Understanding Batteries: A Comprehensive Overview

The future is battery-powered. From running smartphones and electric vehicles to providing the footing for our renewables future, getting batteries right is crucial for both society and the planet.

The challenge? Batteries are very complicated, and easy to get wrong. The next few years and decades are set to bring forth battery innovations that will make life even more dynamic, convenient, and productive.

In this edited extract from our eBook, Long-Term Product Success Begins With Understanding the Data Behind Your Batteries, we offer an up-to-date overview of why understanding batteries is so important, so complicated, but ultimately so rewarding.

The Brand Risks of Bad Batteries

Batteries are amazing, but they are also dangerous. Because they store energy that can be released very quickly, they are a recipe for disaster if not handled properly.

Remember the Samsung Galaxy Note 7? When Samsung shipped phones with batteries that weren’t fully understood and weren’t fully characterized, the devices started exploding after getting into the hands of two million consumers. Even today, several years later, the brand is still associated with battery problems. If you Google “Samsung Galaxy Note”, auto-complete still suggests failure and battery safety concerns.

Samsung had to conduct a product recall, and aside from the cost of replacing or refunding two million phones, this disaster damaged their reputation, their future prospects, and the entire industry as a whole.

What’s interesting from this case study is that Samsung’s investigation found that the blame lay with their battery vendor’s manufacturing process — but despite this, the recall is still remembered as the exploding Samsung Galaxy Note 7, not the exploding batteries from their supplier, ATL.

Key takeaway: if there is a problem with your product’s battery, the customer calls you and not your battery vendor, and it is your brand that is tarnished.

The key takeaway is this: if there is a problem with your product’s battery, the customer calls you and not your battery vendor, and it is your brand that is tarnished. That’s why it’s important to fully characterize the battery that goes into your application.

Beyond Explosions: The Impact of Variability

Even if batteries don’t catch on fire and explode, there are still many reasons to care about your battery. High on the list is battery variability.

Figure 1 below shows that out of 48 nominally identical Panasonic battery cells, all operated identically, there is still tremendous variation as to how many cycles an individual cell will last. The worst cells reach end-of-life after 750 cycles while the best ones last up to 1300 cycles. These large variations in battery performance directly impact how much capital you have tied up in warranty reserves.

There are costs associated battery variability — you have to engineer your application to accommodate the worst-performing cell, which leads to overbuilding & increased cost.

There are other costs associated with this variability as well. You have to engineer your application to accommodate the worst-performing cell, which leads to overbuilding & increased cost. Operators and technicians have to spend time troubleshooting and dealing with these defects, lowering your overall productivity and throughput, and customers have to deal with products that have an inconsistent lifetime.

Figure 1. Different aging trends from 48 equal cells under same aging conditions profiles.
Source: T. Baumhöfer et al., Journal 
of Power Sources 247 (2014) 332-338

Another example of battery behavior that can significantly impact your end product is battery swelling. A battery starts swelling because of a gas buildup inside the battery. It doesn’t catch on fire, but the risk is always there in the back of your mind that this probably isn’t right, and it’s probably not the way the product was designed. Your phone’s case starts to bulge a bit, or maybe your laptop’s mousepad won’t click the same way it did when it was new.

The key message is that even if a battery doesn’t explode, additional battery issues still affect customer experience, and ultimately the bottom line.

Harnessing Battery Potential: A Competitive Edge

Now that we’ve touched on how batteries can go wrong, let’s discuss some of the potential benefits of properly understanding batteries.

Because of the complexity of batteries, there is also an opportunity for your organization to develop a competitive advantage when you employ them properly. The most obvious example is battery lifetime. Figure 2 shows a typical EV battery lifetime. The black line shows that the battery behaves with a good lifetime under normal conditions, but the green line shows that if you fast charge this EV battery, it significantly degrades the battery’s lifetime.

Battery vendors, of course, will give you only the data about a good battery lifetime under normal conditions. It’s up to you to find out about lifetime degradation fast charging conditions.

Battery vendors, of course, will give you only the data about the black line – a good battery lifetime under normal conditions – and it’s up to you to find out about the green line – a degraded lifetime under fast charging conditions.

