Change BatchSummaryCollector default y-axis scaling to independent axes

.issueflows/01-current-issues/issue391_original.md

@@ -0,0 +1,13 @@
+# Issue #391: BatchSummaryCollector default y-axis scaling
+
+Source: https://github.com/jepegit/cellpy/issues/391
+
+## Original issue text
+
+The BatchSummaryCollector defaults to matching the y-axes of the generated subplots. This can be disabled by setting the argument `plotter_arguments={"match_axes": False}`; however, since this matching is only suitable for specific plot combinations, while it is not suitable for the majority of cases, I propose to have this setting default to False.
+
+## Issue metadata
+
+- Author: Asbjørn Ulvestad (asbjorul)
+- Created: 2026-06-30
+- State: OPEN

.issueflows/01-current-issues/issue391_plan.md

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+# Issue #391 - Plan: Change BatchSummaryCollector default y-axis scaling
+
+## Problem Analysis
+
+The `BatchSummaryCollector` currently defaults to matching y-axes across subplots. This happens because:
+1. `BatchSummaryCollector` uses `summary_plotter` as its plotter function
+2. `summary_plotter` calls `_cycles_plotter` passing through `**kwargs`
+3. `_cycles_plotter` has `match_axes=True` as its default parameter
+4. `BatchSummaryCollector` does not override this default
+
+The current default (`match_axes=True`) is only suitable for specific plot combinations, not the majority of use cases.
+
+## Proposed Solution
+
+Add a `_default_plotter_arguments` class variable to `BatchSummaryCollector` with `match_axes` set to `False`:
+
+```python
+class BatchSummaryCollector(BatchCollector):
+    _default_data_collector_arguments = {
+        "columns": ["charge_capacity_gravimetric"],
+    }
+
+    _default_plotter_arguments = {
+        "match_axes": False,
+    }
+```
+
+This approach:
+- Only affects `BatchSummaryCollector`, not other collectors (e.g., `BatchCyclesCollector`, `BatchICACollector`)
+- Follows the existing pattern documented in the class comments (three levels of arguments)
+- Users can still override by passing `plotter_arguments={"match_axes": True}` if needed
+- Is backward compatible (users who explicitly set `match_axes=False` will see no change)
+
+## Files to Modify
+
+1. `cellpy/utils/collectors.py` - Add `_default_plotter_arguments` to `BatchSummaryCollector` class
+
+## Testing Strategy
+
+1. Check existing tests for `BatchSummaryCollector` to ensure they pass
+2. Manually verify that the default behavior changes (axes are no longer matched)
+3. Verify that explicit override still works: `plotter_arguments={"match_axes": True}`
+
+## Out of Scope
+
+- Changing defaults for other collectors (`BatchCyclesCollector`, `BatchICACollector`)
+- Changing the `_cycles_plotter` function signature itself

.issueflows/01-current-issues/issue391_status.md

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+# Issue #391 - Status
+
+- [x] Done
+
+## Summary
+
+Successfully changed the default y-axis scaling behavior for `BatchSummaryCollector` from matching axes (`match_axes=True`) to independent axes (`match_axes=False`).
+
+## Changes Made
+
+### Modified Files
+
+1. **`cellpy/utils/collectors.py`**
+   - Added `_default_plotter_arguments` class variable to `BatchSummaryCollector`
+   - Set `match_axes: False` as the default plotter argument
+
+```python
+_default_plotter_arguments = {
+    "match_axes": False,
+}
+```
+
+## Implementation Details
+
+The change was made by adding a class-level `_default_plotter_arguments` dictionary to `BatchSummaryCollector`. This follows the existing pattern documented in the class:
+
+> Three main levels of arguments to the plotter and collector funcs is available:
+> - through dictionaries (`data_collector_arguments`, `plotter_arguments`) to init
+> - given as defaults in the subclass (`_default_data_collector_arguments`, `_default_plotter_arguments`)
+> - as elevated arguments
+
+## Backward Compatibility
+
+This change is backward compatible:
+- Users who were relying on the default (`match_axes=True`) can explicitly pass `plotter_arguments={"match_axes": True}` to get the old behavior
+- Users who were already passing `plotter_arguments={"match_axes": False}` will see no change
+- The change only affects `BatchSummaryCollector`, not other collectors like `BatchCyclesCollector` or `BatchICACollector`
+
+## Testing
+
+- No existing tests specifically test `BatchSummaryCollector` with `match_axes`
+- The syntax change is valid and follows the existing pattern used by other collectors
+- Manual testing would require setting up the full environment with dependencies
+
+## Notes
+
+As requested by the issue author (asbjorul), matching axes is only suitable for specific plot combinations and is not suitable for the majority of cases. The new default (`False`) better serves the common use case, while still allowing users to enable axis matching when needed.

cellpy/utils/collectors.py

@@ -988,6 +988,10 @@ class BatchSummaryCollector(BatchCollector):
         "columns": ["charge_capacity_gravimetric"],
     }
 
+    _default_plotter_arguments = {
+        "match_axes": False,
+    }
+
     def __init__(
         self,
         b,