diff --git a/core/keys/site.go b/core/keys/site.go
index a6ec22e9c..de780b2a6 100644
--- a/core/keys/site.go
+++ b/core/keys/site.go
@@ -53,4 +53,7 @@ const (
 	BatteryMode   = "batteryMode"
 	BatteryPower  = "batteryPower"
 	BatterySoc    = "batterySoc"
+
+	// external battery control
+	BatteryModeExternal = "batteryModeExternal"
 )
diff --git a/core/site.go b/core/site.go
index 4948766b6..37290e567 100644
--- a/core/site.go
+++ b/core/site.go
@@ -103,14 +103,16 @@ type Site struct {
 	pvEnergy    map[string]*meterEnergy
 
 	// cached state
-	gridPower       float64         // Grid power
-	pvPower         float64         // PV power
-	excessDCPower   float64         // PV excess DC charge power (hybrid only)
-	auxPower        float64         // Aux power
-	batteryPower    float64         // Battery power (charge negative, discharge positive)
-	batterySoc      float64         // Battery soc
-	batteryCapacity float64         // Battery capacity
-	batteryMode     api.BatteryMode // Battery mode (runtime only, not persisted)
+	gridPower                float64         // Grid power
+	pvPower                  float64         // PV power
+	excessDCPower            float64         // PV excess DC charge power (hybrid only)
+	auxPower                 float64         // Aux power
+	batteryPower             float64         // Battery power (charge negative, discharge positive)
+	batterySoc               float64         // Battery soc
+	batteryCapacity          float64         // Battery capacity
+	batteryMode              api.BatteryMode // Battery mode (runtime only, not persisted)
+	batteryModeExternal      api.BatteryMode // Battery mode (external, runtime only, not persisted)
+	batteryModeExternalTimer time.Time       // Battery mode timer for external control
 }
 
 // MetersConfig contains the site's meter configuration
diff --git a/core/site/api.go b/core/site/api.go
index 10c52ac61..a514a092d 100644
--- a/core/site/api.go
+++ b/core/site/api.go
@@ -67,4 +67,13 @@ type API interface {
 
 	GetBatteryDischargeControl() bool
 	SetBatteryDischargeControl(bool) error
+
+	//
+	// battery control external
+	//
+
+	// GetBatteryModeExternal returns the external battery mode
+	GetBatteryModeExternal() api.BatteryMode
+	// SetBatteryModeExternal sets the external battery mode
+	SetBatteryModeExternal(api.BatteryMode)
 }
diff --git a/core/site_api.go b/core/site_api.go
index da033413f..d10cd92cb 100644
--- a/core/site_api.go
+++ b/core/site_api.go
@@ -3,6 +3,7 @@ package core
 import (
 	"errors"
 	"strings"
+	"time"
 
 	"github.com/evcc-io/evcc/api"
 	"github.com/evcc-io/evcc/core/keys"
@@ -335,3 +336,65 @@ func (site *Site) SetBatteryGridChargeLimit(val *float64) {
 		}
 	}
 }
+
+// GetBatteryMode returns the battery mode
+func (site *Site) GetBatteryMode() api.BatteryMode {
+	site.RLock()
+	defer site.RUnlock()
+	return site.batteryMode
+}
+
+// GetBatteryModeExternal returns the external battery mode
+func (site *Site) GetBatteryModeExternal() api.BatteryMode {
+	site.RLock()
+	defer site.RUnlock()
+	return site.batteryModeExternal
+}
+
+// SetBatteryModeExternal sets the external battery mode
+func (site *Site) SetBatteryModeExternal(mode api.BatteryMode) {
+	site.Lock()
+	defer site.Unlock()
+
+	site.log.DEBUG.Printf("set external battery mode: %s", mode.String())
+
+	disable := mode == api.BatteryUnknown
+
+	if mode != site.batteryModeExternal {
+		site.batteryModeExternal = mode
+		site.publish(keys.BatteryModeExternal, mode)
+
+		if !disable {
+			site.setBatteryMode(mode)
+
+			// start watchdog if not running
+			if site.batteryModeExternalTimer.IsZero() {
+				go func() {
+					for range time.Tick(time.Second) {
+						if site.batteryModeWatchdogExpired() {
+							return
+						}
+					}
+				}()
+			}
+		}
+	}
+
+	// reset timer
+	if !disable {
+		site.batteryModeExternalTimer = time.Now()
+	}
+}
+
+func (site *Site) batteryModeWatchdogExpired() bool {
+	site.RLock()
+	elapsed := time.Since(site.batteryModeExternalTimer)
+	site.RUnlock()
+
+	if elapsed > time.Minute && !site.batteryModeExternalTimer.IsZero() {
+		site.SetBatteryModeExternal(api.BatteryUnknown)
+		return true
+	}
+
+	return false
+}
diff --git a/core/site_battery.go b/core/site_battery.go
index 7e67cb55d..f9d09eb7b 100644
--- a/core/site_battery.go
+++ b/core/site_battery.go
@@ -2,6 +2,7 @@ package core
 
 import (
 	"errors"
+	"time"
 
