NPN RGB Astable Multivibrator: End-of-Life Battery Runtime

After un-wedging the astable’s synchronized periods and recharging the harvested 18650 lithium cell, I put a sock (not shown) over the radome and let it blink on a corner of the desk:

The periods are much too short and the NPN astable currents much too high, but the thing runs for about ten days before the over-discharge circuit shuts it down.

So a single NPN astable driving a single-color LED with a more reasonable period should get a month or so from an end-of-life 18650 cell and a MOSFET astable might run for two months.