> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ionworks.com/llms.txt
> Use this file to discover all available pages before exploring further.

# 2026 03 30

<Update label="March 30, 2026" description="ECM parameterization, resistance scaling, custom variables, and BaSyTec reader">
  ## ECM parameterization

  A new ECM parameterization page lets you upload cycling data, select 0–5 RC pairs with a live circuit
  diagram, and view fitted parameters including OCV and R0. Results can be downloaded as CSV.

  [Find out more →](/build/ecm-parameterization)

  ## Adjust resistance in protocol simulations

  The protocol simulator now uses Equivalent Circuit Models (ECM) instead of SPM for faster, more robust
  cycler protocol simulations. ECM parameter sets are available for all six supported chemistries, and a
  new resistance scaling parameter in the UI lets you adjust the overall cell resistance before running a
  simulation.

  [Find out more →](/simulate/simulating-commercial-protocols)

  ## Custom variables on models

  You can now define custom derived quantities on models — such as electrode potentials or temperature in
  different units — as PyBaMM expressions stored in the model configuration. These custom variables are
  evaluated at simulation time and included in result data, making it easy to track application-specific
  metrics across design sweeps.

  [Find out more →](/build/custom-variables)

  ## BaSyTec battery cycler reader

  Data processing now supports BaSyTec CSV exports (CTS, X50 series). The reader
  auto-detects BaSyTec files by header signature, parses `HH:MM:SS.sss` timestamps (including values
  above 24 hours), applies the correct current sign convention, and extracts start times from companion
  `_meta.txt` files.

  [Find out more →](/data/format#supported-cycler-formats)

  <AccordionGroup>
    <Accordion title="Studio">
      **Improvements**

      * Added dark mode with a theme toggle in the dashboard header.
      * Moved optimization templates from organization scope to project scope with project-level management
        pages.
      * Made optimization name optional when creating optimizations.
      * Added pagination to cell specification, instance, and measurement list endpoints.
      * Added OCV traces to drive cycle simulation result plots.
      * Unified EIS column naming to `Z_Re [Ohm]` / `Z_Im [Ohm]` across simulation, measurement ingestion,
        and frontend rendering.

      **Fixes**

      * Fixed `LumpedSPMR` model crash due to a missing internal reference.
      * Fixed an issue where datafit setup configuration could be mutated between runs.
    </Accordion>

    <Accordion title="Pipeline">
      **Improvements**

      * Added support for computing lithium inventory from maximum stoichiometries without requiring maximum
        concentration values.
      * Adopted PyBaMM's native model and experiment serialization.
      * Added `abs` as a unary operation for composed metrics.

      **Fixes**

      * Fixed thermal model using incorrect heat generation variable in ECM.
      * Fixed trailing space in electrode balancing direction parameter names.
      * Fixed validation to discover sub-parameters inside function-based parameters.
    </Accordion>

    <Accordion title="Protocol Simulator">
      **Improvements**

      * Unified EIS impedance columns to `Z_Re [Ohm]` / `Z_Im [Ohm]` with SI units and standard sign
        convention.

      **Fixes**

      * Fixed CCCV resolution to apply consistently to all sub-steps within a protocol.
    </Accordion>

    <Accordion title="Python API">
      **Improvements**

      * Added local data caching for cell measurements, reducing repeated downloads.
      * Added pagination support (`limit`/`offset`) to cell list methods, returning a `PaginatedList` with a
        `.total` attribute.
      * Improved sign detection algorithm for measurement current data.
    </Accordion>

    <Accordion title="Data Processing">
      **Improvements**

      * Added BioLogic plain CSV reader for non-MPR exports.
      * Added automatic derivation of `Z_Re` and `Z_Im` from `Z_Mod` and `Z_Phase` when impedance
        components are missing.

      **Fixes**

      * Fixed CSV reader to skip auto-detection for explicitly mapped columns.
      * Fixed plotting bugs in data visualization utilities.
    </Accordion>
  </AccordionGroup>
</Update>