Fast charging

31Mar 2020

While the current situation has put us all in unfamiliar territory, one bright spot has been the willingness of so many people and organizations to offer advice and assistance. With hundreds of millions of us isolated in our homes, making especially intensive and important use of our phones and computers, it seems like an opportune moment to share four battery-specific recommendations that can help ensure your personal safety and extend the lifespans of all our devices as we adjust to this period of uncertainty, and WFH normalcy.

First, and most imperatively in the near term, never ignore a battery that is swelling. This can happen over the course of just a few days, especially in aging devices, and is a sign of internal failure that can put you and your family at risk of fire or injury. If your phone starts bulging or separating, even slightly, or your laptop or tablet won’t sit flat, its battery is likely swelling. In this case, stop using the device immediately and contact its manufacturer for help. Second, watch out for heat. If the backside of your phone gets uncomfortably hot while it’s charging, that’s a warning sign, and once again time to contact the device manufacturer. More broadly, avoid placing devices in high-heat situations, especially when charging. The classic case is of a ride-share driver, with their windshield-mounted phone continuously charging while baking in direct sun, but it can also occur at home if your phone is charging on a sunny windowsill, above a radiator, or nestled into a blanket. The combination of an elevated charge situation and high ambient heat may increase the risk of a fire and is certain to degrade a battery’s health prematurely. More detail about heat and batteries can be found here.

Third, be especially careful with aftermarket batteries and chargers, even ones that carry a familiar brand name, because counterfeiting has become more and more common, and incentives to do so will only increase during a global emergency. This is a good reason to extend the life of your original batteries for as long as possible. While it can be annoying when smartphone manufacturers restrict users and unauthorized repair shops from doing battery replacements, it’s done in part because there’s ample evidence that fake replica batteries have a much higher risk of fire than authentic ones, and because the replacement process is often not straightforward. Likewise, cheap chargers can create overheating by delivering too much current, which can create a similar fire risk for your batteries.

Finally, extending the lifespan of our phones, laptops, tablets, and other daily-use devices will take on extra importance, especially with phone prices creeping into four digits. In my experience, preserving battery health is the single best way of doing this. I wrote some time ago about basic strategies; here are some updated recommendations to consider:

  • Avoid “fast-charge” approaches and use the lowest amount of charging current possible. Although it takes longer, charging your phone from a computer using a USB cable is much gentler on the internals of the battery. (Note that this principle also applies to electric vehicles – super-fast charging stations are hard on your vehicle battery.)
  • Avoid charging your phone overnight, because it’s better to not keep the battery at 100 percent charge for extended periods. I aim to keep my charge levels between 25 and 85 percent unless I’m traveling, and my year-old smartphone battery health has not degraded at all.
  • Per the previous point, Apple’s iOS operating system offers battery health monitoring, and in the newest version(13.0)  the option of “Optimized Battery Charging,” which learns your daily charging routine. This is worthwhile, and we’re starting to see other manufacturers and even mobile operators become more attuned to this type of functionality, particularly in Asia.

We all have plenty to worry about in these unusual times; hopefully these bits of advice will help prevent battery-related problems from adding to your load.

09Mar 2020

Is it true that electric vehicles (EV) need 800-V battery packs for ultrafast charging? Is it true that the Porsche Taycan uses 800-V packs to enable ultrafast charging? Why did GM announce that its new battery platform will support 800 V? Let’s find out.

Let’s start with two essential ingredients required for ultrafast charging:

1. A charging station that is capable of providing a lot of electric power;

2. The ability for the battery to accept the extra charging power without being damaged or degraded.

Charging stations are like AC adapters we use to charge our smartphones. Of course, they provide a lot more power. Standard fast-charging stations in the Tesla network are rated to provide 72 kW; upgraded stations are capable of providing up to 150 kW. Electrify America’s network is adding stations that can charge at up to 350 kW — that’s sufficient to run about 50 average residential homes. 