 	"github.com/evcc-io/evcc/api"
 	"github.com/evcc-io/evcc/core/keys"
@@ -16,13 +17,6 @@ func (site *Site) batteryConfigured() bool {
 	return len(site.batteryMeters) > 0
 }
 
-// GetBatteryMode returns the battery mode
-func (site *Site) GetBatteryMode() api.BatteryMode {
-	site.RLock()
-	defer site.RUnlock()
-	return site.batteryMode
-}
-
 // setBatteryMode sets the battery mode
 func (site *Site) setBatteryMode(batMode api.BatteryMode) {
 	site.batteryMode = batMode
@@ -39,12 +33,24 @@ func (site *Site) SetBatteryMode(batMode api.BatteryMode) {
 	if site.batteryMode != batMode {
 		site.setBatteryMode(batMode)
 	}
+
+	if site.batteryModeExternal == api.BatteryUnknown {
+		site.batteryModeExternalTimer = time.Time{}
+	}
 }
 
 // requiredBatteryMode determines required battery mode based on grid charge and rate
 func (site *Site) requiredBatteryMode(batteryGridChargeActive bool, rate api.Rate) api.BatteryMode {
 	var res api.BatteryMode
 	batMode := site.GetBatteryMode()
+	extMode := site.GetBatteryModeExternal()
+
+	var extModeReset bool
+	if extMode == api.BatteryUnknown {
+		site.Lock()
+		extModeReset = !site.batteryModeExternalTimer.IsZero()
+		site.Unlock()
+	}
 
 	mapper := func(s api.BatteryMode) api.BatteryMode {
 		return map[bool]api.BatteryMode{false: s, true: api.BatteryUnknown}[batMode == s]
@@ -53,6 +59,11 @@ func (site *Site) requiredBatteryMode(batteryGridChargeActive bool, rate api.Rat
 	switch {
 	case !site.batteryConfigured():
 		res = api.BatteryUnknown
+	case extModeReset:
+		// require normal mode to leave external control
+		res = api.BatteryNormal
+	case extMode != api.BatteryUnknown:
+		res = extMode
 	case batteryGridChargeActive:
 		res = mapper(api.BatteryCharge)
 	case site.dischargeControlActive(rate):
diff --git a/core/site_battery_test.go b/core/site_battery_test.go
new file mode 100644
index 000000000..16a1528a7
--- /dev/null
+++ b/core/site_battery_test.go
@@ -0,0 +1,92 @@
+package core
+
+import (
+	"testing"
+	"time"
+
+	"github.com/evcc-io/evcc/api"
+	"github.com/evcc-io/evcc/util"
+	"github.com/evcc-io/evcc/util/config"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestExternalBatteryMode(t *testing.T) {
+	for _, tc := range []struct {
+		internal, ext, new api.BatteryMode
+	}{
+		{api.BatteryUnknown, api.BatteryUnknown, api.BatteryUnknown},
+		{api.BatteryUnknown, api.BatteryNormal, api.BatteryNormal},
+		{api.BatteryUnknown, api.BatteryCharge, api.BatteryCharge},
+
+		{api.BatteryNormal, api.BatteryUnknown, api.BatteryUnknown},
+		{api.BatteryNormal, api.BatteryNormal, api.BatteryNormal},
+		{api.BatteryNormal, api.BatteryCharge, api.BatteryCharge},
+
+		{api.BatteryCharge, api.BatteryUnknown, api.BatteryNormal},
+		{api.BatteryCharge, api.BatteryNormal, api.BatteryNormal},
+		{api.BatteryCharge, api.BatteryCharge, api.BatteryCharge},
+	} {
+		t.Logf("%+v", tc)
+
+		site := &Site{
+			log:           util.NewLogger("foo"),
+			batteryMeters: []config.Device[api.Meter]{nil},
+		}
+
+		site.batteryMode = tc.internal
+		site.batteryModeExternal = tc.ext
+
+		mode := site.requiredBatteryMode(false, api.Rate{})
+		assert.Equal(t, tc.new.String(), mode.String(), "internal mode expected %s got %s", tc.new, mode)
+	}
+}
+
+func TestExternalBatteryModeChange(t *testing.T) {
+	for _, tc := range []struct {
+		internal, ext, expired api.BatteryMode
+	}{
+		{api.BatteryUnknown, api.BatteryUnknown, api.BatteryNormal},
+		{api.BatteryUnknown, api.BatteryNormal, api.BatteryNormal},
+		{api.BatteryUnknown, api.BatteryCharge, api.BatteryNormal},
+
+		{api.BatteryNormal, api.BatteryUnknown, api.BatteryNormal},
+		{api.BatteryNormal, api.BatteryNormal, api.BatteryNormal},
+		{api.BatteryNormal, api.BatteryCharge, api.BatteryNormal},
+
+		{api.BatteryCharge, api.BatteryUnknown, api.BatteryNormal},
+		{api.BatteryCharge, api.BatteryNormal, api.BatteryNormal},
+		{api.BatteryCharge, api.BatteryCharge, api.BatteryNormal},
+	} {
+		t.Logf("%+v", tc)
+
+		site := &Site{
+			log:           util.NewLogger("foo"),
+			batteryMeters: []config.Device[api.Meter]{nil},
+		}
+
+		site.batteryMode = tc.internal
+
+		assert.True(t, site.batteryModeExternalTimer.IsZero())
+		site.SetBatteryModeExternal(tc.ext)
+
+		// timer started
+		if tc.ext != api.BatteryUnknown {
+			assert.False(t, site.batteryModeExternalTimer.IsZero())
+		}
+
+		// expire timer
+		site.batteryModeExternalTimer = site.batteryModeExternalTimer.Add(-time.Hour)
+		site.batteryModeWatchdogExpired()
+
+		// mode reverted to unknown, timer still active
+		assert.Equal(t, site.batteryModeExternal, api.BatteryUnknown)
+		assert.False(t, site.batteryModeExternalTimer.IsZero())
+
+		mode := site.requiredBatteryMode(false, api.Rate{})
+		assert.Equal(t, tc.expired.String(), mode.String(), "external mode expected %s got %s", tc.expired, mode)
+
+		// timer disabled
+		site.SetBatteryMode(mode)
+		assert.True(t, site.batteryModeExternalTimer.IsZero())
+	}
+}
diff --git a/server/http.go b/server/http.go
index 32b5cf1a2..3c6572cd1 100644
--- a/server/http.go
+++ b/server/http.go
@@ -138,6 +138,8 @@ func (s *HTTPd) RegisterSiteHandlers(site site.API, valueChan chan<- util.Param)
 		"batterydischargecontrol": {"POST", "/batterydischargecontrol/{value:[01truefalse]+}", boolHandler(site.SetBatteryDischargeControl, site.GetBatteryDischargeControl)},
 		"batterygridcharge":       {"POST", "/batterygridchargelimit/{value:-?[0-9.]+}", floatPtrHandler(pass(site.SetBatteryGridChargeLimit), site.GetBatteryGridChargeLimit)},
 		"batterygridchargedelete": {"DELETE", "/batterygridchargelimit", floatPtrHandler(pass(site.SetBatteryGridChargeLimit), site.GetBatteryGridChargeLimit)},
+		"batterymode":             {"POST", "/batterymode/{value:[a-z]+}", updateBatteryMode(site)},
+		"batterymodedelete":       {"DELETE", "/batterymode", updateBatteryMode(site)},
 		"prioritysoc":             {"POST", "/prioritysoc/{value:[0-9.]+}", floatHandler(site.SetPrioritySoc, site.GetPrioritySoc)},
 		"residualpower":           {"POST", "/residualpower/{value:-?[0-9.]+}", floatHandler(site.SetResidualPower, site.GetResidualPower)},
 		"smartcost":               {"POST", "/smartcostlimit/{value:-?[0-9.]+}", updateSmartCostLimit(site)},
diff --git a/server/http_site_handler.go b/server/http_site_handler.go
index 20944393b..9037627c8 100644
--- a/server/http_site_handler.go
+++ b/server/http_site_handler.go
@@ -196,6 +196,28 @@ func updateSmartCostLimit(site site.API) http.HandlerFunc {
 	}
 }
 
