SOH is the number that tells you the real story of an EV battery. Whether you are buying, selling, or worried about range — here is what it means and what to do about it.
State of Health (SOH) is a percentage comparing your battery current capacity against its original factory capacity. A new battery starts close to 100% SOH. As the vehicle ages and accumulates charge cycles, that percentage gradually falls — this is degradation.
85% or above is generally healthy. Below 80% you will notice real range impact daily and resale value drops significantly. Aviloo flags anything below 80% as a Red Flag.
Most EVs lose 2-3% SOH per year under normal use. A well-maintained 4-year-old EV should typically sit between 85-93% SOH. Faster degradation suggests charging habit issues or underlying cell faults worth investigating.
Occasional rapid DC charging causes minimal harm. Frequent rapid charging — especially above 80% state of charge or in high temperatures — accelerates cell stress over time. Impact varies by model: Nissan Leaf (no thermal management) is more vulnerable than Tesla or Hyundai.
OBD tools read data the Battery Management System reports about itself — not independent. Aviloo performs a cell-level test that does not rely on the BMS, producing a third-party certified result. Read the full comparison.
PAD is South Wales only Aviloo-certified mobile EV battery testing service. We travel to your address, test in 20 minutes, and email your official certificate the same day.
