Episode 47: Extreme Battery Testing

Lisa Peña (LP): SwRI researchers are taking automotive batteries to their limits to make sure you are safe behind the wheel. Find out how we put them through crushing, explosive, extreme testing for safety. That's next on this episode of Technology Today

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We live with technology, science, engineering, and the results of innovative research every day. Now, let's understand it better. You're listening to the Technology Today podcast presented by Southwest Research Institute. Transcripts and photos for this episode and all episodes are available at podcast.swri.org.

Hello and welcome to Technology Today. I'm Lisa Peña. SwRI is a leader in battery testing and research. When you turn on your car, you're probably not thinking about catastrophic failure. Our guests today are always thinking about battery failure, what could go wrong, and how to prevent it. They beat up batteries in their lab to make them safe for consumers. SwRI engineers Dr. Bapi Surampudi and Ian Smith join us now to talk about our battery testing capabilities and services. Thanks for being here, Bapi and Ian.

SwRI’s Energy Storage Technology Center houses technology, like these chambers, to evaluate and develop battery and energy storage systems for electric, plug-in and hybrid electric vehicles; grid storage; flywheels; and stationary systems such as flow batteries for electric power grid applications.

Dr. Bapiraju Surampudi (BS): It's very good to be here, Lisa.

Ian Smith (IS): Good to be here as well, Lisa. Thank you.

LP: So today we want to understand the battery testing process at SwRI. So first, what types of batteries are you testing?

BS: So we're primarily focused on various chemistries under the lithium ion battery category. These chemistries are most commonly used in electric vehicles and hybrid vehicles. We also test nickel metal hydride batteries, which were used in the original Toyota Prius generation 1 and 2. And we continue to test lead acid battery technology for conventional vehicles and other applications.

IS: Some of the batteries that we've been testing a whole lot more frequently very recently has been solid state battery technology and lithium metal-- and lithium sulfur technologies, helping our customers evaluate things like energy density, safety, performance, and things like that.

LP: So the vast majority of the batteries you test are used in vehicles, but are there examples of other batteries that you test for other products?

BS: Yes. We, for example, test batteries that go in medical devices-- not implantable ones, but even devices that help consumers meet certain health guidelines. So in those applications, you can imagine how important it is for the battery to be reliable delivering the power that's promised and living for the duration of the product's shelf life. So that's another example. I would say we also test batteries for the space industry. When batteries go up on satellites or even interplanetary travel, they are exposed to very cold temperatures and sometimes very hot temperatures, depending on what side they're facing the sun. So they need to be able to live long enough to complete the mission. So those are two primary examples. We also test batteries for aerospace industry for certifying batteries on aircraft and ground vehicle-- sorry-- ground consumer electronics industries like, for example, drill bits, and other types of industries, like laptop and so on.
 

Institute Engineer Dr. Bapi Surampudi and R&D Manager Ian Smith pictured with a power cycler for lithium ion cells. The lithium ion cells on the table are being tested for aging.

LP: So there is a wide range here of batteries you're testing for various products. Now, when we say battery testing and research, it sounds low key for those of us not familiar with the field, and maybe even somewhat calm, but your work is really anything but that. You're crushing batteries. There are explosions, fires. This is all part of what you do. Will one of you walk us through a typical battery testing scenario, if there is a typical scenario?

BS: I can cover maybe a non-abuse scenario, and maybe Ian can cover an abuse scenario. For example, when a vehicle-- electric vehicle is plugged in to a fast charger, you would want to fill that battery as quickly as possible. But if you indiscriminately pump [INAUDIBLE] power into the battery, you have the danger of degrading the battery, or even causing a fire. So an example of the research we do is shape the optimum fast charge power profile that will minimize the charge time so the consumer is not inconvenienced too much. But it also avoids the failure modes, such as lithium plating, which can cause fires. And at the same time, it can make sure that the battery is not degrading or minimizing the aging process so the warranty can still be honored.

