering, charging that early in a journey will add relatively few extra miles per minute. You are better off waiting until the battery is nearly depleted in order to get the maximum possible charging rate. With prismatic NMC cells, the charge rate is virtually the same regardless of the state of charge, which gives drivers more flexibility in how to plan their travels. It makes the car the servant of the operator rather than the operator a servant of the car.

Now that CCS is the official charging standard in Europe, Mac expects it to compete aggressively with Tesla’s proprietary Supercharger network. Interestingly, Tesla quietly joined the CCS consortium in 2016. How Superchargers and CCS networks will fit with each other in the future remains to be seen.

What customers really want is convenience. The Holy Grail for EV drivers is charging up as quickly as possible. Elon Musk is talking about making charging locations that are one part recharging spots and one part amusement park, but do people really want to (A) be entertained while charging or (B) get in and get out as quickly as possible? If Simon Mac is correct, the answer is B. In that case, NMC prismatic cells and CCS charging may well carry the day and Tesla could be on the outside looking in.

Related:

Daimler, BMW, Volkswagen, & Ford Join Forces To Create Ionity Fast Charger Network In Europe

Shell Partnering With Top Auto Manufacturers On IONITY EV Superfast-Charging Network


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About the Author

Steve writes about the interface between technology and sustainability from his home in Rhode Island. You can follow him on Google + and on Twitter.



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