diff --git a/mission/controller/PowerController.cpp b/mission/controller/PowerController.cpp
index 7b7db9e8..202e9906 100644
--- a/mission/controller/PowerController.cpp
+++ b/mission/controller/PowerController.cpp
@@ -156,7 +156,7 @@ ReturnValue_t PowerController::checkModeCommand(Mode_t mode, Submode_t submode,
 
 void PowerController::calculateStateOfCharge() {
   // get time
-  Clock::getClock_timeval(&now);
+  Clock::getClockMonotonic(&now);
 
   // update EPS HK values
   ReturnValue_t result = updateEpsData();
@@ -285,7 +285,12 @@ ReturnValue_t PowerController::calculateOpenCircuitVoltageCharge() {
 }
 
 ReturnValue_t PowerController::calculateCoulombCounterCharge() {
-  double timeDiff = timevalOperations::toDouble(now - oldTime);
+  double timeDiff = 0.0;
+  if (timevalOperations::toDouble(oldTime) != 0) {
+    timeDiff = timevalOperations::toDouble(now - oldTime);
+  } else {
+    return returnvalue::FAILED;
+  }
   if (timeDiff > maxAllowedTimeDiff) {
     // should not be a permanent state so no spam protection required
     triggerEvent(power::TIMEDELTA_OUT_OF_BOUNDS, static_cast<uint32_t>(timeDiff * 10));