+// updateBatteryMode sets the external battery mode
+func updateBatteryMode(site site.API) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		vars := mux.Vars(r)
+		var val api.BatteryMode
+
+		if r.Method != http.MethodDelete {
+			s, err := api.BatteryModeString(vars["value"])
+			if err != nil {
+				jsonError(w, http.StatusBadRequest, err)
+				return
+			}
+
+			val = s
+		}
+
+		site.SetBatteryModeExternal(val)
+
+		jsonResult(w, site.GetBatteryModeExternal())
+	}
+}
+
 // stateHandler returns the combined state
 func stateHandler(cache *util.ParamCache) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
diff --git a/server/mqtt.go b/server/mqtt.go
index 231488821..d5e5a4922 100644
--- a/server/mqtt.go
+++ b/server/mqtt.go
@@ -15,6 +15,7 @@ import (
 	"github.com/evcc-io/evcc/core/vehicle"
 	"github.com/evcc-io/evcc/plugin/mqtt"
 	"github.com/evcc-io/evcc/util"
+	"github.com/samber/lo"
 )
 
 // MQTTMarshaler is the interface implemented by types that
@@ -211,6 +212,12 @@ func (m *MQTT) listenSiteSetters(topic string, site site.API) error {
 			}
 		}))},
 		{"batteryGridChargeLimit", floatPtrSetter(pass(site.SetBatteryGridChargeLimit))},
+		{"batteryMode", ptrSetter(api.BatteryModeString, pass(func(m *api.BatteryMode) {
+			if m == nil {
+				m = lo.ToPtr(api.BatteryUnknown)
+			}
+			site.SetBatteryModeExternal(*m)
+		}))},
 	} {
 		if err := m.Handler.ListenSetter(topic+"/"+s.topic, s.fun); err != nil {
 			return err