IS: And then for some of the typical safety types of work that we do, really anything a battery manufacturer tells you not to do, we tend to do-- so whether that's expose a battery to extremely hot temperatures, or crush it like you said, or poke it with a really sharp nail. And the work that we do at the cell level is really so we can understand, in a worst case scenario, how does this battery fail? And then we can use that information to guide our design choices moving forward for building modules or battery packs-- so what kind of materials do we use, what kind of design do we use to root hot vent gas away from neighboring cells-- all in an effort to make sure that, if we have a single cell that fails or a group of cells that fail, how do we try and keep that from propagating to the rest of the pack to make sure that the pack is as safe as possible?

LP: And when we're talking about battery testing, the term energy storage comes up a lot. Can you define energy storage for our listeners? What falls under this umbrella?

BS: Energy storage is ubiquitous. It's there and pretty much all industries. Whether we like it or not, that's the reality today. And the energy storage definition is anything that can store either electrical energy, or mechanical energy, or kinetic energy.

So for example, a flywheel is an example where we're storing kinetic energy. These flywheels are turning at very high speeds, and when you need power, you would put a generator on the flywheel and suck down the kinetic energy to convert it into electrical power. But we are primarily focused in this discussion especially on batteries, which are a good example of electrical energy storage, where we are pumping coulombs into the battery, and the battery's able to store those coulombs inside one of its electrodes and then release those coulombs back to drive a load. It can light bulb, or it can run a radio, or it can run a laptop, or it can propel a vehicle. So a broad definition of energy storage is something that can save energy and make it available for us when we need it. And that's especially important if we take the example of solar generation where the sun is not out all the time. We are obstructed by clouds, so the energy flow is very intermittent.

And when we have these energy storage to help with the solar panels, we are storing the energy and the load does not see the same interruptions in power. The battery equalizes and stores the energy, and makes it seem like it's always available. The same goes with wind energy, where we-- the wind is not always available, so whenever it's available, we want to store it. Other forms of energy storage are a production of hydrogen, where you can convert the electricity into hydrogen using a process called electrolysis, and then reuse that hydrogen to generate electricity when we need it.

LP: So we're talking about batteries today. That's electrical energy storage, and that's what-- your services are aiming to prevent different catastrophic scenarios. So what could go wrong with a battery? What are you testing for?

IS: So some of the things that we're testing for are what happens with improper use of a battery. So what would happen if a battery cell, a module, or a pack gets overcharged because the correct safety devices weren't in place? What happens if there's a short circuit? Does the fuse open or contactors open? What happens in a severe accident, where there's a very large mechanical force that's exerted upon the battery, or in some instances, a sharp projectile, like a nail or a beam or something like that, that penetrates into the battery? And then we're wanting to try and understand how severe that failure is under a different temperatures, different states of charge.

And then, what kinds of design choices can we make to potentially improve that result? And then in some instances, also measuring things like the gaseous emissions or particulate emissions that come off of these batteries when they go into one of these failure modes-- all of this to try and provide as much information as possible to first responders, and standards organizations, and things like that.

LP: So I want to talk a little bit about our Energy Storage Technology Center. What happens at the ESTC at SwRI?

IS: Sure. So that is the lab where we do the vast majority of all of our battery testing and research. So we have several battery cell cyclers there, up to about 200, 250 channels. And so that's where we do a lot of testing and research related to life, and lithium plating, and fast charging-- so just trying to understand, under what operating conditions can we get these batteries to perform their best and last their longest?

That's also where we do quite a bit of battery module development. So if we take a lot of these battery cells together, and connect them in series in parallel, and then use different materials in between them to try and distribute the temperature across the module-- and again, just from a developmental perspective, try and understand how these modules perform and how long they last. And then typically, tucked away in the back corner of our lab is where we do a lot of safety evaluation. So that would be looking at, again, all the things that a manufacturer tells you not to do. But it's testing that needs to be done to make sure that you've got a safe product in the end.

LP: So can you describe the center for us? There is a lot of unique equipment, really special equipment in there that you use-- that is used in the testing process. Can you tell us about maybe some of your-- the equipment you use the most?

IS: Sure. So when it comes to charging and discharging batteries, we use a piece of equipment that's called a cycler. So we have cyclers that are specific for battery cells. So they're typically a 0 to 5 volt range, and maybe 50 amps per channel. And so those get connected electrically to the battery cells that we test, and those either charge them or they discharge them however we see fit.

