Wednesday, December 23, 2015

Thursday, December 17, 2015

81. THE RACE FOR AUTONOMOUS ELECTRIC VEHICLES                             

The California Department of Motor Vehicles (DMV) proposed today a new set of rules that will govern the operation of autonomous vehicles on the state's roads. Simultaneously, Google announced that it was spinning off its self-driving car unit into a standalone business setting up the stage for a fleet of self-driving taxis that will compete head-to-head with Uber, which itself is investing heavily in self-driving vehicles. Tesla, GM, Mercedes Benz, Ford and several others have not been shy in the media, all announcing efforts and prototypes towards autonomous driving. 

The Google (or perhaps more aptly under its new name of Alphabet) pod-like self-driving vehicles are powered by batteries, so it is fair to say that it is only a matter of time before electric powertrains  become the foundation for this new vision of autonomous cars. The race is early, still very early, but the stakes are potentially immense. 

One of the early metrics of a race worth gauging is each player's present IP position. It is not a simple question to answer but one can glean some insight -- autonomous electric vehicles are very sophisticated systems using complex components, so one would expect that intellectual property will play a central role both in the development of this market segment as well as eventual litigation among the participants.

The next two charts show the extent of the present IP position for a select number of companies. The chart on the left shows the number of US patents issued since 2000 covering two categories: i) battery technology including battery battery materials, manufacturing and battery management systems, and ii) technologies related to designing and building electric vehicles. For the time being, I will focus this post on the "electric" portion of this race, addressing the battery and electric systems for these vehicles -- leaving autonomous driving for others to discuss. I assume that the number of issued US patents will reflect within reason the amount of know-how a company possesses in battery and EV technologies. 

The first observation that stands out is the large number of US patents that Toyota has secured in both areas of batteries and electric vehicle systems. They eclipse the number of patents issued to Tesla and GM. Honda and Ford, two companies that have been relatively quiet in the media, are clearly building their foundations. The German automakers, judging from their US patent portfolio, seem to be lagging -- though this should not be misinterpreted as losing or lagging in the race. Apple has not yet publicly announced that it plans to build cars, but rumors abound in this respect and as such, the companies is categorized with the automakers. Their portfolio, however, is heavily biased towards battery technology, courtesy of their prowess in consumer devices. 

Automakers rely heavily on suppliers of components and subsystems. Among the well-established ones, Robert Bosch stands out with a sizable bag of issued US patents covering both batteries and electrical vehicles. Samsung and LG, two large suppliers of electronic components to the Korean car makers, have a strong IP position in building batteries owing to their respective battery divisions, SDI and LG Chem -- but there is not much evidence of strong IP in electrical powertrain and electric vehicles. It is also surprising to see Delphi and Johnson Controls lagging in both categories -- could this mean that the automakers are choosing to own and control key technologies instead of outsourcing them to their traditional supply chain partners? Time will tell. 

In this evolving race and ambitious vision for the future, these statistics are merely just perturbations for the time being. However, given enough time, they could amplify and influence the outcome of who will win and who will not. Stay tuned!

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp

Wednesday, December 16, 2015

80. HOVER BOARDS CHALLENGING BATTERY SAFETY                                                       

What do Chappaqua, NY and Brentwood, CA have in common? Burning hoverboards....this is a new category of battery-powered levitating boards, sort of electrically-powered, self-balanced skateboards. In both cases, the fires and ensuing explosion were attributed to the lithium-ion battery. Amazon has discontinued the sale of such devices. So what is happening?

I will leave the particulars of each incident to investigative authorities. Instead, I will address the potential failure points of such systems -- and how their designs, or perhaps lack thereof, put the safety of consumers at risk.

Back in the early 2000s, laptops suffered from many recalls because of battery safety issues. Two major sources of problems were identified: i) the quality of the battery design and manufacturing, and ii) operation of the battery under unsafe conditions. The battery & PC industries, under the weight of costly recalls, reacted and implemented rigid processes to ensure the safety of their products. The major Li+ battery manufacturers, in particular Sony Energy, LG Chem, Samsung SDI, implemented extensive safety design features in the cells themselves, as well as exhaustive test procedures to ensure the safety of the battery under a wide range of conditions -- for example, batteries today are designed to withstand a sharp object piercing it (this has become a common test today). In parallel, electronic circuitry with advanced safety features were added alongside. This circuitry ensured that corner conditions, such as excessive voltage or excessive current or even excessive temperature conditions triggered a safe shutdown and isolating the battery from the rest of the electrical systems. The result today is that the vast majority of consumer devices follow stringent safety rules and are by-and-large very safe.

A hoverboard, in contrast, has a much larger lithium-ion battery than any of other consumer electronics. Most smartphones have batteries with capacities in the range of 8 to 15 W.h. Laptops and tablets have capacities in the range of 30 to 80 W.h. A hoverboard's battery has a capacity of 150 to 200 W.h. This is a lot of energy that can cause serious damage if not operated properly and safely. 

There are no known standards yet for hoverboard batteries but judging from the offerings on Internet stores, the battery pack seems to consist of a stack of 11s and 2p (22 cells in total), totaling a nominal voltage of 36V and charge capacity rating of 4,400 mAh. That means that each cell has a rating of 2,200 mAh, and is most likely a cylindrical 18650. These types of cells have become commoditized (they were used in PCs some 10 years ago) and are made in China often by low-tier manufacturers. I estimate the cost to be in the range of $15 to $25 for the entire pack. They sell on eBay for about $75 each. Several of them carry a Samsung label -- I would not be surprised if they are all fraudulently made in China.

