diff --git a/Core/Inc/soc_estimation.h b/Core/Inc/soc_estimation.h
index 237d92e..bf99cf1 100644
--- a/Core/Inc/soc_estimation.h
+++ b/Core/Inc/soc_estimation.h
@@ -8,7 +8,7 @@ extern uint8_t current_soc;
 
 #define N_MODELPARAMETERS 11
 #define BATTERYCAPACITYAs (20000.0*3600) //TODO Check if value is correct Cap in Ah * 3600 (Convert to As)
-
+#define SOAP_MINIMUM_VOLTAGE 2.5
 
 void soc_init();
 void soc_update(int32_t shunt_current);
diff --git a/Core/Src/soc_estimation.c b/Core/Src/soc_estimation.c
index cae26e1..ea07344 100644
--- a/Core/Src/soc_estimation.c
+++ b/Core/Src/soc_estimation.c
@@ -66,7 +66,15 @@ float soe_update()
 }
 void soap_update()
 {
-  //
+  float r0 = soc_approxparameterbysoc(current_floatsoc, R0, N_MODELPARAMETERS);
+  float r1 = soc_approxparameterbysoc(current_floatsoc, R1, N_MODELPARAMETERS);
+  float ocv = soc_approxparameterbysoc(current_floatsoc, OCV_Data, N_MODELPARAMETERS);
+
+  float allowedvoltagedrop = ocv - SOAP_MINIMUM_VOLTAGE;
+  float rin = r0+r1;
+  float maxcurrent = allowedvoltagedrop/rin;
+  //TODO think about how to pass parameters
+
 }
 
 float soc_approxparameterbysoc(float soc,float* lut, uint8_t lutlen)