The EV battery 'leap of faith'

New and evolving electric vehicle battery technology leaves uncertainties for early adopters about their longevity, warranty coverage and resale value – all things that could have even greater impact on the buyers of used EVs.

The technology elicits praise for needing less maintenance than gas-powered vehicles due to their electric motors with fewer moving parts. However, the heart and soul of an EV is its complex battery – which is also its most expensive component.

Gas-powered engines have undergone over a century of testing and refinement – a history EV battery technology lacks – leaving potential owners questioning whether their batteries will last the lifetime of the car, or long enough to resell it without difficulty.

Robert Charette, a longtime systems engineer, contributing editor for IEEE Spectrum, and author of "The EV Transition Explained," told The Center Square, with the lack of quantitative historical data, the consumer is being asked to make decisions on sparse information, and you almost have to buy EVs on a “leap of faith.”

Charette says consumers should be concerned about whether the manufacturer is committed to support these batteries after the warranties run out. The cost of replacing an EV battery can run from $5,000 to upward of $15,000 depending on the brand and model of a vehicle.

In addition, as the cars age, at some point the cost of a new battery may exceed the vehicle’s value.

Third-party companies specializing in battery refurbishing are springing up, which may provide a cost-effective alternative to battery replacement. And Charette says carmakers are also working to improve the design of battery packs to avoid replacing them under warranty, “but it’s not something that’s going to happen tomorrow.”

The battery of an internal combustion engine, or ICE, provides initial energy to start the engine, and afterwards is recharged by the alternator. In contrast, EV batteries not only supply the energy to propel the vehicle but also power accessories such as heating, cooling and electronic systems

According to Kelley Blue Book, warranties between ICE vehicles and EVs are comparable. Powertrain warranties vary, but they typically cover at least five years or 60,000 miles, with some covering 10 years or 100,000 miles.

EV and Hybrid warranties cover batteries for eight years or 100,000 miles. Manufacturers will replace batteries that fall between around 70-75% of their capacity while under warranty.

Beginning with 2026 models, California will require EV batteries to retain at least 70% of their range for 10 years or 150,000 miles, and 2030 models at least 80% for the same timeframe.

Used EV buyers will need to verify the state of the battery, the time left on the warranty, and if it is transferable.

Recurrent is a company working to build buyer confidence in the used EV market by providing data on batteries much like CARFAX does on used ICE vehicle history.

While this has possibilities, Charette said, the statistical set is still very small.

“One really needs multiple thousands of historical battery usage data on each EV model sold for at least eight to ten years – the current warranty limits being offered – for any real confidence to be gained,” he said.

“More importantly, it is the out of warranty data that is most needed to demonstrate true battery longevity for a used EV buyer, which I doubt there is much, if any, available,” Charette added.

Most EVs use lithium-ion batteries. Like the battery in a cell phone, it degrades over time.

The U.S. Department of Energy cites predictive modeling by the National Renewable Energy Laboratory indicating today’s batteries may last 12 to 15 years in moderate climates and eight to 12 years in extreme climates.

The department says that other factors impacting battery life include driving and charging patterns, battery cell chemistry and design and the vehicle-battery-environment thermal system.

Fast charging technology may also shorten the life of an EV battery, which Charette says is disputed by some researchers. However, some manufacturers state that fast charging can rob approximately 10% of a battery’s life over eight years compared to slower alternatives.

He also notes carmakers suggest avoiding charging to 100% - keeping it above 20% and below 80% - to optimize battery longevity.

“So, if you’re following the recommended procedures, you basically have 60% of your estimated range,” Charette said.

Studies show EV batteries degrade at an average rate of about 1% to 2% per year – some faster when new and then slower as they age – and Charette says it remains to be seen what effect that will have on the vehicle’s range over time.

He said that absent of the federal government’s 2030 mandate, within 15 years the technology would be wrung out and an infrastructure would be ready to handle them. At that point, transitioning away from internal combustion engines completely would be feasible.

As it stands now, however, Charette said the unrealistic timeline forces shortcuts that add compounding risks.

“This is so interconnected … and policymakers have a cascade of policy patches on top of policy patches that weren’t thought through,” he said.