diff --git a/st2reactor/st2reactor/timer/base.py b/st2reactor/st2reactor/timer/base.py
index fb53c7eced..d83cb163ba 100644
--- a/st2reactor/st2reactor/timer/base.py
+++ b/st2reactor/st2reactor/timer/base.py
@@ -57,7 +57,10 @@ def cleanup(self):
         self._scheduler.shutdown(wait=True)
 
     def add_trigger(self, trigger):
-        self._add_job_to_scheduler(trigger)
+        try:
+            self._add_job_to_scheduler(trigger)
+        except:
+            LOG.exception('Unable to add timer for trigger: %s', trigger)
 
     def update_trigger(self, trigger):
         self.remove_trigger(trigger)
@@ -111,6 +114,8 @@ def _add_job_to_scheduler(self, trigger):
             self._add_job(trigger, time_type)
 
     def _add_job(self, trigger, time_type, replace=True):
+        if self._jobs.get(trigger['id'], None):
+            raise Exception('Should not try to register timer for trigger %s' % trigger)
         try:
             job = self._scheduler.add_job(self._emit_trigger_instance,
                                           trigger=time_type,
@@ -127,7 +132,6 @@ def _emit_trigger_instance(self, trigger):
 
         payload = {
             'executed_at': str(datetime.utcnow()),
-            'schedule': trigger['parameters'].get('time')
         }
         self._trigger_dispatcher.dispatch(trigger, payload)
 
diff --git a/st2reactor/tests/test_timer.py b/st2reactor/tests/test_timer.py
new file mode 100644
index 0000000000..b7052cd3e6
--- /dev/null
+++ b/st2reactor/tests/test_timer.py
@@ -0,0 +1,107 @@
+# Licensed to the StackStorm, Inc ('StackStorm') under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import copy
+
+import bson
+import eventlet
+import mock
+
+from st2common.constants.pack import SYSTEM_PACK_NAME
+from st2common.models.db.reactor import TriggerDB
+from st2common.models.system.common import ResourceReference
+from st2reactor.timer.base import St2Timer
+from st2tests.base import EventletTestCase
+import st2tests.config as tests_config
+
+
+class TestDispatcher(object):
+    def __init__(self):
+        self.trigger = None
+        self.payload = None
+
+    def dispatch(self, trigger, payload):
+        self.trigger = trigger
+        self.payload = payload
+
+    def assert_payload(self):
+        return self.payload is not None and self.payload.get('executed_at', None)
+
+
+class TimerTest(EventletTestCase):
+    test_trigger = None
+
+    @classmethod
+    def setUpClass(cls):
+        super(TimerTest, cls).setUpClass()
+        tests_config.parse_args()
+        parameters = {}
+        parameters['unit'] = 'seconds'
+        parameters['delta'] = 1
+        ref = ResourceReference.to_string_reference(SYSTEM_PACK_NAME, 'st2.IntervalTimer')
+        TimerTest.test_trigger = TriggerDB(name='testtimer', pack='test', parameters=parameters,
+                                           type=ref)
+        TimerTest.test_trigger.id = str(bson.ObjectId())
+
+    def test_add_remove_timer_trigger(self):
+        timer = St2Timer(local_timezone='America/Los_Angeles')
+        self.assertTrue(len(timer._scheduler.get_jobs()) == 0)
+        timer.add_trigger(TimerTest.test_trigger)
+        self.assertTrue(len(timer._scheduler.get_jobs()) == 1)
+        timer.remove_trigger(TimerTest.test_trigger)
+        self.assertTrue(len(timer._scheduler.get_jobs()) == 0)
+
+    def test_emit_trigger_instance(self):
+        timer = St2Timer(local_timezone='America/Los_Angeles')
+        mock_dispatcher = TestDispatcher()
+        setattr(timer, '_trigger_dispatcher', mock_dispatcher)
+        timer._emit_trigger_instance(TimerTest.test_trigger)
+        self.assertTrue(mock_dispatcher.assert_payload())
+
+    def test_invalid_schema_timer(self):
+        timer = St2Timer(local_timezone='America/Los_Angeles')
+        fail_timer = copy.copy(TimerTest.test_trigger)
+        del fail_timer.parameters['unit']
+        timer.add_trigger(fail_timer)
+        self.assertTrue(len(timer._scheduler.get_jobs()) == 0)
+
+    def test_duplicate_timer_trigger(self):
+        timer = St2Timer(local_timezone='America/Los_Angeles')
+        self.assertTrue(len(timer._scheduler.get_jobs()) == 0)
+        timer.add_trigger(TimerTest.test_trigger)
+        self.assertTrue(len(timer._scheduler.get_jobs()) == 1)
+        try:
+            timer.add_trigger(TimerTest.test_trigger)
+        except:
+            self.assertTrue(len(timer._scheduler.get_jobs()) == 1)
+            pass
+        timer.remove_trigger(TimerTest.test_trigger)
+        self.assertTrue(len(timer._scheduler.get_jobs()) == 0)
+
+    @mock.patch.object(St2Timer, '_register_timer_trigger_types', mock.MagicMock())
+    def test_timer_end_to_end(self):
+        timer = St2Timer(local_timezone='America/Los_Angeles')
+        mock_dispatcher = TestDispatcher()
+        setattr(timer, '_trigger_dispatcher', mock_dispatcher)
+        timer.add_trigger(TimerTest.test_trigger)
+
+        def kickoff_timer(timer):
+            timer.start()
+
+        eventlet.spawn(kickoff_timer, timer)
+        self.assertFalse(mock_dispatcher.assert_payload())
+        eventlet.sleep(2)
+        self.assertTrue(mock_dispatcher.assert_payload())
+        timer.cleanup()