deltaSOC percentage calculation has incorrect scaling

[higherSentinel]

Hi foxBMS team. I was going through the soc counting algorithm under the soc_counting.c file. I spotted this code snippet under the SE_CalculateStateOfCharge function which i think has incorrect scaling.

float_t deltaSOC_perc = (((float_t)soc_tableCurrentSensor.current_mA[s] * timeStep_s) / SOC_STRING_CAPACITY_mAs) * 100.0f / 1000.0f; /* ((mA) * 1s) / 1As) * 100% */

Here the numerator is mA x S and the denominator is also in mA x s. This value is then multiplied by 100 to get the SoC percentage. However it can be seen that there is an additional scaling of 0.001. Why is this there?

The comments on that line suggest that the SOC_STRING_CAPACITY needs to be in As. If this is the case the scaling is correct. However SOC_STRING_CAPACITY in the above code is in mAs.

If the above snippet is incorrect in the source code this leads to a very critical bug.

[foxBMS]

Dear @higherSentinel,

thanks for raising this issue.

The fix will be released in the next version and looks like this:

diff --git a/src/app/application/algorithm/state_estimation/soc/counting/soc_counting.c b/src/app/application/algorithm/state_estimation/soc/counting/soc_counting.c
index bb796b4b..eeebf620 100644
--- a/src/app/application/algorithm/state_estimation/soc/counting/soc_counting.c
+++ b/src/app/application/algorithm/state_estimation/soc/counting/soc_counting.c
@@ -327,7 +327,7 @@ void SE_CalculateStateOfCharge(DATA_BLOCK_SOC_s *pSocValues) {

                             float_t deltaSOC_perc = (((float_t)soc_tableCurrentSensor.current_mA[s] * timeStep_s) /
                                                      SOC_STRING_CAPACITY_mAs) *
-                                                    100.0f / 1000.0f; /* ((mA) * 1s) / 1As) * 100% */
+                                                    100.0f; /* ((mA) * 1s) / 1As) * 100% */

                             float_t charge_As =
                                 fabs((float_t)soc_tableCurrentSensor.current_mA[s] * timeStep_s / 1000.0f);

Best regars,
The foxBMS Team