diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6f2e22249..ea13a5ae3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -54,6 +54,7 @@
 
 ## Bug fixes
 
+-   Fixed a bug where current loaded from data was incorrectly scaled with the cell capacity ([#852](https://github.com/pybamm-team/PyBaMM/pull/852))
 -   Moved evaluation of initial conditions to solver ([#839](https://github.com/pybamm-team/PyBaMM/pull/839))
 -   Fixed a bug where the first line of the data wasn't loaded when parameters are loaded from data ([#819](https://github.com/pybamm-team/PyBaMM/pull/819))
 -   Made `graphviz` an optional dependency ([#810](https://github.com/pybamm-team/PyBaMM/pull/810))
diff --git a/pybamm/parameters/parameter_values.py b/pybamm/parameters/parameter_values.py
index 784dc74db..c4cdc0b15 100644
--- a/pybamm/parameters/parameter_values.py
+++ b/pybamm/parameters/parameter_values.py
@@ -5,6 +5,7 @@ import pybamm
 import pandas as pd
 import os
 import numbers
+import numpy as np
 
 
 class ParameterValues:
@@ -276,8 +277,8 @@ class ParameterValues:
                     value = CrateToCurrent(values["C-rate"], capacity)
                 elif isinstance(values["C-rate"], tuple):
                     data = values["C-rate"][1]
-                    data[:, 1] = data[:, 1] * capacity
-                    value = (values["C-rate"][0] + "_to_Crate", data)
+                    current_data = np.stack([data[:, 0], data[:, 1] * capacity], axis=1)
+                    value = (values["C-rate"][0] + "_to_current", current_data)
                 elif values["C-rate"] == "[input]":
                     value = CrateToCurrent(values["C-rate"], capacity, typ="input")
                 else:
@@ -288,8 +289,11 @@ class ParameterValues:
                     value = CurrentToCrate(values["Current function [A]"], capacity)
                 elif isinstance(values["Current function [A]"], tuple):
                     data = values["Current function [A]"][1]
-                    data[:, 1] = data[:, 1] / capacity
-                    value = (values["Current function [A]"][0] + "_to_current", data)
+                    c_rate_data = np.stack([data[:, 0], data[:, 1] / capacity], axis=1)
+                    value = (
+                        values["Current function [A]"][0] + "_to_Crate",
+                        c_rate_data,
+                    )
                 elif values["Current function [A]"] == "[input]":
                     value = CurrentToCrate(
                         values["Current function [A]"], capacity, typ="input"

Current data gets scaled by I_typ
When loading in current data it gets scaled by I_typ. This is happening during `check_and_update_parameter_values` - when updating the C-rate to be the current data/capacity, the current data is also being altered
diff --git a/tests/unit/test_parameters/test_parameter_values.py b/tests/unit/test_parameters/test_parameter_values.py
index ca8485943..da3adfccf 100644
--- a/tests/unit/test_parameters/test_parameter_values.py
+++ b/tests/unit/test_parameters/test_parameter_values.py
@@ -101,7 +101,7 @@ class TestParameterValues(unittest.TestCase):
         linear = np.hstack([x, 2 * x])
         values = {"C-rate": ("linear", linear), "Cell capacity [A.h]": 10}
         param = pybamm.ParameterValues(values)
-        self.assertEqual(param["Current function [A]"][0], "linear_to_Crate")
+        self.assertEqual(param["Current function [A]"][0], "linear_to_current")
         np.testing.assert_array_equal(
             param["Current function [A]"][1], np.hstack([x, 20 * x])
         )
@@ -110,7 +110,7 @@ class TestParameterValues(unittest.TestCase):
         linear = np.hstack([x, 2 * x])
         values = {"Current function [A]": ("linear", linear), "Cell capacity [A.h]": 10}
         param = pybamm.ParameterValues(values)
-        self.assertEqual(param["C-rate"][0], "linear_to_current")
+        self.assertEqual(param["C-rate"][0], "linear_to_Crate")
         np.testing.assert_array_almost_equal(
             param["C-rate"][1], np.hstack([x, 0.2 * x])
         )

