I have one of these and usually it last longer then when my timer on my TX goes off but i usually mount it at the rear of my Quad or the Tail of my Tricopter for since it has that blue light. Looks good and give me a good sense of direction.
I am ordering another one for this purpose.. Usually wnen TX 9:30 timer goes off when i check my battery it is usually about 11.1 Volts so sometimes i run it a little longer and end up at 10.5
Nice product with more then one use.
The documentation says this buzzes at 9.9V for 3S, however I have found that I think it buzzes at 10.6 which is fine, better on the safe side. I'm not sure if I'm reading my battery voltages wrong or not.