diff --git a/libnymea/interfaces/battery.json b/libnymea/interfaces/battery.json
index 43399cfe..05eeb387 100644
--- a/libnymea/interfaces/battery.json
+++ b/libnymea/interfaces/battery.json
@@ -20,13 +20,9 @@
             "optional": true
         },
         {
-            "name": "charging",
-            "type": "bool",
-            "optional": true
-        },
-        {
-            "name": "discharging",
-            "type": "bool",
+            "name": "chargingState",
+            "type": "QString",
+            "allowdValues": ["idle", "charging", "discharging"],
             "optional": true
         }
     ]
diff --git a/libnymea/interfaces/energystorage.json b/libnymea/interfaces/energystorage.json
new file mode 100644
index 00000000..1670e974
--- /dev/null
+++ b/libnymea/interfaces/energystorage.json
@@ -0,0 +1,17 @@
+{
+    "description": "Interfaces for devices that store electrical energy and can return it at a later point, such as batteries. The currentPower state follows the usual convention that positive is 'consumed' energy and negative values represent 'produced' or in this case 'returned' energy.",
+    "extends": ["battery", "smartmeter"],
+    "states": [
+        {
+            "name": "currentPower",
+            "type": "double",
+            "unit": "Watt",
+            "logged": true
+        },
+        {
+            "name": "capacity",
+            "type": "double",
+            "unit": "KiloWattHour"
+        }
+    ]
+}
diff --git a/libnymea/interfaces/evcharger.json b/libnymea/interfaces/evcharger.json
index 8de3ba15..ed02972e 100644
--- a/libnymea/interfaces/evcharger.json
+++ b/libnymea/interfaces/evcharger.json
@@ -1,6 +1,6 @@
 {
     "description": "An EV-charger. Extends the power interface for charging/not charging an electric vehicle. Supports regulation of the max. charging current in addition to be powered on or off.",
-    "extends": "power",
+    "extends": ["smartmeterconsumer", "power"],
     "states": [
         {
             "name": "maxChargingCurrent",
diff --git a/libnymea/interfaces/interfaces.qrc b/libnymea/interfaces/interfaces.qrc
index d2996531..3d6ee2ca 100644
--- a/libnymea/interfaces/interfaces.qrc
+++ b/libnymea/interfaces/interfaces.qrc
@@ -88,5 +88,6 @@
         <file>cleaningrobot.json</file>
         <file>airquality.json</file>
         <file>indoorairquality.json</file>
+        <file>energystorage.json</file>
     </qresource>
 </RCC>
diff --git a/libnymea/interfaces/smartmeterconsumer.json b/libnymea/interfaces/smartmeterconsumer.json
index e95289c5..69456283 100644
--- a/libnymea/interfaces/smartmeterconsumer.json
+++ b/libnymea/interfaces/smartmeterconsumer.json
@@ -5,13 +5,13 @@
         {
             "name": "totalEnergyConsumed",
             "type": "double",
-            "unit": "KiloWattHour"
+            "unit": "KiloWattHour",
+            "logged": true
         },
         {
             "name": "currentPower",
             "type": "double",
             "unit": "Watt",
-            "optional": true,
             "logged": true
         }
     ]
diff --git a/libnymea/interfaces/smartmeterproducer.json b/libnymea/interfaces/smartmeterproducer.json
index 5d825406..442542ba 100644
--- a/libnymea/interfaces/smartmeterproducer.json
+++ b/libnymea/interfaces/smartmeterproducer.json
@@ -5,13 +5,13 @@
         {
             "name": "totalEnergyProduced",
             "type": "double",
-            "unit": "KiloWattHour"
+            "unit": "KiloWattHour",
+            "logged": true
         },
         {
             "name": "currentPower",
             "type": "double",
             "unit": "Watt",
-            "optional": true,
             "logged": true
         }
     ]