diff --git a/apps/powermanager/boot.js b/apps/powermanager/boot.js
index 2bc2aaa35..801c1f48a 100644
--- a/apps/powermanager/boot.js
+++ b/apps/powermanager/boot.js
@@ -3,11 +3,89 @@
     require('Storage').readJSON("powermanager.default.json", true) || {},
     require('Storage').readJSON("powermanager.json", true) || {}
   );
-  
+
+  if (settings.log) {
+    let logFile = require('Storage').open("powermanager.log","a");
+    let def = require('Storage').readJSON("powermanager.def.json", true) || {};
+    if (!def.start) def.start = Date.now();
+    if (!def.deferred) def.deferred = {};
+    let sen = require('Storage').readJSON("powermanager.sen.json", true) || {};
+    if (!sen.start) sen.start = Date.now();
+    if (!sen.power) sen.power = {};
+
+    E.on("kill", ()=>{
+      let defExists = require("Storage").read("powermanager.def.json")!==undefined;
+      if (!(!defExists && def.saved)){
+        def.saved = Date.now();
+        require('Storage').writeJSON("powermanager.def.json", def);
+      }
+      let senExists = require("Storage").read("powermanager.sen.json")!==undefined;
+      if (!(!senExists && sen.saved)){
+        sen.saved = Date.now();
+        require('Storage').writeJSON("powermanager.sen.json", sen);
+      }
+    });
+
+
+    let logPower = (type, oldstate, state, app) => {
+      logFile.write("p," + type + ',' + (oldstate?1:0) + ',' + (state?1:0) + ',' + app + "\n");
+    };
+    let logDeferred = (type, duration, source) => {
+      logFile.write(type + ',' + duration + ',' + source + "\n");
+    };
+
+    let lastPowerOn = {};
+
+    const TO_WRAP = ["GPS","Compass","Barometer","HRM","LCD"];
+    for (let c of TO_WRAP){
+      let functionName = "set" + c + "Power";
+      let checkName = "is" + c + "On";
+      let type = c + "";
+      if (!sen.power[type]) sen.power[type] = 0;
+
+      lastPowerOn[type] = Date.now();
+
+      Bangle[functionName] = ((o) => (a,b) => {
+        let oldstate = Bangle[checkName]();
+        let result = o(a,b);
+        if (!(oldstate && result)) {
+          if (result) {
+            //switched on, store time
+            lastPowerOn[type] = Date.now();
+          } else {
+            //switched off
+            sen.power[type] += Date.now() - lastPowerOn[type];
+          }
+        }
+        if (settings.logDetails) logPower(type, oldstate, result, b);
+        return result;
+      })(Bangle[functionName]);
+    }
+
+    let functions = {};
+
+    let wrapDeferred = ((o,t) => (a,b,c,d) => {
+      let wrapped = (q,w,e,r)=>{
+        let start = Date.now();
+        let result = a(q,w,e,r);
+        let end = Date.now()-start;
+        let f = a.toString().substring(0,100);
+        if (settings.logDetails) logDeferred(t, end, f);
+        if (!def.deferred[f]) def.deferred[f] = 0;
+        def.deferred[f] += end;
+        return result;
+      };
+      return o(wrapped,b,c,d);
+    });
+
+    global.setTimeout = wrapDeferred(global.setTimeout, "t");
+    global.setInterval = wrapDeferred(global.setInterval, "i");
+  }
+
   if (settings.warnEnabled){
     var chargingInterval;
 
-    function handleCharging(charging){
+    let handleCharging = (charging) => {
         if (charging){
           if (chargingInterval) clearInterval(chargingInterval);
           chargingInterval = setInterval(()=>{
@@ -20,12 +98,12 @@
         clearInterval(chargingInterval);
         chargingInterval = undefined;
       }
-    }
+    };
 
     Bangle.on("charging",handleCharging);
     handleCharging(Bangle.isCharging());
   }
-  
+
   if (settings.forceMonoPercentage){
     var p = (E.getBattery()+E.getBattery()+E.getBattery()+E.getBattery())/4;
     var op = E.getBattery;
diff --git a/apps/powermanager/default.json b/apps/powermanager/default.json
index 6c929dc38..457f79610 100644
--- a/apps/powermanager/default.json
+++ b/apps/powermanager/default.json
@@ -2,5 +2,6 @@
   "warnEnabled": false,
   "warn": 96,
   "forceMonoVoltage": false,
-  "forceMonoPercentage": false
+  "forceMonoPercentage": false,
+  "log": false
 }
diff --git a/apps/powermanager/interface.html b/apps/powermanager/interface.html
new file mode 100644
index 000000000..9434ac16f
--- /dev/null
+++ b/apps/powermanager/interface.html
@@ -0,0 +1,273 @@
+<html>
+  <head>
+    <link rel="stylesheet" href="../../css/spectre.min.css">
+  </head>
+  <body>
+    <div id="content"></div>
+
+    <script src="../../core/lib/interface.js"></script>
+    <script>
+
+var domContent = document.getElementById("content");
+
+function download(filename, callback) {
+  Util.showModal("Downloading power info...");
+  Util.readStorage(filename, data => {
+    Util.hideModal();
+    callback(data);
+  });
+}
+function show() {
+  Util.showModal("Loading...");
