My older APC 1500w UPS does this when powered by my FB21/GB when grid is down. So far no audio equipment affected, but the UPS transformer hum is pr...

@eg4eric OK, great. Ty Saw this issue reported on the forums and decided to wait out a fix. Get to try out my new Firmware updater module!

I'm relatively new to the firmware update process for batteries-For the All Weather 280Ah, is SOP to update both the RS232 and RS485 versions?