diff --git a/charger/helper.go b/charger/helper.go
index 69a7cfad0..a1368276d 100644
--- a/charger/helper.go
+++ b/charger/helper.go
@@ -8,46 +8,48 @@ import (
 	"github.com/evcc-io/evcc/api"
 )
 
-// ensureCharger extracts VIN from list of VINs returned from `list` function
-func ensureCharger(vin string, list func() ([]string, error)) (string, error) {
-	vin, _, err := ensureChargerWithFeature(vin, list, func(v string) (string, string) {
+// ensureCharger extracts ID from list of IDs returned from `list` function
+func ensureCharger(id string, list func() ([]string, error)) (string, error) {
+	id, _, err := ensureChargerWithFeature(id, list, func(v string) (string, string) {
 		return v, ""
 	})
 
-	return vin, err
+	return id, err
 }
 
-// ensureChargerWithFeature extracts VIN and feature from list of chargers of type V returned from `list` function
+// ensureChargerWithFeature extracts ID and feature from list of chargers of type V returned from `list` function
 func ensureChargerWithFeature[Charger, Feature any](
-	vin string,
+	id string,
 	list func() ([]Charger, error),
 	extract func(Charger) (string, Feature),
 ) (string, Feature, error) {
+	var zero Feature
+
 	chargers, err := list()
 	if err != nil {
-		return "", *new(Feature), fmt.Errorf("cannot get chargers: %w", err)
+		return "", zero, fmt.Errorf("cannot get chargers: %w", err)
 	}
 
-	if vin = strings.ToUpper(vin); vin != "" {
+	if id = strings.ToUpper(id); id != "" {
 		for _, charger := range chargers {
-			if v, res := extract(charger); strings.ToUpper(v) == vin {
+			if v, res := extract(charger); strings.ToUpper(v) == id {
 				return v, res, nil
 			}
 		}
 
-		// vin defined but doesn't exist
-		err = fmt.Errorf("cannot find charger %s", vin)
+		// id defined but doesn't exist
+		err = fmt.Errorf("cannot find charger %s", id)
 	} else {
-		// vin empty
+		// id empty
 		if len(chargers) == 1 {
-			vin, res := extract(chargers[0])
-			return vin, res, nil
+			id, res := extract(chargers[0])
+			return id, res, nil
 		}
 
 		err = fmt.Errorf("cannot find charger, got: %v", chargers)
 	}
 
-	return "", *new(Feature), err
+	return "", zero, err
 }
 
 // bytesAsString normalises a string by stripping leading 0x00 and trimming white space
diff --git a/core/site_api.go b/core/site_api.go
index 4832e3941..014d8b228 100644
--- a/core/site_api.go
+++ b/core/site_api.go
@@ -214,8 +214,8 @@ func (site *Site) GetTariff(tariff string) api.Tariff {
 
 // GetBatteryControl returns the battery control mode
 func (site *Site) GetBatteryDischargeControl() bool {
-	site.Lock()
-	defer site.Unlock()
+	site.RLock()
+	defer site.RUnlock()
 	return site.batteryDischargeControl
 }
 
diff --git a/server/http_site_handler.go b/server/http_site_handler.go
index 651ed7152..39ffb4bd7 100644
--- a/server/http_site_handler.go
+++ b/server/http_site_handler.go
@@ -136,7 +136,7 @@ func boolHandler(set func(bool) error, get func() bool) http.HandlerFunc {
 	}
 }
 
-// boolGetHandler retrievs bool api values
+// boolGetHandler retrieves bool api values
 func boolGetHandler(get func() bool) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		jsonResult(w, get())
diff --git a/tariff/edf-tempo.go b/tariff/edf-tempo.go
index abe6fc9c8..48d45acf3 100644
--- a/tariff/edf-tempo.go
+++ b/tariff/edf-tempo.go
@@ -49,7 +49,7 @@ func NewEdfTempoFromConfig(other map[string]interface{}) (api.Tariff, error) {
 		return nil, err
 	}
 
-	if cc.ClientID == "" && cc.ClientSecret == "" {
+	if cc.ClientID == "" || cc.ClientSecret == "" {
 		return nil, errors.New("missing credentials")
 	}