pip install -e .[dev,docs]
parse_log_pytest
pytest
flake8 pytest
apt-get update apt-get install -y gcc gfortran libopenblas-dev liblapack-dev graphviz
3.9
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
alabaster==0.7.16
anyio==4.9.0
anytree==2.12.1
argon2-cffi==23.1.0
argon2-cffi-bindings==21.2.0
arrow==1.3.0
asttokens==3.0.0
async-lru==2.0.5
attrs==25.3.0
autograd==1.7.0
babel==2.17.0
beautifulsoup4==4.13.3
black==25.1.0
bleach==6.2.0
casadi==3.7.0
certifi==2025.1.31
cffi==1.17.1
charset-normalizer==3.4.1
click==8.1.8
comm==0.2.2
contourpy==1.3.0
cycler==0.12.1
debugpy==1.8.13
decorator==5.2.1
defusedxml==0.7.1
docutils==0.21.2
exceptiongroup @ file:///croot/exceptiongroup_1706031385326/work
executing==2.2.0
fastjsonschema==2.21.1
flake8==7.2.0
fonttools==4.56.0
fqdn==1.5.1
guzzle_sphinx_theme==0.7.11
h11==0.14.0
httpcore==1.0.7
httpx==0.28.1
idna==3.10
imagesize==1.4.1
importlib_metadata==8.6.1
importlib_resources==6.5.2
iniconfig @ file:///home/linux1/recipes/ci/iniconfig_1610983019677/work
ipykernel==6.29.5
ipython==8.18.1
ipywidgets==8.1.5
isoduration==20.11.0
jedi==0.19.2
Jinja2==3.1.6
json5==0.10.0
jsonpointer==3.0.0
jsonschema==4.23.0
jsonschema-specifications==2024.10.1
jupyter==1.1.1
jupyter-console==6.6.3
jupyter-events==0.12.0
jupyter-lsp==2.2.5
jupyter_client==8.6.3
jupyter_core==5.7.2
jupyter_server==2.15.0
jupyter_server_terminals==0.5.3
jupyterlab==4.3.6
jupyterlab_pygments==0.3.0
jupyterlab_server==2.27.3
jupyterlab_widgets==3.0.13
kiwisolver==1.4.7
Levenshtein==0.27.1
MarkupSafe==3.0.2
matplotlib==3.9.4
matplotlib-inline==0.1.7
mccabe==0.7.0
mistune==3.1.3
mypy-extensions==1.0.0
nbclient==0.10.2
nbconvert==7.16.6
nbformat==5.10.4
nest-asyncio==1.6.0
notebook==7.3.3
notebook_shim==0.2.4
numpy==2.0.2
overrides==7.7.0
packaging @ file:///croot/packaging_1734472117206/work
pandas==2.2.3
pandocfilters==1.5.1
parso==0.8.4
pathspec==0.12.1
pexpect==4.9.0
pillow==11.1.0
platformdirs==4.3.7
pluggy @ file:///croot/pluggy_1733169602837/work
prometheus_client==0.21.1
prompt_toolkit==3.0.50
psutil==7.0.0
ptyprocess==0.7.0
pure_eval==0.2.3
-e git+https://github.com/pybamm-team/PyBaMM.git@c1101ba2c9b74e76ed8fdd6d121afe41ab696a10#egg=pybamm
pycodestyle==2.13.0
pycparser==2.22
pyflakes==3.3.1
Pygments==2.19.1
pyparsing==3.2.3
pytest @ file:///croot/pytest_1738938843180/work
python-dateutil==2.9.0.post0
python-json-logger==3.3.0
python-Levenshtein==0.27.1
pytz==2025.2
PyYAML==6.0.2
pyzmq==26.3.0
RapidFuzz==3.12.2
referencing==0.36.2
requests==2.32.3
rfc3339-validator==0.1.4
rfc3986-validator==0.1.1
rpds-py==0.24.0
scikit-fem==10.0.2
scipy==1.13.1
Send2Trash==1.8.3
six==1.17.0
sniffio==1.3.1
snowballstemmer==2.2.0
soupsieve==2.6
Sphinx==7.4.7
sphinxcontrib-applehelp==2.0.0
sphinxcontrib-devhelp==2.0.0
sphinxcontrib-htmlhelp==2.1.0
sphinxcontrib-jsmath==1.0.1
sphinxcontrib-qthelp==2.0.0
sphinxcontrib-serializinghtml==2.0.0
stack-data==0.6.3
terminado==0.18.1
tinycss2==1.4.0
tomli @ file:///opt/conda/conda-bld/tomli_1657175507142/work
tornado==6.4.2
traitlets==5.14.3
types-python-dateutil==2.9.0.20241206
typing_extensions==4.13.0
tzdata==2025.2
uri-template==1.3.0
urllib3==2.3.0
wcwidth==0.2.13
webcolors==24.11.1
webencodings==0.5.1
websocket-client==1.8.0
widgetsnbextension==4.0.13
zipp==3.21.0

