Time in Zones Wrong

Due to the way HR data is recorded on the units, the Time In Zones values will almost never equal the total workout times. The overall times also depend on how the Time In Zones is calculated. There are a number of ways to do it. Even Garmin's different software products all come up with different values.

Also, there is time in your workouts where you're not in your zone ranges. This can be confirmed by looking at the MinHR values for each workout and comparing them to your defined HR zones.

For example, your zone 1 for running is 112-144...so anything you do under that won't be in the zone breakdown here...and it seems from the minHr of 73 for the recent workout, that you may have several unaccounted for minutes under 112...so if you want to pull those minutes in, set your zone 1 to 70-144 and it should be a lot closer.

yeah, I mentioned that in the OP, but its no more than 30 sec before I'm up over the 112 threshold, and I can confirm that using Garmin's website data. Using today's run - http://connect.garmin.com/activity/22067721you can see I broke 112 almost immediately and never dropped out of it.  So it was a 71.5 min workout, and less than 30 sec to get to 112, but to play it safe we'll say 1.5 min, so I was in my zones for > 70 min.  BT records approx 65 min.  I understand I lose a little time out of the zones, but definitely not over 5 min.

Again, not a huge deal cause I don't rely on this data and its mostly accurate, but the reason quoted isn't the reason its wrong. 
 

The files in Garmin units store discrete values called trackpoints. Each trackpoint has a timestamp, and if HR data is present, an average BPM value.

In a nutshell, the way we calculate the time in zones is to look at each trackpoint, determine the length of time in seconds between it and the previous trackpoint and determine which zone (if any) it's Average BPM value falls into.  That number of seconds is then added into the running total for the appropriate zone.

We'll use your example here to see if I can determine why the two are different and if our method can be made more accurate. It won't be in the couple of days though, we've got a couple of things we're trying to get finished.

Don't rush on my account. You're right that you're probably doing more important things. I just wanted to let you know in case you didn't.Thanks for all the great work you guys do.