How long do you want the UPS to power the system for? 

For the 12v Devices I'm using 2 of these: https://www.pbtech.co.nz/product/UPSPSD1100/PowerShield-PSDCMIN1218-Mini-UPS-12VDC-1Amp-18Watt

For the 230v devices I went Eaton: https://www.pbtech.co.nz/product/UPSPWR62673/Eaton-5S-1200VA750W-Line-Interactive-Tower-UPS

Initially tried a Cyberpower but the things draw 30-40w just fully charged and idling. The Eaton draws a much more respectible 10w at idle.

Nate001:

 

How long do you want the UPS to power the system for? 

 

30 minutes? I will need to find out what the power draw of all 3 are. 

Sentry Lite [Integrated] from Constant Vigil. The Integrated version has a built-in battery.

A bit more pricy than the PowerShield product. Constant Vigil provided me with a customised verion of the Sentry Lite that works with a 6V battery, so if you have specific requirements, they'll probably be able to assist.

https://www.constantvigil.com/battery-backup-products

Chippo:

 

For the 12v Devices I'm using 2 of these: https://www.pbtech.co.nz/product/UPSPSD1100/PowerShield-PSDCMIN1218-Mini-UPS-12VDC-1Amp-18Watt

 

I don't know how well it would work in practice; but what if you used a solar charge controller?

Instead of solar panel on the input you'd use a 12v power supply. [It would need to be enough for charging a battery and powering the device.]

The rest would be the same, batteries on the correct terminals and the 12v device on load output.

I would assume a solar charge controller would regulate the monitor the batteries and output.

Otherwise a little modification like this may do.

-> I do warn that this example does not have any shutoff for 12v devices if the battery is low or voltage regulation on this 12v output.

If I have entered Youtube BB code above wrong: https://www.youtube.com/watch?v=-Ur-D37-juo

Dont do that to UPS's, many of those cheap ones do not have isolation between the battery and the mains, which is why they are a closed unit. Ones with onboard external battery terminals for a seperate chassis are a better bet to use the batteries for that.

James Bond:

The smaller, the better - as it's going into a media room with the home theatre.