EV Battery Health: What Every Buyer Needs to Know
Used EVs are showing up everywhere in Colorado right now. Lease returns, private sales, dealer lots. And the prices look good. But buying a used EV is not the same as buying a used gas car, and if you go in treating it like one, you might be walking into a very expensive situation.
The battery is why. A battery pack replacement on most EVs runs somewhere between $8,000 and $20,000 depending on the vehicle. That's not a repair. That's close to the value of the car.
State of Health isn't something you can eyeball
SOH (State of Health) is the metric that tells you how much of the original battery capacity is left. A new pack starts at 100%. Degrades maybe 2-3% a year under normal use.
78% SOH on a three year old Bolt? Probably fine for a 30 mile commute. 78% on a car you need to get to the mountains and back without charging? Different math.
You can't figure this out from a test drive. The range estimate on the dash is a guess based on recent driving. I use the Autel Ultra EV scanner to pull actual SOH readings and individual cell voltage balance. Cell balance is the one most people haven't heard of. A pack where one cell group is significantly weaker than the rest can do strange things: sudden range drops, charging that stops early at weird percentages, a car that shows 40% and then shuts down. None of that shows on a Carfax.
Living in Colorado doesn't help
I'm not going to give you a weather report. You already know the winters here. What you might not know is how those cold mornings hit an EV battery that sat outside overnight in Longmont without being plugged in. The thermal management system can't precondition a cold soaked pack if there's no power going to it. That accelerates cell stress over time.
Summer's the other side. I've scanned cars that spent their life charging in open lots in the heat, and the cell degradation pattern is different from one that was always in a garage. It shows up in the data.
Charging habits matter too, and you can't know them from a listing. Someone who ran to the Supercharger on I-70 every other day and topped off to 100% every night put more stress on that pack than someone who did slow Level 2 charging at home. I ask about it, and I cross reference what they tell me with what the scanner says.
What the inspection actually covers
The EV/Hybrid inspection isn't just a battery check with a vehicle inspection tacked on. I go through the thermal management system: cooling loops, coolant condition, pump function. High voltage safety, insulation resistance. Charging port and onboard charger.
Regenerative braking is one people don't think about. EVs barely use their friction brakes in normal driving, which sounds good until you realize the rotors can glaze over from sitting there doing nothing for 30,000 miles. Then you hit the brakes hard on a wet day and the pedal feel is wrong. I've seen it.
And the 12V auxiliary battery. Every EV has one. It's what actually boots up the car's systems before the main pack takes over. They die on used EVs more than you'd expect, and depending on the model the replacement can be weirdly expensive. Worth knowing before you own it.
The price question
If a used EV is priced well below comparable listings, I'd want to know why. Could be a motivated seller. Could be a lease return where the dealership wants it gone. Could also be that the range is noticeably worse than advertised and they figured that out.
$649 for the EV/Hybrid inspection. When you're buying something with an $8,000 to $20,000 component that you literally cannot evaluate without specialized equipment, the inspection isn't optional. It's the difference between knowing what you're buying and hoping for the best.