Battery health tells you how much usable capacity your EV’s pack has left compared to when it was new, usually shown as a state of health (SOH) percentage. It naturally drops a little each year, and most of that loss is normal, not a fault. This section covers how to read an SOH number correctly, when a reading is wrong rather than the battery, and what to do if a module has actually failed. Start with why an EV battery reading can be incorrect before assuming the worst, then use how to tell if your EV needs a battery module replacement if a real fault looks likely. For the full list of common problems across every EV, see our main battery guide.
How to check your EV battery health without going to a dealer — the best OBD2 apps and adapters for every major EV brand, how to interpret the readings, and what the numbers mean for your battery’s future.
Your EV battery health dropped overnight — but batteries can’t physically degrade that fast. Here’s what actually causes apparent overnight SOH drops and how to tell if it’s a real problem or a BMS measurement update.
A bad cell in your EV battery pack shows specific warning signs before it fails completely. Here’s how to identify a failing cell early, what the BMS tells you, and when to act.
What exactly happens inside an EV battery during a deep discharge, whether the damage can be fixed, and the recovery steps that give your battery the best chance after a deep discharge event.
EV battery swelling — what causes it, whether it’s visible in an EV, the warning signs an owner can detect, and exactly what to do if you suspect your battery pack is swelling.
Step-by-step guide to diagnosing EV battery cell imbalance at home — which OBD2 tools to use for each EV brand, how to read cell voltages, what the spread means, and when to act on what you find.
EV battery reconditioning is frequently recommended — but what does it actually do, when does it work, and when is it a waste of money? Here’s an honest breakdown of reconditioning for every major EV.
Your EV is showing an incorrect State of Health percentage — either too low or too high for how the battery actually performs. Here’s every reason SOH readings are inaccurate and how to get a reliable number.
How do you know if your EV genuinely needs a battery module replacement versus reconditioning or recalibration? Here are the specific signs that confirm module replacement is necessary and when other interventions are sufficient.