We also have a lot of thermal chambers that are located in our lab, and we use that to make sure that we have a very controlled environment around our test articles. So we can basically go from Arctic negative 20 degrees C ambient temperatures all the way up to Death Valley, positive 45 degrees C temperatures, again, to try and evaluate the full operating envelope of these batteries.

When it comes to the battery module or pack testing, we use the same kind of piece of equipment. It's a cycler. They just have different power and voltage ranges. So we've been investing pretty heavily in some high voltage, high power battery cyclers that are modular. So they're in 100 kilowatt cabinets basically that you can connect together. And so recently, we've been doing some very high power battery cycling work with a battery pack up to just a little bit under 1 megawatt of power.

The last bit of equipment that I'll talk about is we've been doing a lot of research looking at dielectric fluids that are directly cooling batteries. So we've developed our own flow rigs and controllers to be able to circulate this dielectric fluid at the same time we're cycling these batteries, again, to understand the fluid's impact for battery performance, and life, and things like that.

LP: So we've been testing batteries for a while. How long have we been testing batteries at SwRI?

IS: Bapi?

BS: Yeah. Since 1995, more continuously since 1995-- before that it was a little intermittent. So we used to do on average about two to three projects related to batteries from '95 to 2011, when we began the first phase of the Battery Consortium, the SS1. After that, our volume of work increased.

LP: So we've definitely seen growth, as you just mentioned, in this area. What are we doing now? How have our capabilities changed since the inception of this service?

BS: So when we started off, there was not a lot of regulations, not many testing houses around the world. And when batteries are tested, people didn't know what to expect in terms of how to manage the test and what kind of gases could be emitted that needs to be cleaned up.

So we had makeshift facilities for every single project in the early phases to make sure that we are capturing all these gases, cleaning them up, and-- before we release them. And most of the projects were following test procedures that were customized from our suppliers, our customers themselves, so there was no-- not enough standards out there.

Since then-- that's where we started. Oh, by the way, at the beginning, we also used to build prototype electric vehicles because there were several component manufacturers, like battery manufacturers or motor manufacturers, or even integrators, that would come to us to pull together a full powertrain. We would take a vehicle like a Ford Excursion or Ford-- a Chevy Suburban or something like that, strip out the engine and all the powertrain components, and then add in a battery pack, electric motors, transmission, control systems, and thermal management systems to demonstrate that together all these components can actually drive the vehicle.

And in those days, getting a range of 50 miles to 90 miles was already quite an achievement. And one nice milestone at that time was that we ended up testing the GM EV1 components in our labs. It's one of the first electric vehicles that was ever released after electrification had its research-- [? Renaissance, ?] I should say.

And now we have matured to a point where we have test cells, we have test equipment all organized. We have processes that are streamlined to a point where we can look at the test procedures and give good feedback to the customers at the get-go, and then actually execute the tests, not just to check a box, and complete the test, and throw the data across, but with more of an engineering presence, an engineering sense of what is going on with our own insights-- which are actually more valued by the customers than just the data itself.

So that's where we are. And I think we continue to build the prototypes, large prototypes. The 1 megawatt example that Ian gave is also going into an extremely large off-highway vehicle. And so we're still quite engaged in the powertrain integration business as well.

LP: So I like that example you gave us. So you were building electric cars basically from scratch, it sounds like, even before they were-- you could see them out on the road. I guess you have to do the testing before they're safe for drivers, so you are that lab testing, making, building--

BS: Yes.

LP: --from scratch and getting them out on the roads.

BS: Yes. When car makers have a concept first, they want to build the hardware around the concept, and check it out and see, is it feasible? Is it something that's worth doing a lot more R&D on? So they need a go/no go check out of these concepts. And we were, very luckily, involved in several of these concepts car builds for many OEMs.

LP: And we continue to grow, so there is a test cell expansion underway right now set to be ready in January. Ian, can you tell us a little bit about that?

IS: Sure. So over the past three to four years, we've seen a significant increase in the amount of work that our group has been conducting, especially when it comes to safety. Currently, we have two safety test cells at our Energy Storage Technology Center, and we found that just really isn't enough to keep up with the demand that we're seeing.

