For awhile today it was me. I forgot to wrap the little velcro doo-dad around the (4 x AA) battery holder of the rear Dinotte before I stuffed it into my seatpack. Battery musta popped out while going over a bump. Don't think it was like it for long- I can remember being aware of the red glow in my mirror at a few points during my commute, but I think it was off while I was negotiating a gyratory and doing a bit of traffic jamming just before I got home. Update: I think it might've been off for quite a while. It only took 30 mins to charge the batteries up.