# Error with pybamm base thermal model source code

**URL:** <https://pybamm.discourse.group/t/error-with-pybamm-base-thermal-model-source-code/419>\
**Category:** General\
**Created:** [27 November 2025 09:50 UTC](https://pybamm.discourse.group/t/error-with-pybamm-base-thermal-model-source-code/419 "2025-11-27T09:50:01Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![alex.0249](https://avatars.discourse-cdn.com/v4/letter/a/ec9cab/32.png) [@alex.0249](https://pybamm.discourse.group/u/alex.0249)\
**Post date:** [27 November 2025 09:50 UTC](https://pybamm.discourse.group/t/error-with-pybamm-base-thermal-model-source-code/419/1 "2025-11-27T09:50:01Z")

</div>

Hi,

Just thought I’d mention that changing the parameter:

Negative electrode OCP entropic change [V.K-1] to a non-zero value gives the error:

ShapeError: Cannot find shape (original error: operands could not be broadcast together with shapes (20,1) (11,1) )

when using the thermal lumped model. This stems from the reversible heat loss calculation: Q\_rev\_n += a\_j\_n \* T\_n \* dUdT\_n

Does anyone have any suggestions to why this occurs or some potential fixes to the source code ?

All the best,

Alex