The ACR/4F Firefly Rescue Light

Known by the military as the SDU-5/E, this strobe light puts out 250,000 peak lumens per flash.  I bought it in 1993 and tucked it away with my flight gear.

It wasn't until fifteen years later that I remembered that I had it and decided it might be time to replace the batteries. Imagine my amazement when it fired right up!

The strobe light came with a custom battery sealed in blue shrink tubing and marked with the date of manufacture. It looked suspiciously like two lithium 123A cells in series so I cut it open and found two Duracell 123's.

Initially the cells tested at 100% but they didn't last very long. Still, after fifteen years most cells would have leaked and destroyed the light.