When the vehicle is charging, its on-board computer communicates with the charging station. In essence, the vehicle tells the station, among other things, how much power it needs to charge the battery. It is the vehicle, not the charging station, that sets the charging power, and consequently the charging time — as long as the charging power is lower than the maximum power available at the charging station. The reason is that the vehicle must balance the charging power vs. the likelihood of battery degradation during charging.

When we speak of battery in an EV, we usually refer to a “pack.” A battery pack is made of hundreds or even thousands of individual smaller battery cells that are assembled together to increase the amount of stored electrical energy. A single battery cell may store anywhere from 17 W.h (e.g., Panasonic 21700 cell used in a Tesla) up to 300 W.h (e.g., cells used in some of the German-made EVs). 

The standard 50-kWh pack in the base Tesla Model 3 includes a total of 2,976 cells, organized into 96 modules, each module consisting of 31 individual cells.  A BMW i3 pack, by contrast, has a total capacity of 43 kWh and uses 96 modules, each module consisting of two cells. The cells in the BMW packs are substantially larger than the ones used by Tesla.

So we notice that the number “96” appears regularly in the pack design. That’s because there are 96 modules electrically connected “in series”: in other words, the electrical wiring of the pack is such that the voltage of the entire pack is the sum of the voltages of each individual cell or module. For the vast majority of lithium-ion cells used in automotive, the module voltage is on average 3.7 V, but can range from 3.1 V when the cell is depleted to  4.2 V when the cell is fully charged. 

We can now calculate the maximum voltage of the pack: 96 multiplied by 4.2 V equals 403 V. This is nominally the pack voltage for the vast majority of EVs on the market including all Tesla models, Chevy Bolt, Nissan Leaf, BMW i3, and many others.

Let’s now calculate the maximum charging current that a 400-V battery pack will request at an ultrafast-charging station. Porsche says that its Taycan can accept up to 270 kW at its dedicated Turbo Charging stations, so we will use this figure.

You may recall from basic physics that power equals voltage multiplied by current. Therefore, the charging current is power (270 kW) divided by voltage (403 V) equals 670 A !!! By any standard, this is a very large current that will require a thick copper cable harness, adding significant weight and cost. Porsche says the extra harness weight amounts to 66 pounds (30 kg) — quite a bit when compared to the pack’s overall weight of 1,389 pounds.

So what if we raise the voltage to 800 V, up from 400 V? You guessed correctly: the charging current drops by half…thus saving significant weight and cost.

That is exactly what the Porsche Taycan’s battery design does. Its packs contains a total of 396 individual cells made by LG Chem, mechanically arranged into 33 modules of 12 cells each. Electrically, the 396 cells are divided into two sets connected in parallel. In each set, there are 198 cells connected in series. The maximum voltage of the pack is 835 V (that’s 198 multiplied by 4.2 V).  Each LG Chem cell is rated at 64.6 A.h, equivalent to an energy capacity of 236 W.h. When the energy from all 396 cells is added, we calculate a total pack maximum energy capacity of 93.4 kWh — just a little less than the maximum pack energy capacity of the Tesla Model S (100 kWh).

So will it be 400-V or 800-V for future EV packs? You decide!

30Dec 2019

Whether related to the stock market, presidential elections or climate, December is the month to make predictions for the coming year and decade. So what battery trends should we expect for the upcoming 2020-2030 decade?

1.Lithium-ion batteries will power more applications — electrification of everything:  The 2019 Nobel Prize in Chemistry highlights the progress lithium-ion batteries achieved in the past four decades. From a laboratory experiment in the 1970s, they are now ubiquitous in consumer devices. Increasingly, they are making inroads in transportation and grid storage applications. 

There is no question that the 2020s are the decade of electrification of transportation, from electric vehicles to buses and trucks. The number of available electric-vehicle (EV) models jumped from about ten in 2015 to over 75 in 2020, including categories of sports cars, sedans, SUVs and light trucks. Automotive companies and their supply chain are inexorably transforming. This will not be an easy transformation — there will be winners and losers. Car manufacturers and Tier-1 suppliers that will not adapt in the next couple of years risk becoming irrelevant. The nature of skilled labor in transportation is also transforming. Labor unions are taking notice but much training is needed for this new labor force.

