As more battery-electric cars are sold and more drivers become aware of them, the question of battery life recurs among pretty much every potential buyer.
How long will the battery last? Will I have to replace it every 18 months as I do in my smartphone?
Data on the liquid-cooled battery packs of older Tesla Model S and Chevrolet Volt cars offers encouraging prospects—one 2012 Volt in particular.
DON'T MISS: Durable 2012 Chevrolet Volt: 300,000 miles, no battery loss (Mar 2016)
Nicknamed "Ol' Sparkie," that one specific Volt has now crossed a breathtaking 400,000 miles in the hands of long-distance commuter Erick Belmer.
More than a year ago, Sparkie logged 300,000 miles, and as the data on the car's VoltStats page clearly shows, Belmer has added another 100,000 miles in just 16 months, retaining his # 1 spot both for electric miles and total miles driven.
The 2012 Chevy Volt range-extended electric car has covered 141,800 of those miles, or about one-third (35.4 percent), on electric power alone from grid electricity.
2012 Chevrolet Volt
That's not surprising given its 35-mile EPA range rating.
Belmer drives roughly 6,500 miles each month on his commute from home in Bellville, Ohio, to his millwright job in a General Motors assembly plant in Lordstown, Ohio.
READ THIS: Tesla Model S battery life: what the data show so far
Determined to stay in his home with his family, Belmer calculated the effective cost per mile of the lengthy commute before he accepted that position.
With a 37-mpg combined fuel-economy rating when running in hybrid mode, plus the lower-cost electric miles, the Volt came out as the most economical GM car for the miles he knew he'd drive.
2012 Chevrolet Volt
Belmer's stats show he's achieved about 38.1 mpg once the battery is depleted, reflecting the efficiency of the Volt's small 1.4-liter inline-4, which both recharges the battery and powers the drive wheels directly at highway speeds.
Most impressively, the car's rated electric range has stayed constant even after those 400,000 miles.
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As Volt owners note, the car's battery capacity may actually be declining, but GM engineered the Volt pack conservatively, giving it a considerable buffer to ensure the car's performance wasn't compromised as the battery aged with use.
At his current rate of travel, Ol' Sparkie should cross the half-million mark somewhere early in 2019. Check back with us then ...