6v 4.5AH lead acid battery shell for retrofitting emergency lights with LiFePo4 or Sodium Ion batteries!

Many buildings still have emergency lights powered by a 6v 4.5ah lead acid battery. They go dead every few years and I've decided to start building sodium-ion battery replacements, using 2-series LiFePo4 BMS circuits for the two sodium-ion batteries. This keeps the sodium ion batteries charged at only like 80% power, and they could last decades and decades this way. I plan to add to this later. I used the 1x2 battery holder I uploaded a month or so ago for 2670 cells.