+  domContent.innerHTML = "";
+    var htmlOverview = `<table class="table table-striped table-hover">
+      <div>This needs "Log" to be enabled in power manager settings. The deferred function calls table is only updated on the bangle on reloads.</div>
+      <thead>
+        <tr>
+          <th>Type</th>
+          <th></th>
+        </tr>
+      </thead>
+      <tbody>
+          <tr>
+            <td>Deferred function calls</td>
+            <td>
+              <button class="btn btn-primary" filename="powermanager.def.json" task="deftable">Table</button>
+              <button class="btn btn-error" filename="powermanager.def.json" task="clear" style="float: right;margin-right: 5px;">Clear</button>
+            </td>
+          </tr>
+          <tr>
+            <td>Sensors</td>
+            <td>
+              <button class="btn btn-primary" filename="powermanager.sen.json" task="sensorstable">Table</button>
+              <button class="btn btn-error" filename="powermanager.sen.json" task="clear" style="float: right;margin-right: 5px;">Clear</button>
+            </td>
+          </tr>
+          <tr>
+            <td>Details</td>
+            <td>
+              <button class="btn btn-primary" filename="powermanager.log" task="detailstable">Table</button>
+              <button class="btn btn-error" filename="powermanager.log" task="detailsclear" style="float: right;margin-right: 5px;">Clear</button>
+            </td>
+          </tr>
+        </tbody>
+    </table>`;
+  domContent.innerHTML = htmlOverview;
+  Util.hideModal();
+  var buttons = domContent.querySelectorAll("button");
+  for (var i=0;i<buttons.length;i++) {
+    buttons[i].addEventListener("click",event => {
+      var button = event.currentTarget;
+      var filename = button.getAttribute("filename");
+      if (!filename) return;
+      var task = button.getAttribute("task");
+      if (task=="detailsclear") {
+        Util.showModal("Clearing...");
+        Util.eraseStorageFile(filename,()=>{
+          Util.hideModal();
+          show();
+        });
+      }
+      if (task=="clear") {
+        Util.showModal("Clearing...");
+        Util.eraseStorage(filename,()=>{
+          Util.hideModal();
+          show();
+        });
+      }
+      if (task=="deftable") {
+        viewDeferredTable(filename);
+      }
+      if (task=="sensorstable") {
+        viewSensorsTable(filename);
+      }
+      if (task=="detailstable") {
+        viewDetailsTable(filename);
+      }
+    });
+  }
+}
+
+function viewDeferredTable(filename) {
+  Puck.eval(`require("Storage").list("powermanager.def.json").length > 0`, (f)=>{
+    if (f) {
+      Util.showModal("Reading summarized info...");
+      Util.readStorage(
+        filename, data => {
+          Util.hideModal();
+          let parsed = JSON.parse(data);
+          
+          let sum = 0;
+          let rows = [];
+          for (var i in parsed.deferred) {
+            sum += parsed.deferred[i];
+            rows.push({func: i, time: parsed.deferred[i]});
+          }
+          rows.sort((a,b)=>{return b.time/sum - a.time/sum;});
+          let tableRows = "";
+          for (var i in rows) {
+            let c = rows[i];
+            tableRows += `<tr>
+            <td>${(c.time/1000).toFixed(2)}s</td>
+            <td>${(c.time/sum*100).toFixed(2)}%</td>
+            <td>${c.func}</td>`
+          }
+
+          let duration = parsed.saved - parsed.start;
+
+          var htmlOverview = `<h1>Deferred function calls</h1>
+            <button class="btn btn-primary" id="back" style="float: right;margin-right: 5px;margin-left: 10px;">Back</button>
+            <div>
+              This are functions used in timeouts and intervals and their accumulated execution times. Recorded in a time span of <b>${Math.round((duration)/1000)}s</b>. Timeouts/intervals have run for <b>${Math.round(sum/1000)}s (${(sum/duration*100).toFixed(2)}%)</b>. Percentages are calculated from summarized timeout/interval running time.
+            </div>
+            <table class="table table-striped table-hover">
+            <thead>
+              <tr>
+                <th>Time</th>
+                <th>Percentage</th>
+                <th>Function</th>
+              </tr>
+            </thead>
+            <tbody>\n`;
+          htmlOverview += tableRows;
+          htmlOverview += `</tbody></table>`;
+          domContent.innerHTML = htmlOverview;
+          domContent.querySelector("#back").addEventListener("click",event => {
+            show();
+          });
+
+          //try finding possible sources for the given function, currently does not work because function.toString() not being identical to code in the *.js files.