Figure 2. Impact of DC fast-charging (DCFC) use on battery state of health (SOH)

An excellent case study of this behavior comes from Nissan and Tesla in the mid-2010s. Tesla developed a significant competitive advantage by becoming essentially the first EV with a reliable and cost-effective battery, which they leveraged to capture significant market share. During this time period, one of their primary competitors was the Nissan Leaf, which unfortunately suffered from really poor press as a result of its battery issues.

The Nissan Leaf sold well in the southwest United States, however in that climate where summer temperatures can exceed 120 degrees Fahrenheit (50 degrees Celsius), the Leaf frequently exhibited tremendous battery degradation in the first few years due to insufficient cooling systems. (The Nissan Leaf battery was air-cooled, while Tesla and most other contemporary EVs use active liquid cooling systems.) The Leaf has an advertised range of 84 miles, but Leafs were showing up in CarMax lots with ranges of only 10 miles. Why did this happen to Nissan but not Tesla? The answer is that there was a lack of test data about the effect of temperature on the battery’s lifetime. This is an example of knowing more about your battery translates into significant advantages in the marketplace.

Deciphering Battery Metrics & Making Informed Decisions

Hopefully, at this point, you fully understand why it’s important to understand your battery. But what information do you actually need?

You wouldn’t rent an apartment based solely on how many bedrooms it has. You obviously need more information… Likewise, with a battery, a single plot of capacity versus a number of cycles is insufficient to determine if a battery is right for your application.

The majority of battery vendors will send you a battery lifetime plot and some basic specs. You should ask whether that’s all you really need in order to make an intelligent decision. You wouldn’t rent an apartment based solely on how many bedrooms it has. You obviously need more information such as where the apartment is located, what amenities it has, and if it’s a good fit for your life. Likewise, with a battery, a single plot of capacity versus a number of cycles is insufficient to determine if a battery is right for your application. If your application uses a lot of power, you need to know how this plot changes with increasing power demand. If your application requires a long shelf storage time before use, you need to know how this plot changes if the battery is not operated for long periods.

Essentially, you need additional information to make an informed decision. But where do you start? Batteries are extremely complex electrochemical devices that have many underlying reactions evolving constantly. It’s hard to know what data to collect, how to interpret this data, and to know what to look for.

The question always comes down to, “How do you tell if a battery is good or not?” Unfortunately, there really is no simple equation. Batteries are like organisms in that no two batteries are exactly the same. This is very problematic for mass production because it’s very hard to tell when those small variations will suddenly matter a lot.

We’ve established why it’s important to understand batteries, and how metrics are the key to developing that understanding. The most common battery metrics are displayed on the spider chart below. You have attributes such as energy density, specific energy, cycle life temperature, etc. The next challenge is that different applications care about different battery metrics. A battery that’s optimized to be great for one application would be terrible for another. For example, power tools prioritize a battery’s ability to charge and discharge quickly, and the battery must be lightweight. This is the exact opposite of the requirements for a battery paired with a solar photovoltaic system, to enable continuous power when the sun isn’t shining. This application needs a battery that has a long cycle life and is inexpensive. The battery’s weight doesn’t matter in this case.

Figure 3. Spider chart comparing battery attributes for different applications

Similarly, what you want in a pacemaker is the exact opposite of what you’d want in a speedboat. You need to identify which key metrics are relevant to your application so you can determine what target you’re aiming for. The next step is to analyze the data and generate insight into how to turn this knowledge into a competitive advantage.

Data Is King

The ultimate takeaway here is that, when it comes to batteries, sophisticated data collection and analysis are absolutely critical.

Proper comprehension of batteries goes beyond merely examining simple metrics like capacity vs. cycle number. Understanding batteries means scrutinizing the metrics that are pivotal for your specific application and translate this knowledge into a competitive edge.

Here at Voltaiq, we’ve been at the cutting edge of battery intelligence since 2012, offering a comprehensive analytics platform that delves into battery data from all conceivable sources. Our Enterprise Battery Intelligence platform is designed to integrate a deep understanding of batteries into the core of your organization. For partners in the field of electric vehicles, consumer electronics, medical devices, and energy storage, we provide the insights and tools necessary to meet requirements and ensure reliability.

For those seeking a deeper dive into the world of batteries, our comprehensive eBook offers further insights.