So how can these batteries be unsafe? Many factors come into consideration. First, 18650 cylindrical cells, especially with lower capacity ratings (2 to 2.5Ah) are virtually all made in China, many in factories that lack the quality control and safety measures that their Japanese and Korean counterparts learned the hard way 10 to 15 years ago. Second, the operation of the hoverboard requires relatively large currents (typically 3 to 6 A). Wirings, solder junctions, and battery contact points all become potential failure points if not designed properly. Thermal design in such tight volumes becomes paramount -- leading potentially to fatiguing of the wirings and connectors. In a nutshell, when several such considerations lack in the design and manufacture of the product (as is commonly the case with products coming out of China), the outcome is quite unsafe leading to fires, explosion and possibly loss of life.

So before you run out a buy yourself or  your family a hoverboard for the holidays, do yourself a favor, complete your diligence to ensure that the product has gone through stringent qualification tests and procedures.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp

Thursday, December 10, 2015

79. CAN I FAST-CHARGE MY TESLA OR EV?                                                     

Before I start this post, I encourage all new readers to go back to the early posts if they desire to learn more about the basics of lithium-ion batteries and their operation.

This post is dedicated to deciphering the growing complexity of charging stations for plug-in hybrid and pure electric vehicles (xEVs), especially as their popularity grows among drivers. 

The charging of xEVs, whether at your home or at dedicated charging stations, is usually governed by a set of standards agreed upon by a vast number of contributing organizations, such as the automakers, electric utilities, component makers and many others. Several organizations including SAE International, ANSI and IEEE have led the  coordination and development of such standards -- they are numerous -- covering, for instance, the types and interoperability of connector designs and charging power levels (SAE J1772), communication and signaling protocols  (SAE J2931/1) between the xEV and the charging station (also known as EV supply equipment -- EVSE), wireless charging (SAE J2954) as well as many others related to diagnostics, safety, DC charging...etc. Today's post addresses charging from the perspective of the SAE J1772 standard and its competing standard CHAdeMO.

So let's start with understanding what charging levels are and how they are defined by the various standards. There are 4 levels of charging:  two levels using conventional AC charging, and two additional levels using higher-voltage DC  charging. They are summarized in the next table:

Let's start with AC levels 1 and 2. Level 1 is what you get using the charging cord supplied to you by the car maker if you own an xEV. It plugs into the standard 120V household outlet and delivers, in theory 1.7kW. Some of you are probably tempted to multiply 120V by 20A and realize that's more than 1.7kW...if you are that person, remember that this is an AC current, so you need to multiply by 0.707. This is the maximum power delivered to the connector plugged into the car. It is not the power delivered to the battery. The battery's power is delivered by an on-board battery management system (on-board charger) that has to convert the voltage to a level appropriate for the battery. In reality, the car battery receives a best-case power of about 1.2 - 1.3kW to account for the electrical efficiency of the system -- taking an average consumption of 250Wh per mile, that is equivalent to about 5 to 6 miles for each hour of charging...ouch!

Reality is a little worse than that: standard household power plugs are limited to 15A (instead of 20A) thereby decreasing the power delivered to the battery to a measly 900W. At this power level, a Nissan Leaf's battery (nominal 24kWh / effective 20kWh) takes 22 hours to fully charge. Yikes! Now one can begin to understand why xEV owners do not line up near a Level 1 charger...but it does get crowded at a Level 2 charger.

AC Level 2 uses a 240V single-phase mains. The lowest current level is 20A corresponding to a maximum power (again at the output of the connector) of 3.4kW. The typical public charging stations, such as the ones managed by ChargePoint, provide 6.7kW. However, there is a catch. The on-board charging circuitry in your xEV must be able to use that power. Early Nissan Leaf models had 3.3kW-circuitry -- in other words, regardless of the maximum power at the charging station, the maximum power the car is willing to accept is 3.3kW.  Newer xEV models, e.g., Nissan Leaf, Ford Focus Electric, Chevy Volt, have on-board chargers capable of up to 6.6kW. Again, this means if the charging station were to provide 19.2kW, your car cannot accept more than 6.6kW...this is by far the most common charging level as dictated by the presently deployed infrastructure. It equates to about 25 miles for each hour of charging. Once again, using the Nissan Leaf as an example, its battery will fully charge in 3.5 hours with a Level 2 charger (6.6kW). That's not fast charging, but it sure is a heck-of-a-lot faster than Level 1.

Fast charging with DC gets more complex because there are competing approaches. Of course, we are also now talking about insanely high power levels, and consequently very expensive charging stations  and associated installation costs ($50,000 to $100,000 each).

SAE has the J1772 Combo DC standard. CHAdeMO has another competing standard. Tesla has its own proprietary fast-charging using their network of Superchargers (though not DC). But what they have in common is that they all seek to provide high power levels to the vehicle...up to 120kW. This infrastructure is still relatively scarce -- Tesla is the only one aggressively deploying fast charging Superchargers along specially designated highway corridors.

Naturally, charging a car battery at such high power levels begs a new series of questions on whether this creates any significant and permanent damage to the battery. The brief answer is: YES, damage does occur...but super fast charging is so rare that no one is really paying attention to this question, at least not for now. Besides, with the exception of Tesla, your average xEV cannot charge faster than 6.7kW, so having a fast charging station is a moot point. 

A final word on fast charging the Tesla batteries. At 120kW of input power, this equates to a charging rate of 120/85 = 1.4C -- this is guaranteed to cause serious damage to your Tesla battery if you were to charge on a regular basis. But then again, if Elon Musk and Tesla Motors are willing to cover you under their warranty, do you really care?

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp