Fix determining required battery mode (#15255)

core/site_battery.go

@@ -41,8 +41,8 @@ func (site *Site) requiredBatteryMode(batteryGridChargeActive bool, rate api.Rat
 	batMode := site.GetBatteryMode()
 
 	switch {
-	case batteryGridChargeActive && batMode != api.BatteryCharge:
-		res = api.BatteryCharge
+	case batteryGridChargeActive:
+		res = map[bool]api.BatteryMode{false: api.BatteryCharge, true: api.BatteryUnknown}[batMode == api.BatteryCharge]
 	case !batteryGridChargeActive && site.dischargeControlActive(rate) && batMode != api.BatteryHold:
 		res = api.BatteryHold
 	case batteryModeModified(batMode):

core/site_test.go

@@ -3,7 +3,9 @@ package core
 import (
 	"testing"
 
+	"github.com/evcc-io/evcc/api"
 	"github.com/evcc-io/evcc/util"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestSitePower(t *testing.T) {
@@ -143,3 +145,31 @@ func TestGreenShare(t *testing.T) {
 		}
 	}
 }
+
+func TestRequiredBatteryMode(t *testing.T) {
+	tc := []struct {
+		gridChargeActive bool
+		mode, res        api.BatteryMode
+	}{
+		{false, api.BatteryUnknown, api.BatteryUnknown}, // ignore
+		{false, api.BatteryNormal, api.BatteryUnknown},  // ignore
+		{false, api.BatteryHold, api.BatteryNormal},
+		{false, api.BatteryCharge, api.BatteryNormal},
+
+		{true, api.BatteryUnknown, api.BatteryCharge},
+		{true, api.BatteryNormal, api.BatteryCharge},
+		{true, api.BatteryHold, api.BatteryCharge},
+		{true, api.BatteryCharge, api.BatteryUnknown}, // ignore
+	}
+
+	for _, tc := range tc {
+		t.Logf("%+vv", tc)
+
+		s := &Site{
+			batteryMode: tc.mode,
+		}
+
+		res := s.requiredBatteryMode(tc.gridChargeActive, api.Rate{})
+		assert.Equal(t, tc.res, res, "expected %s, got %s", tc.res, res)
+	}
+}