How to Extend EV Battery Life

When Tesla owner Thomas Katainen of Finland learned last year that his 2013 Model S needed a new battery pack that cost $22,000, he didn’t blow his top—he blew up his Tesla, along with an Elon Musk effigy. (Search for “Tesla Explosion Finland” on YouTube for a video of the spectacle.)

Indeed, battery packs can be expensive. Like the engine of a conventional gasoline vehicle, the battery pack is the heart of an electric vehicle (EV). Though the packs are generally long-lasting, and automakers typically warrant them for 8 to 10 years or 100,000 miles, over time they provide fewer miles between charges.

It may be possible to save money by replacing individual modules within a battery pack or by buying a refurbished battery pack. Otherwise, pack replacement can start at around $5,000 for a Nissan Leaf battery, rising to perhaps more than $20,000 for a Tesla.

Fortunately, EV owners have some control over their battery pack’s health. EV lithium-ion batteries produce energy when the ions inside move from a negative electrode to a positive electrode. If the tiny devils move too forcefully between states of charge and discharge, the battery may degrade more quickly.

How batteries are used, charged, and stored affects the amount of degradation. Recurrent, a Seattle-based company, produces monthly battery-pack health reports for EV owners and onetime reports for sellers and prospective buyers of used EVs. How many miles an EV can travel on a single charge—its range—is a good indication of a battery’s health, says company spokesperson Liz Najman.

Tips to maximize your EV battery’s life

Recurrent provides tips for maximizing an EV pack’s range and its long-term health. Most of these tips also apply to battery packs for plug-in hybrids.

Keep the battery cool

Heat, internal and external, is a battery killer. Charging a battery pack in hot weather can accelerate unwanted chemical reactions that permanently degrade battery materials and lead to lithium loss; 60 to 70 degrees is ideal for charging.

EVs have battery-management systems that automatically reduce the charging rate if there’s excessive heat. Still, it’s a good idea to park an EV in the shade and store it in a cool garage during the summer.

Keep your battery charge centered

A lithium-ion battery is most stable when about half the ions are on one side and half are on the other—a 50% state of charge. Avoid completely draining the battery pack or charging it to very high levels. A 100% charge is okay if you drive the car immediately, but not if it’s left to sit, especially in hot weather. A state of charge between 30% and 80% is best.

Be moderate with EV charging

Level 3 DC fast chargers generate more heat inside batteries than typical Level 1 or 2 home chargers. Fast charges are like bacon cheeseburgers, Najman says. It’s fine to eat them on occasion, but don’t make a steady diet of them. Small, frequent charges are healthier for batteries than large, infrequent ones.

Go easy on your EV

Using an EV’s air conditioner and heater won’t damage the battery pack, but they do reduce range between charges. Heaters especially use up a lot of the battery pack’s energy, which is why EVs lose range in very cold weather. Likewise, high-speed driving and jackrabbit starts—tempting because brisk acceleration is an EV hallmark—won’t damage the pack but will diminish driving range.

The takeaway: Give your EV’s battery pack some TLC and you might be less likely to blow your top—or want to blow up your EV.

AAA Automotive Correspondent Peter Bohr has been writing about cars for more than 4 decades.