name: PyBaMM
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - exceptiongroup=1.2.0=py39h06a4308_0
  - iniconfig=1.1.1=pyhd3eb1b0_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=3.0.16=h5eee18b_0
  - packaging=24.2=py39h06a4308_0
  - pip=25.0=py39h06a4308_0
  - pluggy=1.5.0=py39h06a4308_0
  - pytest=8.3.4=py39h06a4308_0
  - python=3.9.21=he870216_1
  - readline=8.2=h5eee18b_0
  - setuptools=75.8.0=py39h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - tomli=2.0.1=py39h06a4308_0
  - wheel=0.45.1=py39h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - alabaster==0.7.16
      - anyio==4.9.0
      - anytree==2.12.1
      - argon2-cffi==23.1.0
      - argon2-cffi-bindings==21.2.0
      - arrow==1.3.0
      - asttokens==3.0.0
      - async-lru==2.0.5
      - attrs==25.3.0
      - autograd==1.7.0
      - babel==2.17.0
      - beautifulsoup4==4.13.3
      - black==25.1.0
      - bleach==6.2.0
      - casadi==3.7.0
      - certifi==2025.1.31
      - cffi==1.17.1
      - charset-normalizer==3.4.1
      - click==8.1.8
      - comm==0.2.2
      - contourpy==1.3.0
      - cycler==0.12.1
      - debugpy==1.8.13
      - decorator==5.2.1
      - defusedxml==0.7.1
      - docutils==0.21.2
      - executing==2.2.0
      - fastjsonschema==2.21.1
      - flake8==7.2.0
      - fonttools==4.56.0
      - fqdn==1.5.1
      - guzzle-sphinx-theme==0.7.11
      - h11==0.14.0
      - httpcore==1.0.7
      - httpx==0.28.1
      - idna==3.10
      - imagesize==1.4.1
      - importlib-metadata==8.6.1
      - importlib-resources==6.5.2
      - ipykernel==6.29.5
      - ipython==8.18.1
      - ipywidgets==8.1.5
      - isoduration==20.11.0
      - jedi==0.19.2
      - jinja2==3.1.6
      - json5==0.10.0
      - jsonpointer==3.0.0
      - jsonschema==4.23.0
      - jsonschema-specifications==2024.10.1
      - jupyter==1.1.1
      - jupyter-client==8.6.3
      - jupyter-console==6.6.3
      - jupyter-core==5.7.2
      - jupyter-events==0.12.0
      - jupyter-lsp==2.2.5
      - jupyter-server==2.15.0
      - jupyter-server-terminals==0.5.3
      - jupyterlab==4.3.6
      - jupyterlab-pygments==0.3.0
      - jupyterlab-server==2.27.3
      - jupyterlab-widgets==3.0.13
      - kiwisolver==1.4.7
      - levenshtein==0.27.1
      - markupsafe==3.0.2
      - matplotlib==3.9.4
      - matplotlib-inline==0.1.7
      - mccabe==0.7.0
      - mistune==3.1.3
      - mypy-extensions==1.0.0
      - nbclient==0.10.2
      - nbconvert==7.16.6
      - nbformat==5.10.4
      - nest-asyncio==1.6.0
      - notebook==7.3.3
      - notebook-shim==0.2.4
      - numpy==2.0.2
      - overrides==7.7.0
      - pandas==2.2.3
      - pandocfilters==1.5.1
      - parso==0.8.4
      - pathspec==0.12.1
      - pexpect==4.9.0
      - pillow==11.1.0
      - platformdirs==4.3.7
      - prometheus-client==0.21.1
      - prompt-toolkit==3.0.50
      - psutil==7.0.0
      - ptyprocess==0.7.0
      - pure-eval==0.2.3
      - pycodestyle==2.13.0
      - pycparser==2.22
      - pyflakes==3.3.1
      - pygments==2.19.1
      - pyparsing==3.2.3
      - python-dateutil==2.9.0.post0
      - python-json-logger==3.3.0
      - python-levenshtein==0.27.1
      - pytz==2025.2
      - pyyaml==6.0.2
      - pyzmq==26.3.0
      - rapidfuzz==3.12.2
      - referencing==0.36.2
      - requests==2.32.3
      - rfc3339-validator==0.1.4
      - rfc3986-validator==0.1.1
      - rpds-py==0.24.0
      - scikit-fem==10.0.2
      - scipy==1.13.1
      - send2trash==1.8.3
      - six==1.17.0
      - sniffio==1.3.1
      - snowballstemmer==2.2.0
      - soupsieve==2.6
      - sphinx==7.4.7
      - sphinxcontrib-applehelp==2.0.0
      - sphinxcontrib-devhelp==2.0.0
      - sphinxcontrib-htmlhelp==2.1.0
      - sphinxcontrib-jsmath==1.0.1
      - sphinxcontrib-qthelp==2.0.0
      - sphinxcontrib-serializinghtml==2.0.0
      - stack-data==0.6.3
      - terminado==0.18.1
      - tinycss2==1.4.0
      - tornado==6.4.2
      - traitlets==5.14.3
      - types-python-dateutil==2.9.0.20241206
      - typing-extensions==4.13.0
      - tzdata==2025.2
      - uri-template==1.3.0
      - urllib3==2.3.0
      - wcwidth==0.2.13
      - webcolors==24.11.1
      - webencodings==0.5.1
      - websocket-client==1.8.0
      - widgetsnbextension==4.0.13
      - zipp==3.21.0
prefix: /opt/conda/envs/PyBaMM

tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_check_and_update_parameter_values
tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_evaluate tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_init tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_inplace tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_interpolant_against_function tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_multi_var_function_parameter tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_multi_var_function_with_parameters tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_process_complex_expression tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_process_empty_model tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_process_function_parameter tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_process_inline_function_parameters tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_process_input_parameter tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_process_interpolant tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_process_model tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_process_symbol tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_read_parameters_csv tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_update tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_update_from_chemistry tests/unit/test_parameters/test_parameter_values.py::TestParameterValues::test_update_model
pybamm/parameters/parameter_values.py CHANGELOG.md
pybamm/parameters/parameter_values.py CHANGELOG.md