So we're investing in building two new dedicated safety test cells located in our Energy Storage Technology Center just to improve the amount of testing and research that we can do with the cell and small module level. And then, in addition to that, we're building a separate test cell for more developmental types of purposes.

So if we have a prototype or a module that's in development-- now, we still haven't gone through 100% of the safety tests with, we want to be sure that that's in a dedicated secure room to make sure that nobody can just walk up to it while it's under test. So it's pretty exciting to see that there's been so much growth and appetite for growth on our side. And I'm pretty excited come January, when those two new test cells-- I guess three new test cells are going to be ready.

LP: All right, since 1995 going strong in this area-- so we want to turn now to the Electrified Vehicle and Energy Storage Evaluation Consortium. This consortium is celebrating 10 years, and recently had a name change. Can you tell us a little bit about that?

IS: So I am the program manager for it. I took over actually from Bapi, who was the manager for the first and second version of the consortium, what used to be called the SS1 and SS2 Consortium. We did recently have a name change, and one of the reasons why we had that name change was the scope of work or the type of testing and research that we conduct has grown over the years.

So as there's been more and more electric vehicles that have been released, we found that a lot of our customers are very interested in doing more testing and research at the vehicle level to understand overall thermal management system strategy, control strategy, electric motor and inverter operation and efficiency at different conditions. And so the scope has morphed from solely battery focused to encompass more of the entire powertrain or vehicle system.

And so for the first year, we tested the Volkswagen ID.3. For the second year we tested, the Ford Mustang Mach-E. And then for this third year, we're scheduled to be able to take delivery of a Ford F-150 lightning so all of these are commercial passenger vehicles that you can go out and buy.

But we've been doing testing and evaluation on them to understand, again, thermal management system strategy, operating strategy, component level performance. And then we use that to try and build an understanding of what the current state-of-the-art technology is, and then work with our members to try and understand what the current gaps are.

So where do we want to be in terms of fast charge performance, or life, or durability, or safety? And where are we at right now with these state of the art technologies? And then try and identify, well, what are those gaps, and then how can we potentially address those gaps moving forward?

LP: All right, continuously looking ahead-- and so I want to move on a little bit away from automotive, because as we've discussed a little bit, our capabilities at SwRI extend beyond automotive, but it also includes utility grids and electricity distribution. Can you tell us about your research and testing in this area? And how does it differ from automotive? What are the goals when testing batteries for these types of applications?

BS: Yeah. Sure. For the grid side, the so-called use cases are duty cycles that the batteries will experience are somewhat different compared to automotive propulsion needs. For example, one duty cycle that's common in grid storage is so-called frequency regulation.

We all know that, when we plug in to the wall, we get a 50 hertz or a 60 hertz standard frequency signal at 110 wolves or 240 volts, depending on the type of plug we plugged into. And any time we plug in a load, it's adding to the load on the grid supply.

When the supply from the grid and all the loads all together don't balance, then this frequency can start varying from the target 60 hertz or 50 hertz. And any time this frequency varies, the quality of the power suffers and it could damage the equipment that's plugged in. And there's some liability for the utilities because of that.

So the utilities would like to keep that frequency very well controlled within a very small fraction, almost to a 0.01 or 0.02 hertz, or even better, plus minus 60. So how can they do that? They found that, with energy storage or having batteries near large sized load-- loads are at a-- at the generating station or at a distribution center, they can supplement the power from the main production with this battery storage when the demand is high.

And then, when the demand is not high, they can charge this acid-- this battery acid to be ready for the next high demand period. So when we try to watch the frequency and pitch in extra charge from this battery, or extra discharge from the battery to maintain that frequency, that's called frequency regulation. And so the battery will experience a charge and discharge pattern that's relatively high frequency compared to a normal automotive driving pattern. And the battery aging for this type of a duty cycle can be somewhat different.

Another example duty cycle is what is called peak shaving. So whenever, during the day-- maybe in San Antonio, it's closer to 5:00 or 6:00 in summer-- the loads are-- go to a peak. Then the utilities need to not only regulate the frequency that I just described, but also needs to supply power from the battery for a long period of time.

