Preparing HPPC and OCV data for a battery cell model

Start with time, current, voltage and temperature

Keep the original time series and identify each signal's units. Include measured temperature where available, the chamber setpoint, cell identity and the test protocol. Document the current sign convention and any changes in sampling rate, timestamp resets or missing intervals.

Capacity measurements help connect accumulated charge to state of charge. Preserve the charge and discharge limits, rest periods and the way the initial state was established. These details matter when two files appear to describe the same test but begin from different conditions.

What OCV and low-rate tests contribute

Open-circuit voltage measurements and low-rate charge/discharge curves help describe how voltage changes with state of charge. They are not interchangeable without assumptions: a cell under current can include polarization, and an insufficient rest can leave relaxation in the apparent equilibrium voltage.

Provide the raw data and protocol so those assumptions can be assessed. Identify the temperature, current, rest duration and whether measurements came from a full cell or separate electrodes.

What HPPC pulses contribute

For a published testing reference, see the Idaho National Laboratory FreedomCAR Battery Test Manual. Your protocol should be chosen for the cell and the model you intend to fit.

Hybrid pulse power characterization applies current pulses and observes the voltage response. Pulse magnitude, duration, state of charge and the intervening rests affect which behavior the data can reveal. Keep the full trace around each pulse rather than exporting only an estimated resistance.

Multiple temperatures can help describe temperature dependence. Measurements outside a model's fitted range are especially useful for testing its limitations, but do not assume extrapolation will be accurate.

Keep independent validation data

Reserve at least one suitable current profile that is not used for fitting. Compare predicted and measured voltage over the full trace, report the test conditions, and inspect where errors grow. A small average error can hide a large local error near the end of discharge.

For AmpLabs beta onboarding, describe the cell chemistry, file formats, available tests and intended operating range. We will confirm which files are useful for your model and what additional measurements may be needed.