How to Monitor the lifespan of an Electric Vehicle Battery

There’s an old saying – what gets measured, gets managed. The same applies to EV batteries. When you know how your fleet EV batteries are being used and the effect it’s having on battery life, then you can take steps to extend the battery life.

Telematics and onboard systems provide most of the data you need. You can get key metrics such as state of charge (SoC), depth of discharge (DoD), charge cycles, temperature, charging speed, energy consumption, and vehicle load and usage patterns.

When you sync all this data with your charging management system, you can monitor your EV fleet closely to make sure everything is optimal. For instance, you don’t want to let the battery run too low (deep discharges) or charge them all the way to 100% too often (overcharging). 

Both undercharging and overcharging can wear the battery out faster. 

As well as real-time monitoring of your charging operations, it’s also a good idea to run regular capacity and diagnostic checks to get a full battery health status of your EVs.

In this guide, we’ll take a closer look at what causes EV batteries to degrade and how you can slow it down.

Understanding Battery Degradation

Battery degradation refers to the gradual loss of a battery’s ability to hold charge over time. In EVs it means that as the battery ages, it’s unable to hold as much energy as when it was new. This makes the EV range shorter and can increase the time it takes to charge the battery. 

What is Battery Degradation and Why Does It Occur?

The reason for battery degradation is that the chemical reactions inside the battery become less efficient after repeated charging and discharging cycles. 

Most EVs use lithium-ion batteries. When you charge the EV battery, lithium ions move from the cathode (positive side) to the anode (negative side). The anode stores the ions until they’re needed to power the car.

When driving the EV, the lithium ions flow back from the anode to the cathode, releasing electrons which generate electric current to power the motor. 

After many charge and discharge cycles, the electrodes start to wear down. This reduces how well they store and release lithium ions. Lithium plating can also occur, which is a build up of metal on the anode surface, reducing the number of ions that get stored.

The electrolyte, which facilitates ion movement between electrodes, can also degrade over time. This is especially true under high temperatures (known as thermal stress) or if the battery is regularly overcharged.

Factors that Influence Battery Degradation

There are three main factors that contribute to EV battery degradation.

• Temperature: Operating and charging EVs in extreme temperatures, whether very hot or cold, has an impact on battery health. Heat accelerates chemical reactions inside the battery, known as thermal stress, leading to faster wear. Cold temperatures slow down ion movement which reduces the battery’s ability to hold charge. 
• Charging Speed: Using fast chargers generates more heat, which speeds up the degradation of battery cells. The intense current used in fast charging also forces the battery to work harder, causing wear on internal components, especially if done often. 
• Driving Patterns: Aggressive driving, such as rapid acceleration, frequent stops, or driving at high speeds, also affects battery health. These driving behaviors use more power, which drains the battery faster. You end up needing to charge the battery more frequently which puts extra strain on the battery. 

Measuring and Tracking Battery Degradation

Most EVs come equipped with a battery management system (BMS), which monitors the battery’s overall health. The system tracks charge cycles (how many times the battery has been charged and discharged), battery temperature, and state of charge (SoC). You can use this data to prevent overcharging and deep discharges.

Capacity tests give you a clear picture of how much the battery has degraded over time. It’s recommended that you carry out capacity tests at least once a year. If you notice a significant drop between tests, it could be a sign of increased battery wear and tear. 

You can also generate regular battery health reports to summarize performance. This makes it easier to spot any signs of degradation early enough that you can do something about it. For instance, you can proactively manage charging schedules or arrange driver training to help prevent rapid acceleration or speeding.

Understanding EV Battery Lifespan

EV battery lifespan refers to how long the battery continues functioning properly before you notice a drop in performance. 

Average Lifespan of Electric Vehicle Batteries

On average, EV batteries lose around 20% of their capacity within 7 to 10 years or 100,000 to 200,000 miles. That’s why most manufacturers offer a battery warranty for up to 8 years or 100,000 miles.

The actual battery lifespan depends on a number of factors, including:

• Vehicle driving behavior 
• Efficiency of charging management
• Whether the battery and EV have been well maintained
• What conditions the EV has been exposed to (especially extreme temperatures) 

Factors that Affect Battery Lifespan

As mentioned earlier, extreme temperatures can degrade EV batteries more quickly. If your fleet is operating in a very hot or cold climate, you need to take extra care to monitor battery health. 

Maintenance of your EVs is also important. Follow proper charging practices, such as avoiding charging to 100% or letting the battery drain too much. Also make sure that your vehicle and charging software is up to date, as manufacturers often tweak things to optimize battery performance. 

The intensity of use also matters. If your EVs rack up 1000’s of daily miles and you’re relying on fast charging for high uptime, then your batteries might degrade faster. Try to strike a good balance between fast and slow charging if possible to maximize battery life.

Comparing Battery Lifespan Across Different Vehicle Makes and Models

The type of battery can affect how long it lasts. 

Most brands use lithium-ion batteries as they offer high energy density. However, some automakers are starting to use lithium iron phosphate (LFP) batteries which might be longer-lasting and more stable, especially in terms of thermal management. The Tesla Model 3 uses an LFP battery, for instance.

The efficiency of the EV makes a difference too. The battery of an EV with a highly efficient motor or more aerodynamic design (like the Tesla Model S) might last longer than a less efficient vehicle model.

Optimizing Battery Performance

To make sure you get the most out of your EV batteries and keep vehicles on the road for longer, you need to take steps to optimize charging and battery care.

Best Practices for Charging an Electric Vehicle Battery

• Avoid Overcharging: Charging the battery to 100% every time might seem like you’re maximizing its use, but overcharging puts extra stress on the battery. Keeping it around 80% for regular driving helps prevent that wear. 
• Limit Fast Charging: Fast charging is convenient, but doing it frequently generates a lot of heat, which degrades the battery faster. For everyday use, slow or regular charging is kinder to the battery, allowing it to cool down and reducing thermal stress.
• Charge When Cool: Aim to charge during cooler periods of the day or in a cooler environment. Heat is one of the main factors that shorten battery life, so charging your EV when it's cool minimizes that risk.

Maximizing Battery Range and Efficiency

Below you’ll find some best practices for ensuring that each charge takes your EV as far as possible.

• Drive Smoothly: Avoid aggressive acceleration and braking as they eat up battery power faster. Smooth driving preserves battery life and stretches your range per charge. 
• Efficient Route Planning: Use route-planning software to avoid heavy traffic and terrain. This will avoid unnecessary stops and energy-intensive routes. 
• Manage Vehicle Load: The heavier the load, the more energy the vehicle needs to move. Optimize what’s being carried to avoid unnecessary weight and you’ll improve vehicle energy efficiency. 
• Optimize Charging: Using smart charging strategies allows you to manage energy use effectively. This means charging vehicles during off-peak times to reduce energy costs, and ensuring that each vehicle is charged just enough to meet its needs, not overcharged or unnecessarily fast-charged. 

Ampcontrol smart charging software helps you to preserve EV battery life by managing energy loads and avoiding battery overcharging. See what Ampcontrol can do for your fleet – book a demo today.