diff --git a/core/wrapper/chargerater.go b/core/wrapper/chargerater.go
index 8e27d62fb8..2d5932cbee 100644
--- a/core/wrapper/chargerater.go
+++ b/core/wrapper/chargerater.go
@@ -46,7 +46,7 @@ func (cr *ChargeRater) StartCharge(continued bool) {
 	if m, ok := cr.meter.(api.MeterEnergy); ok {
 		if f, err := m.TotalEnergy(); err == nil {
 			cr.startEnergy = f
-			cr.log.DEBUG.Printf("charge start energy: %.3gkWh", f)
+			cr.log.DEBUG.Printf("charge start energy: %.3fkWh", f)
 		} else {
 			cr.log.ERROR.Printf("charge total import: %v", err)
 		}
@@ -71,7 +71,7 @@ func (cr *ChargeRater) StopCharge() {
 	if m, ok := cr.meter.(api.MeterEnergy); ok {
 		if f, err := m.TotalEnergy(); err == nil {
 			cr.chargedEnergy += f - cr.startEnergy
-			cr.log.DEBUG.Printf("charge final energy: %.3gkWh", cr.chargedEnergy)
+			cr.log.DEBUG.Printf("charge final energy: %.3fkWh", cr.chargedEnergy)
 		} else {
 			cr.log.ERROR.Printf("charge total import: %v", err)
 		}