diff --git a/lib/plugins.js b/lib/plugins.js
index 63dedfa8..186dd73b 100644
--- a/lib/plugins.js
+++ b/lib/plugins.js
@@ -165,14 +165,14 @@ function plugins (settings, deviceId) {
     .then(row => row.id)
   }
 
-  function pollQueries (deviceTime, deviceRec) {
+  function pollQueries (serialNumber, deviceTime, deviceRec) {
     const config = configManager.machineScoped(deviceId, settings.config)
     const fiatCode = config.fiatCurrency
     const cryptoCodes = config.cryptoCurrencies
 
     const tickerPromises = cryptoCodes.map(c => ticker.getRates(settings, fiatCode, c))
     const balancePromises = cryptoCodes.map(c => fiatBalance(fiatCode, c))
-    const pingPromise = recordPing(deviceTime, deviceRec)
+    const pingPromise = recordPing(serialNumber, deviceTime, deviceRec)
     const currentConfigVersionPromise = fetchCurrentConfigVersion()
 
     const promises = [
@@ -201,15 +201,15 @@ function plugins (settings, deviceId) {
     return wallet.sendCoins(settings, tx.toAddress, tx.cryptoAtoms, tx.cryptoCode)
   }
 
-  function recordPing (deviceTime, rec) {
-    const event = {
+  function recordPing (serialNumber, deviceTime, rec) {
+    const r = {
       id: uuid.v4(),
-      deviceId,
-      eventType: 'ping',
-      note: JSON.stringify({state: rec.state, isIdle: rec.idle === 'true', txId: rec.txId}),
-      deviceTime
+      device_id: deviceId,
+      serial_number: serialNumber,
+      device_time: deviceTime
     }
-    return dbm.machineEvent(event)
+
+    return db.none(pgp.helpers.insert(r, null, 'machine_pings'))
   }
 
   function isHd (tx) {
diff --git a/lib/postgresql_interface.js b/lib/postgresql_interface.js
index 42410a80..1059814c 100644
--- a/lib/postgresql_interface.js
+++ b/lib/postgresql_interface.js
@@ -44,7 +44,7 @@ exports.machineEvent = function machineEvent (rec) {
   const deleteSql = `delete from machine_events
   where device_id=$1
   and event_type=$2
-  and created < now() - interval '2 hours'`
+  and created < now() - interval '2 days'`
 
   return db.none(sql, values)
   .then(() => db.none(deleteSql, [rec.deviceId, rec.eventType]))
diff --git a/lib/routes.js b/lib/routes.js
index 9d96a259..204c2e0a 100644
--- a/lib/routes.js
+++ b/lib/routes.js
@@ -29,6 +29,7 @@ const devMode = argv.dev || options.http
 function poll (req, res, next) {
   const deviceId = req.deviceId
   const deviceTime = req.deviceTime
+  const serialNumber = req.query.sn
   const pid = req.query.pid
   const settings = req.settings
   const config = configManager.machineScoped(deviceId, settings.config)
@@ -36,7 +37,7 @@ function poll (req, res, next) {
 
   pids[deviceId] = {pid, ts: Date.now()}
 
-  return pi.pollQueries(deviceTime, req.query)
+  return pi.pollQueries(serialNumber, deviceTime, req.query)
   .then(results => {
     const cassettes = results.cassettes
 
@@ -203,7 +204,7 @@ function httpError (msg, code) {
 
 function filterOldRequests (req, res, next) {
   const deviceTime = req.deviceTime
-  const delta = Date.now() - deviceTime
+  const delta = Date.now() - Date.parse(deviceTime)
 
   if (delta > CLOCK_SKEW) {
     logger.error('Clock skew with lamassu-machine too high [%ss], adjust lamassu-machine clock', (delta / 1000).toFixed(2))
@@ -312,7 +313,7 @@ function populateDeviceId (req, res, next) {
   : null
 
   req.deviceId = deviceId
-  req.deviceTime = Date.parse(req.get('date'))
+  req.deviceTime = req.get('date')
 
   next()
 }
diff --git a/migrations/032-create_machine_pings_table.js b/migrations/032-create_machine_pings_table.js
new file mode 100644
index 00000000..25588e7a
--- /dev/null
+++ b/migrations/032-create_machine_pings_table.js
@@ -0,0 +1,29 @@
+var db = require('./db')
+
+exports.up = function (next) {
+  var sql = [
+    `create table machine_pings (
+    id uuid PRIMARY KEY,
+    device_id text not null,
+    serial_number integer not null,
+    device_time timestamptz not null,
+    created timestamptz not null default now())`,
+    `create table aggregated_machine_pings (
+    id uuid PRIMARY KEY,
+    device_id text not null,
+    dropped_pings integer not null,
+    total_pings integer not null,
+    lag_sd_ms integer not null,
+    lag_min_ms integer not null,
+    lag_max_ms integer not null,
+    lag_median_ms integer not null,
+    day date not null)`,
+    'alter table machine_events drop column device_time',
+    'alter table machine_events add column device_time timestamptz'
+  ]
+  db.multi(sql, next)
+}
+
+exports.down = function (next) {
+  next()
+}