The (Probable) Story Behind the Tesla / Maxwell Deal — 5 minute charging.
By: Stefan Nagey
Tags: Electric Vehicles, Tesla, Transportation, Battery, Cars

Maybe not to the stars, but a 5 min charge? Even better.

A week ago, Maxwell Technologies announced that they were being acquired by Tesla for $218MM. That’s a 55% premium on what the market thought the company was worth. In the most basic sense, this means that Tesla isn’t buying the business (i.e., Maxwell’s current customers or probably even products), they’re buying the technology.

The thing that surprises me, is that no one is talking about the most likely reason why.

Yes, this is speculation, but if I’m right, it’s the most exciting thing to happen in transportation since the Model T.

OK, so, some background. Tesla, as you know makes electric cars. Electric cars suck because you have to spend about an hour every 300mi charging them up. There are some people working on this (Porsche is all excited about their fast charging), but these efforts are largely meaningless. Charging a chemical storage battery will always involve a chemical reaction. These take time, and there’s a limit to how much they can be sped up. They (probably) won’t ever be as fast as filling up a tank with gas.

Maxwell technologies makes ultracapacitors. These are energy storage devices that charge quickly. They have numerous drawbacks, they don’t hold their charge for terribly long, and they have a low energy density. (Sidebar: energy is measured in kW, whereas power is energy over time measured in kWh ).

So, if you think about the implications here, this kinda sucks. Batteries will always be slower than just transporting energy, since you’re converting the energy, and ultracapacitors probably won’t ever be a workable long-term storage device.

Everyone has been saying that Tesla is going to switch to solid-state batteries. Maybe, but no time soon. I think that Tesla’s real plan here is to not try to fight the time that batteries take to charge, but instead to take the charger with you.

Imagine a car with a traditional chemical storage battery but that also has an ultracapacitor. Theoretically, you plug in for the minute or two that it would take the ultracapacitor to charge, and then you unplug. Normally, now you could access the energy in the UC to drive, but what if we use the ultracapacitor to charge the battery instead.

Now you’ve got a system where you get the long(er) storage life and higher energy density of a chemical battery, but you get the benefits of the fast charge of the capacitor.

My guess is that a system like this could result in an EV that charges as fast, or faster than a gas vehicle, and certainly much much faster than any other EV that’s anywhere near the market. This is probably why we haven’t heard much about Supercharger V3 lately, even though everyone has been crowing about how fast they charge their cars.

One major caveat — the power density of ultracapacitors currently on the market (and in academic literature) is an order of magnitude lower than what would be needed to achieve a plan like what I describe above. However, it is completely possible that a breakthrough like that has already happened within Maxwell Technologies, and that’s what they’re selling on.

Tesla doesn’t seem to be the sort of company to invest in pure research — they’re more about putting together technologies that already exist to make great products (they’re more like Apple than Google that way — and yes, Autopilot is a notable exception). Given that, I’m going to further guess that this kind of tech is a lot closer to market than anyone thinks. I wouldn’t be surprised if the 2020 Roadster (or maybe 2022 realistically) would feature not only the much vaunted 600mi range, but also a charge time of less than five minutes.

I have no inside knowledge of Tesla, and I could be completely off base, but I would place a considerable bet that Tesla is moving toward hybrid solid state / chemical battery technologies.

DISCLAIMER: I do own a Tesla, and I do hold some of their stock in my personal portfolio.