The Mid-Continent TS835 is a lighter weight alternative for the PS-835 power supplies. The TS835 weighs only 4.5 pounds while the PS-835 weighs 13 pounds. The TS835 has a battery life expectancy of 10 years. No rewiring or changing of the mounting rack is required when upgrading to the TS835 from the PS-835. Certification of the installation is not affected since TSO'd parts are being interchanged.

According to L3 Service Letter SL-80 (Rev. W), the condition of the batteries should be checked every 3 to 6 months according to the Periodic Check procedure outlined in the bulletin. If the "Voltage Level 24VDC LED" does not illuminate while the 20VDC is illumined, then the unit is incapable of providing emergency power. The "Cell Isolation Test" must then be performed to identify if the unit requires repair or charging.