+
+          /*Puck.eval(`require("Storage").list(/.*.js$/)`, (f)=>{
+            console.log("Found files:", f, rows[1].func);
+            for (let file of f){
+              let query = `require("Storage").read('${file}').includes('${rows[1].func}')`;
+              console.log("Query: " + query);
+              Puck.eval(query, (r)=>{
+                if (r) domContent.querySelector("#row_1").innerHTML = file;
+                console.log("Found", file, r)
+              });
+            }
+          });*/
+        });
+      } else {
+        var htmlOverview = `<h1>Deferred function calls</h1>
+          <button class="btn btn-primary" id="back" style="float: right;margin-right: 5px;">Back</button>
+          <div>
+            No data available.
+          </div>`;
+        domContent.innerHTML = htmlOverview;
+        domContent.querySelector("#back").addEventListener("click",event => {
+          show();
+        });
+    }
+  });
+}
+
+
+function viewSensorsTable(filename) {
+  Puck.eval(`require("Storage").list("powermanager.sen.json").length > 0`, (f)=>{
+    if (f) {
+      Util.showModal("Reading sensor info...");
+      Util.readStorage(
+        filename, data => {
+          Util.hideModal();
+          let parsed = JSON.parse(data);
+          console.log("Sensors", parsed);
+          let duration = parsed.saved - parsed.start;
+          
+          let rows = [];
+          for (var i in parsed.power) {
+            rows.push({func: i, time: parsed.power[i]});
+          }
+          rows.sort((a,b)=>{return b.time/duration - a.time/duration;});
+          let tableRows = "";
+          for (var i in rows) {
+            let c = rows[i];
+            tableRows += `<tr>
+            <td>${(c.time/1000).toFixed(2)}s</td>
+            <td>${(c.time/duration*100).toFixed(2)}%</td>
+            <td>${c.func}</td>`
+          }
+
+
+          var htmlOverview = `<h1>Sensor power</h1>
+            <button class="btn btn-primary" id="back" style="float: right;margin-right: 5px;margin-left: 10px;">Back</button>
+            <div>
+              Recorded in a time span of <b>${Math.round(duration/1000)}s</b>. Percentages are calculated from recording time.
+            </div>
+            <table class="table table-striped table-hover">
+            <thead>
+              <tr>
+                <th>Time</th>
+                <th>Percentage</th>
+                <th>Sensor</th>
+              </tr>
+            </thead>
+            <tbody>\n`;
+          htmlOverview += tableRows;
+          htmlOverview += `</tbody></table>`;
+          domContent.innerHTML = htmlOverview;
+          domContent.querySelector("#back").addEventListener("click",event => {
+            show();
+          });
+        });
+      } else {
+        var htmlOverview = `<h1>Sensor power</h1>
+          <button class="btn btn-primary" id="back" style="float: right;margin-right: 5px;">Back</button>
+          <div>
+            No data available.
+          </div>`;
+        domContent.innerHTML = htmlOverview;
+        domContent.querySelector("#back").addEventListener("click",event => {
+          show();
+        });
+    }
+  });
+}
+
+
+function viewDetailsTable(filename) {
+  Util.showModal("Reading details info...");
+  Util.readStorageFile(
+    filename, data => {
+      Util.hideModal();
+      
+      var htmlOverview = `<h1>Detailed logging</h1>
+      <button class="btn btn-primary" id="back" style="float: right;margin-right: 5px;">Back</button>
+      <table class="table table-striped table-hover">
+      <thead>
+        <tr>
+          <th>Type</th>
+          <th></th>
+          <th></th>
+          <th></th>
+        </tr>
+      </thead>
+      <tbody>\n`;
+        let rows = data.trim().split("\n");
+        for (var row of rows) {
+          let cols = row.split(",");
+          htmlOverview += `<tr>
+          <td>${cols[0]}</td>
+          <td>${cols[1]}</td>
+          <td>${cols[2]}</td>
+          <td>${cols[3]}</td>
+          <td>${cols[4]}</td>
+          </tr>`
+      }
+      htmlOverview += `</tbody></table>`;
+      domContent.innerHTML = htmlOverview;
+      domContent.querySelector("#back").addEventListener("click",event => {
+         show();
+      });
+    });
+}
+
+function onInit() {
+  show();
+}
+
+    </script>
+  </body>
+</html>
diff --git a/apps/powermanager/metadata.json b/apps/powermanager/metadata.json
index 456831aa9..3bfa47d88 100644
--- a/apps/powermanager/metadata.json
+++ b/apps/powermanager/metadata.json
@@ -9,6 +9,7 @@
   "tags": "tool",
   "supports": ["BANGLEJS2"],
   "readme": "README.md",
+  "interface": "interface.html",
   "storage": [
     {"name":"powermanager.boot.js","url":"boot.js"},
     {"name":"powermanager.settings.js","url":"settings.js"},
diff --git a/apps/powermanager/settings.js b/apps/powermanager/settings.js
index fe4719275..9df8b3534 100644
--- a/apps/powermanager/settings.js
+++ b/apps/powermanager/settings.js
@@ -36,6 +36,12 @@
         writeSettings("forceMonoVoltage", v);
       }
     },
+    'Log': {
+      value: !!settings.log,
+      onchange: v => {
+        writeSettings("log", v);
+      }
+    },
     'Charge warning': function() {
       E.showMenu(submenu_chargewarn);
     },