Electric utilities will implement more energy storage projects on their grids — partly driven by regulations as well as the proliferation of clean-energy grids with distributed wind and solar generation. 

Industrial applications with historically smaller unit volumes will benefit from the increased proliferation of lithium-ion batteries. As communities seek cleaner air, we will see local regulations banning just about anything powered by fossil fuel, from forklifts to lawnmowers.

2. Batteries will deliver better performance but with optimized compromises:

Bill Gates’ famous quote in 1981 “640KB ought to be enough [memory] for everybody” stands as a stark reminder that there is not enough of a good thing. Just like computers flourished with more computational power and memory, mobility will continue to thrive with more available battery capacity. Next-generation 5G wireless smartphones require more battery capacity. Electric vehicle drivers require longer driving ranges (300+ miles). More battery capacity means a continued drive to look for newer materials with higher energy density. 

The public will become more discerning and expecting better battery warranties. Longer cycle life (lifespan) while fast charging will become a standard of performance especially in transportation.

But at what cost? Manufacturers will learn to optimize the battery’s capacity, size, cycle life and charging time to the target application or user case. Electric vehicles in fleets will have  vastly different battery designs than those for, say, residential commuters. Backup batteries used in conjunction with solar power will be even more different. Buyers of electric vehicles will learn how to make informed choices based on the battery. Much like buyers historically learned to understand the difference between 4- and 8-cylinder engines, they will become more literate in understanding the differences between kWh-ratings.

3. Battery prices will continue to decline, but at a slower pace:

The cost of lithium-ion batteries declined in the past decade from over $1,100 per kWh to $150 per kWh in 2019. Forecasters expect this figure to drop below $100 in 2023. At such levels, electric vehicles will reach cost parity with traditional vehicles using internal combustion engines (ICE) — without government buyer incentives. Driven by scale, increased volumes, and a dominant battery manufacturing based in China, standard batteries are increasingly become commoditized. Supply chains are becoming more specialized in addressing the commoditization of batteries. In an effort to improve the profitability of EV models, auto manufacturers will increasingly apply traditional cost disciplines to their battery supply chain, spanning improved manufacturing efficiencies to hedging. A few select applications in need of higher performance will benefit from new developments in advanced materials, e.g., providing higher energy density, albeit at a higher cost, but probably with limited penetration.

The risk of trade tensions with China will continue to loom over the battery supply chain. Even as lithium-ion battery manufacturing facilities come online in other parts of Asia and Europe, China will continue to dominate the lithium-ion battery supply chain, from sourcing raw materials to final assembly. The United States federal and state governments will need to formulate clear policies to address the rapid transition to a battery-centric transportation system — or risk escalating trade tensions with China around battery technologies and manufacturing.

4. Batteries will become safer in the field:

Smartphones routinely catch fire in many parts of Asia — and it’s not even headline news. That will change. That must change. The expected standard of battery safety must improve substantially, especially as larger battery capacities become available (in electric vehicles or electric grids). Efficient inspection methods at the manufacturing site and intelligent battery management systems in the field can improve battery safety by orders of magnitude. 

Yet, it is sadly inevitable that battery fires will become headline news in the future before the industry invests heavily in improving battery safety, possibly even with intervention of some governments.

5. Governments will step in to regulate the recycling of lithium-ion batteries:

The industry will recognize that the recycling of lithium-ion batteries is existential to its future growth. The impact of lithium-ion batteries on the environment, from mining raw materials to disposal of depleted batteries, will be devastating if economic recycling methods are not put in place. For example, lead acid batteries are the no. 1 recycled consumer item in the United States with a recycling rate in excess of 99%. Unfortunately, history shows that governments will need to step in and regulate certain recycling targets for lithium-ion batteries. 

