- Cell or block spread is condition-dependent.
- State of charge is not state of health.
- Capacity requires measured energy over a valid test window and a trustworthy reference.
- High-voltage systems require trained personnel and exact procedures.
What the battery controller may expose
Depending on the application and licensed access, a controller may report cell or block voltages, temperatures, current, contactor state, isolation information, cooling commands, state of charge, calculated power limits, imbalance flags, and internal resistance estimates. Generic OBD-II does not guarantee these signals.
Static spread versus dynamic response
A voltage spread at rest is one observation. A weak group may separate more clearly during repeatable charge or discharge load and recover differently afterward. Temperature gradients, state of charge, balancing activity, sensor accuracy, and current direction must be considered.
Capacity and state of health
A controller-reported health estimate is a model output, not a universal measurement. Defensible capacity needs energy or charge throughput across known state boundaries, stable conditions, and a rated or validated reference. A short scan cannot invent missing capacity evidence.
Safety boundary
Do not open, probe, bypass, energize, discharge, or service a high-voltage battery without the required training, personal protective equipment, insulated tools, service information, and facility controls. Collision damage, isolation faults, heat, odor, smoke, liquid intrusion, or damaged orange cabling require immediate professional handling.
Can OBD data tell me the exact remaining battery life?
No single reading can predict exact remaining life. Condition, history, measured capacity, imbalance, temperature, faults, and application-specific evidence all matter.
Is one low cell voltage enough to condemn a battery?
No. Confirm signal identity and repeatable behavior under comparable conditions, then follow the exact service procedure.
This is general educational material designed to improve questions and evidence capture. Definitions, thresholds, enabling conditions, wiring, service steps, and safety requirements can differ by vehicle application. Use current official manufacturer information and qualified judgment for the actual repair.