It appears that the Eggtimer needs at least two batteries function. Both Eggtimers I have are set up for a 9v battery for deployment leaving a 3.7v battery (Lipo, I presume) for everything else. If so, where do people put the second battery on an Adaptive Aerospace 54mm altimeter sled? There is dedicated space for a 9v but it is not clear where another battery would fit? Any photos of how you did this would be very helpful.