29Nov 2017

Congratulations, you just purchased a new Tesla model S electric vehicle (EV). You also committed an extra $2,000 to install a level-2 charger on a wall in your spacious garage. A level-2 charger will deliver 6 kW of power at 240 V to charge your big car battery overnight. Better yet, you are even considering investing an additional $20,000 to install solar panels on your roof and live a life with zero carbon. You might be cringing by now and thinking: “Wow, this is for the rich, not me.

So let’s consider instead a more socially responsible scenario. You leased a much more affordable Chevy Bolt that promises to give you 200+ miles of electric driving. You don’t have a garage. Perhaps you live in a large city so your car may be parked on the street. You are scratching your head: “How will I charge my car battery?” You might be lucky to charge your car during the day at work instead of overnight at home. But what about the weekends? No quick and easy answer.

As the adoption of electric vehicles becomes more widespread especially in congested urban geographies, questions about the charging infrastructure become prominent. Tesla leads in the deployment of their Supercharger network with over 1,000 charging stations installed worldwide, especially near major transportation corridors and highways. But the Tesla fast charging network is not compatible with other electric vehicles. Imagine that you can refuel your present vehicle at only one brand of gas stations, say at Shell only but not Exxon. No practical!

The buildup over the coming decade of a charging infrastructure that is publicly available to all electric vehicles is a must if EVs are to become a real alternative to vehicles powered by gasoline (or diesel). A fundamental requirement for charging is the availability of fast charging, more specifically, charging that can provide at least half-a-tank (or ¾ of a tank) in about 10 minutes.

Let’s do some simple math. An electric vehicle with a 200-mile range equates to a battery size of approximately 60 kWh. Half-a-tank is 30 kWh (or 100 miles). Charging 30 kWh in 10 minutes equals to 180 kW (or 3C effective rate). By the time we factor inefficiencies, the charging station needs to deliver a minimum of 200 kW. To put that in perspective, that is the amount of power used by an entire residential block! These chargers are big, expensive and hence have to be shared among dozens if not hundreds of vehicles.

But the infrastructure for fast charging is only half the problem. The elephant in the room remains: Can the battery itself charge at such a fast rate without being damaged?

The data suggest otherwise for the time being, unless we add a lot more intelligence to how we charge the battery.

The following chart shows the results of charging a battery at a slow rate compared to fast charging the same battery 30% of the time (or about once every three days) and 50% of the time (every other day).

The green curve shows how the battery retains its charge with slow charging. After 700 charge cycles (or about 130,000 miles of driving), it still retains 90% of its original charge. In other words, you can still drive 180 miles in what used to be a driving range of 200 miles. That is good!

The blue curve shows what happens if you charge 30% of the time. The capacity retention drops to 80% after 600 charge cycles. That is a rapid degradation. After 100,000 miles, your driving range is now 160 miles. It might be acceptable to some EV buyers but just barely. The resale value of your car has depreciated substantially below the average value.

The red curve spells major trouble. If you fast charge your electric vehicle every other day, your battery capacity drops to 75% of its original charge after only 300 cycles. That means that your driving range drops from 200 miles to 150 miles after about 50,000 miles of driving. What this graph does not show is that this battery is failing rapidly and has now become a serious safety hazard because of the presence of lithium metal plating. This is a serious problem!

So, if you own an electric vehicle such as a Tesla, and you are tempted to use the Supercharger network frequently, consider an alternative charging solution !!

31Aug 2017

We proudly announced today that the new LG flagship smartphone, the LG V30, includes Qnovo’s adaptive charging technology. The V30 uses Qnovo’s QNI solution, our most sophisticated algorithms to manage its lithium-ion battery. In this post, we open our doors to give our readers insight to our technology and QNI in particular.

As complex and exotic as the battery may seem, you, the consumer, care only about a handful of things.

First, will the battery last you a whole day of use, no marketing gimmicks?

