electrical

So I've had this UPS around 5 years: Cyberpower PFC Sinewave Series 1500VA UPS (CP1500EPFCLCD) Recently something tripped the fuse in our house and my UPS started complaining. Went and looked at the display and it says "Fault F02" or something on the screen. Because it's been on for about 5...

Hi all, I am a mechanical engineer attempting electronics so please be nice :p I have a lithium ion battery pack (about 12V) for an electronics circuit and I have a separate circuit, independently powered by a 9v battery that has the sole purpose of protecting the main battery from over...