Samlex BBM-1225 12V/24V 25A Battery Backup Charger - Marine, RV & Solar Power System Charging Solution for Boats, Campers & Off-Grid Applications

I use this DC UPS for my backup sump pump. The UPS gets DC power from a linear 12 Amp "13.8V" (13.72v measured) regulated power supply. When the backup sump pump is not running the UPS trickle charges a new lead acid 12V backup battery at the constant 13.72V and the current between 90mA to 110mA.Test:I simulated a power outage by turning off the DC power supply. Then I manually triggered the backup sump pump float switch to start the pump. The UPS used the power source from the backup battery. When I turned the DC power supply back on the UPS switched to use the power from the power supply. It worked as designed!