SOH

📖 YOUCANIC Automotive Glossary

SOH (State of Health) represents the overall condition of the vehicle’s battery compared to its original capacity when new, expressed as a percentage. A new battery starts at 100% SOH and gradually decreases as the battery ages through charge/discharge cycles, temperature exposure, and chemical degradation of the internal plates. The vehicle’s battery management system calculates SOH by tracking the battery’s ability to accept and deliver charge over time — a battery that can only hold 70% of its original capacity has 70% SOH.

SOH is critical for the intelligent charging system’s decisions about charging strategy and start-stop functionality. When SOH drops below a manufacturer-defined threshold (typically 50-70%), the system may disable start-stop, increase charging voltage, or display a battery replacement warning. The YOUCANIC UCAN-II can display battery SOH where supported, helping DIYers determine if a battery needs replacement before it fails. After installing a new battery, performing BRT resets the SOH counter to 100% so the system accurately tracks the new battery’s aging from its starting point.