this is my first post on this site (but I will have more, have no doubt), so if I have posted in the wrong section or something please forgive me.
Anyway, I am currently doing a battery powered pc build and I have wired up a DPDT mechanical relay to automatically switch between a battery and a 12V regulated powersupply. The problem I have run in to is that the amount of time when the relay actually switches over from one pin to the next is too long and it will shut off my dc-dc powersupply for the computer (it is an M4 ATX PSU). My first thought was to try to find a make-before-break relay but those seem scarce and may damage my lithium battery. The other idea that I had was to maybe use a capacitor bank to supply the necessary 20A at 12V for about 10-50 milliseconds, but I have honestly no idea how to find the right size of capacitors for the job. I might have to deal with the shut-down when plugging it in if the capacitor bank is too large because space is tight in the case I'm building.
Thanks for your help, Kevin