PSU with Battery backup Pass through

[Showbiz]

This may be a stupid question, but does anyone know why there aren't power supplies featuring a battery backup pass through? or Mother Boards with power circuits? Essentially I'm wondering why no one has designed Desktop class mother boards that could interface directly with a battery in the same manner as a laptop does.

My living situation is very unique, and part of that means that I lose power quite frequently. I have a 1500VA battery backup which suffices most of the time. However I can't help but wonder how many amp hours are lost converting from DC to AC, and then again from AC to DC. If there was a way to eliminate the dual conversion when running on batteries, then perhaps I could get another 25%-30% of runtime out of the batteries. And it seems to me that if a laptop can do it, then there's really no reason as to why a desktop couldn't either.

I can certainly appreciate that there are issues connecting all the different components to power, however perhaps this is something that could be done in conjunction with the chassis. Has anyone ever thought of attempting something like this, or heard of a product like this?

Thank you,

 

[bloodypulp]

some enterprise Server and Network hardware run directly from DC power.

Batteries are large and heavy, taking a lot of space in a computer chassis. Cumbersome to move a desktop/tower PC with an additional 30+ lbs weight.