diff --git a/custom_components/senec/const.py b/custom_components/senec/const.py
index ecc6287..4c72ace 100644
--- a/custom_components/senec/const.py
+++ b/custom_components/senec/const.py
@@ -88,7 +88,7 @@ class ExtBinarySensorEntityDescription(BinarySensorEntityDescription):
         name="Spare Capacity",
         device_class = NumberDeviceClass.BATTERY,
         mode = NumberMode.SLIDER,
-        native_max_value = 100,
+        native_max_value = 50,
         native_min_value = 0,
         native_step = 1,
         native_unit_of_measurement = PERCENTAGE,