Second, will it charge fast enough? You don’t need blink-of-an-eye-charging but you don’t want to wait long too.

Third, will it last you at least two years or more, given that you are paying a premium price?

And lastly, can you rely that it will not risk your safety and the safety of those around you?

These attributes collectively define your overall battery experience; not one of them, but all of them together.

To last you a full day, the battery must have plenty of charge capacity, i.e., a lot of mAh. This is equal to a range between 3,000 to 3,500 mAh for today’s crop of smartphones. Anything more than that will make the smartphone unwieldy or too thick. To fit a 3,000 mAh battery in the small physical space inside a smartphone means high energy density. Today’s state of the art is near 650 Wh/l operating at a maximum voltage of 4.4 V. That’s the first headache already. At this high voltage and high energy density, the battery is really not happy and needs a lot of caring. I mean a lot of caring!

Fast charging the battery amplifies all the concerns of high voltage and high energy density, and makes them a lot worse. And if you have to charge more than once a day, well, this battery will need even more caring.

High energy density, high voltage and fast charging together are the factors that make the battery fail before two years, and risk making your battery unsafe.

Therein lies the challenge. How do we care for the battery ? and why has this required level of care become so much more sophisticated than ever before ?


As the old adage goes, “You can’t fix what you can’t measure.”

This leads to an important and critical new concept for batteries: Measuring what is happening within the battery, all the time, in real time, and then deciding what to do. By “within” I mean the “chemistry” that is taking place inside the battery…the stuff that you don’t see. This is called, in engineering terms, closed-loop feedback. Engineers know it, study it, and use it in countless situations.

Qnovo’s software adapts to your smartphone a measurement technique widely used in battery laboratories. It is called electrochemical impedance spectroscopy (abbreviated as EIS). It helps our scientists understand what happens inside the battery without destroying it. Qnovo’s innovation is in implementing EIS in your smartphone so that it is always monitoring your battery’s internal chemical processes.

We announced earlier this year that the Qualcomm® Snapdragon 835 that powers the LG V30 includes hardware that accelerates Qnovo’s algorithms. Indeed, the additional hardware in the Qualcomm Snapdragon 835 chipset extends the utility of EIS inside the smartphone. The hardware in this new chipset enables measurements and frequencies that were not available in older chipsets. Qnovo’s QNI software takes advantage of this new hardware to gain deeper insight into the battery, again all in real time.

Now we get to the second portion of closed loop: What to do after making a measurement. As it turns out, and we thank science for that, charging the battery is a powerful knob to alter and affect what happens inside the battery. Qnovo’s adaptive charging takes the information from the EIS measurement, and then adjusts the charging current to reduce and mitigate possible harmful reactions detected during previous measurements.

With QNI, this “closed loop” happens a lot faster than its sister software product, QNS. As a result, it is able to detect more potential problems and react appropriately. Throughout a single charge, QNS makes approximately 200 measurements on the battery, whereas QNI makes close to 20,000 measurements.

Over the past years, we have collected a gigantic database of measurements on batteries from the vast majority of battery manufacturers. We have tested large quantities of batteries under diverse and extreme conditions. This knowledge allows Qnovo to train our algorithms to make them more efficient and more accurate especially as battery materials continue to evolve.


The skeptic might ask, “Great, but how does it help me, the end user?”

The most important benefit that the user derives is the health of the battery. You get a healthy battery AND more capacity AND fast charging…in other words, the consumer gets a great battery experience encompassing the attributes mentioned at the beginning of this post.

You, the consumer, do not have to worry whether your usage might hurt the battery. You don’t have to worry about fast charging because it might damage the battery. You don’t have to worry about charging to less than full because it helps the battery’s longevity. None of these should be your concerns and none should keep you thinking about the battery. Qnovo’s adaptive charging takes care of these battery issues in the background, and gives you a healthy battery with the best user experience.

So, if you are in the market for a new smartphone, do consider an LG V30 and do enjoy its battery experience.