A cheap Kia reports 100% battery health after 265,000 miles — but that isn't the full story

A used electric Kia with more than 265,000 miles on the odometer surprised its new owner with a battery-health reading of 100%.

Here's what to know

In a YouTube video, Efficient Alex (@Efficient-Alex) revealed he purchased the car at auction. Alex paid £4,100 ($5,429), including fees, for the 2021 Niro without seeing it first.

After putting the car through its paces for months and saying it "still drives remarkably well," Alex wanted to see just how healthy the battery was. That's not to say everything was hunky-dory with the vehicle.

Noise from the motor and reduction-gear bearings remained an unresolved problem. The former taxi had accumulated its enormous mileage in about five years and had already undergone servicing, an inspection, and repairs that included replacing its reversing camera. Alex faced a potentially larger bill if the battery needed replacing. 

Using the free Car Scanner app and a Bluetooth diagnostic adapter, Alex retrieved a 100% state-of-health reading from the battery management system. A professional Vault Test assessment returned the same stored figure and found very well-balanced cell voltages.

More background

The battery could have experienced some degradation while still returning that reading.

According to EV Database, as cited in the video, the Kia's battery has 67.5 kilowatt-hours of gross capacity, with 64 kWh advertised as usable. Its battery management system protects the cells by keeping some capacity in reserve at the charging and discharging limits.

Vault Test's representatives explained that the stored health calculation uses a 64-kWh reference. Capacity above that threshold can still produce a 100% reading, allowing some degradation before the displayed percentage begins to fall.

The car's usage records in Car Scanner offered further insight into its years on the road. They showed 22,757 operating hours and 1,955 charging sessions, including 402 rapid-charging sessions. About 88% of its recorded charging energy came from lower-powered charging.

Alex reported driving 250 to 260 miles on a charge. He also noted that the Kia had active battery cooling to help manage temperatures during intensive use.

"My six-year-old Kona showed 100% battery health until I had a BMS update not long ago, then it dropped to 97.6% nearly straightaway," a user shared.

They added that efficiency had gone up since the update and range seemed unchanged or even up.

What can be done?

For drivers considering a used electric vehicle, Alex demonstrated a starting point for checking battery condition. He advised selecting the appropriate vehicle profile in Car Scanner, connecting a compatible diagnostic adapter, and reviewing the available data.

Compatibility varies by vehicle, but this Kia provided access to its charging history, operating hours, cell voltages, and stored health percentage.

For buyers who need help interpreting those figures, Vault Test serves dealerships, which can provide battery information to customers. Its representatives explained both the Kia's cell balance and the reference capacity behind its reported health score. Alex also had the Niro serviced and its underside inspected.

"That's the best battery health video I've seen," one commenter wrote. "It's a whole new world of learning from traditional ICE technology."

Where can I learn more?

Drivers find that EVs with a ton of mileage often do surprise when it comes to their battery health.

• A used Volkswagen ID.3 showed 100.3% battery health, but owners cautioned that the figure could be misleading.

• A dealer warned a 200,000-mile EV's 79 battery-health score could jeopardize its $8,000 trade-in value.

• A Tesla Model 3 owner detailed battery loss and repairs after driving 250,000 miles.

• A 471,000-mile Chevrolet Bolt kept going after 330,000 miles on a replacement battery.

• A $13,000 Tesla Model S with 140,000 miles still delivered 221 miles of range.

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