Re: making lights
I was manager of facilities for a Denver based manufacturing company for many years. We had just over 300 battery powered emergency egress lights and like you, I wanted to see if we could extend the life of the batteries.
I used a charge/discharge schedule whereby we shut off power to each emergency fixture, initiating the battery power to run the lights and allowed them to operate for near their design run time. We did this on a monthly basis. I found the battery life was extended by over half compared to simply allowing them to sit, unused and trickle charge with the built in charger in each fixture. With 300 plus fixtures that equated to a substantial annual savings on battery replacement.
They need to work to be happy. Use them, charge them and use them. You'll get better life from your SLAs.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"