I also use a Garmin Varia with an Edge 830. By happy surprise we found it also works with a Garmin 735XT watch so when on a tandem both stoker (with the watch) and captain (with the Edge) can see the traffic notifications. The Varia picks up traffic further back than we can reliably see in the mirrors, and lets us know about multiple cars when we can only see the first car in the mirror. It's been a great help when trying to change lanes across 3 lanes of traffic to make a left turn. We had it on for 8 hours last weekend and it didn't run out of battery so maybe blink pattern makes a difference. I wonder if number of cars passing makes a difference in battery usage...we had 545 on that day.