So they don't have to start what is called spinning reserves. Spinning reserves are more high expensive methods of generating electric power for short periods of time. By using the battery, they can save a huge amount of money, operating expenses in that kind of situation. And that's called a peak shaving duty cycle.

So in the ESTC at Southwest, we are able to replicate these kinds of duty cycles. There's about 30 to 40 different duty cycles similar to the two I described. We can replay those duty cycles and subject batteries to aging, and see if those batteries are meant to match that particular duty cycle 'or they're not a good match.

And that allows designers to select the right type of chemistry for those duty cycles. So that's an example for grid storage application. I can talk a little more about the grid consortium here and activities very soon here.

LP: Yeah, is that BESS?

BS: Yes.

LP: OK, so yeah, if we could move into that, because that's the battery energy storage system for electric grid joint industry program-- tell us a little bit about this.

BS: The collaboration that existed in the automotive industry doesn't quite exist in the grid storage side. So the primary goal of the BESS consortium is to bring together the utilities, the power transmission service providers, and many of their supply chain members together to focus on identifying and prioritizing technology challenges that they face. The consortium then selects and prioritizes one topic for each phase, and does research on that topic, and reports back to all these members. The IP that comes out of these type of research is available to the members free to try for a limited period. After that they have to pay a royalty fee to have use of it.

And this model is because this consortium is primarily being funded by Southwest in this first phase, and in the second phase the members will all pay their subscriptions and they'll have better IP policy.

LP: Safety is your focus. That's your priority. As you test and you're researching, does that inform how you buy things? When you're out in the world, are you looking for certain-- I don't know if-- certain inspection numbers? Or is there something-- some tips you can give for those of us out buying? If we're buying it, should we assume it's safe, or is there something more?

IS: [INAUDIBLE] I think that's a good question to ask. The headlines typically always like to have a lot of information about either battery electric vehicle fires or laptops or cell phones that catch fire because there was some kind of abuse condition or internal manufacturing defect. But maybe the tip or advice that I would give for all of the consumers is just really trust and understand that there's a ton of work and research that's going into continuously improving the safety of these batteries.

And so a lot of those headlines that you see are pretty rare and don't happen all that frequently. And again, there is just a ton of work that's being done not just by us, but by other research organizations, vehicle manufacturers, machine manufacturers, and everything, all with the hope of having a vehicle or a system that's as safe as possible.

BS: On the tips to consumers, I think Ian underscored a good point, that there's a huge amount of research and testing that is undertaken by the manufacturer, and even the regulators, to make sure that the products are reasonably safe by the time they reach the consumer, whether it's an automotive electric vehicle, or whether it's a consumer electronic device, or medical device, or anything like that.

So beyond that, let's say on the automotive side, if you are trying to buy an electric vehicle, those are not cheap. The first thought that jumps into your mind is, oh my god, this is a little more expensive than the normal internal combustion engine car that I would have bought. How do I know I'm getting the performance and the range that I'm looking for in this car?

So one thing I would advise is to drive the vehicle, if possible, in hot and cold weather conditions to see if the full range of the vehicle is available. You don't want to be driving a vehicle that has lower range than you think it has. Then you can't plan your trip. And so you would want to understand your vehicle better before you invest your money. And so it's nice to be able to check it out. And it's not always easy to find hot and cold weather where you want to buy it, and so it takes a little bit of research and help from other consumers.

LP: All right, so many battery testing and research capabilities here at SwRI-- and it's important work that keeps us all safe when we're using all kinds of products. So thank you both for sharing your expertise with us today, Bapi and Ian.

IS: Yes, thank you.

BS: Oh, thank you very much for the opportunity to share what we've learned in the last few years. Yeah.

And thank you to our listeners for learning along with us today. You can hear all of our Technology Today episodes and see photos and complete transcripts at podcast.swri.org. Remember to share our podcast and subscribe on your favorite podcast platform.

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Ian McKinney and Bryan Ortiz are the podcast audio engineers and editors. I am producer and host, Lisa Peña.

Thanks for listening.

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